Landslide Risk Reduction in the United States—Signs of ...icy to counter landslide risk through...

Landslide Risk Reduction in theUnited States—Signs of Progress

JEROME V. DE GRAFF1

Department of Earth & Environmental Sciences, California State University,Fresno, CA 93740, USA

WILLIAM J. BURNS

Oregon Department of Geology and Mineral Industries, 800 NE Oregon Street #28,Suite 965, Portland, OR 97232, USA

VICKI MCCONNELL

Geological Society of America, 3300 Penrose Place, Boulder, CO 80301, USA

Key Terms: Landslides, Risk Reduction, State GeologicalSurveys, United States

ABSTRACT

Scientific literature is replete with papers describingadvances in applying new technologies to the study oflandslides and advances in our understanding of factorsaffecting landslide occurrence, distribution, and move‐ment. Far fewer papers look at how this knowledge isimplemented to achieve landslide risk reduction. Stateand local governments exercise the greatest controlon how landslide risk reduction is accomplished. Datagenerated from a questionnaire to state geologicalsurveys, review of their agency Web sites, and twocase studies demonstrate that progress has been madeduring the last 20 years in implementing actionablepolicy changes and programs to achieve a reductionis landslide risk in the United States. Progress isevident from the pivotal role played by state andlocal government in the areas of: (1) developingguidelines and training, (2) increasing publicawareness and education, (3) implementing loss reduc‐tion measures, and (4) conducting emergencypreparedness, response, and recovery. The number ofstates requiring registration for practicing geologistshas nearly doubled during the last 20 years. Thisincrease was accompanied by a shift from indi‐vidual state tests as part of determining competencyto a uniform national test. During this period, stategeological surveys established Web sites as a primarymeans for promoting public awareness and edu‐cation about landslide hazards. Measures reducingthe impact of landslides have included providing

information specific to residents and landowners, aswell as supporting land-use planning efforts by localgovernments. Many state geological surveys areinvolved with emergency management of landslidehazards.

INTRODUCTION

On Wednesday, October 11, 1995, the organizationthen named the Association of Engineering Geologists(AEG; now Association of Environmental & Engi-neering Geologists) held free public forums across theUnited States to disseminate information on landslidehazards to practicing professionals and the generalpublic (DeGraff, 1995). National Landslide Aware-ness Day, as it was called, coincided with the UnitedNations’ International Decade for Natural DisasterReduction (IDNDR) Day. It consciously followedthe style of teach-ins popularized during the late1960s and early 1970s, including the first Earth Day.AEG regional sections organized local events ran-

ging from outdoor exhibitions at the WashingtonPark landslide in Portland, OR, to a day-long forumfeaturing speakers in St. Louis, MO, addressing tech-nical topics for specialists in the morning and generaltopics for the public in the afternoon. Public field tripsto local landslides were conducted by local geologistsin the San Francisco Bay area. These events generatedinformative landslide feature articles in local mediaincluding in the Portland Oregonian (Hill, 1995) andthe Salt Lake Tribune (Siegel, 1995). Other articles inthe print media were generated by press releases issuedby the U.S. Geological Survey (USGS), AEG sections,and state geological surveys from Colorado to New

1Corresponding author.

Environmental & Engineering Geoscience, Vol. XXII, No. 3, August 2016, pp. 225–243 225

Hampshire. State geological surveys participated in anumber of other ways. They disseminated landslideinformation in their monthly non-technical publica-tions like New Mexico Bureau of Mines and Geol-ogy’s Lite Geology (Haneberg, 1995) and issuance ofnew general publications such as one on landslides inOhio by their Division of Geological Survey (Hansen,1995). The Utah Geological Survey made a displayin their Salt Lake City office where the public couldperuse landslide publications they had produced.In Denver, CO, the USGS’s National LandslideInformation Center held a news conference and dis-tributed selected publications about reducing landslidehazards. They also featured a lunch-time talk aboutlong-term research at the Slumgullion Landslide, CO.During the 20 years since National Landslide

Awareness Day, there have been many examples ofan improved scientific understanding of landslide pro-cesses and a greater array of technology available forinvestigating landslide problems and mitigating theirimpact. While the relevant published literature istoo numerous for a comprehensive listing, it is possibleto highlight some significant advances. Scientificadvances in understanding factors important to land-slide occurrence include refining our knowledge ofhow precipitation initiates and promotes landslideoccurrence and movement (Iverson and Major, 1987;Guzzetti et al., 2008; Priest et al., 2011; and McKennaet al., 2012). Other insights dealt with factors initiatingparticular types of landslides (Cannon, 2001; Stocket al., 2012). Still others have refined our knowledgeof landslide movement and deposition (Major andIverson, 1999; Petley et al., 2002; and Santi et al.,2008). Global positioning system (GPS), light detec-tion and ranging (LiDAR), differential interferometricsynthetic aperture radar (DinSAR and SAR), andother remote-sensing techniques and platforms haveadvanced the ability of researchers to measure andrecord aspects of movement, sediment transport, andother landslide process factors that had previouslyeither eluded detection or were ineffectively measured(Tarchi et al., 2003; Schulz, 2007; Roering et al.,2009; Jomard et al., 2010; Stock et al., 2011; andJaboyedoff et al., 2012). Some of these technologicalmethods have improved the ability to monitor land-slides in order to provide warnings useful in emergencyresponse (Baum and Godt, 2010; Reid et al., 2012).In addition to monitoring to warn of possible landslideoccurrence, modeling has improved prediction ofthe likelihood or characteristics of future landslides(Guzzetti et al., 2003; Gartner et al., 2008; Cannonet al., 2010; and De Graff et al., 2015b).Less clear is the extent to which public policy and

awareness have changed during this same period.Put another way: Has our ability to achieve landslide

hazard reduction kept pace with our increased knowl-edge of this natural phenomenon? Just as major disas-trous landslides like the 1983 Thistle landslidein Utah and the 1985 Mameyes landslide in PuertoRico called attention to issues of landslide risk atthe time of their occurrence, the 2014 Oso landslidein Washington gives renewed urgency to the questionof whether the past 20 years of refining our knowledgeand improving related technology have contributedto additional risk reduction. While we may not beable to highlight direct linkage, we can examine effortsto incorporate current scientific information into pol-icy to counter landslide risk through land-use plan-ning, decision making, regulatory frameworks, andpublic education.This paper will specifically attempt to assess

whether efforts to institute actionable policy forreducing landslide hazard at the state and local levelsmirror the trend in our improved scientific understand-ing. Positive trends are needed to compensate for thegreater need arising from both population growthand urban expansion. The reason for the state andlocal emphasis in this analysis is based on the authorityfor making land-use planning decisions and theirregulatory enforcement throughout the United States,which rests almost entirely in the hands of state andlocal government (Burby et al., 2000; Berry, 2005;Hart, 2005; Mader, 2005; Preuss et al., 2005; Baumet al., 2008; and De Graff, 2012).National direction and actions directed toward

landslide hazard reduction are certainly importantand necessary to support these local efforts. In 1999,Congress passed Public Law 106-113 requiring theUSGS to develop a comprehensive strategy to addressthe widespread hazard posed by landslides in thenation (Spiker and Gori, 2003). The resulting strategywas termed “a framework for loss reduction” andreceived review and support from the National Re‐search Council (Committee on Review of the NationalLandslide Hazards Mitigation Strategy, 2004). Theelements of this strategy are identified as: (1) research,(2) hazard mapping and assessments, (3) real-timemonitoring, (4) loss assessment, (5) information collec-tion, interpretation, and dissemination, (6) guidelinesand training, (7) public awareness and education,(8) implementation of loss reduction measures, and(9) emergency preparedness, response, and recovery(Spiker and Gori, 2003; Wieczorek and Leahy, 2008).We think it is significant that the National Research

Council titled its review assessment, “Partnerships forReducing Landslide Risk.” The strategy they reviewedidentified new roles and partnership opportunities forstate and local government and private individualsunder each of the nine elements (Table 1 in Spikerand Gori, 2003). The importance of state and local

De Graff, Burns, and McConnell

226 Environmental & Engineering Geoscience, Vol. XXII, No. 3, August 2016, pp. 225–243

governments in accomplishing landslide risk reductionis made especially evident by their roles in the elementsof: (1) developing guidelines and training, (2) increas-ing public awareness and education, (3) implementingloss reduction measures, and (4) fostering emergencypreparedness, response, and recovery.

METHODOLOGY

As noted in the introduction, the metrics for asses-sing landslide risk reduction need to reflect actionsat the state and local government levels. Ideally, oneof these metrics would be changes in monetary costsdue to landslide occurrence. However, this type ofassessment even at a state level has proven difficultto quantify comprehensively (Highland, 2012). Lack-ing consistent and clear cost figures, we looked formeasures at the state and local government level thatemphasize the national strategy elements.

We draw upon data from Internet searches and aquestionnaire together with two case studies to yieldqualitative and quantitative measures in our assess-ment of state- and local-level actionable policy forreducing landslide hazard. The data compiled focuson measures that ensure: (1) an appropriate level oftraining for professional geologists involved withlandslide hazard assessment and loss reduction work,(2) ongoing efforts to educate the public about generaland specific landslide hazards that might affecttheir lives and property, (3) actions taken to facilitateloss reduction measures, and (4) development of effec-tive emergency preparedness, response, and recoveryactions (per Table 1 in Spiker and Gori, 2003).

A review of publically accessible Web sites main-tained by each state geological survey was completedduring May and June 2015 and reviewed for changesin September 2015. Examination of the survey Websites focused on identifying landslide information suit‐able for the needs of: (1) the general public, (2) resi-dents and landowners, and (3) an employee of localgovernment with responsibility for land-use planningor emergency response and geological professionalswho may be providing support to governmental enti-ties. This provided an objective, albeit qualitative,measure of a state survey’s ability to use Internettechnology to disseminate information for publiceducation, professional development, and local gov-ernment assistance. Each state geological survey Website homepage was accessed using a common internetbrowser. On each homepage, a link to “landslides,”“geologic hazards,” “hazards,” or similar keyword wassought on the assumption that these would be knownto an interested member of the public, governmentemployee, or practicing professional. This link wasused to open related Web pages with subsequent links

accessed depending on the options presented. It isimportant to note that this examination is suitablefor understanding what is being communicated aboutlandslides by a state geological survey’s Web site butis not necessarily a complete look at their efforts tounderstand and reduce landslide hazard.While homepages commonly had a link to publica-

tions, this link was not accessed as part of the examina-tion because publications represent a different media.There were two exceptions. One exception was toidentify published maps and documents in digitalform that were reached via links found on the Website. The other exception was to determine whetherguidance documents for practicing geological profes-sionals existed. Where the publications were search-able online, the search terms, “guidelines,” “geologichazard reports,” and “preparing reports,” were used.If the publications were not searchable online, themain publication list was downloaded in its portabledocument format (PDF) format, and the “find” func-tion was used with the search terms to accomplishthe search.Series of questions were prepared to gather informa-

tion on various aspects of landslide hazard assessmentand prevention and compiled into a questionnaire.This questionnaire was sent to each of the state sur‐veys represented in the American Association ofState Geologists (AASG). Twenty-nine questionnaireswere returned, representing a 58 percent return rate.Responses to questions directly relating to the topicsin the following sections were compiled. The question-naire results together with two relevant case studies,one drawn from a co-author’s recent experience andthe other from published data, are used to further illus-trate the issues of loss reduction and emergencyresponse, respectively.

ANALYSIS AND RESULTS

Guidelines and Training

Geologists are the primary professionals identifyingand defining landslide hazards and investigating fac-tors important to mitigation designs and regulatoryrequirements. States play a key role in ensuring thatcompetent geologic professionals are available forassessing and carrying out investigations suitable foravoiding or reducing landslide risk. Ensuring the com-petence of geologic professionals is usually carried outby requiring certification or licensure, which ofteninvolves continuing education requirements.A simple measure for assessing the way in which

states are ensuring the availability of competent,trained geologists over the last 20 years is to look atprofessional registration of geologists. Figure 1 is a

Landslide Risk Reduction in the United States


graph showing the number of states requiring profes-sional registration of geologists between 1956 and2014. The cumulative upward trend in the number ofstates enacting laws requiring registration visiblyincreased between 1991 and 2002. With the November2014 passage of a licensure act in New York, 32 stateshave or are implementing this requirement for geolo-gists practicing within their state (Figure 2). Figure 2compares states that implemented registration ofgeologists to a generalized map of landslide hazardin the conterminous United States. Clearly, not juststates where significant landslide hazard exists haveenacted registration laws. This likely reflects the factthat requiring practicing geologists to be registeredor licensed is deemed necessary for a broad range ofenvironmental and engineering geologic work, includ-ing water resource protection, mineral extraction,and construction. While landslide hazard is certainlyimportant in order to ensure public safety, it isonly one reason for requiring competency amongpracticing geologists.A related change has occurred in the way in which

states determine which geologists will be granted regis-tration or licensure. States where registration wasestablished early, like California, generally requiredboth academic and experience requirements before ageologist could apply for registration. Registrationfor those who met the requirements was then basedon their performance on a state-administered test.Similar procedures were adopted as other states beganregistration of geological professionals. Testing variesamong states in terms of both testing procedures andthe substantive content of the tests. Those differencesaffect questions of reciprocity and associated issuesfor geologists registered in one state but needing topractice in another one. Some of the State Boards ofGeology charged with the responsibility for registra-tion came together to discuss these differences in1988. This meeting and subsequent ones culminatedin the 1990 formation of the Association of StateBoards of Geology (ASBOG, 2015). One significantoutcome from the formation of ASBOG is a stan‐dardization of written tests used to determine if acandidate is competent for registration. ASBOG alsoprovides a means for state boards to facilitate unifor-mity of registration procedures, including more stan-dardization of experience required to qualify to testand register. As of November 2015, 30 states usedthe ASBOG test as part of their registration process(ASBOG, 2015).Another measure of how the states can ensure com-

petency of geological professionals is by looking at theguidance provided for the ways in which they shouldcarry out their work. While such guidelines may existfor specific projects, such as the state of Oregon’s

guidelines for proposed energy-related facilities (seehttp://www.oregon.gov/energy/Siting/docs/rules/div22.pdf), we will focus on those broadly covering environ-mental and engineering project work. Prior to 1995,California, Colorado, and Utah issued guidance docu-ments describing what information should be includedin geologic reports (Shelton and Prouty, 1977; Slosson,1984; and Association of Engineering Geologists-UtahSection, 1986). These guidance documents ranged insize from two-page notes with a brief explanationand annotated report outline to a 67 page tome. Todate, California has issued additional guidance docu-ments (CGS, 2013a, 2013b). The Colorado GeologicalSurvey has incorporated their current report guidanceinto their Web site (see http://coloradogeologicalsurvey.org/land-use-regulations/report-requirements/).In 1999, Oregon also issued Guideline for PreparingEngineering Geologic Reports. It was later updatedand reissued as a 14 page document developed andadopted by the Oregon Board of Geologist Examiners(OSBGE, 2014). Because the search for documents,which provide guidance to practicing geologists, wasconfined to publications issued by state geological sur-veys, similar technical direction issued by State Boardsof Geology overseeing registration or licensure mayalso exist (see http://www.dol.wa.gov/business/geologist/docs/georptguide.pdf). While it is not as compre-hensive a measure nationally as the increased numberof states requiring registration or their widespreadadoption of a standardization of testing, the increasein updated or new guidance documents issued since1995 is indicative of an effort to improve competency.Registration of geological professionals can serve as

a measure of how states have acted to ensure the avail-ability of competent, trained geologists for involve-ment in landslide hazard reduction activities. From1995 to present, there has been nearly a doubling ofstates requiring registration of practicing geologists.Because many of these states do host a significantpotential for adverse impact due to landslides, it sup-ports the concept that states have made progress inensuring practicing geologists within their jurisdictionare well qualified to address landslide hazard issues.Similarly, this period coincides with a shift from indi-vidual state-prepared examinations as part of theregistration process to adoption of a shared uniformexamination (ASBOG, 2015). This uniformity in test-ing adds to the likelihood that geologists addressinglandslide issues in different states are applying thesame level of competency due to their training. Therehas also been an increase in the number of technicalguidance documents for conducting engineering geol-ogy work applicable to landslides and slope instability.Less clear is whether the issuing of such technicalguidance documents for practicing geological



professionals has kept pace with the increased numberof states requiring registration.

Public Awareness and Education

Whether a geologic researcher is searching for rele-vant scientific articles or the public is trying to findpersonally useful information, Internet search enginesare often the initial place to begin (Wishard, 1998;DeGraff et al., 2013). These search engines electroni-cally survey the Internet to identify Web sites whereinformation, linked to key words entered by the user,can be found. So, it is not surprising that all 50 stategeological surveys have publically accessible Web sitesfor distributing information to both practicing profes-sionals and the general public. This means such Websites are a primary mechanism for public awarenessand education. At the time of National Landslide

Awareness Day, state geological surveys shared infor-mation with various interested parties mainly throughpublications, displays in public locations, and profes-sional workshops. While these methods continue tobe used, widespread computer accessibility and theubiquity of Internet search engines make the state geo-logical survey Web sites the current medium of choicefor education and outreach. The present-day domi-nance of the Internet for this purpose is a consequenceof privatization and governance efforts that haveencouraged the widespread proliferation and accessi-bility of publicly accessible Web sites after 1995 (Lei-ner et al., 1997).A recent example of the importance of the Inter-

net occurred during the year after the Oso landslide.The March 22, 2014, Oso landslide (Washington)stimulated interest in landslide hazard in the PacificNorthwest. Consequently, the Statewide Landslide

Figure 1. Cumulative graph of states requiring registration for practicing geological professionals between1956 and 2014. The year whenimplementation of registration occurred was used, which in some instances differed from the year the registration law was enacted. Forexample, the New York registration law was enacted in 2014, but the implementation will be in 2016 (ASBOG, 2015; NYSED, 2015).



Information Database for Oregon (SLIDO) experi-enced a 400 percent increase in views compared to2013. SLIDO was the 25th most visited of all OregonDepartment of Geology and Mineral Industries(DOGAMI) interactive Web maps in 2013. This pageclimbed to second most visited in 2014 and continuesto have higher page views in 2015 (Alison Ryan Han-sen, DOGAMI, personal communication, September17, 2015).The questionnaire to AASG members had posed the

question: “Do you conduct education and outreachregarding landslide hazards?” This question referred

to all media and was not limited to use of the Internetfor this purpose. Of the 29 questionnaire respondents,nineteen (66 percent) stated they did do educationand outreach to the general public about landslidehazards. Similarly, our review of state geological sur-vey Web sites found that 32 (64 percent) of the 50 stategeological surveys were providing some level of readilyaccessible landslide hazard information on their homeWeb page (Table 1). These results are suggestive thatmost state geological surveys providing landslideinformation to the public are currently making cred-ible use of the Internet.

Figure 2. Two maps of the conterminous United States comparing landslide potential (upper map) to those states requiring registration ofpracticing geological professionals (lower map).The upper map was prepared from digital files (Godt, 1997). The lower map was compiledfrom the same sources noted for Figure 1.



Of the 32 state geological survey home Web pageswhere landslide hazard information is accessible, eightsurveys only make mention of landslides as being ahazard, provide very brief or general descriptions, ordescribe a very specific landslide-prone situation(Table 1). For example, the home Web page link tohazards for the New Hampshire Geological Surveyonly mentions landslides in the following statement:“While geologic hazards encompasses a multitude ofnatural phenomena, including landslides and earth-quakes, flood inundation and river erosion constituteNew Hampshire’s #1 natural hazard risks.”

The amount and detail of landslide hazard informa-tion and the potential user groups being addressedvary considerably among the remaining 24 state geolo-gical survey home Web pages offering more extensivecontent (Table 1). The Web site content was examinedconsidering three user categories: the general public,residents and landowners, and local government staffand practicing professionals. Twelve state geologicalsurvey home Web pages offer access to landslidehazard information useful to all three of these usergroups (Table 1). On Figure 3, these 12 states are indi-cated by their U.S. Postal Service abbreviation.

Table 2 explains how to access landslide hazardinformation on these state geological survey Web sitesand provides thumbnail descriptions of the contentavailable for the three different user groups. Thereare some noteworthy features among these 12 stategeological survey Web sites. California, Colorado,and Utah Web sites all include information specificto landslide activity from areas burned during wild-fires. Colorado provides brief, but very effective,videos of different landslide types narrated by theirstaff in a field setting. Online interactive interfacesfor accessing landslide maps are present on the

Colorado, Kentucky, Maine, Oregon, and Washing-ton Web sites. The Utah Web site has a high degreeof interconnectedness among subheadings and con-tent, ensuring that relevant information is notoverlooked.The landslide hazard content of the other 12 state

geological survey home Web pages is not responsiveto the needs of all three defined user groups(Table 1). Of these 12 Web sites, the North DakotaGeological Survey has the only home Web page thatgives access to landslide hazard information primarilyuseful only to one potential user group—local govern-ment staff and practicing professionals. A link toLandslide Maps enables those users to open a pageshowing the entire state index of 1:100,000 scale map-ping. Clicking on a sheet in the index opens a pageshowing whether there are landslide maps availableand, if so, providing an index for opening them. TheNorth Dakota Geological Survey is one of only 18state geological surveys that offer public access tolandslide mapping or a state-wide database of land-slides (Table 1).The high proportion of state geological survey Web

sites providing landslide hazard information begs thequestion of why the remaining 18 (36 percent) stategeological survey are not doing so on their Web sites.Figure 3 enables comparison of 17 of these 18 states(excluding Alaska and Hawaii) within the contermi-nous United States to their relative landslide incidenceand susceptibility. While there is not a similar map forAlaska and Hawaii, it is known that these states haveboth physical conditions favoring landslide occurrenceand have experienced disastrous landslide events (Jib-son et al., 2004; Deb and El-Kadi, 2009). For somestates, such as Florida, Rhode Island, and Delaware,which show no landslide susceptibility or incidence,

Table 1. Categories of landslide hazard information found during examination of state geological survey Web sites. A through D represent infor-mation categories characterizing all 50 states. E and F in the lower table are two information types that may be provided.

Landslide Information No. of State Surveys Surveys Listed by State*

A. Only identifies landslides as a hazard or includesa very brief or generalized description

8 MD, MO, MT, NH, NM, NV, NY, OH

B. Provides information specifically for the generalpublic,residents/landowners, and localgovernment/practicing professionals

12 AL, AR, CA, CO, ID, KY, ME, NE, NC, OR, UT, WA

C. Provides information for two of the abovecategorical groups

12 AK, AZ, IN, MA, ND#, NJ, PA, SC, VT, VA, WV, WY

D.Does not specifically mention landslide hazards 18 CT, DL, FL, GA, HI, IL, IA, KS, LA, MI, MN, MS, OK,RI, SD, TN, TX, WI

E. Provides access to landslide mapping and/orstate-wide database

18 AL, CA, CO, ID, KY, MA, ME, NE, NV, NJ, ND, NC,OR, PA, SC, UT, WA, WV

F. Makes available a homeowner’s guide to landslidesor a listing of observable warning signs

9 AL, AZ, ID, IN, NC, OR, UT, WV, WA

*U.S. Postal Service abbreviations for states used.#North Dakota provides only landslide maps on its Web site, which are mainly useful to local government/practicing professionals.



and Iowa, Kansas, Michigan, and Minnesota, whichshow only small areas of moderate susceptibility, notmentioning landslides as a hazard is understandable(Table 1). It is unclear is why states like Georgia, Okla-homa, and Tennessee, where there are either signifi-cant areas of high incidence and susceptibility or highsusceptibility for landslides, make no mention of thispotential hazard on their home Web pages. The factthat these states do not mention landslide hazard ontheir home Web pages may reflect their emphasizingmineral or groundwater issues, an internal financiallimitation, or their being part of a larger agency wheregeologic issues are only a subset of the topicsaddressed via their agency home Web page. For exam-ple, Hawaii’s failure to mention landslide hazards maystem from the fact that their State Water Commissionserves as the only state entity addressing geologic sur-vey issues.Both the response to the questionnaire and the

examination of state geological survey home Webpages are indicative of a significant number of statesurveys recognizing a need to provide education andoutreach to various public groups about landslidehazards in their state. The Web site reviewdemonstrates progress in this aspect of landslidehazard reduction since 1995. The results describedhere show that much of their effort comprehensivelyreaches potential user groups and makes effective useof changing technology.

Implementation of Loss Reduction Measures

While important to landslide hazard reduction, thepresence of well-trained practicing professionals andeffective outreach and education to the public areinsufficient to fully accomplish this task. There mustbe a response to the information provided by bothknowledgeable professionals and the public to actuallyachieve loss reduction (DeGraff, 2012; DeGraff et al.,2015a). The state geological surveys provide a frame-work for this response as it is carried out at multiplelevels involving state and local government. This per-spective is supported by the responses to the question-naire. Of the 29 AASG questionnaire respondents,only nine (31 percent) conducted their landslide hazardefforts in response to statutory regulation or mandates(Table 3). The questionnaire responses indicate thatstate geological surveys contribute to implementationof landslide loss reduction by working with other stateagencies (15 [52 percent] of respondents) and federalagencies (16 [55 percent] of respondents; Table 3).State geological survey involvement for achievinglandslide loss reduction appears most active at thelocal community level (cities and counties). Of the 29AASG respondents, 22 state geological surveys (76percent) are working with local communities (Table3). Local community involvement is importantbecause it is only at this governmental level thateffective regulation permitting the establishment ofgeologic hazard districts, promulgation of zoning

Figure 3. Overview map showing landslide incidence and susceptibility in the conterminous United States with the abbreviations for statesadded indicating those state geological surveys providing the widest range of landslide hazard information to the public (modified fromWieczorek and Leahy, 2008).



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nelof

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Maine

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aine.gov

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Con

tinu

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State

Survey

Nam

eWeb

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ean

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Lan

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ation

Lan

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ation

General

Resident/Lan

downer

Local

Gov

ernm

ent/Practicing

Professiona

ls

Nebraska

Con

servation

andSu

rvey

Division

(Nebraska

Geological

Survey)

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l.edu

/csd/

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”an

dthen

on“L

andslid

esin

Nebraska”

underthehead

ing“G

eologic

Hazards”

Brief

introd

uction

toland

slides

withseveral

photos

andhead

ings

linkedto

“Definitions”

and“D

atab

ase”

Definitions

prov

idediag

rams,ph

otos,an

ddescriptions

foreach

oftheland

slides

typescommon

toNebraska;

theseare

accessed

bytabs,w

hich

also

prov

idea

Varnesclassification

diag

ram

anda

photosequ

ence

ofadeveloping

land

slide

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seof

inventoriedland

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etype

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withph

otos

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details

onlocation

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itud

e,topo

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eology

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repa

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Survey

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rtal.ncdenr.org/web/lr/

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ical_h

ome

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ailableto

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ation.

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isto

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icklin

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se“L

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es”;

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clickon

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ation”

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uction

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sentencesan

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otos;it

also

states

coun

ties

that

have

completed

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inventorymap

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dlin

ksto

otherpa

geswithmore

detailedinform

ation;

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giveslin

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dpu

blications

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kof

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useto

homeowners

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owto

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slides

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todeal

withthem

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ofinstab

ility

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aresident

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owner

might

observean

ddifferentmitigation

possibilities

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rietyof

land

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typesareprov

ided

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perm

itdo

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ofPDF

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ties

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land

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thotherpa

rtsof

“Lan

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ndinform

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ent

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ngeology

.org/

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arang

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land

slide

resourcesinclud

inglin

ksto

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reveal

apa

getitled

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subh

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ing:

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eologic

HazardAssistance,

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Techn

ical

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Clickon

thesubh

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ation

anddescriptionof

recent

events

inUtah;

access

tomap

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land

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da

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pedan

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ordinances addressing slope stability, and buildingpermit restrictions in landslide-prone areas can beaccomplished.A measure of how state geological survey involve-

ment at the local community level has changed since1995 involves looking at landslide reduction effortsfocused on homeowners. Nine state geological surveysmake available landslide hazard guides to home-owners and buyers, or a list of non-technical, observa-ble changes that might indicate landslide movement(Table 1). Several guides are actual publications thatmay be purchased in print form or downloaded in aPDF (Harris and Pearthree, 2002; Potter et al., 2013;and WDGER, 2015). In some cases, landslides areone of several geologic hazards covered by the publica-tion (Harris and Pearthree, 2002) and others are speci-fic to landslide hazard (Potter et al., 2013; WDGER,2015). Potter et al. (2013) produced “Landslides andYour Property” under a collaborative effort by theIndiana Geological Survey, Kentucky Geological Sur-vey, and the Ohio Division of Geological Survey.Other Internet-accessible homeowner guidance andlists include: “Landslide Hazards and You” (AlabamaGeological Survey), “Reducing Landslide Loss”(Idaho Geological Survey), “How to Recognize Land-slides and How to Deal with them” (NorthCarolina Geological Survey), “Homeowner’s Guideto Landslides” (Oregon Geological Survey), “A Guideto Homebuyers & Real-Estate Agents” (Utah Geolo-gical Survey), and “Homeowner’s Guide to GeologicHazards” (West Virginia Geological Survey), whichare viewable on their respective state geological surveyWeb sites. In some cases, these Web-based guides arealso freely downloadable in PDF format. Many ofthe guides and lists available only on state geologicalsurvey Web sites, if not all of them, were producedafter 1995. Similarly, the three state geological sur-vey–published homeowner guides have publicationdates ranging from 2002 to 2015. This demonstratesthat all of these efforts to communicate specific actionsthat the residents and landowners can take for land-slide risk reduction were initiated during the last20 years.It is more difficult to fully gauge the extent of state

geological survey involvement in achieving landsliderisk reduction at the local level (communities andcounties). The information provided on many stategeological survey Web sites includes reports of dam-aging landslide incidents, which are certainly instruc-tive for loss reduction efforts at the local level.Similarly, there are many landslide maps (location ofpast landslide events or features, landslide susceptibil-ity or incidence, and landslide hazards) and some stu-dies prepared specifically for guiding land use anddevelopment (Lund et al., 2008). As noted on the

Tab

le2.

Con

tinu

ed.

State

Survey

Nam

eWeb

Hom

ePag

ean

dPathto

Lan

dslid

einform

ation

Lan

dslid

eInform

ation

General

Resident/Lan

downer

Local

Gov

ernm

ent/Practicing

Professiona

ls

Washing

ton

Departm

ento

fNatural

Resou

rces

Geology

&Earth

Sciences

http://www.dnr.wa.go

v/prog

rams-an

d-services/

geolog

y-an

d-earth-resources

Clickon


amon

gGeology

topics

onthe

homepa

ge

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eologicHazards”

page,clickon

the

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dslid

es”icon

orin

thelisting

ontheleft;the

page

offers

links

togeneralinformation

under“w

hydo

land

slides

happ

en,”

“typ

esof

land

slides,”

and“som

ehistoric

land

slides

inWashing

tonState”

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geoffers

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ksuseful

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k“w

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oPDFdo

cuments

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ationon

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nism

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dpa

stWashing

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ge,thelin

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Web pages of the California Geological Survey (http://www.consrv.ca.gov/cgs/geologic_hazards/landslides/Pages/Index.aspx), specific studies were undertaken bytheir staff that produced maps and guidance docu-ments to help local governments deal with landslidehazard where urban expansion was happening or wasexpected to happen in the near future. An example ofthe work done is Geology for Planning in WesternMarin County, California, by David L. Wagner(Wagner, 1977). These publications and later onesinstigated under California’s Landslide Hazard Map-ping Act are no longer mandated as a result of changesin state law.While there is value in the landslide-related maps

and documents produced by state geological surveys,the extent to which such technical assistance is effec-tively introduced into landslide risk reduction effortsat the local level is less clear. Given the potential num-ber of local governmental bodies in the United States,determining how many have implemented mandatorymeasures to prevent or reduce landslide damage isdifficult to assess. There are certainly documentedexamples in parts of California, Colorado, and Utah(Fleming et al., 1979; McCalpin, 1985; and DeGraff,2012). While these examples of mandated measuresgenerally remain in effect now, it should be notedthat none of them was instituted after 1995.Lacking a readily definable metric, we are left to

find examples that are illustrative of landslide riskreduction resulting from such technical assistance.One such example is the California Geological Sur-vey’s involvement with timber harvest plans to limitlandslide-contributed sediment degrading water qual-ity as part of the Timber Harvest Plan (THP) Reviewproject. Since 1975, California Geological Surveygeologists conduct reviews of timber harvesting plansprepared by a state-licensed forester in an effort tolimit the detrimental effect of landslide occurrence inCalifornia’s watersheds. California Geological Surveygeologists carry out an engineering geology review ofplanned timber sales to provide advisory commentson slope stability concerns to the California Depart-ment of Forestry and the Board of Forestry, the stateregulatory agencies that grant approval of timber

sale harvest plans. Under this program, the technicalassistance from the California Geological Surveyensures that approved plans achieve the desired limitson landslide-generated sediment attributable to theharvest activities. The program’s effectiveness isdemonstrated by its continuing existence after 40 yearsof operation.A case study undertaken by DOGAMI and the

coastal City of Astoria, OR, provides a more compre-hensive illustration of effective landslide risk reductionresulting from interaction between a state geologicalsurvey and local government. The Landslide RiskReduction Process highlights the partnership betweenstate surveys and the U.S. Geological Survey Land-slide Program (USGS-LP) to facilitate implementationof risk reduction measures at the local governmentlevel.To fully understand this case study, we need a brief

description of how the Landslide Risk Reduction Pro-cess was developed. In the fall of 2012, the USGS-LPand DOGAMI completed a 5 year CollaborativeLandslide Hazard Project in Oregon. The collabora-tion focused on research and methods developmentto improve the quality and capacity to deliver land-slide hazard and risk information to the local govern-ments in Oregon. During the project, groundbreakingnew light detection and ranging (LiDAR)–basedmethods for detailed landslide inventory and suscept-ibility mapping fundamentally changed the abilitiesand understanding of the landslide hazard in Oregon.This 5 year project focused on development of

standardized methods of procedure based on recentresearch at the USGS-LP, North Carolina GeologicSurvey, California Geologic Survey, and others(Schulz, 2004; Harp et al., 2006). The goal was tohave the standardized methods in place, so that futureprojects could focus on performing the mapping, mod-eling, and risk analysis at an accelerated rate. Some ofthe methods have been finalized and published, includ-ing the landslide inventory and the shallow landslidesusceptibility methods (Burns and Madin, 2009; Burnset al., 2012). Other methods are in progress, includingdeep landslide susceptibility and landslide risk analysis(Burns et al., 2013).

Table 3. Summary of responses to AASG questionnaire inquiries related to landslide loss reduction.

QuestionsNumber of Respondents

Answering “Yes”Percent of Respondents

Answering “Yes”

A. How are your efforts related to statutory regulations or mandates(state, local, federal) policies, and land use? 9 31

B. Do you work with other state agencies on landslide hazards? 15 52C. Are you working with federal agencies (e.g., USGS, FEMA)? 16 55D. Are you working with local communities (e.g., cities, counties,

other state agencies)? 22 76



Throughout the USGS-LP/DOGAMI collaborative5 year project and the years following, DOGAMIpartnered with several local governments (Oregon stateagencies, cities, and counties) to work on landslide riskreduction projects. These community projects helpedto establish the Landslide Risk Reduction Process(Figure 4). DOGAMI discovered that completing theseprojects with a willing local partner is a very importantpiece of the process, because a large portion of the land-slide risk reduction takes place at the community level.It is the partnership between state and local govern-ments that results in the best available landslide hazarddata being used to perform landslide risk reduction.Following the Landslide Risk Reduction Process andmethods, DOGAMI continues to work with local part-ners on projects.

The specific example mentioned previously was aproject carried out by the City of Astoria andDOGAMI (Burns and Mickelson, 2013). In 2007, thecity was experiencing several active landslides and con-tacted DOGAMI for assistance. DOGAMI and theCity of Astoria government applied and received fund-ing from the Federal Emergency Management Agency(FEMA) Hazard Mitigation Grant Program to con-duct a landslide risk assessment and risk reductionproject. The first step was to create a landslide inven-tory using LiDAR-generated base maps. In total,120 landslides were found within the city boundary.Eighty-three landslides in this inventory were esti-mated or known to have moved during historic time.Seventeen of these had caused significant damage.For instance, the Irvine Road landslide destroyed 23homes in 1950. The second step was to create shallowand deep landslide susceptibility maps. It was foundthat 55 percent of the city was classified as highlysusceptible to shallow landslides, and 37 percent wasclassified as highly susceptible to deep landslides.Exposure risk analysis was performed, and it wasfound that 59 percent of the tax lots intersected withexisting landslides (Burns and Mickelson, 2013).FEMA’s HAZUS software was used to model a vari-ety of earthquake scenarios and estimate regionaldamages such as building damage, lifeline damage,and injuries (FEMA, 2005). However, the HAZUSsoftware does not have a landslide-only module, soan earthquake was modeled with and without the seis-mic-induced landslide hazard. This was done to esti-mate the range of potential damage and losses thatcan be expected from landslides during a major earth-quake in the Astoria area. The loss ratio (ratio of totallosses to the inventory of assets) was found to increasefrom 12 percent to 21 percent when the landslidehazard was included. These results indicate a signifi-cant increase in losses caused by the landslides trig-gered by an earthquake. This increased hazard effect

is likely to occur in other localities with high seismicand landslide hazard, like many portions of theOregon coast.The City of Astoria is now using this landslide

hazard and risk information to inform their land-useplanning and update their regulations related to grad-ing and development proposals. For example, the cityhas purchased lands associated with historic landslidesand is using them as parks and open space. The cityhas begun to implement the integration of the land-slide data into a Geologic Hazard and Hillside Devel-opment Ordinance.

Emergency Preparedness, Response, and Recovery

Whether effective landslide loss reduction efforts arein place locally or not, unexpected landslide eventsmay still occur. Consequently, there is a need for stategeological survey involvement in subsequent emer-gency response actions. The AASG questionnaireincluded three questions pertinent to emergency situa-tions. Among the 29 questionnaire respondents, onlyMaryland and Vermont indicated an actual involve-ment with installation or construction of mitigationor stabilization measures when an unexpected land-slide takes place (Table 4). This is not surprising giventhat the landslides are most likely to be occurring onprivate or non-state public land. It is unlikely the stategeological survey would have the authority to under-take mitigation or stabilization actions or to incurthe liability of taking on such a responsibility. In situa-tions where the interest of the state may be paramount,there are likely to be other entities such as departmentsof transportation, parks and recreation, and forestryor local county departments with the authority andengineering capability for carrying out mitigation orstabilization.Landslide warning systems are a means for ensuring

public safety by notifying people of an impendinglandslide threat. Often such warnings are part of acomprehensive emergency management plan involvingevacuation, temporary shelters, and other supportmeasures. This can be particularly effective when othermitigation or stabilization measures are not practicalor have yet to be implemented. There are only a fewexamples in the United States of such systems beingused in real-time so that notification and other emer-gency response measures can be effectively initiatedbefore the threatened movement occurs (Reid et al.,2012; NASA, 2013). As noted by Baum and Godt(2010), many of the landslide warning systems thatare or have operated in the United States are for occur-rence of shallow landslides or debris flows triggered byprecipitation events. Because shallow landslide predic-tion depends on precipitation thresholds, it means the



National Weather Service (NWS) of the NationalOceanic and Atmospheric Administration (NOAA) istypically a partner in operating these systems (Baumand Godt, 2010; Cannon et al., 2011). Such warningsystems use precipitation duration or intensity thresh-olds linked to the relative likelihood of movement orpossible landslide occurrence (Baum and Godt, 2010;De Graff et al., 2015b). In 1986, the USGS success-fully deployed a warning system based on precipita-tion thresholds in California (Keefer et al., 1987).More recently, similar systems in California providedearly warning for locations burned by wildfires in con-junction with emergency response plans developed byaffected counties (USGS, 2005; Cannon et al., 2011).Colorado, North Carolina, Oregon, and Washington(representing 14 percent of respondents) indicated par-ticipation in landslide warning systems as part of theAASG questionnaire response. Because technologicaland scientific advances since 1995 have made anincreased use of landslide warning systems possible, itprovides us with one measure indicating progress bystate geological surveys in emergency response.The third question related to emergency response

in the AASG questionnaire asked whether the stategeological surveys worked with their respective depart-ment of emergency management. Twenty-one Stategeological surveys (72 percent of the respondents)answered affirmatively to this question. Unfortunately,

there are no comparative data with which to assesswhether this is greater involvement than existed in 1995.The case study of the Rockville rock-fall response

in 2013 is an example showing rapid, effective emer-gency response to a current landslide event (Lundet al., 2014). On its Web site, the Utah GeologicalSurvey identifies providing geologic hazard assis-tance as one of the services it offers to local govern-ments. More specific to emergency response, themission of the agency as defined in the state codeincludes: “...determine and investigate areas of geolo-gic and topographic hazards that could affect thesafety of, or cause economic loss to, the citizens ofthe State” (Bowman, 2015). Any such work is doneby assisting both the local government and theUtah Division of Emergency Management (UDEM).Bowman (2015) highlights the following importantquestions that guide the Utah Geological Survey’sresponse actions:

. “Is the site likely safe for first responders and othersto enter and work?”

. “What geologic information is needed to reducethe risk?”

. “Is geologic monitoring needed to increase safety?”

. “Is another event likely to occur within a short timeframe?”

Table 4. Summary of responses to AASG questionnaire inquiries related to emergency response.

QuestionsNumber of Respondents

Answering “Yes”Percent of

Respondents

A. Do you work on any hard mitigation (e.g., stabilization)? 2 7B. Landslide warning system? 4 14C. Do you work with your state Department of Emergency Management? 21 72

Figure 4. Diagram of the steps in the Landslide Risk Reduction Process as applied by the Oregon Department of Geology and MineralIndustries.



. “Are other nearby areas at risk from geologichazards?”

The town of Rockville is located on Utah StateRoute 9 about 6.5 km west of Springdale, UT, andthe south entrance to Zion National Park. The townlies on the floodplain of the Virgin River between theriver channel and the base of a cliff forming the south-ern edge of Rockville Mesa (Lund et al., 2014). Thecliff exposes the interbedded sandstone and shalebedrock of the Moenkopi Formation capped by theShinarump conglomerate member of the Chinle For-mation. This stratigraphy is conducive to basal erosionof the sandstone and shale, resulting in underminingof the more resistant conglomerate rocks. At approxi-mately 5:00 p.m. on December 12, 2013, a large blockof Shinarump conglomerate detached and boundeddown the cliff face (Lund et al., 2014). When thefast-moving rock-fall debris reached the base of thecliff, it destroyed a Rockville residence along with itsgarage and car. More importantly, it killed two peoplein the home (Lund et al., 2014). Two Utah GeologicalSurvey geologists arrived at first light the followingday to assist the Springdale chief of police, who wasserving as the incident commander for the emer‐gency response (Bowman, 2015). A reconnaissance ofthe rock-fall source area and the area leading to thedestroyed residence was carried out to determine thesafety of emergency responders (Bowman, 2015). Inaddition to collecting the geologic circumstances ofthis particular event, the geologists carried out a rapidassessment of expected rock-fall runout (Lund et al.,2014). This was an important part of the geologicinformation needed to determine whether risk couldbe reduced. From observations made of the cappingconglomerate and downslope rock-fall deposits, itwas concluded that hazard from rock fall remainedhigh, but predicting the timing of future events wasnot possible (Lund et al., 2014). This conclusion wasconsistent with Rockville experiencing at least fiveother large rock falls over the past 35 years priorto the 2013 event. The destroyed residence and othernearby ones are within a zone of mapped rock-fall hazard (Knudsen and Lund, 2013). Consultationbetween the local government authorities and theUtah Department of Transportation determined thatstandard engineered rock-fall mitigation measureswere not feasible for protecting at-risk residences(Lund et al., 2014). The report outlined options forthe residents remaining within any high-hazard area:(1) continue to reside there knowing the consequence ofthe decision could include significant property damageand may prove fatal or (2) relocate from high-hazardareas (Lund et al., 2014). A recommendation was

made that the Town of Rockville ensure that presentand future residents and land owners in the high-hazard areas be made fully aware of the hazard. Itfurther noted that some local governments had pur-chased or retired the properties of homeowners whowished to relocate or to move their houses to saferlocations (Lund et al., 2014). These recommendationsrepresented a response to the question, “Are othernearby areas at risk from geologic hazards?” (Bow-man, 2015).

DISCUSSION AND CONCLUSIONS

It is evident that both our understanding of land-slide processes and the technology that can be appliedto furthering this knowledge have undergone signifi-cant improvement during the 20 years since NationalLandslide Awareness Day. Emphasizing the actionstaken at the state level of government, we can see animprovement in actionable policy for reducing land-slide hazard. Table 5 shows some of the metrics fromour analysis for comparing pre- and post-1995 changesfor accomplishing landslide risk reduction for the cate-gorical elements of developing guidelines and training,increasing public awareness and education, imple-menting loss reduction measures, and achieving emer-gency preparedness, response, and recovery (Table 5).Changes in the number of states requiring practicing

geologists to be registered, the uniformity introducedinto tests used to determine which individuals arequalified to be registered, and the guidelines availablefor conducting geological investigations are indicativeof improvement in the categorical element of guide-lines and training. Table 5 shows that states requiringregistration or licensure for practicing geological pro-fessionals has nearly doubled since 1995 and is nowinstituted in 64 percent of the states. The testing usedto determine which geologists are qualified for regis-tration was up to individual states prior to 1995.Now this testing employs the same procedures innearly all states requiring registration (Table 5). Onlythree states provided guideline documents applicableto landslide hazard work prior to 1995. Now five stateshave such guidance documents, including recentlyupdated versions for two of the three states with pre-1995 guidance documents (Table 5). It is recognizedthat none of these measures is directed solely towardlandslide risk reduction. If practicing geologic profes-sionals are generally more skilled and knowledgeable,we assume those who specialize in landslide-relatedissues will be too. The end result is to have a greaterworkforce capacity at the state level to accomplishlandslide risk reduction.Public awareness and education are enhanced by the

adoption by all state geological surveys of Internet-



based outreach to the general public, residents, andlandowners, and local government staff and practicingprofessionals. Table 5 indicates that 31 state geologicalsurveys (62 percent) use this technology specificallyto communicate landslide hazard information. Conse-quently, a post-1995 communications medium is facil-itating dissemination of information on landslidehazards to these stakeholder groups.Implementation of risk reduction due to landslide

activity requires incorporating our current understand-ing of the landslide process into land-use planning andconstruction. Schwab et al. (2005) published a notablenational-level handbook assisting planning profes-sionals with facilitating implementation of landsliderisk reduction. Certainly, efforts to ensure that resi-dents and landowners are able to recognize early signsof landslide activity represent progress. Such recogni-tion enables residents and landowners to determine iftheir property’s intended use might be impaired or totake early action to forestall damage. Table 5 showsthat prior to 1995, there were no guides specificallydirected at individual homeowners that would enablethem to make such determinations. Currently, thereare nine states where the state geological survey siteoffers lists of observable indicators of impending orongoing landslide activity or an actual publicationproviding such information. The Oregon case studyinvolving DOGAMI and the City of Astoria clearlydemonstrates how an effective landslide risk reductioneffort can be implemented at the local governmentlevel.Many state geological surveys have an ongoing

relationship with their state’s agency for emergencymanagement. As such, they have an important rolein providing geological information for emergencypersonnel and disaster response planning. Warningsystems provide an indicative measure of progressby state geological surveys in conducting emergencyresponse actions. Table 5 shows that one state, Cali-fornia, had effectively used an early warning systembefore 1995. During the last 20 years, five stateshave established early warning systems to somedegree and with varying success. All of these effortshave been fostered to a greater or lesser extent bythe USGS. The case study explaining the work

done by the Utah Geological Survey during the2013 rock-fall emergency in Rockville, UT, is illus-trative of how a state geological survey can contri-bute to emergency preparedness, response, andrecovery actions.Based on the metrics presented in this paper, we

conclude there are signs of progress during the last 20years toward implementing actionable policy changesand programs to achieve landslide risk reduction inthe United States. Local communities can accelerateprogress toward greater landslide risk reduction byimplementing land-use requirements based on ourimproved understanding of landslide hazard. Stategeological surveys are key actors in furthering thistrend because of their public education efforts andpartnership with local communities to develop manda-tory measures that assure risk reduction at the locallevel. Motivations for reducing landslide risk wouldbe helped by more comprehensive efforts to documentactual losses, particularly on a monetary scale. Dataof this type would not only be meaningful to electedofficials, but also the insurance and banking sectors.Population growth and urban expansion mean thatefforts toward the following will need to continueand expand: having an appropriate level of trainingfor professional geologists involved with landsliderisk reduction work, fostering efforts to educate thepublic about general and specific landslide hazardsthat might affect their lives and property, takingactions at the local government level to implementrisk reduction measures, and developing effectiveemergency preparedness, response, and recoveryactions.

ACKNOWLEDGMENTS

The authors wish to express their appreciationfor those AASG members who participated in thesurvey used as part of the data in this paper. Thethoughtful and thorough reviews provided by JamesMcCalpin and two anonymous reviewers are greatlyappreciated, too.

Table 5. Change in measures between pre- and post-1995 for the four categorical elements.

Category Metric Pre-1995 (No. States) Post-1995 (No. States)

Guidelines & training Registration/licensure 19 32ASBOG testing 0 30Guidance documents 3 5

Public awareness & education Landslide hazard information on Web page 0 31Implementation of loss reduction Lists or guides directed at homeowners 0 9Emergency response Warning systems 1 5



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