High School SMILE Club Activities Winter 2008 Oceanography:...

High School SMILE Club Activities Winter 2008 Teacher Resources Booklet

SMILE Winter Teachers Workshop Friday February 1st 2008

High School SMILE Club Activities Winter 2008

Oceanography: Tsunamis

Teacher Resources Booklet

Subduction Zones Modeling a Tsunami Tsunami Inundation

Past Evidence for Tsunamis in Oregon Warning Systems

Communicating Science to the Public

Material Compiled by Laura Dover, Marine Resource Management Masters GRA, SMILE, Oregon State University

[email protected]


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Contents Title Page # Preface: Tsunamis 101

Tsunami Facts…............................................ 2 What Causes a Tsunami……………………………………. 3 Where do Tsunamis Occur?............................ 5 How Does this Relate to Oregon?.................... 6 Can Tsunamis be Predicted?.......................... 7 What Has Been Done to Prepare for a Tsunami? 8 Tsunami Safety Advice……………………………………… 10 1. Under Pressure: Subduction Zones Subduction Zones and Tsunamis...................... 11 Icosahedron Globes…………………………………………… 14 2. Blatant Displacement: Modeling a Tsunami…………………….. 16 3. Pop Goes the Wave: Tsunami Inundation……………………….. 18 4. Tsunami Shake ‘n’ Quake: Past Evidence for Tsunamis in Oregon Evidence of the Great Quake of 1700............... 20 Native Tales of Cascadia Earthquakes……………… 22 5. Faster than a Speeding Tsunami: Warning Systems Tsunami Warning Systems............................... 24 DART Buoys…………………………………………………………. 27 6. Talking Risk: Communicating Science to the Public Public Service Advertising…............................. 30 Well Known PSAs…………………………………………………. 31


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Tsunamis 101

TSUNAMI FACTS TSUNAMI:

• From Japanese word, tsu = harbor, nami = wave • Series of waves produced when ocean (or another body of

water) is rapidly displaced • Can be caused by earthquakes, volcanic eruptions, landslides,

underwater explosions, meteorite impacts and nuclear weapons testing

• Has a small wave height offshore, but a very long wavelength • Tsunamis are often unnoticeable at sea, but can be

devastating onshore – also historically known as tidal waves as they appear as a huge rushing tide as they hit land

• Can cause widespread damage – force of water can bring down buildings and move large debris, literally ‘washing’ away coastal areas

• Media/common perception is often different from scientific fact – viewed as mega waves which tower over the town it hits, when in fact the wave height is actually relatively small – it is the continuous incoming of the wave which can make them deadly

DIFFERENT TYPES?

• Tidal bore (a closer definition of a tidal wave) often confused with tsunamis, but are very different. Tidal bore is a standing wave created as tide moves upstream of a river/estuary and wave of tidal water breaks on top of fresh river water – density driven. During 2004 Indonesian tsunami, tidal bore pictures taken in China were sold as photographs of the tsunami event

• Also Mega-tsunamis exist – these are waves larger than the tsunami norm – over 40m to giants over 100m – caused by massive impacts or landslides where the water body cannot disperse in all directions – often tsunamis are perceived as these

• Rogue waves also confused with tsunamis – these are however rare ‘freak’ or extreme ocean waves only encountered offshore. They are thought to be caused by diffraction/current focusing of the wave energy, sucking


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energy from waves around them as part of the wave train, sometimes encouraged by high winds

• Sneaker waves again confused with tsunamis – similar to rogue waves but encountered onshore and caused by the focusing of smaller waves into one larger one by constructive interference – known to catch unwary swimmers and take them out to sea

RECENT TSUNAMIS

• Solomon Islands Apr 2007 (8.1 M) • Kuril Islands Nov 2006 (8.1 M) • South of Java Island Jul 2006 (7.7 M) • Indian Ocean Dec 2007 (9.3 m) • Papua New Guinea Jul 1998 (7.1 M) • Hokkaido, Japan Jul 1993 (7.8 M) • Alaska Mar 1964 (9.2 M) • Chile May 1960 (9.5 M) • Hawaii Apr 1946

HISTORICAL TSUNAMIS • 1929 Newfoundland • 1908 Messina, Italy • 1868 Chile • 1826 Japan • 1782 South China Sea • 1755 Lisbon • 1707 Japan • 1700 Cascadia • 1607 Bristol Channel

WHAT CAUSES A TSUNAMI? UNDERWATER EARTHQUAKES

• Plate boundaries abruptly displaces overlying water – subduction zone earthquakes most effective

• Displaced water moves under the influence of gravity radiating across the water body similar to ripples on a pond

• Examples: o 2004 Indonesian quake o 1960 Chilean quake o 1964 Alaskan Good Friday quake


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VOLCANIC ERRUPTIONS • Water displacement by:

o Volcanic earthquakes o Undersea eruptions o Pyroclastic flows o Caldera collapse o Landslides/flank failure o Lahars o Phreatomagmatic eruptions o Lava bench collapse o Airwaves from large explosions

• Examples: o 1638 Santorini, Greece o 1883 Krakatoa, Indonesia o 1980 Mount St Helens o 1996 Karymsky, Russia o 2002 Stromboli, Italy

UNDERWATER EXPLOSIONS • Collision of vessels, e.g. 1917 Halifax explosion • Nuclear testing, e.g. 1946 BAKER test

LANDSLIDES/ROCKFALLS • Impact of rock/mud into water causes displacement • Can be triggered by earthquakes and/or collapse of flank of a

volcanic island • Can cause mega-tsunamis • Examples:

o 1958 Lituya Bay, Alaska o 1963 Vajont dam, Monte Toc, Italy o 1888 Ritter Island, Papua New Guinea

METEORITE IMPACT • Huge impact creates mega-tsunamis • No historical examples known to have produced a tsunami • Possible evidence from deposits along Gulf Coast of Mexico

and US from 65 million years ago


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WHERE DO TSUNAMIS OCCUR? As tsunamis are most often generated by earthquakes in marine coastal regions, they are most commonly found in the Pacific, where dense oceanic plates, slide underneath lighter continental plates (subduction zones)

Areas most at risk from tsunamis: • Western S America

o Chile (May 1960) o Peru (Jun 2001) o Ecuador (Jan 1958)

• Western Central America o Panama (April 1991) o Costa Rica (Sept 1992) o Nicaragua (Sept 1992) o El Salvador (Sept 1992) o Guatemala (May 1960) o Mexico

• Western USA o California (Mar 1964) o Oregon (Mar 1964) o Washington (Mar 1964) o Alaska (Mar 1964) o Hawaii (Apr 1946)

• Western Canada o British Columbia (Mar 1964)

• Africa o Somalia (Dec 2004) o Madagascar o Seychelles (Dec 2004)


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• Asia o Japan (July 1993) o Sri Lanka (Dec 2004) o India (Dec 2004) o Thailand (Dec 2004) o Indonesia (Dec 2004) o Malaysia (Dec 2004) o Philippines (Aug 1976) o Myanmar (Burma) (Dec 2004)

• Australasia o Papua New Guinea (Jul 1998) o New Zealand (Mar 1947) o Solomon Islands (Apr 2007) o Samoa (May 2006) o Fiji (May 2006) o Tonga (May 2006)

Although Europe has shown less tsunami activity in recent years, history has shown accounts of tsunami destruction in areas such as Portugal, Greece, UK and France.

HOW DOES THIS RELATE TO OREGON? The Oregon coast is part of the Northwest tsunami risk area,

• Alongside California, Washington and BC (Canada) • Tsunami waves propagating across the pacific could

potentially threaten Oregon from East or South Pacific sources • However we are more at risk from underwater earthquakes

sourced at Alaska or Hawaii The most devastating tsunami would occur as a result of a subduction earthquake off the Oregon coast

o The Cascadia Subduction Zone – very long sloping fault stretching from Vancouver island to Northern California

o Juan de Fuca plate slides under North American plate o Last subduction earthquake thought to have been 1700

– based on Native American legends and sediment data o Thought to occur average of every 500yrs, thus next

one is supposedly due by 2200..uh oh!


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CAN TSUNAMIS BE PREDICTED?

No! In the same context as earthquakes cannot be predicted 2 most likely tsunami sources

• LOCAL SOURCE - i.e. cascadia subduction zone earthquake • DISTANT SOURCE – i.e. from Alaska

But, much research is being carried out into the frequency and patterns of tsunami occurrence, whilst maintaining a more accurate warning system

• If Cascadia subduction zone earthquake occurs then warning would be the earthquake movement itself – as soon as you feel it move to higher ground! Warning system is your feet! In this situation, the actual warning system may be damage due to the size of the quake, this why it is important to increase tsunami awareness on the west coast

• Tsunamis propagating from Eastern Pacific or Alaska/Hawaii would give a varying number of hours of warning.

Oregon warning system from West Coast and Alaska Tsunami warning centre

• DART buoy system (Deep-ocean Assessment and Reporting of Tsunamis)

Palmer, Alaska monitors for earthquakes and subsequent tsunami events. If a tsunami is generated, they issue tsunami watches and warnings, as well as tsunami information bulletins for Alaska, British Columbia and Washington, Oregon and California.

• Tsunameter measures seismic information from earthquake event, sends signal to surface buoy

• Surface buoy measures sea level changes and reports back to warning centers

• DART system can also send data on request (for example tsunami propagation from earthquakes outside that locations seismic monitoring area)


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WHAT HAS BEEN DONE TO PREPARE FOR A TSUNAMI? Upon receipt of tsunami watches and warnings:

• Coastal National Weather Service (NWS) offices such as those in Seattle and Portland, activate the Emergency Alert System (EAS) via NOAA Weather Radio

• All broadcasters (TV, AM/FM radio, cable TV) receive the tsunami EAS message simultaneously as well as those with weather radio receivers in homes, businesses, schools, health care facilities, etc. NOAA Weather Radio also activates the All-Hazard Alert Broadcast (AHAB) units located in remote coastal areas, alerting people in those isolated locations.

• Local emergency management officials can decide to activate the Emergency Alert System (EAS) to evacuate low-lying coastal areas in advance of the initial tsunami wave

• EAS messages are also received by broadcasters, weather radio receivers and All Hazard Alert Broadcasts (AHABs) to help provide widespread dissemination of these messages

Types of Warnings LOCAL SOURCE

• If you feel violent shaking for several minutes, head for higher ground. The earthquake is your warning. The most likely source for a violent earthquake of this magnitude is from the Cascadia Subduction Zone just off our coast. The last associated earthquake was estimated to be 9.0 in magnitude on Jan 26, 1700, and was similar to the Dec 26, 2004 Sumatra 9.0 magnitude earthquake and subsequent Indian Ocean Basin tsunami.

**THE EARTHQUAKE IS THE ALERT TO AN INCOMING TSUNAMI AS WARNING SYSTEMS MAY FAIL IN SUCH A MAJOR EARTHQUAKE**

DISTANT SOURCE • Pacific-wide Tsunami Warning. A Pacific-wide tsunami

warning bulletin is issued by the PTWC after confirmation has been received that a tsunami has been generated in the Pacific that has caused damage, or has the potential to cause damage, at distances greater than 1000 kilometers from the epicenter, and thus poses a widespread threat to any populated coastal area within the Pacific Basin

• Regional Tsunami Warning. A regional tsunami warning bulletin is a tsunami warning issued initially to coastal areas near the earthquake epicenter. It is usually based only on


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seismic information without tsunami confirmation, and is initially issued as a means of providing the earliest possible alert of a potentially destructive tsunami to the population near the epicentral area of a potentially tsunamigenic earthquake

• Urgent Local Tsunami Warning. An urgent local tsunami warning is a tsunami warning issued by the PTWC to Hawaii for tsunamis generated in Hawaiian coastal waters. It may be based only on seismic information without tsunami confirmation, or on a combination of seismic and sea level data, and is issued as a means of providing the earliest possible alert of a potentially destructive local tsunami. Areas in an urgent local tsunami warning may have only minutes or seconds before tsunami waves arrive, so urgent action is required to save lives

• Final Warning Supplement. A final warning supplement bulletin is issued following a damaging or potentially damaging tsunami

• Warning Cancellation. A warning cancellation is issued as the final bulletin indicating when there is no longer the threat of a damaging tsunami

• Regional Tsunami Watch. A regional tsunami watch is a tsunami watch issued in conjunction with a regional tsunami warning to coastal areas near the earthquake epicenter, but outside the warning area. Areas in a regional tsunami watch are generally less than six hours from the estimated tsunami arrival time, and a list of estimated arrival times for watch areas is provided in the bulletin.

• Tsunami Advisory Bulletin. A tsunami advisory bulletin is issued to areas not currently in either warning or watch status when a tsunami warning has been issued for another region of the Pacific.

• Tsunami Information Bulletin. A tsunami information bulletin is issued for informational purposes for events that will not cause a destructive tsunami but were large enough in size to have been detected by the tsunami warning center’s seismic monitoring networks. Some of these earthquakes may have been large enough, however, to cause earthquake-related damage.


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Under Pressure: Subduction Zones Subduction Zones and Tsunamis A subduction zone is an area on Earth where two tectonic plates meet and move towards one another, with one sliding underneath the other and moving down into the mantle, at rates typically measured in centimeters per year. An oceanic plate ordinarily slides underneath a continental plate; this often creates an orogenic zone with many volcanoes and earthquakes. In a sense, subduction zones are the opposite of divergent boundaries, areas where material rises up from the mantle and plates are moving apart. Subduction zones mark sites of convective downwelling of the Earth's lithosphere (the crust plus the strong portion of the upper mantle). Subduction zones exist at convergent plate boundaries where one plate of oceanic lithosphere converges with another plate and sinks below it to depth of approximately 100 km. At that depth the peridotite of the oceanic slab is converted to eclogite, the density of the edge of the oceanic lithosphere increases and it sinks into the mantle. It is at subduction zones that the Earth's lithosphere, oceanic crust, sedimentary layers, and trapped water are recycled into the deep mantle. Earth is the only planet where subduction is known to occur; neither Venus nor Mars have subduction zones. Without subduction, plate tectonics could not exist and Earth would be a very different planet: Earth's crust would not have differentiated into continents and oceans and all of the solid Earth would lie beneath a


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global ocean.

Subduction results from the difference in density between lithosphere and underlying asthenosphere. Where, very rarely, lithosphere is denser than asthenospheric mantle, it can easily sink back into the mantle at a subduction zone; however, subduction is resisted where lithosphere is less dense than underlying asthenosphere. Whether or not lithosphere is denser than underlying asthenosphere depends on the nature of the associated crust. Crust is always less dense than asthenosphere or lithospheric mantle, but because continental crust is always thicker and less dense than oceanic crust, continental lithosphere is always less dense than oceanic lithosphere. Oceanic lithosphere is generally not denser than asthenosphere but continental lithosphere is lighter. Exceptionally, the presence of the large areas of flood basalt that are called large igneous provinces (LIPs), which result in extreme thickening of the oceanic crust, can cause some sections of older oceanic lithosphere to be too buoyant to subduct. Where lithosphere on the downgoing plate is too buoyant to subduct, a collision occurs, hence the adage "Subduction leads to orogeny". Most subduction zones are arcuate, where the concave side is directed towards the continent. This is especially so where a back-arc basin develops between the subduction zone and the continent. An example of a subduction zone is that of the Cascadia Subduction Zone, which is located off the Pacific Northwest Coast. The zone separates the Juan de Fuca, Explorer, Gorda and the North American Tectonic Plates.


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The width of the Cascadia subduction zone fault varies along its length, depending on the temperature of the subducted oceanic plate, which heats up as it is pushed deeper beneath the continent. As it becomes hotter and more molten, it eventually loses the ability to store mechanical stress and generates earthquakes. The Cascadia subduction zone can produce very large earthquakes, magnitude 9.0 or greater, if rupture occurred over its whole area. When the "locked" zone stores up energy for an earthquake, the "transition" zone, although somewhat plastic, can rupture. Thermal and deformation studies indicate that the locked zone is fully locked for 60 kilometers (about 40 miles) down dip from the deformation front. Further down dip, there is a transition from fully locked to aseismic sliding. (Nedimovic, et al., 2003)

In 1999, a group of Continuous Global Positioning System sites registered a brief reversal of motion of approximately 2 centimeters (0.8 inches) over a 50 kilometer by 300-kilometer (about 30 mile by 200 mile) area. The movement was the equivalent of a 6.7 magnitude earthquake. (Dragert, et al., 2001) The motion did not trigger an earthquake and was only detectable as silent, non-earthquake seismic signatures. (Rogers & Dragert, 2003)

The last known great earthquake in the northwest was in January of 1700, the Cascadia Earthquake. Geological evidence indicates that great earthquakes may have occurred at least seven times in the last 3,500 years, suggesting a return time of 300 to 600 years. There is also evidence of accompanying tsunamis with every earthquake, and one line of evidence for these earthquakes are tsunami damage, and through Japanese records of tsunamis.

A future rupture of the Cascadia Subduction Zone would cause widespread destruction throughout the Pacific Northwest.

Other similar subduction zones in the world usually have such earthquakes every 100–200 years; the longer interval here may


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indicate unusually large stress buildup and subsequent unusually large earthquake slip. Subduction zones are capable of producing tsunamis. Here, a sudden pressure release (built up by frictional forces between the plates) and subsequent movement of the zone (the earthquake) causes a massive displacement of water from its equilibrium position, creating a tsunami. Gravity works to restore the water to its equilibrium position as the waves travel outward from the origin in all directions. The water transfers the energy of the subduction zone earthquake. Icosahedron Globes The Ancient Greeks discovered that a representation of a spherical object could be made from a flat sheet of paper using specific flat polygons, for example an octahedron is a solid object comprised of 8 triangles or ‘faces’. An increase in the number of faces on a regular-sized solid will increase the more spherical look of the object. With 20 faces, the icosahedron is the best "flat" sphere available and hence will be used to make a globe.


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Icosahedron

Each face of the icosahedron displays a part of the (nearly-spherical) Earth's surface as a flat map and once folded, adjacent triangles are joined exactly at their closest edges and the cut-out pattern forms the complete globe with the North and South Poles at opposite vertices. Facts about icosahedrons! • Many viruses, e.g. herpes virus, have the shape of an icosahedron.

Viral structures are built of repeated identical protein subunits and the icosahedron is the easiest shape to assemble using these subunits. A regular polyhedron is used because it can be built from a single basic unit protein used over and over again; this saves space in the viral genome.

• In some role-playing games, the twenty-sided die is used in determining success or failure of an action. This die is in the form of a regular icosahedron. It may be numbered from "0" to "9" twice.

• An icosahedron is the three-dimensional game board for Icosagame, formerly known as the Ico Crystal Game.

• An icosahedron is used in the board game Scattergories to choose a letter of the alphabet.

• The die inside of a Magic 8-Ball that has printed on it 20 answers to yes-no questions is a regular icosahedron.


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Blatant Displacement: Modeling a Tsunami

A tsunami is a series of waves created when a body of water, such as an ocean, is rapidly displaced. Tsunamis have a much smaller amplitude (wave height) offshore, and a very long wavelength (often hundreds of miles long), which is why they generally pass unnoticed at sea, forming only a passing "hump" in the ocean. Tsunamis have been historically labeled tidal waves because as they approach land, they take on the characteristics of a violent onrushing tide rather than the sort of cresting waves that are formed by wind action upon the ocean (with which people are more familiar). Since they are not actually related to tides the term is considered misleading and its usage is discouraged by oceanographers.

A tsunami can be generated when the plate boundaries abruptly deform and vertically displace the overlying water. Such large vertical movements of the Earth's crust can occur at plate boundaries. Subduction earthquakes are particularly effective in generating tsunami. Also, one tsunami in the 1940's in Hilo, Hawaii, was actually caused by an earthquake on one of the Aleutian Islands in Alaska. That earthquake was 7.8 on the Richter scale.

In fluid mechanics, displacement occurs when an object is immersed in a fluid, pushing it out of the way and taking its place, so that it can be weighed. In the case of a tsunami being created by a subduction zone earthquake, it is the plate boundaries that create a sudden deformation that creates the displacement.

The objective of tsunami modeling research is to develop numerical models for faster and more reliable forecasts of tsunamis propagating through the ocean and striking coastal communities. The primary responsibility of the NOAA Center for Tsunami Research (NCTR) is to provide assistance to the Tsunami Warning Centers (TWC) in the form of Forecast Modeling software products specifically designed to support the Tsunami Warning Center’s forecasting operations. In addition to this, the NCTR has traditionally been committed to Inundation Modeling to assist coastal communities in their efforts to assess the risk, and mitigate the potential of tsunami hazard

Forecast modeling provides an estimate of wave arrival time, wave


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height and inundation area immediately after a tsunami event. Tsunami forecast models are run in real time while a tsunami is propagating in the open ocean, consequently they are designed to perform under very stringent time limitations.

Given the time constraints of this type of study, the process of computing the three stages of tsunami modeling, namely, wave generation, propagation and inundation has been expedited by generating a database of pre-computed scenarios. The pre-computed database contains information about tsunami propagation in the open ocean from a multitude of potential sources. When a tsunami event occurs, an initial source is selected from the pre-computed database. In the initial stages of the tsunami, this selection is based only on the available seismic information for the earthquake event. As the wave propagates across the ocean and successively reaches the DART systems these report the recorded sea level information back to the TWCs which, in turn, process the information and produce a new and more refined estimate of the tsunami source. The result is an increasingly accurate forecast of the tsunami that can be used to issue, watches, warnings or evacuations.

When an event similar to one of the pre-computed scenarios occurs, the available propagation information is used to compute the last stage of the study, wave inundation. [http://nctr.pmel.noaa.gov/model.html]

Computerized tsunami model displacing water at its source and moving omni -directionally across the Pacific Ocean


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Pop Goes the Wave: Tsunami Inundation

Tsunamis rank high on the scale of natural disasters. Since 1850 alone, tsunamis have been responsible for the loss of over 420,000 lives and billions of dollars of damage to coastal structures and habitats. Most of these casualties were caused by local tsunamis that occur about once per year somewhere in the world. For example, the December 26, 2004, tsunami killed about 130,000 people close to the earthquake and about 58,000 people on distant shores. Predicting when and where the next tsunami will strike is currently impossible. Once the tsunami is generated, forecasting tsunami arrival and impact is possible through modeling and measurement technologies

[http://www.tsunami.noaa.gov/tsunami_story.html]

An inundation modeling study attempts to recreate the tsunami generation in deep or coastal waters, wave propagation to the impact zone and inundation along the study area. To reproduce the correct wave dynamics during the inundation computations high-resolution bathymetric and topographic grids are used in this type of study. The high quality bathymetric and topographic data sets needed for development of inundation maps require maintenance and upgrades as better data becomes available and coastal changes occur.

Inundation studies can be conducted taking a probabilistic approach in which multiple tsunami scenarios are considered, and an assessment of the vulnerability of the coast to tsunami hazard is evaluated, or they may focus on the effect of a particular ‘worst case scenario” and assess the impact of such a particularly high impact event on the areas under investigation.

The results of a tsunami inundation study should include information about the maximum wave height and maximum current speed as a function of location, maximum inundation line, as well as time series of wave height at different locations indicating wave arrival time. This information can be used by emergency managers and urban planners primarily to


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establish evacuation route and location of vital infrastructure. [http://nctr.pmel.noaa.gov/model.html]

Rapid growth in the last twenty years has led to the development of the coastal areas in most of the developing or developed Pacific nations. This is the result of a population explosion and of technological and economic developments that have made the use of the coastal zone more necessary than before. Fortunately, tsunami are not frequent events and therefore their effects have not been felt recently in all developing areas of the Pacific. History, however, has proved that although infrequent, destructive tsunamis indeed do occur. A major Pacific-wide tsunami is likely to occur in the near future. Among the countries bordering on the Pacific, a number are not prepared for such an event while others have let their guard down. The social and economic impact of future tsunami, therefore, cannot be overlooked.

Part of a tsunami inundation map for Kodiak produced by Alaska scientists. Image courtesy Elena Suleimani [http://www.gi.alaska.edu/ScienceForum/ASF17/1734.html].


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Tsunami Shake ‘n’ Quake: Past Evidence for Tsunamis in Oregon

The January, 1700 Cascadia Subduction Zone earthquake and tsunami Between 9:00 PM and 10:00 PM, local time, on January 26th 1700, a great earthquake shook the Pacific Northwest. This quake, with magnitude estimated at 9.0, rocked the region with strong shaking for several long minutes while coastal Washington plummeted as much as 1.5 meters relative to coastal waters.

How is it possible to know that any event on the Cascadia Subduction ever occurred, let alone to place it within one hour of its occurrence 300 years ago? Let the evidence speak for itself and discover an ancient earthquake in the Pacific Northwest.

Evidence of the Great Quake of 1700

• Land Levels - Geological evidence shows that Washington's coast cycles through changes in land levels that subduction zone quakes typically produce.

• Tree Rings - Ancient trees along Washington's coast put an accurate date on a likely seismic event occurring in the Pacific Northwest.

• Tsunami Traces - Uncharacteristic sand deposits in Washington's coastal soil give evidence of local tsunamis.

• Historic Records - Japanese government records from 1700 describe a large tsunami likely originating from the Pacific Northwest.

• Turbidite Record - Layers of sediment off Washington's coast show that widespread, simultaneous shaking of the region was very likely.

• Native Tales - Native American stories from the Pacific Northwest describe an event strikingly similar to a large Cascadia subduction zone quake.

Turbidite evidence for Cascadia Subduction Zone Earthquakes Rivers carry sediment (soil and other debris) into the ocean, and


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sediment collects on the continental shelf and continental slope, which slopes into deeper water. More and more material builds up on the continental shelf sea floor until it becomes unstable and slides down the continental slope, much like an avalanche, in what is called a turbidity current. The resulting layer of sediment this current deposits on the sea floor is called a turbidite.

A number of events can potentially trigger turbidity currents. These events include tsunamis, storm induced waves, slope failures, and earthquakes. The turbidite record strongly suggests the latter — coastal Washington and Oregon experienced strong coast-wide shaking typical of a large subduction zone earthquake.

Large storms are an unlikely source of a coast- wide event because these storms produce waves not much larger than smaller, more common storms. If common and rare storms produce waves that are approximately the same magnitude, the turbidite record should reflect more than 13 events in the last 5,000 years.

The 1964 Alaska earthquake generated the most recent damaging tsunami that struck the Oregon-Washington coast. Although this earthquake is one of the largest seismic events of the 20th century, it did not produce any recorded turbidites. If this large tsunami did not trigger a turbidity current, it is highly unlikely the turbidite record reflects the occurrence of tsunamis.

In a slope failure, so much sediment develops on the inclined continental slope that it slips, much like an avalanche triggered by


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excessive snowfall. When enough sediment accumulates at a given point on a coastal slope, slope failure will occur. This underwater avalanche can cause turbidity currents to spread sediment throughout the underwater sea channels. Although these kinds of currents are likely to occur given enough time, the different rates of sedimentation and inclination of coastal regions make the synchronized turbidity currents implied shown in the core samples unlikely.

Cascadia zone earthquakes, on the other hand, prove to provide enough force and affect a large enough region of coast to have caused the turbidites in the core samples. Subduction zone earthquakes are cyclical and have large recurrence intervals, as do turbidity currents. Radiocarbon dating of each turbidite in Adams' core samples show a recurrence interval of about 590 years, closely matching the interval of coastal subsidence observed in coastal Washington. The Cascadia Subduction Zone - Latest Research The latest exciting scientific news about the Cascadia Subduction Zone (first discovered in 2001, and confirmed in 2002) is the observation of silent, aseismic (no shaking) slip events on the CSZ. The silent slip events have occurred regularly, every 14 months, since at least 1998. The largest of these events involved a 60-kilometer-by-300-km area about 30 km or more beneath Vancouver Island and Puget Sound that slipped about 30 mm over a period of 12 days or so. [http://www.ess.washington.edu/SEIS/PNSN/HAZARDS/CASCADIA/turbidite_record.html]

Native Tales and Traditions of Cascadia Megathrust Earthquakes Many Native American (U.S.) and First Nations (Canada) stories describe earthquake effects: shaking, tsunamis, and subsidence. Native peoples have inhabited the Cascadia coast for thousands of years and witnessed cycle after cycle of great earthquakes. Some stories are myths, others are historical.

One northern-California story describes a huge earthquake in which elders tell the young to run for high ground because of ensuing floodwaters. After spending a cold night in the hills, the young people find that all trace of their village has been washed away.

Other stories depict supernatural beings that caused the earthquake while at battle. Stories from the Hoh and Quileute tribes of the Olympic Peninsula of northwest Washington describe an epic battle


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between the supernatural beings Thunderbird and Whale.

"The great Thunderbird finally carried the weighty animal to its nest in the lofty mountains and there was the final and terrible contest fought. There was a shaking, jumping up and trembling of the earth beneath, and a rolling up of the great waters." By examining a variety of Native American tribal accounts, Ruth Ludwin, Deborah Carver and other researchers have identified consistencies in Native American lore that support a great earthquake in the Pacific Northwest. [http://www.ess.washington.edu/SEIS/PNSN/HAZARDS/CASCADIA/native_lore.html]


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Faster than a Speeding Tsunami: Warning Systems

A tsunami warning system is a system to detect tsunamis and issue warnings to prevent loss of life and property. It consists of two equally important components: a network of sensors to detect tsunamis and a communications infrastructure to issue timely alarms to permit evacuation of coastal areas.

There are two distinct types: international tsunami warning systems, and regional warning systems. Both depend on the fact that, while tsunamis travel at between 500 and 1,000 km/h (around 0.14 and 0.28 km/s) in open water, earthquakes can be detected almost at once as seismic waves travel with a typical speed of 4 km/s (around 14,400 km/h). This gives time for a possible tsunami forecast to be made and warnings to be issued to threatened areas, if warranted. Unfortunately, until a reliable model is able to predict which earthquakes will produce significant tsunamis, this approach will produce many more false alarms than verified warnings. In the correct operational paradigm, the seismic alerts are used to send out the watches and warnings. Then, data from observed sea level height (either shore based via tide gauges or deep ocean DART buoys) are used to verify the existence of a tsunami. Other systems have been proposed to augment the warning paradigm. For example, it has been suggested that the duration and frequency content of t-wave energy (which is earthquake energy trapped in the ocean SOFAR channel) is indicative of an earthquakes tsunami potential [Salzberg, 2006]. The first rudimentary system to alert communities of an impending tsunami was attempted in Hawaii in the 1920s. More advanced systems were developed in the wake of the April 1, 1946 and May 23, 1960 tsunamis which caused massive devastation in Hilo, Hawaii. [http://en.wikipedia.org/wiki/Tsunami_warning_system]

How does the Tsunami Warning System work? There are two sources of tsunami for Washington coastal waters - a distant source and a local source. Local source - if you feel violent shaking for several minutes, head for higher ground. The earthquake is your warning. The most likely source for a violent earthquake of this magnitude is from the Cascadia Subduction Zone just off our coast. The last associated earthquake was estimated to be 9.0 in magnitude on Jan 26, 1700, and was similar to the Dec 26, 2004 Sumatra 9.0 magnitude earthquake and subsequent Indian Ocean Basin tsunami.


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Simulations show the initial tsunami wave from the 1700 event reached the coast in 20 to 30 minutes - so time is limited. Geologic history showed waves with this event were as high as 30 feet. So you must get at least that high above sea level.

To top it off, the earthquake will also result in the coastal area subsiding as much as six feet, meaning the ground and roadways will likely be very uneven, and you are now that much lower to sea level. Since the roads will be in pieces, evacuation must be on foot. Another form of evacuation is vertical evacuation into a sturdy building of at least three stories and climb to at least the third story.

Other area earthquake faults could produce such strong violent quakes, such as the Seattle fault that produced a tsunami in Puget Sound about 1100 years ago. Yet, the most likely source for a local tsunami is the Cascadia Subduction Zone off our coast

A Distant Source - The perimeter of the Pacific Ocean Basin, nicknamed the Ring of Fire, has a number of earthquake sources that can produce strong earthquakes of 7.0 magnitude or greater. During the 20th century, there were three 9.0 magnitude or greater quakes, the last was the 1964 Alaskan quake of 9.2 magnitude that produced a tsunami throughout the Pacific Basin. These kinds of earthquakes permit a lead-time of hours before their subsequent tsunami reaches the Washington coastline. Tsunamis from distant locations like Japan or Chile will take over 10 hours to get here, while from Alaska, only three to six hours.

Tsunamis generated from both sources of earthquakes do penetrate into the Puget Sound region via the Strait of Juan de Fuca and up coastal rivers, harbors and bays, but lose energy as they move further inland.

Tsunami Warning System has been put into place to help minimize loss of life and property. The West Coast/Alaska Tsunami Warning Center in Palmer, Alaska monitors for earthquakes and subsequent tsunami events. If a tsunami is generated, they issue tsunami watches and warnings, as well as tsunami information bulletins for Alaska, British Columbia and Washington, Oregon and California.

The Pacific Tsunami Warning Center in Ewa Beach, Hawaii provides the same service for the Aloha state as well as all other American territories in the Pacific. They also serve as the International Tsunami Warning Center for 25 other member countries in the Pacific Ocean


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Basin.

Both of the tsunami warning centers use earthquake information, tide gauges and now a new tool from NOAA - tsunami detection buoys, developed by NOAA's Pacific Marine Environmental Laboratory. Six of these buoys are now deployed in the north Pacific to help scientists determined whether a tsunami has been generated and moving across the Pacific before reaching North American coastlines - another tool in the tsunami warning centers warning toolbox to help avoid any false alarms. More of these buoys would help detection as well as provide backup to each other since the buoys suffer outages in the harsh North Pacific Ocean.

Once a tsunami watch or warning is issued

Upon receipt of tsunami watches and warnings, coastal National Weather Service (NWS) offices such as those in Seattle and Portland, activate the Emergency Alert System (EAS) via NOAA Weather Radio. All broadcasters (TV, AM/FM radio, cable TV) receive the tsunami EAS message simultaneously as well as those with weather radio receivers in homes, businesses, schools, health care facilities, etc. NOAA Weather Radio also activates the All-Hazard Alert Broadcast (AHAB) units located in remote coastal areas, alerting people in those isolated locations.

Upon receipt of tsunami watch and warning messages, local emergency management officials (see Clallam County, WA as an example) can decide to activate the Emergency Alert System (EAS) to evacuate low-lying coastal areas in advance of the initial tsunami wave. Their EAS messages are also received by broadcasters, weather radio receivers and All Hazard Alert Broadcasts (AHABs) to help provide widespread dissemination of these messages. Follow the directions provided by your area emergency management officials - they will help save your life and those of your loved ones.

If you want your own tsunami warning message receipt system, obtain a NOAA weather radio receiver with EAS-programmable features. They are available from most radio electronic retailers and on the Internet.

Role of Education in developing the Tsunami Resilient Community

Education is another key element in the tsunami warning system. Many coastal areas have designated tsunami inundation zones and marked evacuation routes to assist residents and visitors to higher ground. Emergency management officials also distribute tsunami


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education information, conduct community meetings and workshops, and many more awareness activities.

The National Weather Service recognizes communities with strong tsunami warning and awareness programs through the TsunamiReady Community program. Such communities are recognized for their efforts to enhance their tsunami warning system, widespread use of weather radio receivers and community awareness activities. TsunamiReady road signs are also a part of NWS recognition. [http://www.tsunami.noaa.gov/warnings_forecasts.html]

About DART™ tsunami monitoring buoys

How the DART™ Network helps forecasting:

To ensure early detection of tsunamis and to acquire data critical to real-time forecasts, NOAA has placed Deep-ocean Assessment and Reporting of Tsunami (DART™) stations at sites in regions with a history of generating

destructive tsunamis. NOAA completed the original 6-buoy operational array (map of original six stations) in 2001 and plans to expand to a full network of 39 stations by the end of 2008 (Planned DART™ Array).

Originally developed by NOAA, as part of the U.S. National Tsunami Hazard Mitigation Program (NTHMP), the DART™ Project was an effort to maintain and improve the capability for the early detection and real-time reporting of tsunamis in the open ocean.

DART™ presently constitutes a critical element of the NOAA Tsunami Program. The Tsunami Program is part of a cooperative effort to save lives and protect property through hazard assessment, warning guidance, mitigation, research capabilities, and international coordination. NOAA’s National Weather Service (NWS) is responsible for the overall execution of the Tsunami Program. This includes


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operation of the U.S. Tsunami Warning Centers (TWC) as well as leadership of the National Tsunami Hazard Mitigation Program. It also includes the acquisition, operations and maintenance of observation systems required in support of tsunami warning such as DART™, local seismic networks, coastal, and coastal flooding detectors. NWS also supports observations and data management through the National Data Buoy Center (NDBC).

[http://www.ndbc.noaa.gov/dart/dart.shtml]

The information collected by a network of DART™ systems positioned at strategic locations throughout the ocean plays a critical role in tsunami forecasting. The map at right shows the conceptual plan for DART™ locations.

When a tsunami event occurs, the first information available about the source of the tsunami is based only on the available seismic information for the earthquake event. As the tsunami wave propagates across the ocean and successively reaches the DART™ systems, these systems report sea level information measurements back to the Tsunami Warning Centers, where the information is processed to produce a new and more refined estimate of the tsunami source. The result is an increasingly accurate forecast of the tsunami that can be used to issue watches, warnings or evacuations. DART™ buoy development

Over the past 20 years, NOAA's Pacific Marine Environmental Laboratory (PMEL) has identified the requirements of the tsunami measurement system through evolution in both technology and knowledge of deep ocean tsunami dynamics. The tsunami forecasting technology developed at PMEL is based on the integration of real-time measurements and modeling technologies, a well-tested approach used in most hazard forecast systems.

The first-generation DART™ design featured an automatic detection and reporting algorithm triggered by a threshold wave-height value. The DART™ II design incorporated two-way communications that enables tsunami data transmission on demand, independently of the automatic algorithm; this capability ensures the measurement and reporting of tsunamis with amplitude below the auto-reporting threshold. The next generation DART™ ETD (Easy To Deploy) buoy is presently under development at PMEL.


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Developed by PMEL and deployed operationally by NOAA's National Data Buoy Center (NDBC), DART™ is essential to fulfilling NOAA's national responsibility for tsunami hazard mitigation and warnings.

[http://nctr.pmel.noaa.gov/Dart/[


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Talking Risk: Communicating Science to the Public

Public service advertising is the use of commercial advertising techniques for non-commercial purposes. Typical topics for public service advertising include public health/public safety issues, emergency preparedness instructions, natural resources conservation information, and other topics of broad interest.

Public service advertising campaigns are widespread around the world. Such advertising is generally produced and distributed on a cooperative basis by governmental agencies or nonprofit organizations acting in concert with private advertising and mass media companies. In most cases, the nonprofit provides the programming that is to be advertised, while the participating advertising agency and media companies provide creative services, media planning, and dissemination services. A public service announcement (PSA) or community service announcement (CSA) is a non-commercial advertisement typically on radio or television, ostensibly broadcast for the public good.

The main concept is to modify public attitudes by raising awareness about specific issues. The most common topics of PSAs are health and safety, although any message considered to be "helpful" to the public can be a PSA. A typical PSA will be part of a public awareness campaign to inform or educate the public about an issue such as smoking or compulsive gambling.

Often, an organization releasing a PSA may enlist the support of a celebrity, examples being Michael J. Fox's PSAs in the U.S. supporting research into Parkinson's Disease, or Crips street gang leader Stanley "Tookie" Williams speaking from prison, urging youth not to join gangs.

Some religious groups produce PSAs on non-religious themes such as family values, as a means of increasing awareness of their church, and to show the role the church has in serving the community. Examples include the long-running "Homefront" campaign from The Church of Jesus Christ of Latter-day Saints, and more recently the United Methodist Church. Also, the military produces PSAs to recruit enlistees, alongside paid advertising and sponsorship efforts.

In the U.S, the role of PSAs was affected by deregulation of the broadcasting industry in the 1980s. Previously, a broadcast license was assigned to a television or radio station that was expected to


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serve as a "public trustee" by airing, among other requirements, frequent PSAs. Continued licensure no longer depends strictly on programming content, and the number of PSAs that are deliberately scheduled has declined, yet new PSAs continue to be produced and aired.

Today, TV and radio stations will use PSAs to demonstrate their commitment to a particular cause, or as an easy way to fill unsold commercial time. Some large non-profit organizations, such as the American Cancer Society and Red Cross, choose to ensure play by purchasing commercial time for their campaigns. Smaller organizations, such as the American Indian College Fund, rely solely on voluntary media space to get their message out.

The Ad Council is the largest producer of PSAs in the United States, many of which involve a substantial budget and are distributed commercially. Other producers such as Salo Productions specialize in traditional PSAs distributed to station PSA directors.

Well-known PSAs

• Don't Copy That Floppy • The Incredible Crash Dummies: "You can learn a lot from a Dummy." • G.I. Joe and Transformers: "And knowing is half the battle!" • Mr. Funercise • Just Say No • Crying Indian (sponsored by Keep America Beautiful) • McGruff the Crime Dog: "Take a bite out of crime!" • Smokey Bear: "Only you can prevent forest fires!" and "Only You

Can Prevent wildfires!" • Woodsy Owl: "Give a hoot, don't pollute!" and "Lend a hand — care

for the land!" • Click It or Ticket • FUR...You Deserve It (anti-fur trading) [http://en.wikipedia.org/wiki/Public_service_advertising]


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