Workshop to Launch the GEM Regional Programme in the CaribbeanKapok Hotel, 2nd to 4th May, 2011.

Julio Garcia Ph.D.Risk Group - OGS

The National Institute of Oceanography and Experimental Geophysics, Trieste, Italy

e-mails: jgarcia@inogs.it , julgp@yahoo.com

Contributions from D. Slejko and L. Alvarez

THE AREA OF STUDY

EVOLUTION OF THE SEISMIC HAZARD ESTIMATIONS

WORKS IN PROGRESS…

SUMMARY

16°N. - 24°N.

67°W. -

86°W.

4

From Mann et al., (2002) Oblique collision in the northeastern Caribbean from GPS measurements and geological observations, Tectonics, 21, pp.1057

1 = Hispaniola microplate; 2 = Septentrional microplate; 3 = Gonave microplate.

?

Plate boundary interactions: From the west to the east A: Transtension; B: Transpression; C: Oblique collision;D: Oceanic subduction.

A

B C

D

CSC: Cayman spreading center

WFZ: Walton fault zone

OFZ: Oriente fault zone

SDB: Santiago deformed belt

PGFZ: Plantain Garden fault zone

EFZ: Enriquillo fault zone

SFZ: Septentrional fault zone

NHZF: North Hispaniola Fault Zone

PRT: Puerto Rico trench

LMT: Los Muertos trench

CCB: Cabo Cruz basin

CSC: Cayman spreading center

WFZ: Walton fault zone

OFZ: Oriente fault zone

PGFZ: Plantain Garden fault

zone

EFZ: Enriquillo fault zone

SFZ: Septentrional fault zone

NHZF: North Hispaniola Fault

Zone

PRT: Puerto Rico trench

LMT: Los Muertos trench

CCB: Cabo Cruz basin

SDB: Santiago deformed belt

From Cotilla et al.(2007)

Interplate seismicity:It is due to the direct interaction between the plates, and affects the southeastern region with strongest and most frequent eventsIntraplate seismicity:Affects the rest of the region,It is localized in the vicity of tectonic structures of 2nd order,Small and moderate events (less frequent)

Interplate seismicity:It is due to the direct interaction between the plates,Affects the southeastern region,Strongest and most frequent eventsIntraplate seismicity:Affects the rest of the region,It is localized in the vicity of tectonic structures of 2nd order,Small and moderate events (less frequent)

1. Historical Determinism,

2. Historical Probabilism,

3. Seismotectonic Probabilism,

4. Non-Poissonian Probabilism,

5. Earthquake Prediction

Destroyed four times in 500 years

No serious damages in 200 years

Valdivia: faster convergence between the NAZCA and SA plates,Portland: tectonic and geotechnical studies evidence higher hazard

1960-Mw9.5

1690

2010-Mw8.8

First generation Second generation Third generation

Alvarez (1970) Chuy and Rodriguez (1980) Chuy et al. (1983) Shepherd et al.(1997) Shedlock K.M. (1999)Tanner and Shedlock (2004)Garcia et al. (2008)

Rubio (1985) Alvarez and Bune (1985)Alvarez et al. (1989) Orbera et al. (1990) Alvarez et al. (1991) Chuy et al. (1992) Gonzalez et al.(1994) Chuy and Alvarez (1995) Rodriguez et al. (1997) Alvarez et al. (1999) Garcia et al. (2000) Garcia et al. (2003) Garcia et al. (2006)

Annual number of seismic hazard studies

12

First seismic hazard zonation, It was based on historical (pre-1900) macroseismic data, The zones represent the maximum intensity value (MSK scale) reported, Some regions remained as "unknown" intensityAlvarez (1970)

? ?

?

Chuy et al. (1983)

Revisited version of Alvarez (1970), It was based on historical and instrumental macroseismic data, The zones represent the maximum intensity value (MSK scale) reported for a return period of 100 years, Included in the first Cuban seismic building code (NC 53-114:84, 1984)

T=100 yearsI (MSK-64 scale)

general comments at this stage…

The previously cited studies lack of a detailed analyses on seismicity (completeness, declustering) and seismogenesis (non zonified approach)

In addition, no attenuation has been applied to the intensity data and the maps represent simply the maximum observed shakings

Tanner and Shepherd, 1997; Shepherd et al., 1997; Shedlock, 1999

Tanner and Shedlock (2004)

Historical Parametric method - Veneziano et al.(1984)

PSHA according to the historical parametric method (Veneziano et al. (1984) The first PGA map (1997-1999) was part of the global GSHAP mapHigher values of PGA in the Tanner and Shedlock (2004)

2. Historical Probabilism

Garcia et al. (2008)

PSHA according to the smoothed seismicity approach (Frankel, 1996),

In the logic tree was considered 2 seismicity model (M3, M5), 3 different distribution of Mmax and the b value and 2 GMPR (Ambraseys, 1996 and Dhale (1995) for rock conditions.

Seismic activity profiles

PGA (10% in 50 years)

rock

Garcia et al. (2008)

general comments at this stage…

Similar PGA values with the exception of those obtained by Tanner and Shedlock (2004),

Maps based on earthquake history had “bull's-eyes” at sites of past large (M7) earthquakes

Concentrated hazard inferred from historic seismicity alone

3. Seismotectonic Probabilism

In the eighty was started the PSHA of third generation as part of detailed seismic zoning for singular objectives( nuclear power plant, hydroelectric power plant, ect…),

Later, with the same approach hazard estimates for the entire Cuban territory was obtained

19

3. Seismotectonic Probabilism (according to Kramer,1996)

1. Identification and characterization of earthquakes sources,2. Seismicity characterization (recurrence),3. Estimation of ground motion at site (considering the uncertainty),4. Hazard at the site as the probability that the ground motion parameter will be exceeded during a particular time period

PSHA

SZ’z Eq. GMPR

Alvarez et al. (1991)

Seismogenic zonation:Intraplate: point source,Interplate: areal source,GMPR: Attenuation of intensities in terms of elliptical isoseismals (Alvarez andChuy (1985)Method:Risznichenko (1979), considering a probabilistic chacarter of the recurrence periods

Int (MSK scale) prob=10% in 50

years)

Chuy and Alvarez. (1995)

Seismogenic zonation:detailed seismic zones (faults) GMPR: PGA from Intensity (Trifunac and Brady (1975)Method:Risznichenko (1979), considering a probabilistic character of the recurrence periods.PGA(%g)

prob=15% in 50 years)

Average soil

Garcia et al. (2003)

Earthquake Catalog: Unified parametric catalog [Alvarez et al. (1999)]

Seismogenic zonation:Modified version of Cotilla et al.(1991) zonation (wide sz’s).

GMPR: PGA [ Joyner and Boore(1981), Ambraseys(1995) and Quijada et al.(1993)] and proper Intensity relations followings five different formulations (von Kovesligethy, 1907; Blake,1941; Grandori et al., 1987 and Berardi et al.,1994)Method:Cornell (1968) using SEISRISK III

Cotilla et al.(1991)

Garcia et al.(2003)

SZ seismicity rates (number of earthquakes in a 100 years) for small earthquakes (short-dashed line: M < 3.8, Io <= IV–V), moderate earthquakes (dashed line: 3.8 <= M <= 5.7, V <= Io <= VI–VII), and large earthquakes (solid line: M > 5.7, Io >= VII): (a) for magnitude classes; (b) for intensity classes.

Int (MSK scales) prob=10% in 50 years)

PGA(%g) prob=10% in 50

years)

Santiago de Cuba

25

Three Zonations:ZS-A: Chuy and Alvarez (1995) ZS-B: Garcia et al. (2003)ZS-C: Garcia (2007)Mmax:1SB: Slejko et al. (1998)TEC: geology-tectonicKIJKO: Kijko and Graham (1998)

Revisited version of earthquake catalog of Alvarez (1970),

Garcia (2007), unpublished

PGA (rock and soil):A1: Ambraseys et al. 1996;A2: Dahle et al. 1995).

Logic Tree

26

Chuy and Alvarez (1995)

Garcia et al. (2003)

Garcia (2007)

Modified (improved)

versions of the source

zone zonations used

before (A and B),

A new zonation (C)

Source zones for

Puerto Rico region

was considered

A)

B)

C)

ROCK

SOIL

PGA(%g) prob=10% in 50

years)

general comments at this stage…

Maps based on earthquake history had “bull's-

eyes” at sites of past large (M7) earthquakes

Concentrated hazard inferred from historic seismicity alone

In addition, no attenuation has been applied to the intensity data and the maps represent simply the maximum observed shakings

Seismic hazard zoning of Cuba

As, in a seismic hazard map is represented a point of the curve of hazard,Due the need of considering for a seismic zoning much more information than usually is done,And, due we have this information on hand,

We decided to classify the seismic hazard curves using logical combinatorial pattern recognition techniques to obtain a new seismic hazard zonation for the Cuba

PGA 475y curves

Classification

PatternsNew zonation

31

classification of PGA-475 curves using pattern recognition techniques

Seismic zoning of Cubarock conditions

33

Parametric earthquake catalogue for SHA

New seismic zonation for the Cuban seismic zonation (building code)

34

Parametric earthquake catalogue(in collaboration with CENAIS)

Revisited and update version of the Alvarez et al. (1999) parametric catalog.

Main activities

Selection of the most reliable current information,

merging and clustering processess,

and selection of the most reliable, based on the quality of the supporting dataset.

1. SisFrance database (http://www.sisfrance.net)

2. IPGH catalog: Tanner and Shepherd (1997),

2. NOAA - National Geophysical Data Center - Earthquake Data

Global Significant Earthquake Database, 2150 B.C. to present

(http://www.ngdc.noaa.gov/hazard/earthqk.shyml)

4. Catalog of historical earthquakes [Chuy (1999)] – Cuba

5. Catalog of Felt Earthquakes for Puerto Rico and neighbouring Islands1492-1899, with some additional information for some 20th Centuryearthquakes, McCann et al. (unpublished).

GLOBAL

REGIONAL

LOCAL

1. International Seismological Centre - ISC,2. National Earthquake Information Center – NEIC (USGS), 3. NOAA - National Geophysical Data Center - Earthquake Data 4. EHB Bulletins: Engdahl and Villaseñor (2002)- Global seismicity 1900 – 1999.

Hosted by ISC, 5. Global Centroid Moment Tensor database (former Harvard CMT catalog)

1. Northern California Earthquake Data Center (Advanced National Seismic System – ANSS)

2. IPGH catalog: Tanner and Shepherd (1997)

1. National Centre of Seismological Researchers (CENAIS) – Cuba2. University of the West Indies – Jamaica3. Puerto Rico Seismic Network – PRSN 4. Santo Domingo Autonomy University (UASD) - Instituto Sismologico

Universitario– Rep. Dominicana

OTHERS

1. Papers, historical sources, technical reports, ect…

SA-0.1

SA-0.2

SA-1.0

considering the epistemic

variability in seismogenic

zonation, seismicity, maximum

magnitude, and ground

motion attenuation Cornell standard approach

Seismic zonation for the Cuban seismic building code

UHRSSantiago de Cuba

Allow me therefore to summarize some ideas:

At present time robust PSHA results have been obtained for the region,

The model used agree the GEM initiative,

Nevertheless, some input parameters must be improved, as the quality of the earthquake catalog, the association of historical event to the sz’s-faults and the selection of the most reliable GMPR.

Therefore, does the Caribbean to assume the challenges of the GEM regional programme?

The answer is Yes

Yes, because several working groups have emerge, providing a ground for the exchange of data, ideas and expertise.

Thanks

GrazieGracias

PhD. Julio Garcia Risk Group National Institute of Oceanography and Experimental Geophysics Borgo Grotta Gigante 42c, 34010 Sgonico (Trieste), Italy tel. +39 040 2140303 fax +39 040 327307 cell. +39 348 8846228 e-mails: jgarcia@inogs.it , julgp@yahoo.com

43

INTRODUCTION

PSHA FOR HAITY (state of the art and ideas for a project)

Significant Worldwide Earthquakes

HISTORICAL SEISMICITY

44

INTRODUCTION

PSHA FOR HAITY (state of the art and ideas for a project)

HISTORICAL SEISMICITY

MODELLING THE SITE EFFECTS FOR EASTERN CUBA Z. Rivera, J. Garcia, M. Santulin, D. Slejko, L. Alvarez 45

INTRODUCTION SEISMICITYAVAILABLE DATA

ISC (1900-2009)

46

INTRODUCTION SEISMICITYAVAILABLE DATA

PSHA FOR HAITY (state of the art and ideas for a project)

USGS/NEIC (1973 - 2009)

47

INTRODUCTION

NEIC (2150 B.C. - 1994 A.D.)Significant Worldwide Earthquakes

SEISMICITYAVAILABLE DATA

1946/08/04M8.1

1946/08/08M7.9

1916M7.2

1971M6.51691

M7.7

1842M7.7

1953M5.7

48

INTRODUCTION

PSHA FOR HAITY (state of the art and ideas for a project)

NEIC/USGS (2010/01 – 2010/11)

SEISMICITYAVAILABLE DATA

MODELLING THE SITE EFFECTS FOR EASTERN CUBA Z. Rivera, J. Garcia, M. Santulin, D. Slejko, L. Alvarez 49

INTRODUCTION SEISMICITYAVAILABLE DATA

ISC (2010/01-2010/11)