S OUTHERN C ALIFORNIA E ARTHQUAKE C ENTER SCEC: Decade 1 Bernard Minster SCEC Annual meeting, 2000

SOUTHERN CALIFORNIA EARTHQUAKE CENTER

SCEC: Decade 1

Bernard Minster

SCEC Annual meeting, 2000

SCEC: Decade 19/18/00 2


SCEC and its Mission• The Southern California Earthquake

Center’s mission is to promote earthquake loss reduction by:– Defining when and where future damaging

earthquakes will occur in Southern California,– Calculating the expected ground motions, and– Communicating this information to the public.



SCEC Objectives• To estimate the earthquake potential, or the probability of earthquake

occurrence as a function of location, magnitude, and time,

• To advance our understanding of earthquake rupture dynamics and source physics,

• To understand the nature of wave propagation through complex geology,

• To predict ground motions, or complete theoretical seismograms, at any site from plausible future damaging earthquakes, and

• To transfer this knowledge to communities of end users.



Master Model

"… the goal of SCEC is to integrate research findings from various disciplines in earthquake-related science to develop a prototype probabilistic seismic hazard model (master model) for southern California.”

(Keiiti Aki, 1989)





Seismicity of Southern California



GPS Velocity Map of Southern California



Southern California Integrated GPS Network (SCIGN)

168 stations

installed

78 more to be

installed (by

late 2000)…

Total of 250

stations



GPS in the Los Angeles Basin

The Los Angeles basin is being squeezed closed (e.g., Palos Verdes is moving towards JPL).



Integration of GPS into Risk Estimation





Regional stress changes caused by the Landers, Big Bear and Joshua Tree earthquakes. Areas in red are regions where nearby faults are brought closer to failure. Note that segments of the San Andreas fault pass through red zones.

From R.S. Stein, G.C.P. King and J. Lin (Science, 1992), G.C.P. King, R.S. Stein and J. Lin [BSSA, 1994)



Evidence for Fault Zone Healing following the 1992 Landers Earthquake from Fault Zone Trapped Waves and Body Waves. Left Panel: Shot points (SP-X) and receiver locations (Lines 1 and 3) along Johnson Valley segment. Center Panels: Time differences in arriving phases between 1994 and 1996 as a function of distance from the fault trace along Line 1. Right Panels: Time differences in arriving phases between 1996 and 1998 as a function of distance from the fault trace along Line 1. (From Li, 2000)



The probability of a large earthquake on the San Bernardino segment of the San Andreas fault was increased by the 1992 Landers and 1999 Hector Mine earthquakes.



Sub-Surface Fault Map of the Los Angeles Area

(Dolan, 2000)



The Puente Hills Blind Thrust Fault and 1987 Whittier Narrows Earthquake Sequence



SCEC Phase III Report

An investigation of how and if site effects can be accounted for in probabilistic seismic hazard analysis (PSHA) in southern California

Conclusions:1) Detailed classification (beyond rock versus soil) is justified

with the Wills et al. (2000) map.

2) Basin depth is a significant factor, even for PGA (but may be a proxy).

3) Uncertainty (sigma) remains high after site corrections.



Deterministic Ground Motion Prediction: Input to Performance-based Engineering Design



Los Angeles Regional Seismic ExperimentLARSE

Top panel:

Crustal structure image across the Los Angeles basin and San Gabriel Mountains from seismic transect.

Bottom panel: Interpretation of fault structure based on data from top panel.



LARSE II Transect from

Santa Monica Bay to the

Mojave Desert

Features crossed include:

• Santa Monica Fault

• Santa Monica Buried Thrust Fault

• Santa Monica Mountains

• San Fernando Valley/Basin

• 1994 Northridge Earthquake Fault

• Santa Susana Thrust Fault

• Santa Susana Mountains

• San Gabriel Fault

• Central Transverse Ranges

• San Andreas Fault

• Mojave Block

• Garlock Fault

• Tehachapi Mountains



Fence Diagram from the SCEC Seismic Velocity Model of Southern California



The Basin-edge Effect from the1994 Northridge Earthquake



Simulating Dynamics of Fault RuptureTough computational problem because...

Inner scales are small:< 10 meter< .01 second

Outer scales are large:> 100 kilometers> 100 years

+46



Critical Point Model

• The largest earthquake on a given fault network is possible only when the network is in a critical state.

• The crust is not in a continual critical state. Earthquake cycles can be viewed as repeated approaches and retreats from the critical state.

• The critical state is characterized by spatial stress correlations at all scales up to the size of the regional fault network.

• A large earthquake destroys the stress correlation on its regional fault network, producing a quiescent period for intermediate and large events.

• Small earthquakes rebuild stress correlation, making the next large earthquake possible. Each earthquake roughens the stress field at longer wavelengths and smoothes it at shorter ones.



Simulations for the San Andreas Fault

(Olsen, 2000)





Collaboration between Earth Scientists and Engineers



Partners in Academia

National2 SCEC Institutions:

Columbia; UNR

Carnegi-Mellon

Central WA University

GA Institute of Technology

Harvard, MIT, NAU, OSU,Texas Tech Univ., U of AK, U of CO, U of DE, U of Memphis (CERI), U of WA, U of NM, Woods Hole Oceanographic Inst., Univ of Utah

DLESE

MCEER

MAE

InternationalIRIS, EERI

CICESE, Mexico

Institute de Physique du Globe, Paris

Univ of Athens & Thessaloniki, Greece

Istituto Nazionale de Geofisica, Rome

State Seismology Bureau, China

Building Research Institute, Japan

Disaster Prevention Research Institute, Kyoto, Japan

Geological Surveys of Canada, Japan

Univ of Tokyo Earthquake Research Institute

State7 SCEC Institutions:

Caltech; UC San Diego, Davis, Santa Barbara, Los Angeles; USC; SDSU

CSUN, CSULB, UC Berkeley, SFSU, Stanford, UC Irvine, CS Fullerton, CSULA, Whittier College

PEER

CUREe



Partners in Education(980)

IRIS (E-3 Project, middle school education modules support

DLESE (E-3 Project, digital libraries community involvement)

Museums (earth science / earthquake exhibits, docent training, educational curricula, hands-on activities, field trips)

LACOE (earth science curricula)

ARC (earth science curricula)

IBHS (Seismic Sleuths video)

AGU, FEMA (Seismic Sleuths curriculum revisions)

SCEC Community of Researchers, Students

USGS (Civic presentations; web-based curricula; K-12 products)

PEER (interns)

CUREe (Woodframe Project, Engineering/Science Symposia, HAZUS, E-3 Project)

California K12 Alliance (education modules creation and review)



Partners in Government

State (230)

CA Div Mines & Geology

CA OES

CA Seismic Safety Commission

NV Bureau Mines & Geology

Federal (328)

USGS

FEMA / NEP

National Labs: NASA’s JPL, Lawrence Livermore, Los Alamos

Local (679)

Cities and Counties of southern California:

Building Officials

Emergency Planners & Responders

Urban Planners

Public Utilities (water, power)



Partners in Industry(For-profit, Non-profit)

Nonprofit (150)Insurance Education Association

CA Assoc. of Insurance Professionals

SEAOSC

American Red Cross

BICEPP

Assoc. of Contingency Planners

California Earthquake Authority

EERI

EPARR (Emerg. Prep. Response & Recovery Committee)

Private/For-profit (2538)

Insurers & Reinsurers

Institute for Business & Home Safety

Risk Analysis Consultants

Design, Engineering Consultants

Geotechnical Consultants

Contingency Planning Consultants

Media Organizations



SCEC Webservices

www.scec.org www.scecdc.scec.org

~4,500 Visitors per week1200 view Outreach1000 view INSTANeT News1000 view Research 300 view worldwide Eq’s300 view “About SCEC”

~250,000 Visitors per week



“Putting Down Roots in Earthquake Country” a USGS-SCEC Product

• Largely funded by USGS

• Produced by SCEC Outreach

• 1.8 million distributed bySCEC, USGS, local community • Featured on local TV, at earthquake fairs eachApril



SCEC Transition Process•Funding as NSF S&T Center ends 02/02

–STC funding base: $1.4M–Cannot be renewed under STC Program

•Joint proposal to NSF/EAR and USGS to be submitted in 12/00

•Transition objectives–Strengthen partnership with USGS

–Tie in with NSF EarthScope initiatives

–Increase integrated, system-level studies of

earthquake phenomena

–Augment strong Education & Outreach

program



The Beginning!

Documents

S OUTHERN C ALIFORNIA E ARTHQUAKE C ENTER SCEC: Decade 1 Bernard Minster SCEC Annual meeting, 2000