Kenneth W. Hudnut USGS, Pasadena, CA

West Newport Beach AssociationPublic Forum, Newport Beach City Hall

March 5, 2003

Coping withCoping with‘‘quakesquakes

What is an earthquake?What is an earthquake?What is an earthquake?What is an earthquake?

Sudden slip of one block of rock across another

Produces shaking as one of its effects

The shaking is what you feel

Earthquakes are driven by plate Earthquakes are driven by plate tectonic motiontectonic motion

As the Farallon plate subducted, the San Andreas fault was born

In the past 5 million years, this motion has been steady at about 2 inches per year (that’s 15 feet per century or 30 miles per million years!)

Movie by T. Atwater, UCSB

QuickTime™ and aAnimation decompressorare needed to see this picture.

Earthquakes are driven by plate Earthquakes are driven by plate tectonic motiontectonic motion

In the past 5 million years, this motion has been steady at about 2 inches per year (that’s 15 feet per century or 30 miles per million years!)

Yes, LA will be in San Francisco

No, LA will not fall into the sea

Movie by T. Atwater, UCSB

QuickTime™ and aAnimation decompressorare needed to see this picture.

Earthquake Earthquake TerminologyTerminology

Strike-slip FaultsStrike-slip FaultsRupturesurface

Hypocenter

Hypo-center

Epicenter

Faultplane

Fault

strike-slipstrike-slip - Hector Mine (M - Hector Mine (Mww7.1)7.1)

Photo by Paul ‘Kip’ Otis-Diehl,USMC, 29 Palms

‘A rip in the desert canvas’- Los Angeles Times

Katherine Kendrick, USGS

Chris Walls, Earth Consultants International

What Controls theWhat Controls theLevel of Shaking?Level of Shaking?What Controls theWhat Controls theLevel of Shaking?Level of Shaking?

Magnitude– More energy released

Distance– Shaking decays with distance

Local soils– Amplify the shaking

Undamaged buildings on the faultUndamaged buildings on the fault

1906San Francisco

Damage at Damage at great great

distancedistance

The Bay Bridge

1989 Loma Prieta

The Marina District

Probabilistic Seismic Hazard AnalysisProbabilistic Seismic Hazard AnalysisProbabilistic Seismic Hazard AnalysisProbabilistic Seismic Hazard Analysis

Determine the rate of earth-quakes

Probable earthquake forecast for 30-year time frame for the southern California region

California has many faults!California has many faults! San Andreas fault

carries about 2/3 of the plate boundary motion

Faults such as the Newport-Inglewood and ‘blind thrust’ faults also pose significant hazards

Los Angeles metro region faultsLos Angeles metro region faults

The Newport-Inglewood (NIF) is one of many faults that pose hazard to Newport Beach

NIF has been seriously considered as a potential source for a devastating earthquake

QuickTime™ and aTIFF (Uncompressed) decompressorare needed to see this picture.

Newport-Inglewood faultNewport-Inglewood fault

Killed 120 people in the 1933 earthquake; 70th anniversary next Monday

Oil production from six

fields led to very detailed mapping and subsurface imaging

San Joaquin Hills faultSan Joaquin Hills fault

Grant et al. - suggested on basis of deformed and uplifted marine terraces

Hazard impact is uncertain but official hazard maps will attempt to include it in future revisions

Living with earthquakesLiving with earthquakeswithout without predictionprediction

Living with earthquakesLiving with earthquakeswithout without predictionprediction

Build to withstand earthquakesEarthquakes don’t kill people—buildings do

Evaluate earthquake rates “Climate” not prediction

State-of-the-Art Earthquake Monitoring Improve earthquake response Earthquake early warning

CISNCISNCISNCISN

A network of ground motion sensorsA cooperative project between:

U. S. Geological SurveyCalifornia Institute of Technology California Division of Mines and Geology

The SCIGN array uses GPS The SCIGN array uses GPS to measure the buildup and to measure the buildup and

release of strain on the release of strain on the fault system in southern fault system in southern

CaliforniaCalifornia

Improved responseImproved responseImproved responseImproved response

Post-disaster mitigation

Reducing actual losses

–Fires

–Aftershocks and foreshocks

–Search and rescue

EarthScopeEarthScopeand ANSSand ANSS

CISN and SCIGN in SoCal (since 1994 Northridge earthquake) are state-of-the-art arrays

Prototypes for deployment at large-scale in ANSS and EarthScope

http://pasadena.wr.usgs.gov/

http://www.scign.org/

http://www.trinet.org/

For additional information –

hudnut@usgs.gov

Arthur C. Clarke's 2nd Law:

"The only way of discovering the limits of the possible

is to venture a little way past them into the impossible."

USGS photoby John Galetzka