M. Demirdjian, B. Mckenzie, D. Perera, J. Reschke, D. Rodriguez, C. Sandoval, A. Siripaisan, K. Vargas, J. Ying “ShakeOut Scenario”

Dr. John Dye (Math Department)

Crack (Fault) Model Displacement at GPS station from the fault Fault and Displacement Theory

Displacement GPS station data can show us the amount of displacement of the ground after an earthquake.

INTRODUCTION

After the devastating 1906 San Francisco earthquake, Geology Professor Henry Reid concluded (after examining the displacement of the ground surface) that the earthquake must have involved an "elastic rebound" of previously stored elastic stress. 1 “The gradual accumulation and release of stress and strain is referred to as the ‘elastic rebound theory’ of earthquakes. As plates on opposite sides of a fault are subjected to force and shift, they accumulate energy and slowly deform until their internal strength is exceeded. At that time, a sudden movement occurs along the fault, releasing the accumulated energy, and the rocks snap back to their original undeformed shape.” 2

This picture demonstrates the elastic rebound theory. The two plates are subject to force over a long period of time and begin to deform. Eventually enough energy is accumulated to break the two plates apart along the fault. The two plates are permanently separated, but revert to their original shapes.

Our stick-slip fault demonstration can be found on YouTube!YouTube Information taken from: 1 : 2 :

Cause by breaking of rocks in the fault, which gives off energy Recorded on the seismographs to measure the intensity. Traveling speed can vary based on the density and type of rock. Body waves and surface waves.

Oscilloscope & Transducer

P-wave (Primary wave) – The fastest traveling waves, but not often felt. – Push-and-pull motion – Travels through solids, liquids, and gases. – Can be detected by Seismologists – Used in an early warning system S-wave (Secondary or Shear wave) – Can be felt in an earthquake. – Can only travel through solids – Move the ground perpendicular to the direction the wave is traveling. – Slinky Demo!

Love wave – Fastest surface wave and move the ground side to side. Rayleigh wave – Rolls along the ground and move the ground up and down and side to side.

Moment = Mo = GAD G = shear modulus A = L*W = area D = average displacement during rupture

Sediment-Filled Valleys Amplify Shaking

Liquefaction is a natural phenomenon that occurs when underground water is forced up, causing the surface soil to liquefy, creating an effect similar to quicksand. One of the main causes of liquefaction is earthquakes, due to the pressure generated by heavy seismic activity.

The ShakeOut Scenario By Lucile M. Jones, and others (2008) USGS Greatly affect 8 counties of So. California 300 km (180 mi) rupture Magnitude seconds of fault rupture Ground shaking for over 2 minutes in many places! Disruption of critical lifeline infrastructure (freeway, internet, power and gas lines) along surface rupture; Slip of 3-4 meters at Cajon Pass (I-15)

All lifelines Cross San Andreas Fault

300,000 significantly damaged (1 in 16) – repairs cost at least 10% of replacement cost 45,000 complete losses (1%) Unreinforced masonry buildings 900 destroyed; loss of life near fault not retrofitted Older concrete buildings (most dangerous-rebar) – 50 collapses – 5,000 – 10,000 people in collapsed buildings – 100 red tagged buildings Woodframe buildings (most numerous) – 175,000 wood buildings significantly damaged (1 in 25) 1994 Northridge CA 1992 M7.1 Mendocino Long Beach 1933

Earthquakes cause fire disasters –Numerous simultaneous ignitions –Degraded fire-resistive building features –Reduced pressure in water mains –Saturated communications –Traffic impacts –More fires than firefighting capabilities… Study findings – 1,600 ignitions requiring a fire engine – 1,200 exceed capability of 1 st engine – Northern Orange County & LA Basin: conflagrations destroy 100s of blocks – 200 million square feet burnt ~ 1.5% of total building stock – No Santa Ana winds… not worst case –900 of the 1,800 casualties are from fire Fire risk greatest in areas with strong shaking and densely-packed wood buildings; many such areas in LA Basin and northern OR Counties Where’s the Water??

Widespread need for help Distant mutual aid Widespread disruption of: – communication – transportation and access – water pressure – hospital functionality – staffing

Damaging earthquakes may occur for decades after a magnitude 7.8 – Some may be more destructive than the mag 7.8 mainshock – Some will be larger than Northridge – Will occur over wide area Simulations of realistic aftershock sequences for Scenario – Four aftershocks will be used in Golden Guardian exercises: Mag 7.2 ruptures through Inland Empire toward Pasadena Mag 7.0 ruptures from Salton Sea into Imperial County Mag 5.7 with epicenter in Rialto Mag 6.0 disrupts newly restored rail lines in Cajon Pass Distribution of aftershocks in Scenario simulations

Economic Losses Direct: property damage & business interruption Indirect: ancillary damage & ripple effects Building damage from ground motion Transportation route closure and delays Water shut-off Power outage Gas shut-off Building damage from fire Adjusted for double-counting/multiple sources

Are Californians Prepared? March 5, 2010 Study by UCLA: Less than 20% have prepared their homes 40% have sufficient water Less than 20% have earthquake insurance 80% have first aid kits, flashlights, batteries 40% have no family emergency plan Less than 20% have a neighborhood plan Less than 50% have dust masks; rescue tools; supplies in car or work or CERT or first aid trained

Google Earth Tour Special thanks to Dr. Steve Graves (Geography Department)

Shakeout Scenario “Disaster Equation” Widespread Strong Ground Shaking + Shaking of Long Duration = 300,000 buildings significantly damaged Widespread infrastructure damage $213 billion damages 270,000 displaced persons 50,000 injuries 1,800 deaths