The Next Bay Area Earthquake What to expect Where? When? How Large? Dr. John Boatwright, Bay Area...
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Transcript of The Next Bay Area Earthquake What to expect Where? When? How Large? Dr. John Boatwright, Bay Area...
The Next Bay Area Earthquake
What to expectWhere? When? How Large?Dr. John Boatwright, Bay Area Earthquake Alliance Co-Chair
Co-Regional Coordinator for Northern California US Geological Survey
Pacific platePacific platePacific platePacific plate
North AmericanNorth Americanplateplate
North AmericanNorth Americanplateplate
40 mm/yr Farallons-Sierra Nevada
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15151515
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7777
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What is the History of Large Earthquakes in the
Bay Area?• 1989 Loma Prieta (M6.9)
• 1906 San Francisco (M7.8)
• 1868 Hayward (M6.8)
• 1838 Peninsula (M7?)
• Paleoseismic Earthquakes (pre-1776) identified
by trenching active faults
“We need to correct our style of architecture … to work a savings of untold sums of money in the future” - San Jose Mercury News October 29, 1868
Hayward Earthquake
1868
San Francisco
1906
Cum
ulat
ive
M0,
dyn
e-cm
Moment Accumulation in the SF Bay Region
1989
Loma Prieta
Bay Area Earthquake History
1600-2000 A.D.
In the next 30 years, there is a 63% prob-ability, nearly a 2/3rds chance, of an M6.7 or larger earthquake in the greater Bay Area. Hazard is highest in the East Bay due to the larger number of faults there, including the Hayward fault.(UCERF2 Report, 2007)
2007-2036
21%
31%
3%
1%
3%63%
6%
7%
11%
M ≥ 6.7
Hazard is highest in the East Bay due to the larger number of faults including theHayward Fault.
1868 Hayward1868 HaywardEarthquakeEarthquake
Near-Field MMI Near-Field MMI Intensities areIntensities are strong strong from Sanfrom SanLeandro south Leandro south through Hayward through Hayward towards Alvaradotowards Alvarado(MMI 8-9 & 9)(MMI 8-9 & 9)
But they appearBut they appear moderatemoderate in both in both Oakland and Oakland and MilpitasMilpitas(MMI 7-8 & 8)(MMI 7-8 & 8)
38°
-122.5°
37.5°
-122°
14
Hayward Fault Earthquake:The Infrastructure Earthquake
QuickTime™ and aH.264 decompressor
are needed to see this picture.
Animation of Shaking from a M7.0 on the Hayward FaultFremont Epicenter
http://earthquake.usgs.gov/regional/nca/simulations/hayward/
QuickTime™ and aH.264 decompressor
are needed to see this picture.
Losses by county - M7.0 scenario
16
Solano
Sonoma
Santa Clara
Santa MateoSan
Francisco
Marin
Contra Costa
Alameda
$0 $40B $80 $100
Economic Loss ($Billions)
What can happen in the urban neighborhoods of the Bay Area in next large earthquake?
• Soft-Story Damage & Failures
• Fire Following Earthquake
Soft-Story Buildings
18
soft-story retrofits in San Francisco are still voluntary
rather than mandatory
This photo shows the vulnerability
that the Loma Prieta earthquake exposed
We Were Very Fortunate in 1989
Marina fireTo Have Favorable Fire Conditions
38°
37.5°
37°
123° 122° 121°
google: cisn shakemap nchttp://www.cisn.org/shakemap/nc/shake/