ABAG Shaken Awake Report - Modeling Results

	ABAG Shaken Awake! Report Northern Hayward Earthquake

	from the 1996 report (NOT updated with 2003 data)

Regional Map of Ground Shaking Intensity from the Northern Hayward Earthquake
Chart Showing Bay Area Housing Impacts from the Northern Hayward Earthquake
Map Showing Peak Shelter Population from the Northern Hayward Earthquake

This scenario earthquake is for a magnitude 7.1 earthquake on the northern segment of the Hayward fault between San Pablo Bay and southern Oakland.
The effects of a strong earthquake along any portion of the Hayward fault would be devastating because this area is so heavily urbanized. Of the damage forecasts outlined in this report, the three estimates for events along the Hayward fault (northern segment, southern segment and the entire length) are clearly the most devastating. The predicted damage for an event along the northern segment of the Hayward fault is next in damage only to an event along the entire length of this fault. Almost 88,000 dwelling units are predicted to become uninhabitable and of these, 88% are forecasted to be in either Alameda or San Francisco counties.
In all three scenarios of the Hayward fault, Alameda County is consistently the hardest hit. During an event on the northern segment of the Hayward fault, the estimates of uninhabitable dwellings in Alameda County are higher by a factor of four and eight than in the next hardest hit counties -- San Francisco and Contra Costa counties respectively. An estimated 90% of Alameda County's unreinforced masonry (URM) building stock would be deemed uninhabitable. In terms of actual numbers, the highest damage is estimated to occur to one to three story multi-family construction; an estimated 47% of these units built prior to 1940 and 15% of the units built after 1940 would be deemed uninhabitable in Alameda County.
As in the case of the estimate of uninhabitable dwelling units, Alameda County is again the hardest hit in terms of both displaced and peak shelter populations. Almost 150,000 people in Alameda County would be displaced, creating a need to shelter over 45,000 people in that county alone.
The peak shelter population is not limited to the area adjacent to the fault, however. In fact, the largest shelter requirements are in areas not directly adjacent to the fault but within inner city areas where the shaking intensities would not be the highest. Because shelter population calculations include income and other demographic variables, central city areas are impacted the most. Both Alameda and San Francisco counties are expected to produce the highest percentages of shelter populations relative to their respective displaced population. In each case, approximately 30% of their displaced population, about 5% higher than Marin or Santa Clara counties, is expected to go to shelters.

ABAG, the Association of Bay Area Governments, is the regional planning and services agency for the nine-county San Francisco Bay Area.

This page was last updated 10/20/03 by jbp.