ABAG Shaken
Awake! Report
San Gregorio Earthquake
from
the 1996 report (NOT updated with 2003 data)
|
ABAG Shaken
Awake! Report |
|
|
|
from
the 1996 report (NOT updated with 2003 data)
|
Regional Map of Ground Shaking Intensity from the San Gregorio Earthquake
This scenario earthquake is for a magnitude 7.1 earthquake on the San Gregorio fault in San Mateo County.
The overall damage from an earthquake along the San Gregorio fault is less compared to that on the San Andreas Peninsula earthquake (3.5% of San Francisco County's total stock is made uninhabitable, and only 0.5% of San Mateo County's total stock is made uninhabitable). However, the damage pattern of the San Andreas fault, where San Francisco is impacted more heavily than San Mateo County, is magnified. With an earthquake along the San Gregorio fault, the impacts in San Francisco in terms of uninhabitable dwelling units are almost nine times greater than those in San Mateo County. This damage pattern is due to building stock differences in age and density between the two counties, even though the earthquake source is in San Mateo County.
An analogous effect is taking place in Alameda County. Although Alameda County is significantly farther away from the source of the event than San Mateo County, Alameda County's housing stock tends to be both older and more susceptible to earthquake damage. This is apparent from looking at the damage estimates for the pre- 1940 categories which tend to be higher in both San Francisco and Alameda counties.
Following the pattern of uninhabitable dwelling units, the peak shelter population estimate for San Francisco is almost ten times higher than in San Mateo County, where the earthquake source is located.
The difference between older and denser urban counties and newer and more suburban ones is evident when comparing the uninhabitable dwelling units of Alameda and San Mateo counties with their respective shelter populations. While there are 50% more uninhabitable dwelling units in Alameda County than in San Mateo County, there are only 37% more people displaced due to fewer average people per household. This "reduction" is more than offset by the demographic factors, particularly income, which result in over 72% more people requiring shelter in Alameda County than in San Mateo County. At the same time, 72% of the shelter-seeking population in Alameda County is generated by yellow-tagged dwelling units while in San Mateo County this number drops to 54%. These differences result from statistics showing that individuals within older and denser urban counties are more likely to go to shelters than those living in newer more suburban counties.
 |
 |
 |
.
This page was last updated 10/20/03 by jbp.