The following shaking amplification map was used in the development of the ABAG shaking scenario maps. To view an earthquake hazard map showing shaking amplification for the geologic materials in an area, choose a city from the following list, then click the View Map button:
About Shaking Amplification
All ground in the Bay Area was not created equal. A critical factor affecting intensity at a site is the geologic material underneath that site. Deep, loose soils tend to amplify and prolong the shaking. The worst such soils in the Bay Area are the loose clays bordering the Bay — the Bay mud — and the filled areas. The type of rock that least amplifies the shaking is granite. The remaining materials fall between these two extremes, with the deeper soils in the valleys shaking more than the rocks in the hills. Most development is in the valleys. The map opposite groups the geologic materials in the region into eight categories, each with similar amplification in earthquakes.
If you compare two houses, both of which are the same distance and orientation to the earthquake source, the one on Bay mud will experience stronger and longer shaking than the one on rock.