Liquefaction Hazard and Shaking Amplification Maps
Alameda, Berkeley, Emeryville, Oakland, and Piedmont, California: A Digital Database
Liquefaction Map
This map shows the liquefaction hazard in the communities of Alameda, Berkeley, Emeryville, Oakland, and Piedmont for a magnitude 7.1 earthquake on the Hayward fault. The map predicts the approximate percentage of each designated area that will liquefy and show surface manifestations of liquefaction such as sand boils and ground cracking. Liquefaction is a phenomenon that is caused by earthquake shaking. Wet sand can become liquid-like when strongly shaken. The liquefied sand may flow and the ground may crack and move causing damage to surface structures and underground utilities. The map depicts the hazard at a regional scale and should not be used for site-specific design and consideration. Subsurface conditions can vary abruptly and borings are required to address the hazard at a given location. High quality printable image.
Ground-shaking Amplification Map
This map shows the capability of the ground to amplify earthquake shaking in the communities of Alameda, Berkeley, Emeryville, Oakland, and Piedmont. The National Earthquake Hazards Reduction Program recognizes 5 categories of soil types and assigns amplification factors to each. Type E soils in general have the greatest potential for amplification, and type A soils have the least. These soil types are recognized in many local building codes. Records from many earthquakes show that ground conditions immediately beneath a structure affect how hard the structure shakes. For example, sites underlain by soft clayey soils tend to shake more violently than those underlain by rock. The map depicts the amplification potential at a regional scale, and it should not be used for site specific design. Subsurface conditions can vary abruptly and borings are required to estimate amplification at a given location. High quality printable image.
Complete USGS Open-file report 02-296 includes full text and spatial database files.
