Oakland Geology

A few years back, two guys at the U.S. Geological Survey did an exercise with a database that was subjected to a mathematical version of the Big One on the Hayward fault in the middle of the wet season. Their result was published as Miscellaneous Field Studies Map MF-2379, “Seismic Landslide Hazard for the Cities of Oakland and Piedmont, California.” Here’s a piece of it.

Dark-green areas are relatively fine, red areas are relatively awful, and the in-between colors are in between. Gray areas have slopes less than 5 degrees and don’t count. There’s a purple line running from top left to bottom right representing the Hayward fault; students of our street patterns may recognize the upper left corner as the intersection of 580 and 13. The lower right corner is 580 at the exit to the zoo. The left edge of the band of orange down the middle is Outlook Avenue. There are two bits of blue; the upper left one is the pond at Mills College and the lower one is the big hilltop reservoir near Toler Heights.

This map is of very little real use, because it’s just one worst-case scenario of one particular simulation, but it’s well worth studying anyway. (For real uses, like assessing your own property, you should hire a pro.) One big point is that bedrock matters. The big dark-green swath represents the solid metavolcanic rocks that are exposed in the Leona Quarry; they also underlie King Estates Open Space and part of the hill with the reservoir on top.

This entry was posted on 3 August 2011 at 5:30 pm and is filed under Earthquakes, Landslides. You can follow any responses to this entry through the RSS 2.0 feed. You can skip to the end and leave a response. Pinging is currently not allowed.