10km Deep Sediments Under LA

A new study by Caltech researchers has created a map of the Los Angeles Basin, revealing deep sediments that could amplify earthquake shaking. The map shows that soft sediments are up to 10 kilometers deep beneath downtown Los Angeles.

The study, led by Caltech graduate student Valeria Villa and conducted with seismologist Robert Clayton, professor emeritus of geophysics, used 273 small seismic sensors installed throughout the LA region. The sensors were spread from Pasadena to Long Beach and from Santa Monica to Orange County, at intervals of 1–2 kilometers.

The researchers found that the depth of the sediments varies across the region, with deeper sediments leading to longer-period shaking. This type of shaking affects larger buildings more than shorter-period shaking, which has implications for building safety.

The study's findings have significant implications for understanding how earthquake damage will be distributed across the city. According to the researchers, the underground basin variations control how the damage will be distributed in the event of a large earthquake.

## Why it matters The Los Angeles Basin is a densely populated urban area, and understanding the underlying geology is crucial for preparing for and responding to earthquakes. The study's findings can help inform building codes and emergency response plans, potentially saving lives and reducing damage in the event of a major earthquake. A paper describing the research was published in the journal Journal of Geophysical Research: Solid Earth on August 4.

The study's results can help city planners and emergency responders identify areas that are more likely to be affected by earthquake shaking, and take steps to mitigate the damage. By understanding the underlying geology of the Los Angeles Basin, researchers and policymakers can work together to create a safer and more resilient city.