Mapping Los Angeles Basin Depth With Sp Converted Phases

Abstract The depth of the Los Angeles (LA) basin is a critical factor for seismic hazard assessment and active tectonic studies. By analyzing S‐waves generated by earthquakes below the basin that convert to P‐waves at the sediment‐bedrock interface, we estimate the maximum depth of the LA basin to be 9 km. This estimate depends on the velocities within and below the basin, and the depth presented here is based on the latest community velocity model. To map the basin depth, we use two dense arrays: the Community Seismic Network, a dense network of low‐cost accelerometers in schools across LA region, and a basin‐wide node survey conducted in 2022, consisting of about 300 geophones deployed for a month. Utilizing differential travel times between direct S and Sp converted phases of local earthquakes, we produce a detailed depth map of the LA basin.