The greater Los Angeles area is a megacity by the United Nations definition and the third largest city in the world based on combined statistical area. Here the seismic hazard is driven by the potential proximity of large earthquakes and complicated local structure. Sources of potentially damaging earthquakes in the LA area include the southern San Andreas Fault, located roughly 60 km north-east of the city, as well as the series of faults that lie below the area. The collection of complex sedimentary basins underlying the area are known to amplify the motions from seismic waves, and this effect may be underestimated in current ground motions estimates. The Basin Amplification Seismic INvestigation (BASIN) project was started in 2017. It is a multicomponent earthquake hazard project between LSU, Caltech, Harvard, Cal Poly Pomona and SDSU that focuses on characterizing the amplification of seismic waves as they travel through sedimentary basins. Our goal is to first map the structure of the basins in the Los Angeles area, and to integrate the basins’ structure into computer simulations of ground motion. As part of the BASIN project, we have deployed 744 nodal seismometers along 10 densely-spaced seismic profiles in the greater Los Angeles area. Our deployment teams were comprised of ~60 volunteers. I will present project results, and practical information on our seismic experiment and the community involvement of Los Angeles area residents.
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