Nodal Seismic Experiment at the Berkeley Section of the Hayward Fault

The Hayward fault (HF) in the San Francisco Bay area of California is one of the most hazardous faults of the San Andreas fault system with a total length of 70 km. In November 2020, we conducted a dense array experiment that deployed 182 three-component nodal sensors for about a five-week period at the Berkeley section of the HF. Our primary goal of this experiment was to image the seismic velocity structure in the upper crust of this area to better understand the fault-zone structure and its elastic properties. A linear array (10 stations with 5???10 m spacing) was deployed on the north side of University of California, Berkeley Memorial Stadium where the HF runs underneath, together with 27 stations that were installed surrounding the stadium. Here we detail our scientific motivation, station metadata, and quality of seismic waveforms. We also show initial results of fault-zone guided waves observed from the linear array and provide first-step results of Green???s functions between nodal stations obtained by an ambient noise cross-correlation analysis.