General Seismic Architecture of the Southern San Andreas Fault Zone around the Thousand Palms Oasis from a Large-N Nodal Array

Abstract We discuss general structural features of the Banning and Mission Creek strands (BF MCF) southern San Andreas fault (SSAF) in Coachella Valley, based on ambient noise earthquake wavefields recorded by a seismic array with >300 nodes. Earthquake P arrivals show rapid changes waveform characteristics over 20–40 m zones that coincide surface BF MCF. These variations indicate MCF are high-impedance contrast interfaces—an observation supported presence reflections. Another prominent but more diffuse change SSAF structure is found ∼1 km northeast BF. This feature has average-to-low arrival times (P S) levels (at <30 Hz), likely represents relatively fast velocity block sandwiched between broader zones. The maximal delays ∼0.1 s S ∼0.25 s) highest (>2 median) consistently observed southwest BF—a combined effect Valley sediments rock damage side. Immediately MCF, large minus suggest broad high VP/VS zone associated asymmetric across SSAF. overview shows as mature distinctly different Future analyses will further clarify these other greater detail.