Using Waveform Modeling to Determine the Depth of the Deepest Earthquakes on and Near the Newport-Inglewood Fault Zone in the Los Angeles Basin

Chloe S. Sutkowski, & Jascha Polet

Published August 15, 2016, SCEC Contribution #6816, 2016 SCEC Annual Meeting Poster #227 (PDF)

The depth extent of many faults in the Los Angeles Basin is still poorly determined. It has been suggested that many are part of shallow decollement systems. However, Boles et al. (2015) conclude that a strong mantle helium signal along the Newport-Inglewood Fault Zone indicates that it is a deep-seated fault, directly or indirectly connected with the mantle. To help address this question, we are analyzing seismic waveform data from close-in broadband stations for the deepest earthquakes in the LA basin above a magnitude 2.5 or higher in the last ten years. Initial analysis of the relocated Southern California Seismic Network catalog by Hauksson et al. (2012) reveals that for the thirty-five deepest earthquakes in the LA basin, the majority occurred near or along the Newport Inglewood Fault Zone at depths in a range of 10 km - 17 km. The waveforms for close-in stations for these events will be compared to synthetic seismograms generated using a frequency-waveform approach, for a suite of one-dimensional velocity models for the Los Angeles Basin. Accurate depths will be determined by finding the best match from these synthetics, calculated for a range of depths, and the waveform data. We will present our preliminary results from an analysis of several of these events. We will also show maps and cross-sections of the earthquake focal mechanism catalog by Yang et al. (2012) and the relocated earthquake location catalog by Hauksson et al. (2012) for our area of interest to investigate the correspondence to mapped surface fault traces and the seismotectonic characteristics of the Newport Inglewood Fault Zone along its length.

Key Words
Newport Inglewood Fault Zone, deep earthquakes, synthetic seismograms

Citation
Sutkowski, C. S., & Polet, J. (2016, 08). Using Waveform Modeling to Determine the Depth of the Deepest Earthquakes on and Near the Newport-Inglewood Fault Zone in the Los Angeles Basin. Poster Presentation at 2016 SCEC Annual Meeting.

Related Projects & Working Groups
Seismology