Anti-similar aftershocks in the Ridgecrest, California earthquake sequence

Daniel T. Trugman, Zachary E. Ross, & Paul A. Johnson

Submitted August 13, 2019, SCEC Contribution #9506, 2019 SCEC Annual Meeting Poster #266

Similar earthquakes - pairs of events with highly similar waveforms - rupture overlapping or adjacent fault patches with similar slip mechanisms. Close examination of the characteristics of similar earthquake pairs have been used for a variety of scientific purposes, including to improve earthquake locations, and to image fault creep or subsurface changes in velocity structure. Here we use similar earthquake pairs to gain insight into seismicity in the vicinity of the 2019 Ridgecrest, California earthquake sequence. We document similar earthquake pairs occurring both years before and in the days after the initial M6.4 Ridgecrest earthquake, though few if any pairs bridge this temporal gap. Additionally, we find that a small percentage of Ridgecrest aftershocks exhibit anti-similarity, with waveforms that are nearly identical but with reversed polarity, perhaps indicating a complete reversal of fault slip on a given fault patch. We hope to use these observations to provide improved constraints on the crustal stress distribution and stress transfer during the Ridgecrest earthquake sequence.

Key Words
Ridgecrest, aftershocks, similar earthquakes

Citation
Trugman, D. T., Ross, Z. E., & Johnson, P. A. (2019, 08). Anti-similar aftershocks in the Ridgecrest, California earthquake sequence. Poster Presentation at 2019 SCEC Annual Meeting.


Related Projects & Working Groups
Ridgecrest Earthquakes