Imaging Stress and Faulting Complexity Through Earthquake Waveform Similarity

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

Submitted July 27, 2020, SCEC Contribution #10209, 2020 SCEC Annual Meeting Talk on TBD

While the rupture processes of nearby earthquakes are often highly similar, characterizing the differences can give insight into the details of the local stress field and in-situ fault network. In this work, we perform a comprehensive analysis of the similarity of earthquakes occurring near Ridgecrest, California. We combine a high-precision relocated catalog with the cross-correlation of full waveforms across multiple stations to measure how similar each earthquake is to its nearest neighbors. The July 2019 Ridgecrest mainshocks impose a step reduction in similarity throughout the region, which suggests substantial variability in the residual stress field and activated fault structures on length scales of hundreds of meters or less. Among the Ridgecrest aftershocks, we observe coherent variations of earthquake similarity along the rupture trace of the M7.1 mainshock, and with spatial resolution much improved over that which can be obtained from analysis of earthquake focal mechanisms. We also document several dozen instances of anti-similar aftershock pairs, with waveforms that are nearly identical at multiple stations but with reversed polarity. These observations provide new, high-resolution constraints on stress transfer and faulting complexity throughout the Ridgecrest earthquake sequence.

Key Words
Waveform similarity, Ridgecrest, Stress field, Faulting

Trugman, D. T., Ross, Z. E., & Johnson, P. A. (2020, 07). Imaging Stress and Faulting Complexity Through Earthquake Waveform Similarity. Oral Presentation at 2020 SCEC Annual Meeting.

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