Ten Days of Continuous Aftershock Hum Following the 2019 Ridgecrest, California, Mainshocks Observed With Borehole Seismometers
Description:
Seismograms from two borehole seismometers near the 2019 Ridgecrest, California, aftershock sequence do not return to pre-mainshock noise levels until ten days after the M 7.1 Ridgecrest mainshock. The observed distribution of RMS amplitudes in these records can be explained with the Reasenberg and Jones (1989) aftershock occurrence model, which implies a continuous seismic "hum" of overlapping aftershocks of M > -2 occurring at an average rate of 10 events/second at the ten-day mark. This aftershock-generated hum prevents observing the background aseismic noise level at times between the body-wave arrivals from cataloged and other clearly observed events. Even after the borehole noise levels return at their quietest times to pre-mainshock conditions, the presence of overlapping low-magnitude earthquakes for at least 80 days is implied by waveform cross-correlation results provided using the Matrix Profile (MP) method. These results suggest a hidden frontier of tiny earthquakes that potentially can be measured and characterized even in the absence of detection and location of individual events.
Session: New Directions in Environmental, Seismic Hazard and Mineral Resource Exploration Studies - II
Type: Oral
Date: 4/17/2025
Presentation Time: 04:30 PM (local time)
Presenting Author: Peter
Student Presenter: No
Invited Presentation:
Poster Number:
Authors
Peter Shearer Presenting Author Corresponding Author pshearer@ucsd.edu University of California, San Diego |
Nader Senobari nader.shakibaysenobari@email.ucr.edu University of California, Riverside |
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Ten Days of Continuous Aftershock Hum Following the 2019 Ridgecrest, California, Mainshocks Observed With Borehole Seismometers
Category
New Directions in Environmental, Seismic Hazard and Mineral Resource Exploration Studies