Research ArticleGEOPHYSICS

Revisiting evidence for widespread seismicity in the upper mantle under Los Angeles

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Science Advances  22 Jan 2021:
Vol. 7, no. 4, eabf2862
DOI: 10.1126/sciadv.abf2862
  • Fig. 1 Map of Los Angeles Basin and Long Beach phase B deployment.

    (A) Map of Los Angeles Basin showing the Newport-Inglewood Fault and other faults (LB, Long Beach; VF, Verdugo Fault; ERF, Eagle Rock Fault; EMF, East Montebello Fault; WHF, Workman Hill Fault). Red star shows epicenter of the 1933 Long Beach earthquake. Blue and green polygons outline the Long Beach phase A and B deployments. Blue dot is epicenter of a local M 2.1 earthquake that occurred during the deployment of phase B. OO′ is a profile across the epicenter. (B) Map of Long Beach phase B deployment. Stripe of missing sensors in the upper left is the Long Beach Airport runway. Narrow gap in the northern and eastern part of the deployment tracks the I-405 Freeway. Black lines show mapped surface trace of the Newport-Inglewood Fault. Red dashed rectangle is the surficial boundary for the 3D imaging cube we use in our analysis.

  • Fig. 2 Earthquake imaging/location and statistical results.

    (A) and (B) are the BP imaging results of Julian day 28, 2012 night time (local) on original and trace-randomized data, respectively; (C) is the BP relocation result on the same data in (A) using the new detection criterion; (D) and (E) are the statistical results for detections on 1 and 10 days, respectively. Energy in (D) is calculated by summing up the imaging amplitudes of all the detections.

  • Fig. 3 Horizontal slices for earthquake detection on Julian day 28, 2012 (night time) under the new criterion.

    (A) Horizontal slices for different depth ranges of 0 to 5 km, 5 to 10 km, 10 to 15 km, 15 to 20 km, and 20 to 25 km, respectively. (B) Horizontal slice for 0- to 5-km-depth range under a slightly higher detection threshold.

  • Fig. 4 Schematic plot for the strain rate at seismogenic depth.

Supplementary Materials

  • Supplementary Materials

    Revisiting evidence for widespread seismicity in the upper mantle under Los Angeles

    Lei Yang, Xin Liu, Gregory C. Beroza

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    • Figs. S1 to S10
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