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Were changes in stress state responsible for the 2019 Ridgecrest, California, earthquakes?

2020; Nature Portfolio; Volume: 11; Issue: 1 Linguagem: Inglês

10.1038/s41467-020-16867-5

2041-1723

K. Z. Nanjo,

Geological and Geochemical Analysis

Abstract Monitoring the Earth’s stress state plays a role in our understanding of an earthquake’s mechanism and in the distribution of hazards. Crustal deformation due to the July 2019 earthquake sequence in Ridgecrest (California) that culminated in a preceding quake of magnitude ( M ) 6.4 and a subsequent M 7.1 quake caused stress perturbation in a nearby region, but implications of future seismicity are still uncertain. Here, the occurrence of small earthquakes is compared to larger ones, using b -values, showing that the rupture initiation from an area of low b -values, indicative of high stress, was common to both M 6.4 and M 7.1 quakes. The post- M 7.1-quake sequence reveals that another low- b -value zone, which avoided its ruptured area, fell into an area near the Garlock fault that hosted past large earthquakes. If this area were more stressed, there would be a high-likelihood of further activation of seismicity that might influence the Garlock fault.