Ridgecrest shows how earthquakes damage Earth's crust

Date:
February 24, 2022
Source:
University of California - Davis
Summary:
In July 2019, a series of earthquakes including two major shocks
of magnitude 6.4 and 7.1 a day apart struck near Ridgecrest,
CA, between Los Angeles and Las Vegas. For local residents, it
was a violent interruption to the Fourth of July holiday. For
seismologists, it was a rare opportunity to study how earthquakes
damage the Earth's crust.



FULL STORY ==========================================================================
In July 2019, a series of earthquakes including two major shocks of
magnitude 6.4 and 7.1 a day apart struck near Ridgecrest, CA, between
Los Angeles and Las Vegas. For local residents, it was a violent
interruption to the Fourth of July holiday. For seismologists, it was
a rare opportunity to study how earthquakes damage the Earth's crust.


==========================================================================
The earthquake zone -- which belongs to a network of faults called the
Eastern California Shear Zone -- is sparsely populated and arid, without
much in the way of vegetation or buildings to obscure the surface. But
it is also well- covered by satellite and remote imagery and accessible
to geologists who could be on the scene well before evidence of crust
damage disappeared.

UC Davis doctoral student Alba Rodri'guez Padilla was among the scientists studying the site, along with Professor Mike Oskin, Department of Earth
and Planetary Sciences, Christopher Milliner, California Institute of Technology and Andreas Plesch of Harvard University. They mapped the
surface rupture from LIDAR data and aerial imagery collected by prior
studies, and compared the rupture maps to other datasets to explore the distribution of rock damage from the earthquakes. Their findings are
published Feb. 24 in Nature Geoscience.

"We not only have aridity helping here, improvements in imaging technique
and resolution, together with collecting a large spatial data footprint,
are what make the Ridgecrest coverage cutting edge," Rodri'guez Padilla
said.

Inelastic deformation The rock surrounding the fault suffered from
"inelastic deformation," meaning it was deformed and broken rather than returning to its original configuration.

The deformation was highest within 100 meters of the fault, with
widespread, low-intensity damage up to 20 kilometers (16 miles) away.

This deformation leaves the rock around the fault less rigid than before, softening the crust. This softening dissipates energy from future
earthquakes, increases permeability and focuses deformation.

The study provides a better understanding of how damage from earthquakes accumulates and might affect future events, Rodri'guez Padilla said.

The study was funded by the Southern California Earthquake Center,
which is supported by NSF and the U.S. Geological Survey. Rodri'guez
Padilla was partly supported by a NASA fellowship.

========================================================================== Story Source: Materials provided by
University_of_California_-_Davis. Original written by Andy Fell. Note:
Content may be edited for style and length.


========================================================================== Journal Reference:
1. Alba M. Rodriguez Padilla, Michael E. Oskin, Christopher
W. D. Milliner,
Andreas Plesch. Accrual of widespread rock damage from the
2019 Ridgecrest earthquakes. Nature Geoscience, 2022; DOI:
10.1038/s41561-021- 00888-w ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2022/02/220224112655.htm

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