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Applying Depth Distribution of Seismicity to Determine Thermo-Mechanical Properties of the Seismogenic Crust in Southern California: Comparing Lithotectonic Blocks

Hauksson, Egill and Meier, Men-Andrin (2019) Applying Depth Distribution of Seismicity to Determine Thermo-Mechanical Properties of the Seismogenic Crust in Southern California: Comparing Lithotectonic Blocks. Pure and Applied Geophysics, 176 (3). pp. 1061-1081. ISSN 0033-4553 . http://resolver.caltech.edu/CaltechAUTHORS:20180904-141441844

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Abstract

We analyze waveform-relocated seismicity (1981–2016) and other geophysical and geological datasets from 16 lithotectonic crustal blocks in southern California. We explore how earthquake depth histograms (EDH) are related to crustal strength, lithology, and temperature of the crust. First, we calculate relative EDHs to quantify the depth distribution of seismicity for each lithotectonic block. Second, we calculate depth profiles of maximum differential stress (“yield strength envelopes”, YSEs) using Byerlee’s law and a non-linear dislocation creep law. We use observed average heat flow values, strain rates, and states of stress to parameterize YSEs for five different crustal candidate lithologies in each lithotectonic block. We assume that seismicity ceases where the mechanical rock strength falls below a critical threshold level, and identify the YSE that best predicts the depth extent of seismicity in each block. The lithologies of the best matching YSEs are found to agree well with expectations from past tectonics: they are mostly quartz-dominated except for the feldspar-rich diorite lithologies in the Great Valley, the southernmost western Sierra Nevada, Inner Continental Borderland, and Rifted crust in the Salton Trough. Similarly, the inferred thermo-mechanical properties, including differential stress, lithology, and geotherms reflect the previously mapped tectonic variability between the 16 lithotectonic blocks. On average, the differential yield stress is smaller and peaks at a shallower depth in hotter and more quartz rich crust but is larger and peaks at greater depths for colder and predominantly diorite crust. The good agreement between the modeled YSEs, the EDHs and tectonic considerations suggests that EDHs indeed reflect long-term geophysical properties of the crust and can be used to infer thermo-mechanical properties at depth. In contrast, shallow seismicity may be more likely to reflect short-term strain transients from fluid flow or recent anthropogenic disturbances.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.1007/s00024-018-1981-zDOIArticle
https://rdcu.be/5O9OPublisherFree ReadCube access
ORCID:
AuthorORCID
Hauksson, Egill0000-0002-6834-5051
Meier, Men-Andrin0000-0002-2949-8602
Additional Information:© 2018 Springer Nature Switzerland AG. Received: 26 March 2018; Revised: 16 August 2018; Accepted: 20 August 2018; First Online: 03 September 2018. We thank J.-P. Avouac, N. Beeler, L. M. Jones, J. P. Ampuero, N. van der Elst, and J. Stock for discussions; J. Albaric for sharing her matlab code for calculating the YSEs, and Z. Ross for the declustered catalog. This research was supported by USGS/NEHRP grants G16AP00147 & G18AP00028; NSF award: EAR-1550704; and by the Southern California Earthquake Center, which is funded by NSF Cooperative Agreement EAR- 1033462 and USGS Cooperative Agreement G12AC20038. This paper is SCEC contribution # 8085. We used GMT from Wessel et al. (2013) to make the Figures. We have used waveforms and parametric data from the Caltech/USGS Southern California Seismic Network (SCSN); https://doi.org/10.7914/sn/ci; stored at the Southern California Earthquake Data Center. https://doi.org/10.7909/c3wd3xh1.
Group:Seismological Laboratory
Funders:
Funding AgencyGrant Number
USGSG16AP00147
USGSG18AP00028
NSFEAR-1550704
Southern California Earthquake Center (SCEC)UNSPECIFIED
NSFEAR-1033462
USGSG12AC20038
Subject Keywords:Earthquake depth histograms, yield strength envelopes, lithology, crustal temperature, crustal thermomechanics
Other Numbering System:
Other Numbering System NameOther Numbering System ID
Southern California Earthquake Center8085
Record Number:CaltechAUTHORS:20180904-141441844
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:20180904-141441844
Official Citation:Hauksson, E. & Meier, MA. Pure Appl. Geophys. (2019) 176: 1061. https://doi.org/10.1007/s00024-018-1981-z
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:89363
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:04 Sep 2018 21:48
Last Modified:21 Mar 2019 23:09

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