Systematic comparison of InSAR and seismic source models for moderate-size earthquakes in Western China: implication to the seismogenic capacity of the shallow crust
Earthquake source parameters are important for understanding earthquake physics and crustal fault properties. However, strong trade-offs between parameters (e.g., depth and origin time) and a lack of accurate velocity models and near-field seismic stations could cause large uncertainties of these pa...
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sg-ntu-dr.10356-1709502023-10-23T15:30:44Z Systematic comparison of InSAR and seismic source models for moderate-size earthquakes in Western China: implication to the seismogenic capacity of the shallow crust Luo, Heng Wang, Teng Wei, Shengji Asian School of the Environment Earth Observatory of Singapore Engineering::Environmental engineering Comparative Study Numerical Model Earthquake source parameters are important for understanding earthquake physics and crustal fault properties. However, strong trade-offs between parameters (e.g., depth and origin time) and a lack of accurate velocity models and near-field seismic stations could cause large uncertainties of these parameters in seismic catalogs, particularly for shallow events. To further improve the resolution of earthquake source parameters, we use Interferometric Synthetic Aperture Radar (InSAR) images to derive source solutions of 33 moderate-size (Mw 4.1–6.6) earthquakes that occurred at shallow depths (<20 km) from November 2014 to July 2020 in western China. After evaluating the uncertainties of the InSAR solutions, we systematically compare the location, centroid depth, focal mechanism and magnitude from InSAR models with that from seismic catalogs. We find that all seismic catalogs generally report deeper (4–10 km) hypocenters or centroid depths. The uncertainties of moment tensor solutions are partially related to the percentage of the non-double-couple components in the seismic catalogs. The InSAR solutions indicate that considerable seismic moments (i.e., ∼ (Formula presented.) Nm) were released in the uppermost crust (i.e., <5 km) in a period of ∼6 years, which is not resolvable in the seismic catalogs. The smooth seismic moment distribution along depth indicates a gradual change of the frictional properties from the surface to the middle crust. As most of the studied earthquakes are located on secondary and/or unmapped faults, these findings imply a considerable portion of velocity-weakening friction in the uppermost crust along immature, secondary fault systems, which should be included in the seismic hazard evaluation. Ministry of Education (MOE) Published version Heng Luo and Teng Wang are supported by the National Natural Science Foundation of China (41974017 and U1939202). Shengji Wei was supported by the Singapore MOE project (MOE2019-T2-1-182) and the Earth Observatory of Singapore via its funding from the National Research Foundation Singapore and the Singapore Ministry of Education under the Research Centres of Excellence initiative. 2023-10-20T04:40:40Z 2023-10-20T04:40:40Z 2022 Journal Article Luo, H., Wang, T. & Wei, S. (2022). Systematic comparison of InSAR and seismic source models for moderate-size earthquakes in Western China: implication to the seismogenic capacity of the shallow crust. Journal of Geophysical Research: Solid Earth, 127(10). https://dx.doi.org/10.1029/2022JB024794 2169-9356 https://hdl.handle.net/10356/170950 10.1029/2022JB024794 2-s2.0-85141725489 10 127 en MOE2019-T2-1-182 Journal of Geophysical Research: Solid Earth © 2022 American Geophysical Union. All rights reserved. This article may be downloaded for personal use only. Any other use requires prior permission of the copyright holder. The Version of Record is available online at http://doi.org/10.1029/2022JB024794 application/pdf |
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Engineering::Environmental engineering Comparative Study Numerical Model Luo, Heng Wang, Teng Wei, Shengji Systematic comparison of InSAR and seismic source models for moderate-size earthquakes in Western China: implication to the seismogenic capacity of the shallow crust |
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Earthquake source parameters are important for understanding earthquake physics and crustal fault properties. However, strong trade-offs between parameters (e.g., depth and origin time) and a lack of accurate velocity models and near-field seismic stations could cause large uncertainties of these parameters in seismic catalogs, particularly for shallow events. To further improve the resolution of earthquake source parameters, we use Interferometric Synthetic Aperture Radar (InSAR) images to derive source solutions of 33 moderate-size (Mw 4.1–6.6) earthquakes that occurred at shallow depths (<20 km) from November 2014 to July 2020 in western China. After evaluating the uncertainties of the InSAR solutions, we systematically compare the location, centroid depth, focal mechanism and magnitude from InSAR models with that from seismic catalogs. We find that all seismic catalogs generally report deeper (4–10 km) hypocenters or centroid depths. The uncertainties of moment tensor solutions are partially related to the percentage of the non-double-couple components in the seismic catalogs. The InSAR solutions indicate that considerable seismic moments (i.e., ∼ (Formula presented.) Nm) were released in the uppermost crust (i.e., <5 km) in a period of ∼6 years, which is not resolvable in the seismic catalogs. The smooth seismic moment distribution along depth indicates a gradual change of the frictional properties from the surface to the middle crust. As most of the studied earthquakes are located on secondary and/or unmapped faults, these findings imply a considerable portion of velocity-weakening friction in the uppermost crust along immature, secondary fault systems, which should be included in the seismic hazard evaluation. |
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Asian School of the Environment |
author_facet |
Asian School of the Environment Luo, Heng Wang, Teng Wei, Shengji |
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Article |
author |
Luo, Heng Wang, Teng Wei, Shengji |
author_sort |
Luo, Heng |
title |
Systematic comparison of InSAR and seismic source models for moderate-size earthquakes in Western China: implication to the seismogenic capacity of the shallow crust |
title_short |
Systematic comparison of InSAR and seismic source models for moderate-size earthquakes in Western China: implication to the seismogenic capacity of the shallow crust |
title_full |
Systematic comparison of InSAR and seismic source models for moderate-size earthquakes in Western China: implication to the seismogenic capacity of the shallow crust |
title_fullStr |
Systematic comparison of InSAR and seismic source models for moderate-size earthquakes in Western China: implication to the seismogenic capacity of the shallow crust |
title_full_unstemmed |
Systematic comparison of InSAR and seismic source models for moderate-size earthquakes in Western China: implication to the seismogenic capacity of the shallow crust |
title_sort |
systematic comparison of insar and seismic source models for moderate-size earthquakes in western china: implication to the seismogenic capacity of the shallow crust |
publishDate |
2023 |
url |
https://hdl.handle.net/10356/170950 |
_version_ |
1781793779790905344 |