التفاصيل البيبلوغرافية
| العنوان: |
The Linked Complexity of Coseismic and Postseismic Faulting Revealed by Seismo‐Geodetic Dynamic Inversion of the 2004 Parkfield Earthquake. |
| المؤلفون: |
Schliwa, Nico, Gabriel, Alice‐Agnes, Premus, Jan, Gallovič, František |
| المصدر: |
Journal of Geophysical Research. Solid Earth; Dec2024, Vol. 129 Issue 12, p1-30, 30p |
| مصطلحات موضوعية: |
MARKOV chain Monte Carlo, GROUND motion, EARTHQUAKES, CONSTRAINTS (Physics), SEISMOGRAMS, SUMATRA Earthquake, 2004, SEISMIC waves |
| مستخلص: |
Several regularly recurring moderate‐size earthquakes motivated dense instrumentation of the Parkfield section of the San Andreas fault (SAF), providing an invaluable near‐fault observatory. We present a seismo‐geodetic dynamic inversion of the 2004 Parkfield earthquake, which illuminates the interlinked complexity of faulting across time scales. Using fast‐velocity‐weakening rate‐and‐state friction, we jointly model coseismic dynamic rupture and the 90‐day evolution of postseismic slip in a 3D domain. We utilize a parallel tempering Markov chain Monte Carlo approach to solve this non‐linear high‐dimensional inverse problem, constraining spatially varying prestress and fault friction parameters by 30 strong motion and 12 GPS stations. From visiting > ${ >} $2 million models, we discern complex coseismic rupture dynamics that transition from a strongly radiating pulse‐like phase to a mildly radiating crack‐like phase. Both coseismic phases are separated by a shallow strength barrier that nearly arrests rupture and leads to a gap in the afterslip, reflecting the geologic heterogeneity along this segment of the SAF. Coseismic rupture termination involves distinct arrest mechanisms that imprint on afterslip kinematics. A backward propagating afterslip front may drive delayed aftershock activity above the hypocenter. Trade‐off analysis of the 10,500 best‐fitting models uncovers local correlations between prestress levels and the reference friction coefficient, alongside an anticorrelation between prestress and rate‐state parameters b−a $b-a$. We find that a complex, fault‐local interplay of dynamic parameters determines the nucleation, propagation, and arrest of both, co‐ and postseismic faulting. This study demonstrates the potential of inverse physics‐based modeling to reveal novel insights and detailed characterizations of well‐recorded earthquakes. Plain Language Summary: The Parkfield section of the San Andreas plate boundary hosts regularly recurring moderate‐size earthquakes. Seismic ground motions and slow deformation following the 2004 Parkfield earthquake were recorded by more than 40 seismometers and 13 GPS stations. While this is arguably one of the best‐recorded earthquakes, it remains challenging to constrain the physics and properties at depth governing the earthquake from surface observations. Data‐driven earthquake models solving inverse problems usually describe the kinematics of rupture. Here, we employ a computationally expensive numerical algorithm to invert observations dynamically and find a physics‐based set of parameters that simultaneously explain the earthquake and its afterslip, slow deformation following an earthquake. We find two separate phases of the earthquake that cause a similar amount of permanent displacement, but the rapid rupture of the first phase radiates much more potentially damaging seismic waves. The permanent displacement caused by the afterslip of the 2004 Parkfield earthquake exceeded its coseismic displacement. The local frictional properties that arrest the earthquake imprint on the subsequent afterslip evolution. Our approach illustrates that physics‐based models utilizing modern computing techniques can reveal new insights and unprecedented detail even of well‐studied events. Key Points: We perform a joint seismo‐geodetic dynamic rupture and afterslip inversion of the 2004 Parkfield eventWe find that coseismic rupture is separated into a strongly radiating pulse‐like and a mildly radiating crack‐like phaseDistinct dynamic rupture arrest mechanisms imprint on afterslip evolution and afterslip may drive delayed aftershocks [ABSTRACT FROM AUTHOR] |
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| قاعدة البيانات: |
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