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Thermal pressurization induced the frequency-dependent rupture during the 2019 Mw8.0 Peru intermediate depth earthquake
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  • Heng Luo,
  • Hongyu Zeng,
  • Teng Wang,
  • Mingsheng Liao,
  • Jianya Gong,
  • Jiashun Hu,
  • Shengji Wei,
  • Qibin Shi
Heng Luo
Wuhan University
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Hongyu Zeng
Asian School of the Environment, Nanyang Technological University
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Teng Wang
Peking University
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Mingsheng Liao
State Key Laboratory of remote sensing and Information Engineering,wuhan university
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Jianya Gong
Wuhan University
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Jiashun Hu
California Institute of Technology
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Shengji Wei
Earth Observatory of Singapore

Corresponding Author:shjwei@gmail.com

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Qibin Shi
Earth Observatory of Singapore, Nanyang Technological University
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The rupture process of earthquakes at intermediate depth (~70-300 km) have been rarely illuminated by a joint analysis of geodetic and seismic observations, hindering our understanding on their dynamic rupture mechanisms. Here we present detailed rupture process of the 2019 Mw8.0 Peru earthquake at the depth of 122 km with a holistic approach reconciling InSAR and broadband seismological waveform data. The joint inversion of InSAR observations and teleseismic body waves results in a finite rupture model that extends ~200 km along strike, with unilateral rupture towards north that lasted for ~60 s. There are four major asperities in the finite fault model which are well corresponding to position and timing of the sources in back-projection (BP) and multiple points source (MPS) results. The largest asperity, which occurred ~40 s after the rupture initiation, was featured with longer and smoother risetime, and radiated much weaker high-frequency seismic waves compared to other smaller asperities. This distinct frequency-dependent rupture requires a strong dynamic weakening mechanism, likely thermal pressurization of pore free water rather than thermal runaway. Our frequency content analysis could be generalized to study other earthquakes including those deeper than 300 km.