Volcano-Tectonic Interactions at Sabancaya Volcano, Peru: Eruptions, Magmatic Inflation, Moderate Earthquakes, and Fault Creep

Patricia MacQueen, Francisco Delgado, Kevin Reath, Matthew E. Pritchard, Marco Bagnardi, Pietro Milillo, Paul Lundgren, Orlando Efrain Macedo Sánchez, Victor Aguilar, Mayra Ortega, Rosa Anccasi, Ivonne Alejandra Lazarte Zerpa, Rafael Miranda

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Abstract

We present evidence of volcano-tectonic interactions at Sabancaya volcano that we relate to episodic magma injection and high regional fluid pore pressures. We present a surface deformation time series at Sabancaya including observations from ERS-1/2, Envisat, Sentinel-1, COSMO-SkyMed, and TerraSAR-X that spans June 1992 to February 2019. These data show deep-seated inflation northwest of Sabancaya from 1992–1997 and 2013–2019, as well as creep and rupture on multiple faults. Afterslip on the Mojopampa fault following a 2013 MW 5.9 earthquake is anomalously long lived, continuing for at least 6 years. The best fit fault plane for the afterslip is right-lateral motion on an EW striking fault at 1 km depth. We also model surface deformation from two 2017 earthquakes (MW 4.4 and MW 5.2) on unnamed faults, for which the best fit models are NW striking normal faults at 1–2 km depth. Our best fit model for a magmatic inflation source (13 km depth, volume change of 0.04 to 0.05 km3 yr−1) induces positive Coulomb static stress changes on these modeled fault planes. Comparing these deformation results with evidence from satellite thermal and degassing data, field observations, and seismic records, we interpret strong pre-eruptive seismicity at Sabancaya as a consequence of magmatic intrusions destabilizing tectonic faults critically stressed by regionally high fluid pressures. High fluid pressure likely also promotes fault creep driven by static stress transfer from the inflation source. We speculate that combining high pore fluid pressures with sufficiently large, offset magmatic inflation can promote strong earthquakes during volcanic unrest.

Original languageEnglish
Article numbere2019JB019281
JournalJournal of Geophysical Research: Solid Earth
Volume125
Issue number5
DOIs
StatePublished - 1 May 2020

Bibliographical note

Funding Information:
P. G. M., K. R., and M. E. P. were partly supported by Grant NNX16AK87G issued through NASA's Science Mission Directorate's Earth Science Division. F. D. was supported by the NASA ESSF program for PhD fellowships and by a Centre National D'Etudes Spatiales (CNES) postdoctoral grant. M. B. was supported by an appointment to the NASA Postdoctoral Program at the Jet Propulsion Laboratory, administered by the Universities Space and Research Association (USRA) through a contract with NASA. We thank the Italian Space Agency (ASI) for providing COSMO‐SkyMed data for this project. Original COSMO‐SkyMed product ASI Agenzia Spaziale Italiana (2014–2019). CSK data were provided by an agreement between Agenzia Spaziale Italiana (ASI) and JPL. We acknowledge the CEOS volcano pilot project and the German Space Agency for TSX/TDX data from that project. The European Space Agency provided Sentinel‐1, ERS‐1/2, and Envisat data. F.D. acknowledges Tara Shreve (IPGP) for useful discussions. We would also like to thank the two anonymous reviewers whose detailed comments greatly improved this manuscript. Data and model files for this paper are available via the Zenodo repository (at https://zenodo.org/record/3733800 ).

Funding Information:
P.?G.?M., K.?R., and M.?E.?P. were partly supported by Grant NNX16AK87G issued through NASA's Science Mission Directorate's Earth Science Division. F.?D. was supported by the NASA ESSF program for PhD fellowships and by a Centre National D'Etudes Spatiales (CNES) postdoctoral grant. M.?B. was supported by an appointment to the NASA Postdoctoral Program at the Jet Propulsion Laboratory, administered by the Universities Space and Research Association (USRA) through a contract with NASA. We thank the Italian Space Agency (ASI) for providing COSMO-SkyMed data for this project. Original COSMO-SkyMed product ASI Agenzia Spaziale Italiana (2014?2019). CSK data were provided by an agreement between Agenzia Spaziale Italiana (ASI) and JPL. We acknowledge the CEOS volcano pilot project and the German Space Agency for TSX/TDX data from that project. The European Space Agency provided Sentinel-1, ERS-1/2, and Envisat data. F.D. acknowledges Tara Shreve (IPGP) for useful discussions. We would also like to thank the two anonymous reviewers whose detailed comments greatly improved this manuscript.?Data and model files for this paper are available via the Zenodo repository (at https://zenodo.org/record/3733800).

Publisher Copyright:
©2020. American Geophysical Union. All Rights Reserved.

Keywords

  • InSAR
  • earthquake
  • fault creep
  • geodesy
  • remote sensing
  • volcano

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