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

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.

Source Model for Sabancaya Volcano Constrained by DInSAR and GNSS Surface Deformation Observation

“…The deformation source inferred by the independent inversion of the DInSAR and GNSS deformation velocities shows a deep source (12-15 km below the surface) beneath Hualca Hualca with a volume change rate of 26-43 × 10 6 m 3 /yr, in agreement with the results obtained by [24] for the same period. The residuals in the DInSAR data are related to seismic deformation and provide a clear view of the faults' movement.…”

Rhyolitic volcano dynamics in the Southern Andes: Contributions from 17 years of InSAR observations at Cordón Caulle volcano from 2003 to 2020

“…Wendt et al, 2017 explored the idea that the deformation during the first three days of the eruption was produced by a tectonically controlled dike (Castro et al, 2016), but none of their dike models provide a significant better fit than two deflating spherical sources. Therefore the role of the local tectonics driving the emplacement of magma into the upper crust and their interaction with local faults (e.g., Lundgren et al, 2017;MacQueen et al, 2020) is yet to be explored more thoroughly. The absence of triggered…”

Surface deformation simulation for InSAR detection using a machine learning approach on the hantangang river volcanic field: A case study on the orisan mountain

“…In addition to the various limitations faced, there are still some potentials that arise. Based on previous research, the use of the Mogi model as a source of deformation still limits the influence of other sources of deformation, such as an earthquake that occurs during an eruption (MacQueen et al, 2020). Therefore, in this research the Okada method is used as a deformation model in the synthesis of interferograms which is expected to provide a better image in the training process on the deformation signal.…”