Volcano-tectonic interactions at Sabancaya volcano, Peru (2013-2018): Eruptions, magmatic inflation, moderate earthquakes, and aseismic slip
Abstract
Sabancaya volcano (southern Peru) is one of the most active volcanoes in the Central Andes, with an ongoing period of unrest that began in 2012-2013. Manifestations of unrest include increased fumarolic activity, gas emissions, swarms of volcano-tectonic earthquakes, ground deformation, and explosions starting in 2014 and reaching a maximum VEI of 3 in Nov. 2016, followed by a decrease in earthquake activity.
Several different faults surrounding the volcano have had shallow (< 30 km) moderate earthquakes (Mw > 4.5) during the recent unrest, over 20 within 50 km of Sabancaya since 2013. While few volcanoes globally have large earthquakes without coincident eruption, several volcanoes have displayed a significant decrease in distal earthquakes after the onset of eruptive activity. A key question is whether this seismic activity is related to magmatic inflation. A previous InSAR study using data up to early 2014 found no evidence for magmatic deformation above the detection threshold. However, our InSAR analysis of Sentinel-1, TerraSAR-X, and COSMO-SkyMed missions from 2013/05-2018/05 finds deformation signals including deep seated inflation northwest of Sabancaya as well as creep and rupture on multiple faults. Preliminary modeling of the inflation source shows that the location ( 7 km N of Sabancaya) and depth ( 15 km) are consistent with a previous episode of inflation observed from 1992 to 1996. We also modeled deformation from earthquakes to the northeast of Sabancaya occurring on 10 Jan. (Mw 5.1) and 30 Apr. 2017 (Mw 5.2). The modeled normal fault planes strike NW-SE and dip to the NE, consistent with mapped faults and available focal mechanisms. Moment magnitudes derived from modeling are consistent with seismic catalogs, with no evidence for aseismic deformation of magmatic origin. We also observe creep that is potentially post-seismic after-slip on a fault that ruptured in 2013. To our knowledge, volcano creep has previously only been observed at volcanoes with flank instabilities, but is likely due to other processes near Sabancaya. The similarity in location and timing between tectonic and magmatic deformation at Sabancaya suggests a link between the two processes. Future work will determine the existence and nature of this link by modeling stress changes induced from inflation and fault slip.- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFM.V23C..03M
- Keywords:
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- 1207 Transient deformation;
- GEODESY AND GRAVITYDE: 9305 Africa;
- GEOGRAPHIC LOCATIONDE: 9604 Cenozoic;
- INFORMATION RELATED TO GEOLOGIC TIMEDE: 8178 Tectonics and magmatism;
- TECTONOPHYSICSDE: 8185 Volcanic arcs;
- TECTONOPHYSICSDE: 8415 Intra-plate processes;
- VOLCANOLOGYDE: 8488 Volcanic hazards and risks;
- VOLCANOLOGYDE: 8499 General or miscellaneous;
- VOLCANOLOGY