Seismic triggering of increases and decreases in volcanic outgassing
Abstract
There are many examples in which large earthquakes have triggered volcanic unrest due to either static or dynamic stresses. While eruptions are easy to identify, volcanic systems may respond to external triggers in subtle ways that can be challenging to identify against the background activity. Earthquakes may even trigger decreases in volcanic activity. Studies using satellite-derived thermal flux or gas emission measurements allow for consistent measurements of volcanic activity that can address these types of changes. We created such time series of daily SO2 loading measured by Ozone Monitoring Instrument (OMI) for 12 persistently outgassing volcanoes over six years. The volcanoes were chosen to represent a variety of eruption styles and arc settings in areas where OMI could consistently measure SO2. We then computed synthetic surface waves for all Mw≥ 7 earthquakes over the time period and analyzed the relationship between peak amplitudes and changes in emissions. In some cases, we find no clear change in the emissions from these volcanoes following large earthquakes. But we also find that earthquakes trigger both increases and decreases in emission. The two distinct volcanic responses correlate strongly with eruption style. At open-vent basaltic volcanoes earthquakes trigger increased SO2discharge, while earthquakes tend to lead to decreases in emissions at andesitic volcanoes. While it is clear that the source-receiver geometry and seismic fault model influence the amplitude of the seismic waves, we expand on this to include finite-fault synthetic seismograms and examine the relative influence Rayleigh and Love waves on triggering to better inform models for triggering. Results thus far suggest increased emission at open, low-viscosity volcanoes is consistent with disruption or mobilization of bubbles, or magma sloshing, whereas the latter observation may reflect more dominant controls on degassing in viscous magmas or a post-earthquake reduction in permeability.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.V11B..03W
- Keywords:
-
- 1295 Integrations of techniques;
- GEODESY AND GRAVITY;
- 7280 Volcano seismology;
- SEISMOLOGY;
- 8178 Tectonics and magmatism;
- TECTONOPHYSICS;
- 8485 Remote sensing of volcanoes;
- VOLCANOLOGY