Date of Award

2024

Document Type

Open Access Master's Thesis

Degree Name

Master of Science in Geophysics (MS)

Administrative Home Department

Department of Geological and Mining Engineering and Sciences

Advisor 1

Greg Waite

Committee Member 1

Simon Carn

Committee Member 2

Chad Deering

Abstract

There is an established correlation between large earthquakes and volcanic unrest, however the mechanisms between this connection are not well understood. Relatively small changes in stress within a volcanic system could be enough to initiate a response. One aspect that could serve to amplify small dynamic stress changes is volcanic edifice resonance triggered by surface waves at resonant frequency. In this paper, we investigate the relationship between thermal activity of volcanoes and various minimum thresholds of Love wave amplitudes at resonance caused by teleseismic earthquakes above a 7.0 M. Satellite-derived thermal data from 25 volcanoes are modeled in relation to a variety of threshold values of Love wave amplitudes at resonance. Amplitudes are calculated using the synthetic teleseismic waveforms from 171 earthquakes between January 2000 and September 2023. Two time windows, centered on each earthquake, are used to observe for short term and long-term effects: a 28 day and a 1 year window. Basaltic magma volcanoes, including lava lake volcanoes, exhibit mostly increased activity levels, while andesitic volcanoes display a negative response of thermal emissions. Both these magma types show higher rates of activity at higher amplitude thresholds. Different tectonic environments also saw different reactions to Love wave amplitude values. Extensional environment volcanoes generally show an increase in activity during the long-term window, while compressional environment volcanoes exhibit a decrease in activity at both the long- and short-term windows. Again, the degree of thermal change correlates with amplitude threshold. These observations indicate that dynamic stresses are an influence for the general positive and negative reactions seen in thermal activity at volcanoes following large teleseismic earthquakes. Factors like magma composition also influence the thermal activity with increases in activity being observed due to the low viscosity of basaltic magmas allowing bubbles to escape from the melt when affected by shaking and therefore increasing volcanic activity. The amplitude of the surface waves at edifice resonance are observed to increase the slope amount of base positive or negative reactions. This is due to the increased shaking caused by larger amplitude values to trigger magma movement in an upward, downward, or lateral direction thus influencing thermal activity and triggering higher or lower levels of volcanic activity.

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