Correlating climate phenomena and crustal shear wave velocity changes using ambient seismic noise

Abstract

Previous studies have used seismic ambient noise to calculate how relative seismic velocities change over time, which can provide a way of monitoring volcanic activity. However, precipitation and other meteorological activity can affect seismic velocities, obscuring potential volcanic signals. This study seeks to understand how meteorological activity and seismic velocity changes interact at Akutan Volcano in Alaska between 2019 and 2024. We use MSNoise, a Python module, to cross-correlate transverse and vertical components for 10 seismic stations and calculate relative velocity changes. Both transverse and vertical components are used to characterize how elastic load from precipitation, atmospheric pressure, and other meteorological activity impact both horizontal and vertical cracks in the crust. Seasonal relative velocity changes are observed, with velocity decreases occurring in the winter months and velocity increases in the spring and summer. When temperature is compared with relative velocity changes, velocity increases are shown to occur in the high frequencies when the minimum temperature is below 0°C at a nearby coastal weather station. Modelled subsurface water runoff closely resembles the asymmetric overall shape of the relative velocity changes, suggesting a possible linkage. We also compared relative velocity changes with GPS data and large seismic events with little success.