Seismically Derived Flow Velocities of Surface Mass Wasting Events in the Cascades 2001-2021

The glaciated volcanoes in the PNW pose a threat to the region with the potential for tectonic, volcanic, and surface processes. The volcanic and earthquake seismicity at the volcanoes is relatively well studied and automatically characterized (source location, source size) by seismic networks. However, this is not the case for surface events. We hope to obtain a greater understanding of these events from a labeled data set with events characterized by emergent, elongated waveforms, without clear phases. There are 7523 distinct events, the majority of which are thought to be avalanches. We complete the catalog of waveforms using nearby stations that have good signal to noise ratio, and we use envelope-based phase shift to find pick times and approximate location of the events. We measure differences in the peak frequencies from Fourier amplitude spectra at each station to measure doppler effects and estimate an azimuthal direction relative to the center of the volcano as well as the flow velocity using a near-surface shear wave speed model. Preliminary results show high, yet reasonable velocities and vague direction of flow. We confirm the event labels on Mt Rainier, Mt St Helens, and Mt Hood using visual reports. We find that over two decades, these surface events are seasonal in counts: they are more frequent in the summer than in other seasons and do not increase over time. Discovering velocities and directivity of the events as well as when and where they are most frequent could contribute towards mass wasting warning systems in the future.