Searching for seismic precursors: the Barry landslide hazard

Abstract

Landslides pose a serious geohazard, particularly when they occur in steep coastal or fjord environments where they can generate tsunamis. Barry Arm, located in Prince William Sound, Alaska, exemplifies this threat. The unstable slope, with an estimated failure volume of 500-700 million cubic meters, could produce a tsunami capable of devastating communities such as Whittier, Valdez, and Cordova. Recognizing the potential consequences, the region has been intensively monitored since 2020, providing a valuable opportunity to study the interactions between seismic activity, environmental drivers, and slope stability. Monitoring landslide-prone regions with seismic and geophysical instruments can offer insights into the processes controlling slope movement. However, at Barry Arm, the seismic record is complicated by the presence of nearby glaciers and regional tectonic activity. Among the recorded signals, a specific class of short-duration, high-frequency seismic events—referred to as SI events—displays a distinct seasonal pattern, increasing in frequency from late summer to mid­ winter before ceasing abruptly in early spring. This study examines seismic and environmental datasets to investigate the drivers of these signals, applying detection algorithms to track their occurrence over time. Correlations with environmental variables such as precipitation, temperature, and radar-derived slope motion suggest that SI events are linked to seasonal hydrological changes, particularly the freeze-up of subglacial water pathways. While not directly related to landslide motion, these signals highlight the complex interplay between glaciers, groundwater, and slope stability. Understanding these relationships improves our ability to monitor evolving geohazards in dynamic landscapes and contributes to broader efforts in landslide hazard assessment and early warning.