Long-term analysis of cryoseismic events and associated ground thermal stress in Adventdalen, Svalbard

Abstract

The small-aperture Spitsbergen seismic array (SPITS) has been in continuous operation at Janssonhaugen for decades. The high-Arctic location in the Svalbard archipelago makes SPITS an ideal laboratory for the study of cryoseisms, a nontectonic class of seismic events caused by freeze processes in ice, ice–soil, and ice–rock materials. We extracted a catalog of > 100 000 events from the nearly continuous observation period between 2004 and 2021, characterized by short-duration ground shaking of just a few seconds. This catalog contains two main subclasses where one subclass is related to underground coal-mining activities and the other is inferred to be dominated by frost quakes resulting from thermal-contraction cracking of ice wedges and crack-filling vein ice. This inference is supported by the correspondence between peaks in observed seismicity with peaks in modeled ground thermal stress, based on a Maxwellian thermo-viscoelastic model constrained by borehole observations of ground temperature. The inferred frost quakes appear to be dominated by surface wave energy and SPITS proximal source positions, with three main areas that are associated with dynamic geomorphological features, i.e., erosional scarps and a frozen-debris/solifluction lobe. Seismic stations providing year-round, high-temporal-resolution measurements of ground motion may be highly complementary to satellite remote sensing methods, such as InSAR (interferometric synthetic aperture radar), for studying the dynamics of periglacial environments. The long-term observational record presented in this study, containing tens of thousands of cryoseismic events, in combination with a detailed record of borehole ground temperature observations, provides a unique insight into the spatiotemporal patterns of cryoseisms. The observed patterns may guide the development of models that can be used to understand future changes to cryoseismicity based on projected temperatures.