Title: Cryoseismology: Towards seismic monitoring of calving and surging on Svalbard
Speaker: Andreas Köhler (UiO)
Abstract
Seismic observations can be used to monitor glacier activity such as basal sliding, crevassing, and calving. We use seismic data recorded on permanent broadband stations on Svalbard to detect, locate and analyse the regional glacier seismicity. We observe a high number of icequakes around Kongsfjorden/Ny-Ålesund in northwestern Spitsbergen that are clearly related to individual tidewater glaciers in that area. The clusters show a clear seasonal variability, i.e. much more events are observed during melt season, and we have strong evidences from a local monitoring experiment as well as from direct observations that they are related to calving. A second type of glacier-related seismic emission around Kongsfjorden are tidally modulated tremor-like signals. Their occurrence is correlated with the time of tidal maxima as well as the tidal range in Ny-Ålesund. Tremoring could be related to tidally modulated hydrostatic pressure changes which could influence the flow of water through the basal hydrological system of glaciers. We also find that glacier surges can be observed seismically. A cluster of seismic events in Southern Spitsbergen is related to the surge of the Nathorstbreen glacier system in 2009. We suggest that the source mechanism is bed-failure. Furthermore, as an indirect indicator for surging, we observe a higher number of seismic calving events during surges of Tunabreen (2003) and Wahlenbergbreen (2011) compared to melt seasons in other years. In summary, our results show the great the potential of using seismic observations to quantify calving, to better understand the glacier basal-hydrolocical system, and to detect surging on Svalbard.
About the seminar:
This seminar is offered by the research environments geography and hydrology at the Department of Geosciences.
The seminar is open for all interested in the topic of the seminar.