[J01-1] Monitoring of the cryosphere I

[J01-1-02] Repetitive cryoseismicity at the Fimbulisen Ice Shelf, East Antarctica

^○Myrto Pirli¹, Sebastian Hainzl², Andreas Koehler³, Johannes Schweitzer⁴ (1.Skjetten, Norway, 2.GFZ German Research Centre for Geosciences, Potsdam, Germany, 3.University of Oslo, Oslo, Norway, 4.NORSAR, Kjeller, Norway)

A source region of repetitive cryoseismic activity has been identified at the Fimbulisen ice shelf, in Dronning Maud Land, East Antarctica. The specific area is located at the outlet of the Jutulstraumen glacier, near the Kupol Moskovskij ice rise. Although the activity is mostly expressed through events of small magnitude, they are large enough to be recorded by the permanent seismic stations in the region (SNAA, TROLL, Watzmann-array), within an observation distance range between 210 and 310 km. The use of waveform cross-correlation detectors and Hidden Markov Model classifiers has provided a unique dataset extending over 13 years, from 2003 to 2016. Phases of low seismicity rates are alternating with intense activity intervals that exhibit a strong tidal modulation that is expressed in terms of event occurrence times, their geographic distribution and amplitude variation. The observed correlation follows both the neap-spring and the semi-diurnal ocean-tide cycle. These temporal characteristics of the observed cryoseismicity are approached through rate and state seismicity models with the prospects of constraining the physical mechanisms that trigger this activity and enabling the identification of the corresponding dynamic processes at work at this particular region of the Fimbulisen ice shelf.