ABSTRACT: The Arctic Ocean earthquake swarm of October and November 2008.

CGRG Bibliography of Canadian Geomorphology
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Abstract

During October and November 2008 an earthquake swarm occurred in the Arctic Ocean off the Queen Elizabeth Islands. The activity was sporadic but reached a peak in mid-November when fifty earthquakes large enough to be located occurred over a two day period (17-18 November). Eleven of the earthquakes, nine of which occurred during those two days, were of magnitude 5.0 or greater. Regional moment tensor inversions were performed for these eleven earthquakes. The majority of the focal mechanisms were indicative of thrust faulting on a NE-SW striking plane roughly parallel to the continental margin. Depths, ranging from 6-20 km, correspond to the mid-crust. It is not clear whether the unusually high non-double couple component for many of the solutions is an artifact of the inversion process or is indicative of a true non-double source. Swarm activity is often associated with magmatic or other geothermal activity and it is possible but not confirmed that the non-double couple component is related to the migration of fluids within the crust. The occurrence of a large number of earthquakes in a small area allows for calibration between magnitude scales for the north, where the attenuation relations are less well known than in southern Canada. A primary observation was the mb determined from Canadian stations (regional distances) tends to be smaller than mb by other organizations using teleseismic data. On the other hand, mb determined from the Yellowknife array data is a good match to the teleseismic magnitude suggesting that this path is close to the global average.

Bibliography of Canadian Geomorphology