Thousands of earthquakes occurred in rapid succession under an Antarctic glacier over a nine month period between 2002 and 2003, reports a study published online in Nature Geoscience this week. The findings suggest that tidal motion can influence sub-glacial seismicity.
Lucas Zoet and colleagues analysed seismic activity under a large glacier in East Antarctica that drains into the Ross Sea, using data collected between 2002 and 2003. They identified about 20,000 seismic events during this period, which occurred at regular intervals about 25 minutes apart. The magnitude of the shaking was large, compared to typical subglacial quakes.
The researchers suggest that the movement of the glacier over a rough patch of rock generated the significant sub-glacial shaking. They attribute the regularity of these events to the modulation of glacier movement by ocean tides.