Researchers have come up with a way to register the movements of the glacier without getting close to the object. To do this, they installed a seismometer on the ocean floor.
Scientists have shown that a seismometer installed on the ocean floor near a glacier in Greenland can record continuous seismic radiation from a slip, reminiscent of a slow earthquake. So scientists can track the movement of a block of ice and predict its behavior.
Basal glacier sliding controls the rate at which ice is released into the ocean. However, it is rather difficult to observe such movement and determine what affects it: the area around the glacier is one of the most difficult to access and seismically noisy. The same applies to the surface of the glacier due to cracks and harsh weather conditions.
A team of scientists from Hokkaido University, led by Yevgeny Podolsky of the Arctic Research Center, used seismometers on the ocean floor and on the surface to detect previously unknown coastal tremors caused by glacier sliding. Their results appeared in the journal Nature Communications.
Glacier movement sensors can be placed on top, inside, or under a glacier, but each approach has its drawbacks. For example, glacier surfaces are noisy due to wind, ebb, and flow, which can overwhelm all other signals; the interior of the glacier is quieter, but it is the most inaccessible area. Almost any point on or near the glacier leads to problems such as drift, melting and loss of level, low temperatures, and possible breakdown of instruments due to icebergs collapsing.
In this study, scientists used an ocean floor seismometer (OBS) deployed near the front of the Bowduan Glacier to listen for noises caused by the basal movement of the glacier. Thus, they isolated the sensor from near-surface seismic noise, and also bypassed all the problems that accompany the placement of sensors on the glacier itself and next to it. The OBS data were compared with seismic and ice velocity measurements at the surface.