Researchers have developed a new avalanche monitoring method that uses sound below the range of human hearing to detect and track these deadly and destructive snow slides. The technique can detect an avalanche from the moment it starts, picking up the unheard thump of a rupture in the snowpack that can precede the snow cascade. It can then track the avalanche's path second by second down the mountain.
In a new study published last month in Geophysical Research Letters, a journal of the American Geophysical Union, scientists report using an array of infrasound detectors on a mountainside to pick up low-frequency sound waves emitted from one of a series of January, 2012, avalanches in Idaho's Canyon Creek corridor.
Scientists involved with the Past Global Changes (PAGES) project have developed goals and recommendations for studying the paleoclimate of the past 2000 years.
Regions where the continental lithosphere is slowly deforming may be perceived as stable because they are far away from active plate boundaries, but these regions can and do experience large earthquakes. The lithosphere is relatively cool and thick in these areas, so earthquakes can propagate deeper than in more active regions, and have large magnitudes. Because these earthquakes are rare, surrounding populations may not be well prepared and thus face significant hazard, so it's important for these slowly deforming regions to be well characterized.
Copley et al. present new observations of a slowly deforming area in central India, specifically around the Tapti Fault, which is far away from surrounding plate boundaries. To fully understand and characterize the fault, the authors studied alluvial fans that have been offset by fault motion, and the mountain range that has been produced by repeated earthquakes on the fault. Because the authors only found evidence for large Holocene earthquakes on one section of the fault, they note that the remaining unruptured part results in significant seismic hazard in central India.
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