Saturday, July 27, 2019

How Earthquakes Can Cause Earthquakes

Remote Triggering of Earthquakes is a fascinating story map which explores how the seismic waves caused by large earthquakes can trigger other earthquakes, even on the other side of the Earth.

Remote Triggering of Earthquakes uses a story map format to show how large earthquakes are often shortly followed by further seismic activity, particularly near to the original main shock. In California in June 1992 a large, 7.2 magnitude earthquake occurred in Landers, California, in the Mojave Desert. In the days that followed 192 earthquakes were recorded, not only in the immediate vicinity of the Landers quake, but across much of the western United States. This was one of the first times that the remote triggering of earthquakes was observed.

After the April 11th 2012, M8.6 earthquake, off the coast of Sumatra, there was a nine-fold increase in seismic activity around the globe. The Remote Triggering of Earthquakes story map shows how the majority of these aftershocks were recorded in areas within the seismic waves from the Sumatra quake. Siesmic waves propagate out from a quake. There is some evidence that where these waves converge, often on the other side of the world, there can be further seismic activity. In other words it is possible that a large earthquake can trigger other large earthquakes even at very remote distances.

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