By tracking swarms of very small earthquakes, seismologists are getting a new picture of the complex region where the San Andreas fault meets the Cascadia subduction zone, an area that could give rise to devastating major earthquakes.
By tracking swarms of very small earthquakes, seismologists are getting a new picture of the complex region where the San Andreas fault meets the Cascadia subduction zone, an area that could give rise to devastating major earthquakes. The work, by researchers at the U.S. Geological Survey, the University of California, Davis, and the University of Colorado Boulder, is published Jan. 15 in Science.
“If we don’t understand the underlying tectonic processes, it’s hard to predict the seismic hazard,” said co-author Amanda Thomas, professor of earth and planetary sciences at UC Davis.
Three of the great tectonic plates that make up the Earth’s crust meet at the Mendocino Triple Junction, off the Humboldt County coast. South of the junction, the Pacific plate is moving roughly northwest against the North American plate, forming the San Andreas fault. To the north, the Gorda (or Juan de Fuca) plate is moving northeast to dive under the North American plate and disappear into the Earth’s mantle, a process called subduction.
But whatever is going on at the Mendocino Triple Junction is clearly a lot more complex than three lines on a map. For example, a large (magnitude 7.2) earthquake in 1992 occurred at a much shallower depth than expected.
Read More: University of California - Davis
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