UMass Amherst analysis shows enigmatic pattern in San Bernardino basin is not typical.
A new analysis of thousands of very small earthquakes that have occurred in the San Bernardino basin near the San Andreas and San Jacinto faults suggests that the unusual deformation of some – they move in a different way than expected – may be due to “deep creep” 10 km below the Earth’s surface, say geoscientists at the University of Massachusetts Amherst.
The new understanding should support more refined assessments of fault loading and earthquake rupture risk in the region, they add. Writing in the current online Geophysical Research Letters, doctoral student Jennifer Beyer and her advisor, geosciences professor Michele Cooke say the enigmatic behavior is seen in about one third of the hundreds of tiny quakes recorded during the lull between big damaging quakes, and their possible significance had not been appreciated until now.
Cooke says, “These little earthquakes are a really rich data set to work with, and going forward if we pay more attention than we have in the past to the details they are telling us, we can learn more about active fault behavior that will help us better understand the loading that leads up to large damaging earthquakes.”
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Image via Geophysical Research Letters
