On August 23, 2011, tens of millions of people in the eastern U.S. and southeastern Canada were startled by sudden ground shaking from a rare, magnitude 5.8 earthquake in central Virginia. Several small earthquakes occur every month in the eastern U.S., but this earthquake was among the largest to occur in this region in the last century.

It is estimated that approximately one third of the U.S. population could have felt this earthquake, more than any other earthquake in U.S. history. Around 148,000 people reported their ground-shaking experiences caused by the earthquake on the USGS “Did You Feel It?“? website. Shaking reports came from southeastern Canada to Florida and westward to locations near the Mississippi River.

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There is much still unknown about the earthquake, including details of the fault that produced it and possible relationships to older faults and other geologic features. Although it was a rare event for the east coast, the earthquake was not a surprise, in that it occurred within the Central Virginia seismic zone. This zone has been identified on USGS seismic hazard maps for decades as an area of elevated earthquake risk. However, it is the largest known earthquake to have occurred in that zone.

“Every large earthquake is a learning experience, but it is particularly the case for this Virginia earthquake because of the rarity of such events in the eastern U.S.,”? said USGS Director Marcia McNutt. “For example, what are we doing so right that a record setting number of east coast residents know the value to science of submitting their experiences on ‘Did You Feel It?,’ and yet not enough appropriately responded with ‘duck and cover’ during the seconds of most intense ground shaking?”

Further studies to better understand this earthquake will help ensure public safety in Virginia and other areas of the eastern U.S.

The USGS is actively involved in studying last year’s earthquake in Virginia, as well as earthquake hazards worldwide. The President’s requested FY13 budget includes a proposed increase in funding to expand USGS efforts to assess eastern U.S. earthquake hazards. USGS expertise includes earthquake monitoring and notification, earthquake impact and hazard assessments, geologic mapping and targeted research on earthquake causes and effects.

So what have scientists been up to? Take a glimpse below at some new insights and projects currently underway.

Rapid Response to Record Aftershocks

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