New Hampshire is considered to be an area of moderate seismic hazard. This means that the state could experience large (6.5-7.0 magnitude) earthquakes, but they are not likely to occur as frequently as in a high hazard area like California. The state typically experiences one or two earthquakes per year registering magnitude 2.0 to 3.5.
According to the NH Division of Homeland Security and Emergency Management and the U.S. Geological Survey, the overall earthquake risk to the state is high. This is because of the built environment of New Hampshire. That is, many structures in the state (e.g., buildings, homes, bridges, and highways) are old or not built to modern earthquake standards. Hence, they are unable to withstand quakes. Additionally, due to the unique geology of New Hampshire, earthquake propagation waves travel up to 40 times further than they do in the western United States. This means the area of damage could be larger.
Recognizing the significant danger posed by seismic activity in the New England region, the U.S. Geological Survey is presently installing the Advanced National Seismic System in Boston and New York City to provide emergency responders with real-time earthquake information.
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