Earthquakes

Earthquake FAQS

What is an earthquake? It is sudden shaking of the earth caused by shifting of rock beneath the surface. Earthquakes occur due to slip along faults, volcanic activity or other changes in stress in the earth's crust.

Where do earthquakes occur? 98% of earthquakes occur at plate boundaries where tectonic plates move apart or collide; in the US, most occur west of the Rocky Mountains. We often think of earthquakes as being associated with faults. Although there are numerous faults mapped in Vermont, these are ancient, inactive faults and do not correlate with recent earthquakes.

Where do earthquakes occur in Vermont?  Recent earthquakes (2016-2020) mainly occurred in northern Vermont in such places as Cabot, White River Junction and Johnson. Events near Vermont’s northwest border may be felt in our state and include 5.1 magnitude earthquakes in the Adirondack region in 1983, in Plattsburgh, NY on April 20, 2002 and on June 23, 2010, a 5.1 magnitude event near Ottawa, Canada. The Ottawa earthquake was related to the Western Quebec Seismic Zone, an active zone that extends from Ottawa to Montreal. 

What should people do during an earthquake?  "Drop, Cover and Hold On!"
You may notice gentle shaking, swaying of plants, or rattling of windows. Most injuries are caused by flying glass, broken chimneys or fire from ruptured gas lines and downed power lines. There is usually an aftershock. R. Allen of the Berkeley Seismological Laboratory estimated that the number of injuries could be halved if people would drop, cover and hold on (EOS, Oct 24, 2019). Seismic hazard and preparedness for Vermont (pdf).

Any seismic hazard studies conducted in Vermont? Yes, a number of maps and reports have been produced since 1997.

What are the largest events centered in Vermont?