Earthquakes are not a common
occurrence in Vermont, but they do happen here.
Nationally, most serious damage from an earthquake
results from the collapse of buildings or bridges, damage to utility
lines and resulting fires, shelves and items suspended from the ceilings
falling on people, and broken glass.
Due to the rural nature of Vermont,
most communities are not concerned with collapse of large bridges and
It is difficult to predict when and where an earthquake
will occur, but probability statistics for ground shaking based
on recorded human observations can be given.
Geologists also model and predict the severity of quakes. These
models help citizens prepare for and to allow governments
and communities to plan for this type of emergency.
Excerpts below from: Report on
the Seismic Vulnerability of the State of Vermont , 1994, by J. E. Ebel,
R. Bedell and A. Urzua.
What is an earthquake?
An earthquake is the sudden shaking of the earth caused
by shifting of rock beneath the surface.
Where do earthquakes occur?
Worldwide, 98% of earthquakes
occur at plate boundaries. In the United State most earthquakes occur
west of the Rocky Mountains, although some have occurred in the east.
Earthquakes in Vermont (pdf)
The largest events in Vermont are through 1993 are:
What causes an earthquake?
The cause of earthquakes in Vermont is not clear. The majority of quakes
worldwide occur at plate boundaries. The earth's lithosphere or outer
shell is believed to be comprised of thin slabs or plates which move
over, under, and past each other sliding about over the upper mantle
(a 2800 km thick dense layer surrounding the earth's core) at rates
of 10 to 130 mm per year. The activity and collisions at plate boundaries
are varied: one plate may dive beneath another along a subduction zone;
one plate may be thrust over the other; or plates may slide past each
other. The earthquake zones along plate boundaries are well defined
and are the cause for most of the earthquakes in the world, but do not
explain the earthquakes in Vermont. Vermont is located within a plate
rather than at a plate boundary and the cause for intraplate earthquakes
is poorly understood. Perhaps quakes occur along ancient plate boundaries
where faults are reactivated or serve as a surface along which tectonic
stress is released. However, at the present time the locations of recorded
earthquakes do not correspond to known fault surfaces mapped in the
state or neighboring states.
What would an earthquake feel like and what happens
during an earthquake?
You may notice a gentle shaking, a swaying of plants, light fixtures
and shelves, and a sudden jolt or a low rumbling noise. It is difficult
to move or walk around. Cabinets and shelves are likely to fall, light
fixtures and anything on the ceiling may come down, and doors and windows
may jam shut, bend and break. There is usually a smaller aftershock
associated with an earthquake.
The Richter Magnitude Scale (USGS)
The Modified Mercalli Intensity Scale (Earthquakes Canada).
What type of damage occurs during an earthquake?
During an earthquake, buildings may collapse, foundations may crack,
telephone and power lines may collapse causing fires, and there may
be explosions and landslides. In coastal areas, there may be huge ocean
waves called tsunamis.
What are the major causes of injury from earthquakes?
Most injuries are caused by collapsed buildings, flying glass, and fire
resulting from broken chimneys and ruptured gas and power lines.
What are the risks for Vermonters?
In Vermont, we do not have many large urban areas where collapse of
skyscrapers and overpasses would be a problem. We do, however, have
old masonry buildings and buildings which have not been engineered with
earthquakes in mind. Our lack of preparedness is a concern. The Federal
Emergency Management Agency (FEMA) and the New England States Emergency
Consortium (NESEC) provide information on emergency preparedness.
What should people do during an earthquake?
H-34, September, 1991, Are You Ready? Your Guide to Disaster Preparedness;
and 88A, March 1990, Earthquake Safety Activities for Children;
A Report on the Seismic Vulnerability of the State
of Vermont by Ebel and others, 1995;
Does the Earth Quake in New England by Alan Kafka, 2004.
For more links to past and real-time earthquakes, go to our Hazards Index Page.