Hosting Geophysical Instruments
for EarthScope Experiments
EarthScope, a university research program funded by
the National Science Foundation, is currently deploying
thousands of geophysical instruments across the United
States to explore the structure and evolution of the North
American continent and to understand the processes
controlling earthquakes and volcanoes. The USArray
component of EarthScope uses seismometers to record
earthquakes and magnetotelluric instruments to record
naturally occurring variations in earth’s magnetic field.
Researchers can then apply mathematical models to the
recorded data to develop images of earth’s interior.
To collect data for this research, EarthScope staff and
university researchers seek sites on private and public
lands to temporarily install their instruments. The experi-
ments the scientists are conducting fall into one of three
categories: the Transportable Array, the Flexible Array and
the Magnetotelluric Transportable Array. Each experiment
requires a separate permit with requirements specific to
the type of instrument being sited and the length of time
the instrument remains in place. In all cases, the host is not
liable for any loss of or damage to the instrument on their
property. Because of the different criteria for each experi-
ment, siting more than one type of instrument on the
same property is rare.
The Transportable Array consists of 400 portable seis-
mometers spaced 70 kilometers apart that will leapfrog
across the United States from west to east over a 10-year
period. By the end of the project, 1600 sites will have
been occupied. The seismometers are extremely sensitive
and record local, regional and worldwide earthquakes.
Researchers use the spatial distribution of these earth-
quake recordings to image the interior of the earth.
The housing for the seismometer requires a plastic tube
placed inside a hole four feet wide and seven feet deep.
Concrete is poured into the bottom to make a sealed con-
tainer. About 20 feet from t