Skip to main content
U.S. flag

An official website of the United States government

Volunteer geophysicist uses VLF instrument

Detailed Description

Volunteer geophysicist uses VLF (Very Low Frequency) instrument to measure flux in lava tube near the new shield in background. Note the gas mask, necessary in this obnoxious area. A rootless shield is a pile of lava flows built over a lava tube rather than over a conduit feeding magma from within the earth. Rootless shields along the tube system commonly have a flat top containing a shallow lava pond.


Public Domain.