Has there been any noted correlation between the incidence and
frequency of earthquakes and volcanic activity?
Greg H. Leach
Dear Greg
Yes, there is some generally small correlation between earthquakes
and eruptions, but usually eruptions and significant earthquakes are
unrelated. Confusing? Not meant to be. As magma moves through the
crust and into volcanoes, small (mag. 0.5 - 2.0) earth tremors are
common. And the Mt. St. Helens 1980 eruption followed immediately
following a mag. 5 earthquake caused by the collapse of the side of the
mountain. But eruptions rarely follow deep tectonic earthquakes due to
plate tectonic motions. And, as I recall from some earlier statistical
studies, more frequent eruptions generally are not associated with times
of more frequent earthquakes. This makes sense because earthquakes occur as
a means to reduce accumulated strain in rocks. But if there is molten
magma in the crust (magma chambers) strain can be taken up by flow of
magma, not brittle fracturing of rocks. There are many complications, but
the answer to your question is "generally volcanic eruptions and
earthquakes are unrelated." Happy new year!
Chuck Wood
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