They hope to send out the OSU research ship, Wecoma,
to take water samples, looking for evidence that
sediment on the ocean bottom has been stirred up and
chemicals in the water that would indicate magma is
moving up through the crust, Dziak said.
There have been more than 600 quakes over the past 10
days in a basin 150 miles southwest of Newport. The
biggest was magnitude 5.4 and two others were more than
magnitude 5.0, OSU reported. They have not followed the
typical pattern of a major shock followed by a series of
diminishing aftershocks, and few have been strong enough
to be felt on shore.
It looks like what happens before a volcanic
eruption, except there are no volcanoes in the area,
Dziak said.
The Earth's crust is made up of plates that rest on
molten rock, which are rubbing together side to side and
up and down. When the molten rock, or magma, erupts
through the crust it creates volcanoes. That can happen
in the middle of a plate. When the plates lurch against
each other, they create earthquakes along the edges of
the plates.
In this case, the Juan de Fuca Plate is a small piece
of crust being crushed between the Pacific Plate and
North America, Dziak said.
On the hydrophones, the quakes sound like low
rumbling thunder and are unlike anything scientists have
heard in 17 years of listening, Dziak said. Some of the
quakes have also been detected by earthquake instruments
on land.
The hydrophones are leftover from a network the Navy
used to listen for submarines during the Cold War. They
routinely detect passing ships, earthquakes on the ocean
bottom and whales calling to each other.
