The roughly 8,300-foot volcano erupted in an explosion of hot
ash and gas on May 18, 1980, spewing debris over some 230 square
miles and causing more than a billion dollars in property
damage. Entire forests were crushed and river systems altered in
the blast, which began with a 5.2 magnitude earthquake.
"The magma reservoir beneath Mount St. Helens has been slowly
re-pressurizing since 2008," the U.S. Geological Survey said in
a statement on Wednesday. "It is likely that re-pressurization
is caused by (the) arrival of a small amount of additional magma
4 to 8 km (2.5 to 5 miles) beneath the surface."
The USGS said this is to be expected with an active volcano and
does not indicate "the volcano is likely to erupt anytime soon."
The USGS, and the Pacific Northwest Seismic Network at
University of Washington, closely monitor ground deformation and
seismicity at the volcano. This summer, they will also measure
its released gases and gravity field, measurements that can be
used to monitor subsurface magma and forecast eruptions.
(Reporting by Eric M. Johnson in Seattle;
editing by Larry King
and Sofina Mirza-Reid)
[© 2014 Thomson Reuters. All rights
Copyright 2014 Reuters. All rights reserved. This material may not be published,
broadcast, rewritten or redistributed.