The recent earthquakes at Mount St. Helens occur about 1 to 4 miles beneath the ground, which researchers say are far too small to even be felt at the surface.
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Mount St. Helens has been reminding researchers it is still an active volcano.
Since March 14, Mount Saint Helens has been rocked by more than 130 small earthquakes, plus many more earthquakes too small to be located.
The magma chamber is likely stressing the crust around and above it as the system slowly recharges, the agency said.
The earthquakes have ranged from magnitude 0.5 to 1.3. The low-magnitude quakes have increased in frequency to about 40 a week, as recorded by the Pacific Northwest Seismic Network (PNSN).
Have no fear, though.
The “earthquake swarm” located by the Pacific Northwest Seismic Network is steadily becoming more frequent, but the tremors are not strong enough to be felt at the surface.
The eruption was trigged by a magnitude 5+ natural disaster, which was accompanied by a debris avalanche.
Since mid-March, a succession of small-magnitude earthquakes have occurred beneath Mount St. Helens, the massive volcano in Washington state whose May 18, 1980 eruption killed 57 people.
“It does mean that even as St. Helens sleeps, the magma that will likely take part in the next eruption is working its way up towards the surface, likely stopping along the way to crystallize and interact with the residue of previous eruptions”.
“What we’re looking at [now] is way smaller”, said Seth Moran, the scientist in charge at the USGS Cascades Volcano Observatory in Vancouver, Wash., reported Livescience.
Now, this might make some people nervous, but if you look at the compilation of earthquakes from St. Helens over its periods of repose since 1988 (see above), you can see that it has had a lot of recharge events-and most of these don’t directly lead to an eruption.
No quakes have started close to the surface and no ground inflammation – the sign of an underground buildup of gas – has been detected.
Scientists said that the process can take place for years without an eruption. However, because this quake swarm is occurring under Mount St. Helens, the deadliest volcano in America, scientists and laypeople alike are taking notice.
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November 6, 2004 – A new lava dome formed inside Mount St. Helens’ crater continues to grow, now sprouting a growth that extends upward by almost 330 feet, officials said.
