Scientists are reporting they have recorded over 130 small earthquakes below the surface of Mount St. Helens in Washington state, but they say that doesn’t necessarily mean the active volcano is preparing for an eruption.
In a statement, cited on CNN.com, the U.S. Geological Survey (USGS) said there was “absolutely no sign” of a pending eruption, but the agency added the information they were collecting means the volcano is still very active and “very much alive.”
The volcano, located about 95 miles south of Seattle, and 55 miles northeast of Portland, OR, famously erupted almost 36 years ago, on May 18, 1980. The massive explosion took over 1,000 feet off the top of the mountain and spread hot ash across the northwest. The eruption ignited numerous forest fires and caused flooding from the melting of the snow caps, and resulted in 57 people losing their lives.
Since that eruption, the mountain has been one of the most closely monitored active volcanoes on the planet.
The recent quake outbreak has scientists mildly concerned, not because of the magnitude of the earthquakes, but the increasing frequency. Over the last six weeks, according to the USGS, the mountain has averaged nearly 40 located earthquakes each week.
The agency says the collection of the volcano’s magma is re-pressurizing, and that process may go on for many years before leading to another eruption. The USGS noted there have been similar patterns of small earthquakes since the 1980 eruption, notably in the 1990s, and again in 2013 and 2014.
The earthquakes are small, with the largest registering only at 1.3, and most of them being 0.5 or below. The quakes are occurring anywhere from 1.2 to four miles below the surface of the mountain, and since they are so small and happening at such depths in the ground, they cannot be felt at the surface.
The scientists stress they have not found any anomalous gasses, and no signs of magma collection and inflation that would indicate an eruption is about to occur. Still, they say the volcano is in the process of re-charging.