Just after the minor let off of steam, which gave scientists a sigh of relief, Mt. St. Helens just might be gearing up for another eruption
Scientists have raised the warning level back up to Level-3 on Saturday, just after the threat level had been downgraded to Level-2 when Mt. St. Helens blew off some steam.
Starting shortly after the blowing off of steam, small earth quakes resumed and the pressure is building again. On Saturday, the quakes started being registered at a rate of one to two per minute. Seismic activity decreased shortly after the noon (3 p.m. ET) eruption but picked up again within hours. Peter Frenzen, a scientist with the Mount St. Helens National Volcanic Monument, said "a 2.0 magnitude earthquake was detected".
The lava dome is covered by a 600-foot-deep glacier, and scientists are watching this glacier carefully. A rapid melting would indicate that there is a heating up of the crust and the potential for a blast rises significantly.
Bill Steele, University of Washington, "The growing consensus among scientists is that new magma is probably entering the volcano's upper levels, possibly bringing with it volatile gases that could lead to eruptions".
There are also concerns that the seismic activity has weakened the 1,000-foot lava dome that began forming in the volcano's crater after the 1980 eruption.
A Mt. St. Helens observatory three miles away from the actual mountain has been evacuated of all personnel since the new tremors started. Scientists began measuring a 50-minute long "harmonic tremor," or steady, even vibration, which indicates magma rising to the surface on Saturday and the evacuation order had been issued. U.S. Interior Secretary Gale Norton said: "The data suggests that ongoing, intense earthquake activity has weakened the rock dome, increasing the likelihood of an eruption either in the form of more explosions or perhaps lava flow from the dome".
1980 Mt. St. Helens blast killed 57 people, and destroyed more than 200 homes. The blast reduced the summit of Mount St. Helens from 9,677 feet to 8,364 feet and created a lava dome that is 975 feet across.
In 1986, there was a smaller blast that took no human life or destroyed property.