Mount St. Helens Alert Level Lowered

New Alert Level: Volcano Advisory (Alert Level 2)

Past Alert Level: Volcano Alert (Alert Level 3)

October 6, 2004 9:15 A.M., PDT

Following yesterday morning’s steam-and-ash eruption, seismicity dropped to a low level and has remained low. Low-level tremor observed following the eruption is also gradually declining. Lack of earthquake and rockfall signals suggest that deformation of the uplift area on the south side of the 1980-86 lava dome has slowed. Brief visual observations this morning from Coldwater Visitor Center showed weak steam emissions from the crater. We infer that the vigorous unrest of the past few days has lessened and that the probability of an imminent eruption that would endanger life and property is significantly less than at any time since Saturday, October 2, when the alert level was raised to Volcano Alert (Level 3). Therefore, we are lowering the alert level to Volcano Advisory (Alert Level 2).

Such decreases in the level of unrest, which may reflect a decrease in the rate of magma movement, have been common at Mount St. Helens during eruptions in 1980-86 and also at similar volcanoes elsewhere. Episodic changes in level of unrest over periods of days to weeks, or even months, are possible. We don’t think that the current episode of unrest is over and we expect fluctuations in the level of unrest to continue during coming days and months. Everyone should be aware that escalation in unrest and perhaps an eruption could occur suddenly or with very little warning. There may be little time to raise the Alert Level before a hazardous event occurs. Therefore, we continue to monitor the situation closely and will issue additional updates and changes in Alert Level as warranted.

http://vulcan.wr.usgs.gov/Volcanoes/Cascades/CurrentActivity/current_updates.html