Washington, USA
| The south side of the lava dome has been rising for the past week and has uplifted 250 ft. A new steam vent opened overnight of 6th -7th October, and joined the two that have been present for several days. Steaming from the vents generated a cloud rising above the south side of the lava dome. | |
| The alert level was reduced to 2, after a decrease in earthquake activity at Mt St Helens volcano. Following October 5 steam-and-ash eruption, seismicity dropped to a low level. | |
| A strong steam and ash emission occurred at 9:00 a.m. PDT on October 5. The emissions continued for 1 hour. Steam and ash clouds reached about 12,000 feet and drifted north-northeastward. | |
| There was a steam and ash emission from Mt St Helens volcano at 9:43 AM PDT Oct. 4. The 40 minute emission was not accompanied by significant earthquake activity. Ash reached 10,000 to 12,000 ft. Part of the vent became covered by a boiling lake. | |
| At 2pm on Saturday 2nd October the alert level at Mt St Helens volcano was raised to 3. The level of concern was raised after there was a second small eruption of the volcano, followed by 50 minutes of harmonic tremor, which indicated possible ascent of magma towards the surface. The second eruption created a puff of white cloud, followed by a dust-raising landslide in the crater. Hundreds of visitors at the building closest to the volcano – Johnston Ridge Observatory five miles away – were asked to leave yesterday. Evacuation of the observatory was primarily a precaution in case of heavy ash discharge, which could make it difficult to drive. | |
| Mount St. Helens volcano began blowing a large cloud of smoke and steam Friday afternoon. The event was described as a small explosion. Seismicity immediately dropped after the explosion. The steam cloud poured from the southern edge of a 300 metre tall lava dome in the volcano's crater that has risen in recent days. A seismograph station in the crater was broken or destroyed in the eruption. Following the initial eruption, the volcano appeared to die down and the ash and steam cloud drifted off. The volcano then began to repressurize. | |
| The alert remains at a Volcano Advisory. Overnight the seismic energy level increased slightly and remains elevated with a rate of 3-4 events per minute and now include events as large as magnitude 3.3. All earthquake locations are still shallow and in or below the lava dome. | |
| Increased seismicity overnight prompted raising the alert level to Volcano Advisory (Alert Level 2) at 10:40 A.M., PDT, this morning. Throughout the day the seismic energy level has remained at an elevated with a rate of 3-4 events per minute including an increase in the number of events between Magnitude 2 and 3. All earthquake locations are still shallow and in or below the lava dome. | |
| Throughout the day seismic activity has remained at a fairly constant, but high, rate of about 2 small (less than magnitude 2) earthquakes per minute. All earthquake locations are still shallow and in or below the lava dome. | |
| Seismic activity has very slowly increased throughout the day. All earthquake locations are still shallow and beneath the dome. The largest earthquake recorded in the past 24 hours has been about a M1.5 and no M2 earthquakes have been detected in the past 24 hours. | |
| Seismic activity at Mount St. Helens has changed significantly during the past 24 hours. There is an increased likelihood of a hazardous event, which warranted release of a Notice of Volcanic Unrest. | |
| Seismicity at Mount St. Helens has declined significantly since yesterday. However, small, shallow earthquakes are still occurring at above typical background rates. | |
| The cause of such shallow swarms is uncertain, but may reflect increased ground water levels with the onset of autumn rain. The probability of small steam explosions that hurl rocks a few hundred meters (yards) may also be increased during periods with increased shallow earthquakes. | |
| From about 2 am PDT on the morning of 09/23 an earthquake swam has been occurred at Mount St. Helens. Through 5 P.M. PDT about 200 small (less than magnitude 1) earthquakes have been recorded at MSH. The earthquakes are occurring at shallow depths (less than 1 kilometer, or 1/2 mile) mostly under the lava dome that formed between 1980 and 1986. |