Eruption of 2004

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Eruption of 2004
Back to Mt St Helens
It started with some increased activity. Not really a big deal by itself. Most of the quakes were shallow, and the immediate thought was that water had seeped down into the crater dome and floor, and the steam produced was causing the flurry of small quakes.
September 23
This was the day I noticed something was different. Nothing was in the news or anything, but I saved the webicorder, because I thought it looked cooler than the others I've picked up along the way.
September 24
The ramp-up continued on Friday. The quakes were becoming more frequent, and a bit stronger... The following statement was released...
Mount St. Helens Swarm Activity Special information statement of Sep 24, 2004 10am PDT U.S. Geological Survey Cascades Volcano Observatory, Vancouver, Washington University of Washington Dept. of Earth and Space Sciences, Seattle, Washington Since about 2 am PDT on the morning of 09/23 an earthquake swarm has been occurring at MSH. Through 5 P.M. PDT about 200 small (less than magnitude 1) earthquakes have been located at Mount St. Helens and many smaller events have also been recorded through this morning. 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. Such earthquakes are common at St. Helens, but a swarm with this many earthquakes has not been recorded for several years, most recently on November 3-4, 2001. The probability of small landslides and debris flows in the crater may be enhanced during these periods. Such events could affect areas several kilometers (miles) north of the crater on the Pumice Plain. The probability of small steam explosions that hurl rocks a few hundred meters (yards) may also be increased during periods with increased shallow earthquakes. The cause of such shallow swarms is uncertain, but may reflect increased ground water levels with the onset of autumn rain. Prior to the 2001 swarm, the last period of increased earthquake activity at Mount St. Helens occurred in the spring and summer of 1998 when hundreds of earthquakes per month, most smaller than M=2, were detected at depths as great as 9 kilometers (6 miles). An intrusion of magma, or molten rock, deep under the volcano and resulting increased gas pressure in the conduit that leads to the lava dome likely caused this increase in earthquakes. The current swarm is different in that the events are typically much smaller and shallower. We see no evidence that an intrusion of magma similar to that of 1998 is underway. We continue to monitor the situation closely and will issue additional Updates as warranted.
The Headquarters building of the CVO (Cascade Volcano Observatory)
September 26 - Elevated to Level 2
The ramp-up continued through the weekend, becoming almost continuous. The quakes were still shallow, though, and the USGS was saying that they were probably from steam.


Mount St. Helens Notice of Volcanic Unrest September 26, 2004 3:00 P.M., PDT U.S. Geological Survey Cascades Volcano Observatory, Vancouver, Washington University of Washington Dept. of Earth and Space Sciences, Seattle, Washington Seismic activity at Mount St. Helens has changed significantly during the past 24 hours and the changes make us believe that there is an increased likelihood of a hazardous event, which warrants release of this Notice of Volcanic Unrest. The swarm of very small, shallow earthquakes (less than Magnitude 1) that began on the morning of 23 September peaked about mid-day on 24 September and slowly declined through yesterday morning. However, since then the character of the swarm has changed to include more than ten larger earthquakes (Magnitude 2-2.8), the most in a 24-hr period since the eruption of October 1986. In addition, some of the earthquakes are of a type that suggests the involvement of pressurized fluids (water and steam) or perhaps magma. The events are still occurring at shallow depths (less than one mile) below the lava dome that formed in the crater between 1980 and 1986. The cause and outcome of the earthquake swarm are uncertain at this time. Several causes are possible, but most point toward an increased probability of explosions from the lava dome if the level of current unrest continues or escalates. During such explosions the dome and crater floor are at greatest risk from ballistic projectiles, but the rim of the crater and flanks of the volcano could also be at risk. Explosions would also be expected to produce ash clouds that drift downwind at altitudes up to several thousand feet above the crater rim. Landslides and debris flows from the crater that are large enough to reach the Pumice Plain are also possible. Such events occurred at Mount St. Helens between 1989 and 1991. We continue to monitor the situation closely and will issue additional updates as warranted, whether activity escalates or returns to background levels.
Oblique aerial photograph of north flank, crater, lava dome and new glacier (behind dome), Mount St. Helens, Washington state, USA. USGS photograph taken on 26 September, 2004 by John S. Pallister.


September 27 - Volcanic Unrest (Level 1)
A Hiking ban was instituted around the mountain. No one could go over 4200 feet, which kept most folks quite far away from the crater. These folks on the right, however, either didn't know about it, or didn't care. Outwardly, there was not indication that anything was amiss, but the webicorder really sent home the fact that something was up

Mount St. Helens Notice of Volcanic Unrest Mount St. Helens Daily Update 9/27/04 7:00 PM PDT 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. Cascades Volcano Observatory (CVO) crews installed GPS equipment today to monitor any ground movement on the dome, crater floor and the slopes of the volcano. Preliminary results from a gas flight late this afternoon did not detect any magmatic gas around the lava dome.
Scientist setting up GPS unit Mount St. Helens to monitor any ground movement. Once its set up, there's a great view of the Toutle River Valley, as seen from the lip of the crater.


USGS Scientists installing GPS unit to monitor any ground movement. The equipment was sent in by helicopter, which remained "At the ready" to remove the scientists at a moments notice. The picture of the "New Glacier"'s terminal moraine really exemplifies the hazard that any significant release of heat would cause. The glacier would melt, causing a considerable amount of outflow into the Toutle valley.

Increased eathquake activity at Mount St. Helens gets the attention of the news media.
USGS Scientists installing gas monitoring equipment in helicopter.

Aerial closeup of Mount St. Helens' lava dome, taken during gas survey.
September 28
The pressure and shaking continued... it now seemed to be one quake leading right into the next quake. Other than that, though, it was a relatively quiet day.
USGS Scientist sets up GPS equipment near the "Sugar Bowl". The view of the crater was from where the unit was being set up.

Setting up a GPS unit just below the lip of the crater.
GPS Unit set up on west flank of the mountain. Below, a USGS scientist walks along west ridge to set up a GPS Unit.

September 29 - Volcano Advisory (Level 2)
The rate of earthquakes were now 2-3 per second, mostly in the 1 - 2 mag range. Tilt meters recorded Dome movement to the North, at a rate of about 2-3 inches.
U.S. Geological Survey, Vancouver, Washington University of Washington, Pacific Northwest Seismograph Network, Seattle, Washington Mount St. Helens Volcano Advisory (Alert Level Two) September 29, 2004 10:40A.M., PDT Over night, seismic activity at Mount St. Helens has accelerated significantly, which increases our level of concern that current unrest could culminate in an eruption. We are increasing the alert level to the second of three levels, which is similar to Color Code Orange of the alert system used by the Alaska Volcano Observatory and analogous totheNational Weather Service’s hazardwatch. Earthquakes are occurring at about four per minute. The largest events are approaching Magnitude 2.5 and they are becoming more frequent. All are still at shallow levels in and below the lava dome that grew in the crater between 1980 and 1986. This suggests that the ongoing intense earthquake activity has weakened the dome, increasing the likelihood of explosions or perhaps the extrusion of lava from the dome. The cause and outcome of the accelerating unrest is uncertain. Explosions from the lava dome could occur suddenly and without further warning. During such explosions the dome and crater floor are at greatest risk from ballistic projectiles, but the rim of the crater and flanks of the volcano could also be at risk. Explosions would also be expected to produce ash clouds that rise several thousand feet above the crater rim and drift downwind. During today, wind forecasts from the National Weather Service, combined with eruption models, show that ash clouds will move in a southeasterly direction and could dust areas tens of miles or more from the volcano with ash. Landslides and debris flows from the crater that are large enough to reach the Pumice Plain are also possible. If the current unrest is being driven by a small slug of magma at shallow depth, extrusion of lava could also occur. At present there is no evidence that new gas-rich magma has ascended to shallow levels and could generate a large sustained eruption. But we are being especially vigilant to become aware of such evidence should it appear.
USGS Scientist setting up a GPS unit on the rim of the volcano. Mt Adams can be seen in the distance. After they returned, the scientists mentioned that they could feel the earthquakes, and said it was "ominous".
During the gas sensing flight through the crater itself, photographs were taken of the glacier and crater dome...


They noticed uplift on the South side of the dome. They estimated the cracks, not visible the day before, to be at 10-30 feet wide, and estimated the uplift to be in the "10's of feet". In a press conference, the USGS called the uplift rate, "Shocking".


September 30
The intensity was STILL increasing... the quakes became near continuous. They were still fairly shallow, though, and there weren't any 'volcanic gasses', so the thought was that there wasn't any 'new' magma involved. In a press conference, the USGS Chief out of the Vancouver office said that in his opinion, the 'plug' that had formed over the magma column was still intact.
More equipment being installed. RIGHT: At "Nelson", another GPS unit is installed. BELOW: With Spirit lake in the background, a GPS unit is installed on the Eastern Flanks of the volcano.

U.S. Geological Survey scientist Michael Poland collects information from a GPS station on the east flank of Mount St. Helens.

Detailed photo of the uplifted area, showing steam from the warmth of having the magma column so close to the surface. The uplifted mound was estimated to be 50 feet. The glacier in that area is 200 feet deep.

October 1 - Eruption - Ash and steam
At noon, during the news, they were doing an interview with a USGS scientist about the heightened activity, and the first eruption since 1986 began, right on Cue. I ran and got my camera, and snapped some "live" shots off the TV...


				A quick check on the webicorder showed what it looked like 'on the inside'. At some point during the event, the sensor took a hit, and the USGS lost a valuable resource of information. There's another sensor, about a mile or so outside the crater. Its not as sensitive, but it picks up the shaking very well. Immediately following the eruption, the mountain quieted down a bit, but after an hour or so, the earthquakes started to return...

U.S. Geological Survey, Vancouver, Washington University of Washington, Pacific Northwest Seismograph Network, Seattle, Washington Mount St. Helens Information Statement October 1, 2004, 11:45 P.M., PDT This Information Statement describes a new feature that has developed in the crater of Mount St. Helens over the past few days. Photographs taken by scientists during gas flights show that an area of about 5 to10 acres on the crater glacier, just south of the 1980-86 lava dome, has risen up to several tens of feet (exact amount is not known) and has become increasingly crevassed (cracked). The crevasses are up to several feet wide and perhaps tens of feet deep. We think that this localized deformation is caused by a portion of the south side of the lava dome and crater floor pushing upward in a piston-like motionand lifting overlying snow, glacier ice, and rock debris that is tens to several hundred feet thick. Because there is no sign of steaming or rapid melting, we infer that old, cold dome rock is in contact with the glacier and not new lava, which would be hot enough to cause steaming. This morning a USGS scientist from the Alaska Volcano Observatory is flying over the crater with an instrument that measures surface temperatures of the dome and crater floor. This deformation accompanies the intense seismic activity of the past week and suggests that the dome has been weakened sufficiently that forces at depth are large enough to allow upward displacement of part of the dome and crater floor. Evidence from GPS instruments on the flanks of the volcano indicate that this deformation is limited to a relatively small area between the lava dome and south crater wall and that other sites are stable. Not long after that, came this release... Mount St. Helens Information Statement, October 1, 2004, 1:45 P.M., PDT Mount St. Helens remains at Alert Level 2—Volcano Advisory Shortly before noon today, Mount St. Helens emitted a plume of steam and minor ash from an area of new crevasses in the crater glacier south of the 1980-86 lava dome. This area was described in the prior Information Statement issued at 12:45 P.M. The event lasted from 11:57 to 12:21 PDT and created a pale-gray cloud that reached an altitude of about 9700 ft (from pilot reports). It drifted southwestward, where nearby residents should receive no more than a minor dusting of ash. USGS scientists making thermal measurements witnessed the emission and noted that the clouds were not particularly hot. Blocks of rock and ice ejected by the event fell in the crater and rim areas. The emission was accompanied by an abrupt drop in seismicity, which remains at low levels. Similar events are possible in the future. We will monitor the situation closely over the next several hours anddays in order to determine the outlook for future behavior. Additional updates will be issued as needed.
At noon, during a live interview at the mountain, as if on cue, the mountain erupted with a burst of ash and steam. An estimated 3,000 tourists at Johnston's Ridge were treated to an amazing display of nature's fury. On the Volcanic Energy scale, the event was a minimal 1, on a scale of 1 to 8, with the 1980 eruption measuring in at a 5. The eruption lasted for 24 minutes.


As luck would have it, the eruption burst out during a USGS Gas flight through the crater, and while the photographer aboard was taking pictures of the uplifted region. The eruption burst from the area where the majority of the uplift occurred.


				Although small in Geologic standards, it was quite impressive!

Other than ash marring the snow, not much was done to the crater floor.

A 200 foot wide hole was cut by the blast, reaching down through the glacier to the crater floor. The event was called a "cold" event by the USGS... the release was from "old" magma, which had cooled, limiting the amount of melting. Rocks as large as a car were thrown about a mile from the outburst.... but nothing significant left the crater itself.

October 2 - Eruption - Steam 'puff', then Harmonic Tremors Start
The daily buildup was obvious on the seismograph, and just after noon, a small release of steam caught everyone's attention for a bit, but for the geologists, everything changed...

On the right of this image, you can see the "Long Looking" earthquake... that's the signature for magma on the move... its called a "Harmonic Tremor". That means that things are going to get much larger. The Geologist at a press conference said that he thought that maybe that meant that the "plug" was broken, allowing magma to move. In less than an hour, the Johnston Ridge observatory was evacuated, and the Alert Level was raised to Level 3
Mount St. Helens Notice of Volcano Alert, October 2, 2004 U.S. Geological Survey Cascades Volcano Observatory, Vancouver, Washington University of Washington Dept. of Earth and Space Sciences, Seattle, Washington A notice of Volcano Alert (Alert Level 3) was issued today at 2:00 p.m. PDT Immediately after the small steam emission at 12:15, seismic activity changed from principally rock breakage events to continuous low-frequency tremor, which is indicative of magma movement. We are increasing the alert level to Volcano Alert the highest alert level indicating that an eruption could be imminent. The cause and outcome of the accelerating unrest is uncertain. Explosions from the vent could occur suddenly and without further warning. During such explosions the dome and crater floor are at greatest risk from ballistic projectiles, but the rim of the crater and flanks of the volcano could also be at risk. Explosions would also be expected to produce ash clouds that rise several to tens of thousands of feet above the crater rim and drift downwind. Currently wind forecasts from the National Weather Service, combined with eruption models, show that ash clouds will move to the northwest. If ash emissions are large, drifting ash could affect downwind communities. Minor melting of the glacier could trigger debris flows from the crater that are large enough to reach the Pumice Plain. There is very low probability that downstream communities would be impacted by these hydrologic events. . We continue to monitor the situation very closely and will issue additional updates as warranted, whether activity escalates or returns to background levels.
Dome and Crater from the South, during a gas assessment flight. Significant uplift can be observed to the right of the vent hole from the Oct 1 eruption.

October 3
Early in the morning, there was another Harmonic Tremor. During the tremor, as before, there were no earthquakes during The harmonic event. Once it was over, the earthquakes slowly started rebuilding their intensity. RIGHT: Morning on October 3rd came with a light fog that burned away around 9AM. The image of the mountain with Spirit Lake, still ridden with countless logs, is quite striking.

October 4 - Eruption, major uplift, more harmonic tremors
The morning began with reports of a steam event during the night, at 10:40, followed by a harmonic tremor that lasted 90 minutes, then a rebuilding of the earthquakes. I captured the webicorder images at about 9:00 AM. Additionally, the lava dome grew more than 100 feet over the night, and they also reported more quantities of magmatic gasses, and the average size of quakes were close to the Mag 3 range.

U.S. Geological Survey, Vancouver, Washington University of Washington, Pacific Northwest Seismograph Network, Seattle, Washington Mount St. Helens Update 4 October 2004 7:00 A.M. Current status is Volcano Alert (Alert Level 3); aviation color code RED Overnight seismic activity increased until a steam (and possibly ash) event occurred about 10:40 P.M. Observers at Coldwater Ridge could see the steam plume, which barely made it to the crater rim, in the moonlight. Since then, the seismicity has been significantly lower as after prior steam-and-ash events. Earthquakes are occurring at a rate of about 1 per minute and the largest since the steam event have been in the magnitude 2s. All locations remain shallow. Results from GPS measurements indicate no significant deformation of the outer flanks of the volcano. However, visual observations and photographic analysis show large-scale uplift (10’s of meters) of part of the glacier and a nearby segment of the lava dome. Yesterday a field crew installed a new GPS instrument on the dome and also measured the distance from the Johnston Ridge Observatory to the dome. Yesterday’s gas flight did not detect significant concentrations of carbon dioxide. Two telemetered microphones are now in operation to detect explosions. Today we will receive a remotely operated video camera that will be installed on the crater rim from the USGS Hawaiian Volcano Observatory. Today field crews will work at installing additional seismometers on the flanks of the volcano and will continue to harden the GPS sites and download data. Time permitting, additional flights to acquire thermal imagery and gas measurements will occur. Wind forecasts from the NOAA, combined with eruption models show winds today will be from the east and southeast and any ash clouds would drift to the west and northwest. We continue to be concerned that additional steam-and-ash eruptions could occur at any time. The principal hazard from these types of events is for ash reaching altitudes that could affect aviation. If the current unrest continues there is also an increased probability of larger magnitude and more ash-rich eruptions. We continue to monitor the situation closely and will issue additional updates and Alert Level changes as warranted.
At about 9:40, once again during a press conference, Mt St Helens once again released steam and ash.

The webicorder didn't look like much was going on, nor did the King 5 Seismocam... The USGS said that this was a steam-only event, probably caused by the intrusion of hot material close to the surface causing a pool of water to boil and the resulting pressure causing the outflow.


A few hours after the event, Sky 8, from KGW out of Portland, flew over the crater, and checked out the vent hole that was opened on Oct 1... it was quite a bit different. The cracks on the West edge of the vent show the uplift that had occurred over the night. A detail of the vent showed steam rising out of it... the pilot on the chopper also said that he thought the bottom was water and mud. The new pond was about 100 meters wide, and was bubbling with hot gasses.


October 5 - Large Eruption, then quiet spell
Almost on cue, at about 9:40AM, the mountain again roared to life, tossing primarily ash about 19,000 feet into the air. It ranked in at a "Solid 1" on the Volcanic Explosivity Index.

				Mt St Helens is on the flight path into Portland's Airport... there was a plane passing nearby, well out of harms way, giving the passengers an excellent show!

The wind, a bit stronger than it has been in the last few weeks, quickly carried the ash away from the mountain. Towns downwind, as far as White Castle, WA, sent in reports of falling ash. I used my "EagleCam" grabber to grab a 'live' from the KING5 website, in 5 minute intervals...

The activity dropped off after the event, and later that day, the Alert Level was dropped to Level 2.