Post Eruption Activity
The following summary
table is provided as a courtesy by the U.S.
Geological Survey, Cascades Volcano Observatory, Vancouver, Washington. We
duplicated the table here to assist teachers, educators and students in developing
their educational programs as part of the Mount St. Helens National Volcanic Monument
Teacher's Corner.
If you use any of the material on this page, please credit the U.S.
Geological Survey, Cascades Volcano Observatory, Vancouver, Washington. We
thank them for their support of the Teacher's Corner.
Eruption Summary -
Mount St. Helens Eruptions Since May 18, 1980
|
Date
eruption began |
Explosive
activity /
Ash plumes |
Pyroclastic
flows /
Lahars |
Facts
of interest |
Dome growth
|
Onset
of extrusion |
Duration
(days) |
Erupted
volumea
(million cubic meters |
Dome
volumeb
(million cubic meters |
Dome
dimensionsc
(l x w x h,
in meters)
|
May 25, 1980 |
explosive activity;
plume to 9 miles
| pyroclastic flows
| |
|
|
|
|
|
June 12, 1980
| explosive activity;
plume to 2.5 miles
| pyroclastic flows
| 1/2-inch-size pumice
fell in Cougar, 10 miles downwind |
Jun 13 |
7 |
5 |
5 |
365-365-45
|
July 22, 1980
| three explosive pulses;
plumes to 6-11 miles; June dome destroyed
| pyroclastic flows
| plumes seen in Tacoma,
WA, 100 miles north |
|
|
|
|
|
Aug 7, 1980
| explosive activity;
plume to 7-8 miles
| pyroclastic flows
| |
Aug 8 |
2 |
1 |
1 |
120-120-60
|
Oct 16, 1980
| explosive activity;
plume to 8-9 miles; August dome destroyed
| pyroclastic flows
| |
Oct 18 |
1 |
1.2d |
1.2d |
300-300-34
|
Dec 27, 1980
|
|
| produced two lobes
on dome (N and S) |
Dec 27 |
7 |
1.6 |
2.8 |
440-320-93
|
Feb 5, 1981
| small tephra-laden
plumes accompanied start of extrusion
|
| new lobe on top of
dome |
Feb 5 |
3 |
3.6 |
6.4 |
520-464-120
|
Apr 10, 1981
| small tephra-laden
plumes accompanied start of extrusion, largest reached 1.5 miles above crater
floor
|
| lobe added on NNW flank
of dome |
Apr 10 |
3 |
4.1 |
10.5 |
666-470-129
|
June 18, 1981
| small tephra-laden
plumes accompanied start of extrusion
|
| lobe covered SW flank
of dome to crater floor |
Jun 18 |
2 |
4.1 |
14.6 |
574-520-161
|
Sept 6, 1981
| vigorous gas and ash
emissions preceded start of extrusion
|
| stubby lobe high on
E flank of dome |
Sep 6 |
5 |
3.9 |
18.5 |
680-590-161
|
Oct 30, 1981
| small tephra-laden
plumes accompanied start of extrusion; small hot explosion during eruption produced
ash layer on crater floor
|
| |
Oct 30 |
4 |
3.6 |
22.1 |
680-660-184
|
Mar 19, 1982
| most explosive activity
since October 1980; plume to 9 miles; pumice deposited
| March 19 mudflow reached
Spirit Lake and N.F.Toutle; major hot rock-avalanche of April 4 created mudflow
to N.F.Toutle valley
| produced two lobes
on dome (March, April) |
Mar 19 |
24 |
3.4e |
24.5 |
760-600-195.1
|
May 14, 1982
| small tephra-laden
plumes accompanied start of extrusion
|
| lobe on top dome |
May 14 |
5 |
2.7 |
27.2 |
800-636-198
|
Aug 18, 1982
|
|
| lobe on W side of dome
|
Aug 18 |
6 |
4.6 |
31.8 |
820-692-204.1
|
Feb 7, 1983
| minor eruptive activity
preceded dome growth phase; largest plume to 2-4 miles
| mudflows across crater;
small flow reached Spirit Lake
| produced two lobes
(February, April); 200ft-high spine |
Feb 7 |
368 |
22.4f |
53.2 |
860-780-227.3
|
Mar 29, 1984g
|
|
| |
Mar 29 |
5 |
|
|
|
June 17, 1984g
|
|
| |
Jun 17 |
|
2.0g |
54.2g |
860-790-227.1g
|
Sept 10, 1984
|
|
| |
Sep 10 |
3 |
3.7 |
57.9 |
960-800-225.6
|
May 24, 1985
|
| minor mudflows in crater
| graben formed |
May 24 |
17 |
4.3 |
62.2 |
1000-800-222.9
|
May 8, 1986
|
|
| |
May 8 |
5 |
5.8 |
68.0 |
1040-800-255.9
|
Oct 21, 1986
|
|
| |
Oct 21 |
4 |
6.1 |
74.1 |
1060-860-267.2
|
Notes
- Total volume erupted, including tephra and rockfall debris
- Net volume of dome shown at end of each eruptive episode
- Dimensions at end of each extrusive episode, including talus. L, length; w,
width, h, height above base of October 1980 lobe at assumed elevation of 1,914
meters. All measurements from topographic maps.
- Volume of October 1980 lobe estimated from dimensions
- Includes pumice erupted on Marcy 19 and deposited beyond dome, and rock-avalanche
of April 4
- Includes notch in dome blown out and then refilled
- Includes estimated volume for March and June, 1984, lobes, and crater formed
by explosions in May.
|
Sources
- Brantley and Bobbie Myers, 1997, Mount St. Helens -- From the 1980 Eruption
to 1996: USGS Fact Sheet 070-97;
- Christiansen and Peterson, 1981, Chronology of the 1980 Eruptive Activity:
IN: Lipman and Mullineaux (eds.), The 1980 Eruptions of Mount St. Helens, Washington,
USGS Professional Paper 1250;
- Swanson, et.al., Growth of the lava dome at Mount St. Helens, Washington
(USA), 1981-1983: IN: Fink (ed.), The Emplacement of Silicic Domes and Lava Flows:
GSA Special paper 212;
- Swanson, Casadevall, and Dzurisin, 1983, Predicting Eruptions at Mount
St. Helens, June 1980 Through December 1982: Science, September 1983, v.221;
- Swanson and Holcomb, 1989, Regularities in Growth of the Mount St. Helens
Dacite Dome, 1980-1986: IN: IAVCEI Proceedings in Volcanology, Vol.2, Lava Flows
and Domes: Springer-Verlag;
- Tilling, Topinka, and Swanson, 1990, Eruptions of Mount St. Helens: Past,
Present, and Future: USGS General Interest Publication;
|
Table compiled by Lyn Topinka, USGS/CVO,
June 17, 1997 |
|