Adams

Photo of this volcano
  • Country
  • Volcanic Region
  • Primary Volcano Type
  • Last Known Eruption
  • 46.206°N
  • 121.49°W

  • 3742 m
    12274 ft

  • 321040
  • Latitude
  • Longitude

  • Summit
    Elevation

  • Volcano
    Number

Most Recent Bulletin Report: September 1997 (BGVN 22:09) Citation IconCite this Report


Avalanche moves 5 km down the uninhabited east flank on 20 October

A sizable rock avalanche occurred during 20 October on the E side of Mount Adams. Based on seismic signals, the avalanche began at 0031 and lasted about six minutes. There were no seismic precursors.

On 21 October, a US Geological Survey scientist inspected the avalanche deposit from a small airplane. The avalanche originated at ~3,500 m elevation on the S face of The Castle, a prominent topographic knob at the head of Battlement Ridge. The source area formed an obvious, near-vertical scar roughly triangular in shape with sides ~300 m long. The summit of The Castle remained intact. The avalanche descended the Klickitat Glacier icefall and left a thin veneer of rock debris on the steep upper part of the glacier. Below ~2,500 m elevation the deposit thickened. The avalanche traveled beyond the end of the Klickitat Glacier and continued ~2 km down the valley of Big Muddy Creek, a Klickitat River tributary. The length of the avalanche track totaled ~5 km, and the width may exceed 1 km in places. The average width is ~0.5 km. Maximum deposit thickness may exceed 20 m. The volume of the avalanche debris is probably between 1 and 5 million m3.

The avalanche deposit temporarily blocked the flow of Big Muddy Creek, resulting in the formation of a small lake on the avalanche debris. By noon on 21 October the avalanche dam had breached, and flow in Big Muddy Creek did not appear unusual. Continuing hazards exist due to the threat of additional rockfalls, damming and downstream flooding. However, these hazards exist primarily in unpopulated areas deep within the backcountry of Yakima Nation lands. No evidence suggests that hazards in populated areas far downstream have increased significantly.

This avalanche appeared unrelated to a similar-sized avalanche on the W flank of Mount Adams about seven weeks earlier (31 August). This earlier avalanche consisted of about 90% snow and ice; its source was Avalanche Glacier cirque at ~ 3,650-m elevation on the upper SW flank. Both avalanches originated where rocks evidently had been weakened by intense hydrothermal alteration. Both avalanches may have been triggered in part by wet subsurface conditions associated with late-season thawing of exceptionally heavy snowpack in conjunction with early-season storms. Neither avalanche was triggered by regional earthquake or volcanic activity.

After the 20 October avalanche, a second, smaller one swept down the same path and yielded a much smaller seismic signal that began at 0729 on 24 October. Preliminary reports suggested that the second avalanche traveled only about half the distance of the first.

Mount Adams, one of the largest volcanoes in the Cascade Range, dominates the Mount Adams volcanic field in Washington's Skamania, Yakima, Klickitat, and Lewis counties and the Yakima Indian Reservation of S-central Washington (1,250 km2). At Adams, large landslides and lahars that need not be related to eruptions probably pose the most destructive, far-reaching hazard.

Information Contacts: Cascades Volcano Observatory (CVO), U.S. Geological Survey, 5400 MacArthur Blvd., Vancouver, WA 98661, USA (URL: http://volcanoes.usgs.gov/); Geophysics Program, University of Washington, Seattle, WA 98195, USA (URL: http://vulcan.wr.usgs.gov/).

The Global Volcanism Program has no Weekly Reports available for Adams.

Bulletin Reports - Index


Reports are organized chronologically and indexed below by Month/Year (Publication Volume:Number), and include a one-line summary. Click on the index link or scroll down to read the reports.

09/1997 (BGVN 22:09) Avalanche moves 5 km down the uninhabited east flank on 20 October




Information is preliminary and subject to change. All times are local (unless otherwise noted)


September 1997 (BGVN 22:09) Citation IconCite this Report


Avalanche moves 5 km down the uninhabited east flank on 20 October

A sizable rock avalanche occurred during 20 October on the E side of Mount Adams. Based on seismic signals, the avalanche began at 0031 and lasted about six minutes. There were no seismic precursors.

On 21 October, a US Geological Survey scientist inspected the avalanche deposit from a small airplane. The avalanche originated at ~3,500 m elevation on the S face of The Castle, a prominent topographic knob at the head of Battlement Ridge. The source area formed an obvious, near-vertical scar roughly triangular in shape with sides ~300 m long. The summit of The Castle remained intact. The avalanche descended the Klickitat Glacier icefall and left a thin veneer of rock debris on the steep upper part of the glacier. Below ~2,500 m elevation the deposit thickened. The avalanche traveled beyond the end of the Klickitat Glacier and continued ~2 km down the valley of Big Muddy Creek, a Klickitat River tributary. The length of the avalanche track totaled ~5 km, and the width may exceed 1 km in places. The average width is ~0.5 km. Maximum deposit thickness may exceed 20 m. The volume of the avalanche debris is probably between 1 and 5 million m3.

The avalanche deposit temporarily blocked the flow of Big Muddy Creek, resulting in the formation of a small lake on the avalanche debris. By noon on 21 October the avalanche dam had breached, and flow in Big Muddy Creek did not appear unusual. Continuing hazards exist due to the threat of additional rockfalls, damming and downstream flooding. However, these hazards exist primarily in unpopulated areas deep within the backcountry of Yakima Nation lands. No evidence suggests that hazards in populated areas far downstream have increased significantly.

This avalanche appeared unrelated to a similar-sized avalanche on the W flank of Mount Adams about seven weeks earlier (31 August). This earlier avalanche consisted of about 90% snow and ice; its source was Avalanche Glacier cirque at ~ 3,650-m elevation on the upper SW flank. Both avalanches originated where rocks evidently had been weakened by intense hydrothermal alteration. Both avalanches may have been triggered in part by wet subsurface conditions associated with late-season thawing of exceptionally heavy snowpack in conjunction with early-season storms. Neither avalanche was triggered by regional earthquake or volcanic activity.

After the 20 October avalanche, a second, smaller one swept down the same path and yielded a much smaller seismic signal that began at 0729 on 24 October. Preliminary reports suggested that the second avalanche traveled only about half the distance of the first.

Mount Adams, one of the largest volcanoes in the Cascade Range, dominates the Mount Adams volcanic field in Washington's Skamania, Yakima, Klickitat, and Lewis counties and the Yakima Indian Reservation of S-central Washington (1,250 km2). At Adams, large landslides and lahars that need not be related to eruptions probably pose the most destructive, far-reaching hazard.

Information Contacts: Cascades Volcano Observatory (CVO), U.S. Geological Survey, 5400 MacArthur Blvd., Vancouver, WA 98661, USA (URL: http://volcanoes.usgs.gov/); Geophysics Program, University of Washington, Seattle, WA 98195, USA (URL: http://vulcan.wr.usgs.gov/).

Eruptive History


Summary of Holocene eruption dates and Volcanic Explosivity Indices (VEI).


Start Date Stop Date Eruption Certainty VEI Evidence Activity Area or Unit
0950 (?) Unknown Confirmed 2 Tephrochronology East flank?, Tephra layer 24
0200 (?) Unknown Confirmed 2 Tephrochronology Tephra layer 23
0300 BCE (?) Unknown Confirmed 2 Tephrochronology Tephra layer 22
0400 BCE (?) Unknown Confirmed 2 Tephrochronology Tephra layer 21
0550 BCE ± 1000 years Unknown Confirmed 2 Tephrochronology Tephra layers 19-20
1850 BCE (after) Unknown Confirmed 1 Tephrochronology SSE flank (2100 m)
2650 BCE ± 300 years Unknown Confirmed 2 Tephrochronology Tephra layers 17-18
2950 BCE ± 100 years Unknown Confirmed 1 Tephrochronology SSE flank (2600 m), Tephra layer 16
3250 BCE ± 300 years Unknown Confirmed 2 Tephrochronology Tephra layer 15
3550 BCE (?) Unknown Confirmed 2 Tephrochronology Tephra layer 14
3800 BCE ± 1950 years Unknown Confirmed 1 Tephrochronology NNE flank (2100-2250 m)
4050 BCE ± 500 years Unknown Confirmed 2 Tephrochronology Upper SW flank?, Tephra layers 11-13
4550 BCE (?) Unknown Confirmed 2 Tephrochronology NW flank (2200-2400 m), Tephra layer 10
5150 BCE ± 500 years Unknown Confirmed 2 Tephrochronology Tephra layers 5-9
7050 BCE ± 1000 years Unknown Confirmed 2 Tephrochronology Tephra layers 1-4

This compilation of synonyms and subsidiary features may not be comprehensive. Features are organized into four major categories: Cones, Craters, Domes, and Thermal Features. Synonyms of features appear indented below the primary name. In some cases additional feature type, elevation, or location details are provided.

Photo Gallery


Mount Adams rises above a cloud layer filling valleys in the Cascade Range, viewed from High Knob, NW of the volcano. Adams is constructed on a lower base than its neighbor Mount Rainier, and has a larger volume. Unlike Mount Rainier, where eruptions have mostly been restricted to the summit conduit, Mount Adams has also produced eruptions from numerous flank vents surrounding the volcano. A series of lava flows were erupted on the north, NW, south and east flanks between about 7000 and 1000 years ago.

Photo by Lee Siebert, 1981 (Smithsonian Institution).
See title for photo information.
The elongated form of Mount Adams, constructed by eruptions along a NNW-SSE line, is seen in this view from Mount St. Helens to the west. Eruptive activity continued into the Holocene from both summit and flank vents. Vents on the north, NW, south and east flanks between 2100-2600 m altitude produced lava flows between about 7000 and 1000 years ago.

Photo by Lee Siebert, 1979 (Smithsonian Institution).
See title for photo information.
Mount Adams, the highest peak between Mount Rainier and Mount Shasta, forms a prominent backdrop to the farmlands on the east side of the Cascades. Mount Adams, known to the Columbia River Indians as Pahto or Paddo, was featured prominently in Indian legends. The summit of Adams was said to have been flattened by a mightly blow from its southern brother, Mount Hood (Wyeast), when the damsel St. Helens (La-wa-la-clough) preferred Adams over Hood.

Photo by Lee Siebert, 1982 (Smithsonian Institution).
See title for photo information.
The farmlands of the Trout Lake valley SW of Mount Adams are underlain by a massive mudflow produced by collapse of the upper SW flank of Adams about 6000 years ago. Farmers were forced to remove numerous boulders of altered rocks from near the summit of the volcano that littered the surface of the deposit, which covered 15 sq km of the Trout Lake lowland and reached as far as 60 km to the south. The source of the mudflow was a debris avalanche from the upper White Salmon glacier area, just left of the shadow beneath the summit.

Photo by Lee Siebert, 1995 (Smithsonian Institution).
See title for photo information.
Adams Glacier descends from the summit of Mount Adams, seen rising to 3742 m above Takhlakh Lake on the NW side. The main cone of Mount Adams was constructed primarily of lava flows during the Pleistocene, but flank vents produced lava flows and explosive eruptions during the Holocene. The Tahk Tahk Meadow lava flow, the largest from Mount Adams during the Holocene, originated from a vent low on the NW flank and traveled a total of 10 km, reaching several km beyond the east (left) side of Takhlakh Lake.

Photo by Lee Siebert, 1981 (Smithsonian Institution).
See title for photo information.
Mount Adams, the second highest peak in the Pacific Northwest, rises above forests in the southern Cascade Range of Washington in this view from the SW. The large cirque below the left side of the summit is occupied by the White Salmon and Avalanche Glaciers and was the source of a large mudflow that traveled 60 km down the White Salmon River valley about 6000 years ago.

Photo by Lee Siebert, 1995 (Smithsonian Institution).
See title for photo information.
The massive 4392-m-high glacier-mantled cone of Mount Rainier forms the highest peak of the Cascade Range. This aerial view from the NW also shows neighboring Mount Adams on the right horizon. The steep cirque forming the sheer Willis Wall, named after the 19th-century geologist Bailey Willis, lies in the shadow at the left, below the Winthrop Glacier, which forms the left-hand ridge of Mount Rainier. Two young overlapping cinder cones, their rims kept free of snow by high heat flow, form the flat summit of the volcano.

Photo by Lee Siebert, 1985 (Smithsonian Institution)
See title for photo information.

Smithsonian Sample Collections Database


The following 14 samples associated with this volcano can be found in the Smithsonian's NMNH Department of Mineral Sciences collections. Catalog number links will open a window with more information.

Catalog Number Sample Description
NMNH 116133-1 Scoria
NMNH 116133-2 Andesite
NMNH 116133-3 Andesite
NMNH 116133-5 Andesite
NMNH 117254-1 Eclogite
NMNH 117254-10 Actinolite schist
NMNH 117254-2 Eclogite
NMNH 117254-3 Eclogite
NMNH 117254-4 Eclogite
NMNH 117254-5 Eclogite with pyrite and glaucophane
NMNH 117254-6 Eclogite
NMNH 117254-7 Eclogite
NMNH 117254-8 Eclogite
NMNH 117254-9 Eclogite

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