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Home , Baker Lake (Washington), Black Buttes, Mount Baker, Sherman Crater

USGS

U.S. GEOLOGICAL SURVEY—REDUCING THE RISK FROM HAZARDS —Living with an Active Volcano

VOLCANO HAZARDS AT MOUNT BAKER

LAVA FLOWS

Lava is molten rock () that pours or oozes onto the Earth's surface. Numerous eruptions of lava interbedded with rock rubble constructed Mount Baker.

PYROCLASTIC FLOWS

Pyroclastic flows are hot of lava fragments and volcanic gas formed by the Mount Baker (10,781 feet) viewed from east side with steam plume rising from (left side of summit, inset shows crater interior). Scar of the 1891 flank collapse is visible in lower left of photo. Photos by collapse of Kevin Scott and (inset) Robert Symonds, USGS. lava flows or What Are the Hazards? eruption ount Baker dominates the clouds. M skyline from Bellingham, The next eruption of Mount Baker may , and , British produce lava flows, pyroclastic flows, (), and . Lahars are Columbia. On cold, clear winter TEPHRA by far the greatest concern at Mount Baker Explosive eruptions days, dramatic increases in the because of its history of frequent lahars, the blast fragments of steam plume rising continuously ability of lahars to flow for tens of miles, and rock high into the air. from Sherman Crater can alarm the potential for hazardous future impacts of Large fragments local residents. This apparent lahars on two reservoirs on the east side of the fall to the ground increase in plume vigor occurs volcano. Tephra hazards at Mount Baker are close to the volcano. because of condensation of steam less important than at neighboring Peak in cold, calm air. In 1975, however, Small fragments volcano to the south. (called ash) increased steaming and melting of Lahars can originate in two ways: from the largest and ice around Sherman 1) During eruptions, pyroclastic flows can eruptions can Crater did signify a change in heat melt snow and ice to create torrents of ash, travel hundreds output from the volcano's interior. rock, and water that move downvalley as sandy of miles. Although the increased heat flow (noncohesive) lahars. 2) Because the volcano is locally weakened gradually subsided, it could have LAHARS signaled the start of eruptive and altered to clay by percolating, acidic, hot water and steam (like that venting from activity, and precautions were Lahars are fast-moving slurries of wisely undertaken. Sherman Crater), future volcanic landslides rock, mud, and water that look and So that the public can be warned known as flank collapses can mobilize to form behave like flowing wet concrete. of, and be prepared for, future muddy (cohesive) lahars. eruptions and other hazardous Lahars of collapse origin occur during Landslides can eruptions. They also occur during non-eruptive transform into lahars. events at Mount Baker, U.S. Geo- Pyroclastic flows can logical Survey (USGS) scientists periods triggered by regional , gravity, or increases in hydrovolcanic activity generate lahars are studying the volcano's past not associated with magma intrusion. by melting behavior and monitoring its current When ground water comes in contact with snow and ice. activity. either magma or hot rock, hydrovolcanic

U.S. Department of the Interior USGS Fact Sheet-059-00 U.S. Geological Survey May 2000 Deposit of the largest from Mount Baker, exposed near the confluence of the Middle and North Forks of the , about 20 miles from its source at the Roman Wall. Note the protruding logs and branches from living trees that were knocked down and carried by the lahar. Ice axe, 3 ft, shows scale. Lahars are the greatest hazard at Mount Baker. Inset shows the flow front of a slurry of rock and water, typical of lahars. The flow is about 10 feet deep, moving right to left at 20 miles per hour. Photos by Kevin Scott, USGS.

explosions of steam and rock can occur. Such 400,000 and 300,000 years ago and formerly events, in addition to possibly triggering bigger than today's Mount Baker. collapse, can themselves be hazardous. Although numerous in Oregon and southern Volcanic ash (tephra) layers on Mount Baker's south Washington, cinder cones formed of the rock flank. Lower white band is from an eruption of Crater Mount Baker— Early History type called are rare around Mount Baker. Lake, Oregon (7,700 years ago); upper yellow band is USGS research in the last decade shows A cinder cone that formed 9,800 years ago in from a hydrovolcanic eruption of Mount Baker (6,600 Mount Baker to be the youngest of several years ago). Above the yellow band is a black ash from Schriebers Meadow produced a widespread a magmatic eruption of Mount Baker (also about volcanic centers in the area and one of the tephra layer, and lava flows that reached the 6,600 years ago). Tephra hazards at Mount Baker are youngest volcanoes in the . Vol- . less significant than at neighboring canic activity in the Mount Baker area began volcano to the south. Photo by Kevin Scott, USGS. more than one million years ago, but many of Today's Mount Baker the earliest lava and tephra deposits have been Modern Mount Baker formed during and south of the summit. Both these area are sites removed by glacial . The pale-colored since the last ice age, which ended about of pervasive bedrock alteration, converting rocks northeast of the modern volcano mark 15,000 years ago. Lava flows from the summit to weak, white-to-yellow material rich in the site of ancient Kulshan Caldera that vent erupted between 30,000 and 10,000 years clays, silica, and sulfur-bearing minerals. At collapsed after an enormous ash eruption one ago and, during the final stages of edifice Sherman Crater, collapses of this weakened million years ago. Subsequently, eruptions in construction, blocky pyroclastic flows poured rock created lahars in 1843 and as recently as the Mount Baker area have produced cones and down most of the volcano's drainages. An the 1970's. lava flows of , the rock that makes up eruption 6,600 years ago produced a blanket of much of other Cascade Range volcanoes like ash that extended more than 20 miles to the Past Events — Future Hazards Mounts Rainier, Adams, and Hood. From about northeast. This eruption probably occurred Like most volcanoes, Mount Baker's history 900,000 years ago to the present, numerous from the presently ice-filled summit crater. records great variations in behavior. Scientists andesitic volcanic centers in the area have Subsequently, sulfurous gases have found two believe the following case histories are good come and gone, eroded by . The largest pathways to the surface—Dorr , examples of the range in size and types of is the edifice, active between northeast of the summit, and Sherman Crater, hazardous activity that have occurred in the

Eruptions and flank collapses at Mount Baker Sequence of events about 6,600 years ago Historical events during the past 12,000 years Large Hydrovolcanic Ash Hydrovolcanic collapse, explosion, eruption explosion, Increased large collapse, collapse, Collapse, steam and lahar large lahar lahars lahar heat

Multiple lava flows, pyroclastic flows, AD 1843 1891 1975 ash eruptions, noncohesive lahars Cinder Collapse, Collapse, cone lahar lahar

12 10 8 6 4 2 0 THOUSANDS OF YEARS AGO Sumas

Lynden Maple Falls sa 542 rth Nook ck River No Fork Everson Glacier

Deming M Kulshan i d d Caldera l e Mount F o rk N Roman Wall Baker Dorr Fumaroles ook 9 sa Sherman Crater ck Bellingham R. Black Buttes Lake Whatcom Baker Schriebers Meadow Lake 5 Cinder Cone

WHATCOM COUNTY

SKAGIT COUNTY r e v

i Lake R

r

Shannon e k a Concrete B River Skagit 20 Sedro Woolley

Burlington EXPLANATION Inundation Zone I - Pathways for eruption-related lahars due to large flank collapses or pyroclastic flows, or floods in the valley caused by displacement of water in reservoirs by lahars. Mount Vernon Inundation Zone II - Pathways of lahars resulting from more frequent, small-to-moderate flank collapses from the area of Sherman Crater.

0 5 10 Miles Proximal pyroclastic flowage hazard zone - Area that could be affected by pyroclastic flows and lava flows.

Map showing hazard zones for lahars, pyroclastic flows and lava flows (for more detail see Plate 1 in US Geological Survey Open-File Report 95-498). past and could occur again. Small events are the site of present day Sherman Crater, reported that many salmon were killed. A short more common than large ones, and during a triggering a second collapse of the flank just time later, two collapses of the east side of future hazardous event only parts of the hazard east of the Roman Wall. That collapse also Sherman Crater produced two lahars, the first zones shown on the map may be affected. became a lahar that mainly followed the course and larger of which flowed into the natural of the first one for at least 20 miles, but also , raising its level at least 10 feet. Flank Collapses, Lahars, and Tephra spilled into tributaries of the Baker River. The location of this 19th-century lake is now Eruptions, about 6,600 Years Ago Finally, an eruption cloud deposited several covered by waters of the modern dam- A series of discrete events culminated with inches of ash as far as 20 miles downwind to impounded Baker Lake. Similar but lower level the largest tephra-producing eruption in post- the northeast. glacial time at Mount Baker. First, the largest hydrovolcanic activity at Sherman Crater collapse in the history of the volcano occurred Sherman Crater Forms in 1843 continued intermittently for several decades from the Roman Wall (see map) and trans- The present shape of Sherman Crater afterwards. formed into a lahar that was over 300 feet deep originated with a large hydrovolcanic explo- in the upper reaches of the Middle Fork of the sion. In 1843, explorers reported a widespread Flank Collapse and Lahar in 1891 Nooksack River. It was at least 25 feet deep 30 layer of newly fallen rock fragments "like a In 1891, about 20 million cubic yards of miles downstream from the volcano and snowfall" and the forest "on fire for miles rock fell from the scar shown in the photo on probably reached Bellingham Bay. Next, a around." Rivers south of the volcano were the front page, producing a lahar that traveled huge hydrovolcanic explosion occurred near clogged with ash, and Native Americans more than 6 miles and covered 1 square mile. Sherman Crater Heats Up in 1975, Triggering Concern Beginning in March 1975, the rate of gas CLOSURECLOSURE and steam emission from Sherman Crater REASONS FOR THE CLOSURE increased significantly. Heat flow increased Based on scientific information obtained from the U.S. Geological Survey and scientists studying steam more than tenfold. The activity gradually activity on Mt. Baker, the Forest Service has closed declined over the next 2 years but stabilized at the shoreline and all campgrounds at Baker Lake. a higher level than before 1975. Several small The closure is in the interest of public safety. lahars formed from material ejected onto the There is danger that the heavy steam acitivity will surrounding glaciers. Acidic water was trigger a massive mudslide from the upper slopes discharged into Baker Lake for many months. of Mt. Baker. Such a slide could enter the lake with great force, sending a wave of water along the lakeshore and into the campground areas.

Response to the 1975 Activity— This closure includes Horseshoe Cove, Boulder Creek, Maple Grove, Baker Lake, Park Creek and Strategies for the Future Campgrounds as well as...... In 1975, scientists believed that the dramatic increase in the steam plume and heat output This notice was posted at campgrounds around Baker Lake by the US Forest Service in June 1975. Normally, from Sherman Crater could herald either a new Baker Reservoir approaches capacity during mid-summer. At most other times, reservoir levels are low enough magmatic eruption or hydrovolcanic activity to impound lahars the size of those that occurred in 1843. like that of 1843. Either of these possibilities force advised lowering the level of Baker Lake Facilitating Committee, has drafted a plan would have increased the risk of collapse, so that it could accommodate lahar inflow outlining how agencies will work together in raising concerns that lahars could flow rapidly without displacing water from the reservoir that the event of unrest at either volcano. into Baker Lake or , displacing could have flooded the downstream Skagit water and creating a flood surge or even River valley. Because a lahar could also trigger causing dam failure. The volcano was What You Can Do waves that would inundate areas around the subjected to the most intensive monitoring ever • Learn about the volcano hazards that could lake, shoreline residences, campgrounds, and applied to a Cascade Range volcano up to that affect your community, and determine businesses were evacuated. On the basis of time. As time passed, no signs of rising whether you live, work, play, or go to school recent research, the west side of Sherman magma— earthquakes, significant changes in in a volcano hazard zone. Crater, site of a previous collapse, could also gas composition, or surface deformation— • Plan what you and your family will do if a be unstable. Today, if there were a similar appeared. The main risk, therefore, was of hazardous event occurs. increase in activity at Sherman Crater, USGS flank collapses and lahars similar to those of scientists might also recommend drawdown of • Participate in helping your community be 1843 (Map Inundation Zone II). Had magmatic Lake Shannon, the smaller downstream prepared. activity been confirmed, a much larger collapse reservoir that is the catchment for drainages A few moments spent in preparation now and flow would have been possible (Map from the west side of the crater. could keep you, your family, and your Inundation Zone I), and a magmatic eruption community safe when Mount Baker next could have ensued like those between 30,000 erupts. and 10,000 years ago or that of 6,600 years Monitoring for the Future ago. The University of Washington Geophysics When magmatic activity does recur, all the Program, in cooperation with the USGS, Kevin M. Scott, Wes Hildreth, and drainages of Mount Baker will be at risk from monitors seismic () activity at Cynthia A. Gardner lahars, and upstream areas will be at risk from Mount Baker and other Cascade Range pyroclastic flows and lava flows in the hazard volcanoes. Seismic activity is the most Graphics and design by zone shown on the map. The Dorr Fumaroles common precursor of magma intrusion, which Lisa Faust, Bobbie Myers, and Christine Janda are also a potential site of hydrovolcanic potentially could lead to an eruption. The risk COOPERATING ORGANIZATIONS explosions. Steep headwalls on the north flank and potential size of flank collapse and lahars increase progressively as magma rises toward U.S. Department of Agriculture, Forest Service are also at risk of flank collapse, but Sherman University of Washington, Geophysics Program Crater is the most likely area on Mount Baker and into a volcano's edifice. for renewed failure. The USGS monitors gas emissions from On the basis of conclusions by USGS Sherman Crater in order to detect changes in For more information contact: scientists in June 1975, an interagency task the volcano's "plumbing system" that may be a U.S. Geological Survey warning of impending magmatic activity or an Cascades Volcano Observatory 5400 MacArthur Blvd., Vancouver, WA 98661 increase in hydrovolcanic activity, and thus an Tel: (360) 993-8900, Fax: (360) 993-8980 increased chance of eruption or collapse. http://vulcan.wr.usgs.gov/ or USGS Volcano Hazards Program Preparing for the Future http://volcanoes.usgs.gov/ Scientists do not know when an eruption or or other hazardous event like a flank collapse will your local emergency management agency: occur at Mount Baker, but surely they will Skagit County (360) 428-3250 Whatcom County (360) 676-6681 occur again. As Mount St. Helens taught us, it is best to be prepared. The USGS works with See also Potential Volcanic Hazards from Future Federal, State, Provincial, and local agencies to Activity of Mount Baker, Washington prepare for disruption that might accompany (USGS Open-File Report 95-498), and renewed activity. A coalition of these agencies, What are Volcano Hazards? View looking north at Mount Baker summit, Sherman (USGS Fact Sheet 002-97) Crater, and the Roman Wall. Photo by Dave Tucker. known as the Mount Baker and Glacier Peak

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