Recent Online Volcano-related Reports and Maps

Arizona

Priest, S.S., Duffield, W.A., Riggs, N.R., Poturalski, B. and Malis-Clark, K., 2002, Red Mountain Volcano&#151A Spectacular and Unusual Cinder Cone in Northern Arizona: U.S. Geological Survey Fact Sheet 024-02, 2 p. Available online

Red Mountain, located in the Coconino National Forest of northern Arizona, 25 miles northwest of Flagstaff, is a volcanic cinder cone that rises 1,000 feet above the surrounding landscape. It is unusual in having the shape of a "U," open to the west, and in lacking the symmetrical shape of most cinder cones. In addition, a large natural amphitheater cuts into the cone's northeast flank. Erosional pillars called "hoodoos" decorate the amphitheater, and many dark mineral crystals erode out of its walls. Studies by U.S. Geological Survey (USGS) and Northern Arizona University scientists suggest that Red Mountain formed in eruptions about 740,000 years ago.

Alaska

Brantley, S.R., McGimsey, R.G., and Neal, C.A., 2004, Expanded Monitoring of Volcanoes Yields Results: U.S. Geological Survey Fact Sheet 2004-3084. Availabe online

Recent explosive eruptions at some of Alaska's 41 historically active volcanoes have significantly affected air traffic over the North Pacific, as well as Alaska's oil, power, and fishing industries and local communities. Since its founding in the late 1980s, the Alaska Volcano Observatory (AVO) has installed new monitoring networks and used satellite data to track activity at Alaska's volcanoes, providing timely warnings and monitoring of frequent eruptions to the aviation industry and the general public. To minimize impacts from future eruptions, scientists at AVO continue to assess volcano hazards and to expand monitoring networks.

Miller, T.P., 2004, Geology of the Ugashik-Mount Peulik Volcanic Center, Alaska: U.S. Geological Survey Open-File Report 2004-1009. Available online

The Ugashik-Mount Peulik volcanic center, 550 km southwest of Anchorage on the Alaska Peninsula, consists of the late Quaternary 5-km-wide Ugashik caldera and the stratovolcano Mount Peulik built on the north flank of Ugashik. The center has been the site of explosive volcanism including a caldera-forming eruption and post-caldera dome-destructive activity. Mount Peulik has been formed entirely in Holocene time and erupted in 1814 and 1845. A large lava dome occupies the summit crater, which is breached to the west. A smaller dome is perched high on the southeast flank of the cone. Pyroclastic-flow deposits form aprons below both domes. One or more sector-collapse events occurred early in the formation of Mount Peulik volcano resulting in a large area of debris-avalanche deposits on the volcano's northwest flank.

The Ugashik-Mount Peulik center is a calcalkaline suite of basalt, andesite, dacite, and rhyolite, ranging in SiO2 content from 51 to 72 percent. The Ugashik-Mount Peulik magmas appear to be co-genetic in a broad sense and their compositional variation has probably resulted from a combination of fractional crystallization and magma-mixing.

The most likely scenario for a future eruption is that one or more of the summit domes on Mount Peulik are destroyed as new magma rises to the surface. Debris avalanches and pyroclastic flows may then move down the west and, less likely, east flanks of the volcano for distances of 10 km or more. A new lava dome or series of domes would be expected to form either during or within some few years after the explosive disruption of the previous dome. This cycle of dome disruption, pyroclastic flow generation, and new dome formation could be repeated several times in a single eruption.

The volcano poses little direct threat to human population as the area is sparsely populated. The most serious hazard is the effect of airborne volcanic ash on aircraft since Mount Peulik sits astride heavily traveled air routes connecting the U.S. and Europe to Asia. Activity of the type described could produce eruption columns to heights of 15 km and result in significant amounts of ash 250-300 km downwind.

McGimsey, R.G., 2004, 1998 Volcanic Activity in Alaska and Kamchatka: Summary of Events and Response of the Alaska Volcano Observatory: U.S. Geological Survey Open-File Report 03-423. Available online

In 1998 the Alaska Volcano Observatory responded to eruptive activity or suspect volcanic activity at 7 volcanic centers--Shrub mud, Augustine, Becharof Lake area, Chiginagak, Shishaldin, Akutan, and Korovin.

In addition to responding to eruptive activity at Alaska volcanoes, AVO also disseminated information for the Kamchatkan Volcanic Eruption Response Team about the 1998 activity of 4 Russian volcanoes--Sheveluch, Klyuchevskoy, Bezymianny, and Karymsky.

Hildreth, W., and Fierstein, J., 2003, Geologic Map of the Katmai Volcanic Cluster, Katmai National Park, Alaska: U.S. Geological Survey Geologic Investigations Series Map I-2778. Available online

The Katmai volcanic cluster on the Alaska Peninsula was first brought to national and international attention by the great eruption of June 1912. Although many wilderness travellers and one geological party had previously crossed remote Katmai Pass on foot, the National Geographic Society expeditions of 1915-19 first mapped and reconnoitered the volcanic terrain surrounding the pass in the course of investigating the effects of the 1912 eruption. The explosive ejection of rhyolitic, dacitic, and andesitic magma at Novarupta over an interval of about 60 hr on June 6-8, 1912, was the world's most voluminous 20th century eruption. At least 17 km³ of fall deposits and 11±3 km³ of ash-flow tuff (ignimbrite) were produced, representing a magma volume of about 13 km³. This volume is larger than that erupted by Krakatau (Indonesia) in 1883 and is known to have been exceeded by only four eruptions in the last 1,000 years. Syneruptive caldera collapse at Mount Katmai, 10 km east of the eruption site, and displacements elsewhere in the magmatic plumbing system generated 14 earthquakes in the magnitude range Ms 6 to 7 (extraordinarily energetic for volcanic seismicity) and as many as 100 greater than Ms 5.

Within 15 km of the 1912 vent at Novarupta, five andesite-dacite stratovolcanoes have erupted during the Holocene and remain fumarolically active today: Mount Katmai, Trident Volcano, Mount Mageik, Mount Martin, and Mount Griggs. The first four are virtually contiguous along a N.65°E. trend that defines the Quaternary volcanic front, whereas rear-arc Mount Griggs is centered 12 km behind the front. The frontal trend additionally includes Snowy Mountain, likewise active in the Holocene, which consists of a pair of andesite-dacite cones 10-15 km northeast of Mount Katmai; and the extinct Alagogshak Volcano, an andesite-dacite Pleistocene edifice centered 3 km southwest of Mount Martin. We have recently mapped and studied all of the volcanoes named, some of which are compound multi-vent edifices, as portrayed on the geologic map.

Waythomas, C.F., Miller, T.P., and Nye, C.J., 2003, Preliminary Geologic Map of Great Sitkin Volcano, Alaska: U.S. Geological Survey Open-File Report 03-36. Available online

Introduction does not accompany map, graphs, and data tables.

Waythomas, C.F., Miller, T.P., and Nye, C.J., 2003, Preliminary Volcano-Hazard Assessment for Great Sitkin Volcano, Alaska: U.S. Geological Survey Open-File Report 03-112. Available online

Great Sitkin Volcano is a composite andesitic stratovolcano on Great Sitkin Island (51°05’ N latitude, 176°25’ W longitude), a small (14 x 16 km), circular volcanic island in the western Aleutian Islands of Alaska. Great Sitkin Island is located about 35 kilometers northeast of the community of Adak on Adak Island and 130 kilometers west of the community of Atka on Atka Island. Great Sitkin Volcano is an active volcano and has erupted at least eight times in the past 250 years (Miller and others, 1998). The most recent eruption in 1974 caused minor ash fall on the flanks of the volcano and resulted in the emplacement of a lava dome in the summit crater.

The summit of the composite cone of Great Sitkin Volcano is 1,740 meters above sea level. The active crater is somewhat lower than the summit, and the highest point along its rim is about 1,460 meters above sea level. The crater is about 1,000 meters in diameter and is almost entirely filled by a lava dome emplaced in 1974. An area of active fumaroles, hot springs, and bubbling hot mud is present on the south flank of the volcano at the head of Big Fox Creek (see the map), and smaller ephemeral fumaroles and steam vents are present in the crater and around the crater rim. The flanking slopes of the volcano are gradual to steep and consist of variously weathered and vegetated blocky lava flows that formed during Pleistocene and Holocene eruptions. The modern edifice occupies a caldera structure that truncates an older sequence of lava flows and minor pyroclastic rocks on the east side of the volcano. The eastern sector of the volcano includes the remains of an ancestral volcano that was partially destroyed by a northwest-directed flank collapse.

In winter, Great Sitkin Volcano is typically completely snow covered. Should explosive pyroclastic eruptions occur at this time, the snow would be a source of water for volcanic mudflows or lahars. In summer, much of the snowpack melts, leaving only a patchy distribution of snow on the volcano. Glacier ice is no longer present on the volcano or on other parts of Great Sitkin Island as previously reported by Simons and Mathewson (1955).

Dixon, J.P., Stihler, S.D., Power, J.A., Tytgat, G., Moran, S.C., Sánchez, J., Estes, s., McNutt, S.R., and Paskievitch, J., 2003, Catalog of Earthquake Hypocenters at Alaskan Volcanoes: January 1 through December 31, 2002: U.S. Geological Survey Open-File Report 03-267. Available online

The Alaska Volcano Observatory (AVO), a cooperative program of the U.S. Geological Survey, the Geophysical Institute of the University of Alaska Fairbanks, and the Alaska Division of Geological and Geophysical Surveys, has maintained seismic monitoring networks at historically active volcanoes in Alaska since 1988 (Power and others, 1993; Jolly and others, 1996; Jolly and others, 2001; Dixon and others, 2002). The primary objectives of this program are the seismic monitoring of active, potentially hazardous, Alaskan volcanoes and the investigation of seismic processes associated with active volcanism. This catalog presents the basic seismic data and changes in the seismic monitoring program for the period January 1, 2002 through December 31, 2002. Appendix G contains a list of publications pertaining to seismicity of Alaskan volcanoes based on these and previously recorded data. The AVO seismic network was used to monitor twenty-four volcanoes in real time in 2002. These include Mount Wrangell, Mount Spurr, Redoubt Volcano, Iliamna Volcano, Augustine Volcano, Katmai Volcanic Group (Snowy Mountain, Mount Griggs, Mount Katmai, Novarupta, Trident Volcano, Mount Mageik, Mount Martin), Aniakchak Crater, Mount Veniaminof, Pavlof Volcano, Mount Dutton, Isanotski Peaks, Shishaldin Volcano, Fisher Caldera, Westdahl Peak, Akutan Peak, Makushin Volcano, Great Sitkin Volcano, and Kanaga Volcano (Figure 1). Monitoring highlights in 2002 include an earthquake swarm at Great Sitkin Volcano in May-June; an earthquake swarm near Snowy Mountain in July-September; low frequency (1-3 Hz) tremor and long-period events at Mount Veniaminof in September-October and in December; and continuing volcanogenic seismic swarms at Shishaldin Volcano throughout the year. Instrumentation and data acquisition highlights in 2002 were the installation of a subnetwork on Okmok Volcano, the establishment of telemetry for the Mount Veniaminof subnetwork, and the change in the data acquisition system to an EARTHWORM detection system. AVO located 7430 earthquakes during 2002 in the vicinity of the monitored volcanoes. This catalog includes: (1) a description of instruments deployed in the field and their locations; (2) a description of earthquake detection, recording, analysis, and data archival systems; (3) a description of velocity models used for earthquake locations; (4) a summary of earthquakes located in 2002; and (5) an accompanying UNIX tar-file with a summary of earthquake origin times, hypocenters, magnitudes, and location quality statistics; daily station usage statistics; and all HYPOELLIPSE files used to determine the earthquake locations in 2002.

Miller, T.P.,Waythomas, C.F., and Nye, C.J., 2003, Preliminary Geologic Map of Kanaga Volcano, Alaska: U.S. Geological Survey Open-File Report 03-113. Available online

Kanaga Volcano is a 1,300 m (4,287-foot) high, historically active cone-shaped stratovolcano located on the north end of Kanaga Island in the Andreanof Islands Group of the Aleutian Islands. The volcano is undissected, symmetrical in profile, and is characterized by blocky andesitic lava flows, with well-developed levees and steep flow fronts, that emanate radially from, or near, the 200-m-wide summit crater. The lack of dissection of the cone suggests the entire edifice was constructed in post-glacial Holocene time. Historical eruptions were reported in 1791, 1827, 1829, 1904-1906, and 1993-95 (Miller and others, 1998); questionable eruptions occurred in 1763, 1768, 1786, 1790, and 1933. The upper flanks of the cone are very steep (>30°) and flows moving down these steep flows commonly fragment into breccias and lahars. A non-vegetated lahar, or group of lahars, extends from high on the southeast flank of the cone down to the northeast shore of the intracaldera lake. This lahar deposit was observed in 1999 but does not appear to be present on aerial photos taken in 1974 and is assumed to be part of the 1994- 95 eruption.

Most recent eruptions of Kanaga, including the 1994-95 eruption, were primarily effusive in character with a subordinate explosive component. Lava was extruded from, or near, the summit vent and moved down the flank of the cone in some cases reaching the ocean. In 1994, lava flows going down the very steep north and west flanks broke up into incandescent avalanches tumbling over steep truncated sea cliffs into the Bering Sea. A common feature of Kanaga central vent eruptions is the occurrence of widespread ballistics and accompanying craters. Steam and fine ash plumes rose to 7.5 km ASL and drifted a few tens of kilometers downwind. Plumes such as these are unlikely to deposit significant (i.e., sufficiently thick to leave a permanent record) tephras on other islands downwind.

Waythomas, C.F., and Miller, T.P., 2002, Preliminary Volcano-Hazard Assessment for Hayes Volcano, Alaska: U.S. Geological Survey Open-File Report 02-072, 21 p. Available online

Hayes Volcano is an ice-and snow-mantled, deeply eroded volcanic massif located in the northern Tordrillo Mountains of the north-central Cook Inlet region about 135 kilometers northwest of Anchorage, Alaska. Hayes Volcano consists of a glacially dissected, poorly exposed cluster of lava domes. No historical eruptions of Hayes Volcano are known, and the last period of major eruptive activity occurred within a time interval of 4,400 to 3,600 years ago. During this period, explosive Plinian-style eruptions occurred that dispersed volcanic ash over large areas of interior, south-central, and southeastern Alaska. Pyroclastic flows produced during these eruptions descended Hayes Glacier and entered the Hayes River drainage. The pyroclastic flows initiated volcanic debris flows or lahars that flowed down the Hayes River, into the Skwentna River, and probably reached the Yentna River about 110 kilometers downstream from the volcano. The last major eruptive period of Hayes Volcano may have spanned about 200 years, and at least one of the eruptions during this interval was possibly the largest eruption of any volcano in the Cook Inlet region in the past 10,000 years.

California

Christiansen, R.L., Clynne, M.A., and Muffler, L.J.P., 2004, Geologic Map of the Lassen Peak, Chaos Crags, and Upper Hat Creek Area, California: U.S. Geological Survey Geologic Investigations Series I-2723. Available online

The Lassen Peak, Chaos Crags, and Upper Hat Creek map area lies near the southern end of the Cascade Range in northern California. The map area includes parts of the three elements that together form the Lassen volcanic center: the Lassen dacitic dome field, the Central Plateau andesitic lava field, and the underlying deeply eroded and partly altered Brokeoff andesitic stratocone. The Lassen volcanic center is the southernmost active long-lived center of the present-day Cascades volcanic arc.

This geologic map contributes to understanding the youngest major volcanic events in the evolution of the Lassen dacitic dome field and provides the basis for a revised assessment of its volcano hazards by emphasizing the youngest eruptive products of the dome field. The most recent eruptive activity, mainly steam-blast eruptions, occurred intermittently between May, 1914, and June, 1917, and climaxed during a week of magmatic eruptions of Lassen Peak in May, 1915.

This report consists of a geologic map and an accompanying explanatory pamphlet. Geologic mapping was compiled at a scale of 1:24,000 for the entire mapping area with some 1:2,500-scale mapping for the summit area of Lassen Peak. The geologic mapping was compiled as a digital geologic map database in ArcInfo GIS format.

Clynne, M. A., Janik, C. J., and Muffler, L. P. J., 2002, “Hot Water” in Lassen Volcanic National Park— Fumaroles, Steaming Ground, and Boiling Mudpots: U.S. Geological Survey Fact Sheet 101-02, 4 p. Available online

Hydrothermal (hot water) features at Lassen Volcanic National Park fascinate visitors to this region of northeastern California. Boiling mudpots, steaming ground, roaring fumaroles, and sulfurous gases are linked to active volcanism and are all reminders of the ongoing potential for eruptions in the Lassen area. Nowhere else in the Cascade Range of volcanoes can such an array of hydrothermal features be seen. Recent work by scientists with the U.S. Geological Survey (USGS), in cooperation with the National Park Service, is shedding new light on the inner workings of the Lassen hydrothermal system.

Hill, D.P., Dzurisin, D., Ellsworth, W.L., Endo, E.T., Galloway, D.L., Gerlach, T.M., Johnston, M.J., Langbein, J., McGee, K.A., Miller, C.D., Oppenheimer, D., and Sorey, M.L., 2002, Response Plan for Volcano Hazards in the Long Valley Caldera and Mono Craters Region, California: U.S. Geological Survey Bulletin 2185, 65 p. Available online

This report describes the U.S. Geological Survey's response plan for future episodes of unrest that might augur the onset of renewed volcanism in Long Valley caldera or along the Inyo-Mono Craters chain to the north. Central to this response plan is a four-level color code with successive conditions, GREEN (no immediate risk) through RED (eruption under way), reflecting progressively more intense activity levels. This report replaces the 1991 response plan which describes a five-level alert level scheme.

Hawai`i

Neal, C.A. and Lockwood, J.P., 2003, Geologic map of the summit region of Kilauea Volcano, Hawaii: U.S. Geological Survey Geologic Investigations Series I-2759, scale 1:24,000. Available online

The area covered by this map includes parts of four U.S. Geological Survey 7.5' topographic quadrangles (Kilauea Crater, Volcano, Ka`u Desert, and Makaopuhi). It encompasses the summit, upper rift zones, and Koa`e Fault System of Kilauea Volcano and a part of the adjacent, southeast flank of Mauna Loa Volcano.

The map is dominated by products of eruptions from Kilauea Volcano, the southernmost of the five volcanoes on the Island of Hawaii and one of the world's most active volcanoes. At its summit (1,243 m) is Kilauea Crater, a 3 km-by5 km collapse caldera that formed, possibly over several centuries, between about 200 and 500 years ago. Radiating away from the summit caldera are two linear zones of intrusion and eruption, the east and southwest rift zones. Repeated subaerial eruptions from the summit and rift zones have built a gently sloping, elongate shield volcano approximately 1,500 square kilometers. Much of the volcano lies under water; the east rift zone extends 110 km from the summit to a depth of more than 5,000 m below sea level; whereas the southwest rift zone has a more limited submarine continuation. South of the summit caldera, mostly north-facing normal faults and open fractures of the Koa`e Fault System is interpreted as a tear-away structure that accomodates southward movement of Kilauea's flank in response to distension of the volcano perpendicular to the rift zones. Farther to the south and outside the map area, the large normal fault scarps of the Hilina Pali are structures related to the seaward subsidence of Kilauea's mobile south flank.

Takahashi, T.J., Heliker, C., and Diggles, M.F., 2003, Selected Images of the Pu‘u ‘O‘o–Kupaianaha Eruption, 1983–1997: U.S. Geological Survey Digital Data Series DDS-80. Available online

The 100 images in this CD–ROM have been selected from the collections of the Hawaiian Volcano Observatory as enduring favorites of the staff, researchers, media, designers, and the public over time. They represent photographs of a variety of geological phenomena and eruptive events, chosen for their content, quality of exposure, and aesthetic appeal. The number was kept to 100 to maintain the high resolution desirable. Since 1997, digital imagery has been the predominant mode of photographically documenting the eruption. Many of these photos, from 1998 to the present, are viewable on the website: http://hvo.wr.usgs.gov/kilauea/update/archive/

Heliker, C., Swanson, D.A., and Takahashi, T.J. (eds.), 2003, Pu‘u ‘O‘o-Kupaianaha Eruption of Kilauea Volcano, Hawai‘i: The First 20 Years: U.S. Geological Survey Professional Paper 1676. Available online

The Pu‘u ‘O‘o-Kupaianaha eruption started on January 3, 1983. The ensuing 20-year period of nearly continuous eruption is the longest at Kilauea Volcano since the famous lava-lake activity of the 19th century. No rift-zone eruption in more than 600 years even comes close to matching the duration and volume of activity of these past two decades. Fortunately, such a landmark event came during a period of remarkable technological advancements in volcano monitoring. When the eruption began, the Global Positioning System (GPS) and the Geographic Information System (GIS) were but glimmers on the horizon, broadband seismology was in its infancy, and the correlation spectrometer (COSPEC), used to measure SO2 flux, was still very young. Now, all of these techniques are employed on a daily basis to track the ongoing eruption and construct models about its behavior. The 12 chapters in this volume, written by present or past Hawaiian Volcano Observatory staff members and close collaborators, celebrate the growth of understanding that has resulted from research during the past 20 years of Kilauea’s eruption. The chapters range widely in emphasis, subject matter, and scope, but all present new concepts or important modifications of previous ideas—in some cases, ideas long held and cherished.

Eakins, B.W., Robinson, J.E., Kanamatsu, T., Naka, J., Smith, J.R., Takahashi, E., and Clague, D.A., 2003, Hawaii's Volcanoes Revealed: U.S. Geological Survey Geologic Investigations Series I-2809. Available online

The Japan Marine Science and Technology Center (JAMSTEC) funded and led a four-year collaborative survey of the underwater flanks of Hawaii's shield volcanoes. This exploration, involving scientists from the U.S. Geological Survey (USGS) and other Japanese and U.S. academic and research institutions, utilized manned and unmanned submersibles, rock dredges, and sediment piston cores to directly sample and visually observe the sea floor at specific sites. Ship-based sonar systems were used to more widely map the bathymetry from the sea surface.

The state-of-the-art multibeam sonar systems, mounted on the hull of GPS-navigated research vessels, convert the two-way travel times of individual sonar pings and their echoes into a line of bathymetry values across the ship track. The resulting swaths across the ocean bottom, obtained along numerous overlapping ship tracks, reveal the sea floor in stunning detail. The survey data collected by JAMSTEC form the basis for the bathymetry shown on the map, augmented with bathymetric data from other sources. Bathymetry that is predicted from variations in sea-surface height, observable from satellites, provides the low-resolution (fuzzy) bathymetry in between ship tracks. Subaerial topography is from a USGS 30-m digital elevation model of Hawaii. Historical lava flows are shown in red.

Nakata, J.S., 2003, Hawaiian Volcano Observatory Summary 102; Part I, Seismic Data, January to December 2002: U.S. Geological Survey Open-File Report 03-132. Available online

The Hawaiian Volcano Observatory (HVO) summary presents seismic data gathered during the year and a chronological narrative describing the volcanic events. The seismic summary is offered without interpretation as a source of preliminary data. It is complete in the sense that most data for events of M°Ÿ1.5 routinely gathered by the Observatory are included. The emphasis in collection of tilt and deformation data has shifted from quarterly measurements at a few water-tube tilt stations (“wet” tilt) to a larger number of continuously recording borehole tiltmeters, repeated measurements at numerous spirit-level tilt stations (“dry” tilt), and surveying of level and trilateration networks. Because of the large quantity of deformation data now gathered and differing schedules of data reduction, the seismic and deformation summaries are published separately. The HVO summaries have been published in various forms since 1956. Summaries prior to 1974 were issued quarterly, but cost, convenience of preparation and distribution, and the large quantities of data dictated an annual publication beginning with Summary 74 for the year 1974. Summary 86 (the introduction of CUSP at HVO) includes a description of the seismic instrumentation, calibration, and processing used in recent years. The present summary includes background information on the seismic network and processing to allow use of the data and to provide an understanding of how they were gathered. A report by Klein and Koyanagi (1980) 1 tabulating instrumentation, calibration, and recording history of each seismic station in the network. It is designed as a reference for users of seismograms and phase data and includes and augments the information in the station table in this summary.

Pacific Northwest (Washington and Oregon)

Sherrod, D.R., and Smith, J.G., 2004, Geologic Map of Upper Eocene to Holocene Volcanic and Related Rocks of the Cascade Range, Oregon: U.S. Geological Survey Geologic Investigations Series Map I-2569. Available online

Since 1979, Earth scientists of the Geothermal Research Program of the U.S. Geological Survey have carried out multidisciplinary research in the Cascade Range. The goal of this research is to understand the geology, tectonics, and hydrology of the Cascades in order to characterize and quantify geothermal resource potential. A major goal of the program is compilation of a comprehensive geologic map of the entire Cascade Range that incorporates modern field studies and that has a unified and internally consistent explanation.

This map is one of three in a series that shows Cascade Range geology by fitting published and unpublished mapping into a province-wide scheme of rock units distinguished by composition and age; map sheets of the Cascade Range in Washington (Smith, 1993) and California will complete the series. The complete series forms a guide to exploration and evaluation of the geothermal resources of the Cascade Range and will be useful for studies of volcano hazards, volcanology, and tectonics.

Tabor, R.W., Haugerud, R.A., Hildreth W., and Brown, E.H., 2003, Geologic Map of the Mount Baker 30- by 60-Minute Quadrangle, Washington: U.S. Geological Survey Geologic Investigations Series I-2660. Available online

The Mount Baker 30- by 60-minute quadrangle encompasses rocks and structures that represent the essence of the geology of the North Cascade Range (fig. 1, sheet 2; fig. 2, sheet 1). The quadrangle is mostly rugged and remote and includes much of the North Cascade National Park and several dedicated wilderness areas managed by the U.S. Forest Service. Geologic exploration has been slow and difficult. In 1858 George Gibbs (1874) ascended the Skagit River part way to begin the geographic and geologic exploration of the North Cascades. In 1901, Reginald Daly (1912) surveyed the 49th parallel along the Canadian side of the border, and George Smith and Frank Calkins (1904) surveyed the United States’side. Daly’s exhaustive report was the first attempt to synthesize what has become an extremely complicated geologic story.

Modern geologic work began almost a half a century later when, in 1948, Peter Misch began his intensive study of the North Cascade Range (Misch, 1952, 1966, and see other references). His insights set the stage for all later work in the North Cascades. Considerable progress in understanding the North Cascades in light of modern plate tectonic theory has been made by E.H. Brown and his students. We have used much of their detailed geologic mapping (fig. 3, sheet 2). Although our tectonic reference frame has changed much with the recognition of plate tectonics and exotic terranes, Misch’s observations prove to be remarkably accurate.

Our work in the Mount Baker quadrangle began in 1983 as part of a project to map and compile the geology of the Wenatchee and Concrete 1° by 2° quadrangles at 1:100,000 scale (fig. 1), work that we began in 1975. We have mapped in cooperation with the Division of Geology and Earth Resources, Washington State Department of Natural Resources. We have also benefited by the cooperation and helpfulness of the National Park Service and the U.S. Forest Service.

Ramsey, D.W., Dartnell, P., Bacon, C.R., Robinson, J.E., and Gardner, J.V., 2003, Crater Lake Revealed: U.S. Geological Survey Geologic Investigations Series I-2790. Available online

Around 500,000 people each year visit Crater Lake National Park in the Cascade Range of southern Oregon. Volcanic peaks, evergreen forests, and Crater Lake’s incredibly blue water are the park’s main attractions. Crater Lake partially fills the caldera that formed approximately 7,700 years ago by the eruption and subsequent collapse of a 12,000-foot volcano called Mount Mazama. The caldera-forming or climactic eruption of Mount Mazama drastically changed the landscape all around the volcano and spread a blanket of volcanic ash at least as far away as southern Canada.

Prior to the climactic event, Mount Mazama had a 400,000 year history of cone building activity like that of other Cascade volcanoes such as Mount Shasta. Since the climactic eruption, there have been several less violent, smaller postcaldera eruptions within the caldera itself. However, relatively little was known about the specifics of these eruptions because their products were obscured beneath Crater Lake’s surface. As the Crater Lake region is still potentially volcanically active, understanding past eruptive events is important to understanding future eruptions, which could threaten facilities and people at Crater Lake National Park and the major transportation corridor east of the Cascades.

Recently, the lake bottom was mapped with a high-resolution multibeam echo sounder. The new bathymetric survey provides a 2m/pixel view of the lake floor from its deepest basins virtually to the shoreline. Using Geographic Information Systems (GIS) applications, the bathymetry data can be visualized and analyzed to shed light on the geology, geomorphology, and geologic history of Crater Lake.

Vallance, J.W., Cunico, M.L., and Schilling, S.P., 2003, Debris-Flow Hazards Caused by Hydrologic Events at Mount Rainier, Washington: U.S. Geological Survey Open-File Report 03-368. Available online

At 4393 m, ice-clad Mount Rainier has great potential for debris flows owing to its precipitous slopes and incised steep valleys, the large volume of water stored in its glaciers, and a mantle of loose debris on its slopes. In the past 10,000 years, more than sixty Holocene lahars have occurred at Mount Rainier (Scott et al., 1985), and, in addition more than thirty debris flows not related to volcanism have occurred in historical time (Walder and Driedger, 1984). Lahars at Mount Rainier can be classed in 3 groups according to their genesis: (1) flank collapse of hydrothermally altered, water-saturated rock; (2) eruption-related release of water and loose debris; and (3) hydrologic release of water and debris (Scott et al., 1985). Lahars in the first two categories are commonly voluminous and are generally related to unrest and explosions that occur during eruptive episodes. Lahars in the third category, distinguished here as debris flows, are less voluminous than the others but occur frequently at Mount Rainier, often with little or no warning.

Historically at Mount Rainier, glacial outburst floods, torrential rains, and stream capture have caused small- to moderate-size debris flows (Walder and Driedger, 1984). Such debris flows are most likely to occur in drainages that have large glaciers in them. Less commonly, a drainage diversion has triggered a debris flow in an unglaciated drainage basin. For example, the diversion of Kautz Glacier meltwater into Van Trump basin triggered debris flows on the south side of Rainier in August 2001.

On the basis of historical accounts, debris flows having hydrologic origins are likely to be unheralded, and have occurred as seldom as once in 8 years and as often as four times per year at Mount Rainier (Walder and Driedger, 1984). Such debris flows are most likely to occur during periods of hot dry weather or during periods of intense rainfall, and therefore must occur during the summer and fall. They are likely to begin at or above the elevations of glacier termini and extend down valley.

This report discusses potential hazards from debris flows induced by hydrologic events such as glacial outburst floods and torrential rain at Mount Rainier and the surrounding area bounded by Mount Rainier National Park. The report also shows, in the accompanying hazard-zonation maps, which areas are likely to be at risk from future such debris flows at Mount Rainier. Lahar hazards related to avalanches of altered rock and to the interactions of hot rock and ice during eruptions are discussed in Scott and Vallance (1995) and Hoblitt et al. (1998) and are not addressed in this report.

Klimasauskas, E., Bacon, C., and Alexander, J., 2002, Mount Mazama and Crater Lake: Growth and Destruction of a Cascade Volcano: U.S. Geological Survey Fact Sheet 092-02, 2 p. Available online

For more than 100 years, scientists have sought to unravel the remarkable story of Crater Lake’s formation. Before Crater Lake came into existence, a cluster of volcanoes dominated the landscape. This cluster, called Mount Mazama (for the Portland, Oregon, climbing club the Mazamas), was destroyed during an enormous explosive eruption 7,700 years ago. So much molten rock was expelled that the summit area collapsed during the eruption to form a large volcanic depression, or caldera. Subsequent smaller eruptions occurred as water began to fill the caldera to eventually form the deepest lake in the United States. Decades of detailed scientific studies of Mount Mazama and new maps of the floor of Crater Lake reveal stunning details of the volcano’s eruptive history and identify potential hazards from future eruptions and earthquakes.

International Centers

Russia's Kamchatka Peninsula is home to 29 active volcanoes, including 7 snow-capped stratocones more than 10,000 ft (3,000 m) high. Several eruptions each year in Kamchatka produce ash clouds that threaten the safety of air travel across the North Pacific, including travel between the United States and Russia and Japan. The Kamchatkan Volcanic Eruption Response Team (KVERT), created in 1993 through a cooperative effort of Russian and U.S. scientists, monitors the volcanoes of Kamchatka to provide warnings and rapid reporting of eruptions.

San Miguel volcano, also known as Chaparrastique, is one of many volcanoes along the volcanic arc in El Salvador. The volcano, located in the eastern part of the country, rises to an altitude of about 2130 meters and towers above the communities of San Miguel, El Transito, San Rafael Oriente, and San Jorge. In addition to the larger communities that surround the volcano, several smaller communities and coffee plantations are located on or around the flanks of the volcano, and the Pan American and coastal highways cross the lowermost northern and southern flanks of the volcano. The population density around San Miguel volcano coupled with the proximity of major transportation routes increases the risk that even small volcano-related events, like landslides or eruptions, may have significant impact on people and infrastructure.

San Vicente volcano, also known as Chichontepec, is one of many volcanoes along the volcanic arc in El Salvador. This composite volcano, located about 50 kilometers east of the capital city San Salvador, has a volume of about 130 cubic kilometers, rises to an altitude of about 2,180 meters, and towers above major communities such as San Vicente, Tepetitan, Guadalupe, Zacatecoluca, and Tecoluca. In addition to the larger communities that surround the volcano, several smaller communities and coffee plantations are located on or around the flanks of the volcano, and major transportation routes are located near the lowermost southern and eastern flanks of the volcano. The population density and proximity around San Vicente volcano, as well as the proximity of major transportation routes, increase the risk that even small landslides or eruptions, likely to occur again, can have serious societal consequences.

Major, J.J., Schilling, S. P., Sofield, D.J., Escobar, C.D., and Pullinger, C.R., 2001, Volcano Hazards in the San Salvador Region, El Salvador: U.S. Geological Survey Open-File Report 01-366, 24 p. Available online

San Salvador volcano is one of many volcanoes along the volcanic arc in El Salvador. This volcano, having a volume of about 110 cubic kilometers, towers above San Salvador, the country's capital and largest city. The city has a population of approximately 2 million, and a population density of about 2,100 people per square kilometer. The city of San Salvador and other communities have gradually encroached onto the lower flanks of the volcano, increasing the risk that even small events may have serious societal consequences. San Salvador volcano has not erupted for more than 80 years, but it has a long history of repeated, and sometimes violent, eruptions.

Schilling, S.P., Vallance, J.W., Matiacuteas, O., and Howell, M.M. 2001, Lahar Hazards at Agua Volcano, Guatemala: U.S. Geological Survey Open-File Report 01-432, 16 p. Available online

At 3,760 meters, Agua volcano towers more than 3,500 meters above the Pacific coastal plain to the south and 2,000 meters above the Guatemalan highlands to the north. The volcano is within 5 to 10 kilometers of Antigua, Guatemala and several other large towns situated on its northern apron. These towns have a combined population of nearly 100,000. It is within about 20 kilometers of Escuintla (population, ca .100,000) to the south. Though the volcano has not been active in historical time, or about the last 500 years, it has the potential to produce debris flows (watery flows of mud, rock, and debris -- also known as lahars when they occur on a volcano) that could inundate these nearby populated areas.

Vallance, J.W., Schilling, S.P., Devoli, G., 2001, Lahar Hazards at Mombacho Volcano, Nicaragua: U.S. Geological Survey Open-File Report 01-455, 16 p. Available online

Mombacho volcano, at 1,350 meters, is situated on the shores of Lake Nicaragua and about 12 kilometers south of Granada, a city of about 90,000 inhabitants. Many more people live a few kilometers southeast of Granada in las Isletas de Granada and the nearby Peninsula de Aseses. These areas are formed of deposits of a large debris avalanche (a fast moving avalanche of rock and debris) from Mombacho. Several smaller towns with population, in the range of 5,000 to 12,000 inhabitants are to the northwest and the southwest of Mombacho volcano. Though the volcano has apparently not been active in historical time, or about the last 500 years, it has the potential to produce landslides and debris flows (watery flows of mud, rock, and debris -- also known as lahars when they occur on a volcano) that could inundate these nearby populated areas.

Vallance, J.W., Schilling, S.P., Devoli, G., and Howell, M.M., 2001, Lahar Hazards at Concepción Volcano, Nicaragua: U.S. Geological Survey Open-File Report 01-457, 14 p. Available online

Concepción is one of Nicaragua's highest and most active volcanoes. The symmetrical cone occupies the northeastern half of a dumbbell-shaped island called Isla Ometepa. The dormant volcano, Maderas, occupies the southwest half of the island. A narrow isthmus connects Concepción and Maderas volcanoes. Concepción volcano towers more than 1,600 meters above Lake Nicaragua and is within 5 to 10 kilometers of several small towns situated on its aprons at or near the shoreline. These towns have a combined population of nearly 5,000. The volcano has frequently produced debris flows (watery flows of mud, rock, and debris -- also known as lahars when they occur on a volcano) that could inundate these nearby populated areas.

Vallance, J.W., S. P. Schilling, S.P., Matías, O., Rose, W.I., and Howell, M.M., 2001, Volcano Hazards at Fuego and Acatenango, Guatemala: U.S. Geological Survey Open-File Report 01-431, 24 p. Available online

The Fuego-Acatenango massif comprises a string of five or more volcanic vents along a north-south trend that is perpendicular to that of the Central American arc in Guatemala. From north to south known centers of volcanism are Ancient Acatenango, Yepocapa, Pico Mayor de Acatenango, Meseta, and Fuego. Volcanism along the trend stretches back more than 200,000 years. Although many of the centers have been active contemporaneously, there is a general sequence of younger volcanism, from north to south along the trend. This massive volcano complex towers more than 3,500 meters above the Pacific coastal plain to the south and 2,000 meters above the Guatemalan Highlands to the north. The volcano complex comprises remnants of multiple eruptive centers, which periodically have collapsed to form huge debris avalanches. The largest of these avalanches extended more than 50 kilometers from its source and covered more than 300 square kilometers. The volcano has potential to produce huge debris avalanches that could inundate large areas of the Pacific coastal plain. In areas around the volcanoes and downslope toward the coastal plain, more than 100,000 people are potentially at risk from these and other flowage phenomena.

Yellowstone

Brantley, S.R., Lowenstern, J.B., Christiansen, R.L., Smith, R.B., Heasler, H., Waite, G., and Wicks, C., 2003, Tracking Changes in Yellowstone's Restless Volcanic System: U.S. Geological Survey Fact Sheet 100-03. Available online

The world-famous Yellowstone geysers and hot springs are fueled by heat released from an enormous reservoir of magma (partially molten rock beneath the ground). Since the 1970s, scientists have tracked rapid uplift and subsidence of the ground and significant changes in hydrothermal (hot water) features and earthquake activity. In 2001, the Yellowstone Volcano Observatory was created by the U.S. Geological Survey (USGS), the University of Utah, and Yellowstone National Park to strengthen scientists' ability to track activity that could result in hazardous seismic, hydrothermal, or volcanic events in the region.

Fournier, R. O., Weltman, U.,  Counce, D., White, L. D., and Janik, C. J., 2002, Results Of Weekly Chemical And Isotopic Monitoring Of Selected Springs In Norris Geyser Basin, Yellowstone National Park During June-September, 1995: U.S. Geological Survey Open-File Report 02-344, 50 p. Available online

Each year at Norris Geyser Basin, generally in August or September, a widespread hydrothermal "disturbance" occurs that is characterized by simultaneous changes in the discharge characteristics of many springs, particularly in the Back Basin. During the summer season of 1995, water samples from eight widely distributed hot springs and geysers at Norris were collected each week and analyzed to determine whether chemical and isotopic changes also occurred in the thermal waters at the time of the disturbance. In addition, Beryl Spring in Gibbon Canyon, 5.8 km southwest of Norris Geyser Basin, was included in the monitoring program. 

Christiansen, R.L., 2001, The Quaternary and Pliocene Yellowstone Plateau Volcanic Field of Wyoming, Idaho, and Montana: U.S. Geological Survey Professional Paper 729-G, 145 p., 3 plates. Available online

Yellowstone National Park, the oldest of the areas set aside as part of the national park system, lies amidst the Rocky Mountains in northwestern Wyoming and adjacent parts of Montana and Idaho. Embracing large, diverse, and complex geologic features, the park is in an area that is critical to the interpretation of many significant regional geologic problems. In order to provide basic data bearing on these problems, the U.S. Geological Survey in 1965 initiated a broad program of comprehensive geologic and geophysical investigations within the park. This program was carried out with the cooperation of the National Aeronautics and Space Administration, which supported the gathering of geologic information needed in testing and in interpreting results from various remote sensing devices. This professional paper chapter is one of a series of technical geologic reports resulting from these investigations.

Topical

Symonds, R.B., Janik, C.J., Evans, W.C., Ritchie, B.E., Counce, D., Poreda, R.J., and Iven, M., 2003, Scrubbing Masks Magmatic Degassing During Repose at Cascade-Range and Aleutian-Arc Volcanoes: U.S. Geological Survey Open-File Report 03-435. Available online

Between 1992 and 1998, we sampled gas discharges from =173°C fumaroles and springs at 12 quiescent but potentially restless volcanoes in the Cascade Range and Aleutian Arc (CRAA) including Mount Shasta, Mount Hood, Mount St. Helens, Mount Rainier, Mount Baker, Augustine Volcano, Mount Griggs, Trident, Mount Mageik, Aniakchak Crater, Akutan, and Makushin. For each site, we collected and analyzed samples to characterize the chemical (H2O, CO2, H2S, N2, CH4, H2, HCl, HF, NH3, Ar, O2, He) and isotopic (13C of CO2, 3He/4He, 40Ar/36Ar, 34S, 13C of CH4, 15N, and D and 18O of water) compositions of the gas discharges, and to create baseline data for comparison during future unrest. The chemical and isotopic data show that these gases contain a magmatic component that is heavily modified from scrubbing by deep hydrothermal (150° - 350°C) water (primary scrubbing) and shallow meteoric water (secondary scrubbing). The impact of scrubbing is most pronounced in gas discharges from bubbling springs; gases from boiling-point fumaroles and superheated vents show progressively less impact from scrubbing. The most effective strategies for detecting gas precursors to future CRAA eruptions are to measure periodically the emission rates of CO2 and SO2, which have low and high respective solubilities in water, and to monitor continuously CO2 concentrations in soils around volcanic vents. Timely resampling of fumaroles can augment the geochemical surveillance program by watching for chemical changes associated with drying of fumarolic pathways (all CRAA sites), increases in gas geothermometry temperatures (Mount Mageik, Trident, Mount Baker, Mount Shasta), changes in 13C of CO2 affiliated with magma movement (all CRAA site), and increases in 3He/4He coupled with intrusion of new magma (Mount Rainier, Augustine Volcano, Makushin, Mount Shasta). Repose magmatic degassing may discharge substantial amounts of S and Cl into the edifices of Mount Baker and several other CRAA volcanoes that is trapped by primary and secondary scrubbing. The consequent acidic fluids produce ongoing alteration in the 0.2- to 3-km-deep hydrothermal systems and in fields of boiling-point fumaroles near the surface. Such alteration may influence edifice stability and contribute to the formation of more-hazardous cohesive debris flows. In particular, we recommend further investigation of the volume, extent, and hazards of hydrothermal alteration at Mount Baker. Other potential hazards associated with the CRAA volcano hydrothermal systems include hydrothermal eruptions and, for deeper systems intruded by magma, deep-seated edifice collapse.

Guffanti, M., Brantley, S.R., and McClelland, L., 2001, Volcanism in National Parks: Summary of the Workshop Convened by the U.S. Geological Survey and National Park Service, 26-29 September 2000, Redding California: U.S. Geological Survey Open-File Report 01-435, p. Available online

In recognition of the importance of volcanism to diverse park issues, the Geologic Resources Division of the National Park Service and the Volcano Hazards Program of the USGS convened a workshop in September 2000 to bring together USGS and NPS scientists, managers, and interpreters. The purpose of the gathering was to lay the groundwork for improving scientific input to park management (operations, resource management, interpretation, and planning) and for facilitating volcano research and hazard monitoring in parks. This report summarizes key aspects of the workshop.

Nathenson, M., 2002, Publications of the Volcano Hazards Program 2001: U.S. Geological Survey Open-File Report 02-492, 9 p. Available online

The Volcano Hazards Program of the U.S. Geological Survey (USGS) is part of the Geologic Hazards Assessments subactivity as funded by Congressional appropriation. Investigations are carried out in the Geologic and Water Resources Divisions of the USGS and with cooperators at the Alaska Division of Geological and Geophysical Surveys, University of Alaska Fairbanks Geophysical Institute, University of Utah, and University of Washington Geophysics Program. This report lists publications from all these institutions. This report contains only published papers and maps; numerous abstracts produced for presentations at scientific meetings have not been included. Publications are included based on date of publication with no attempt to assign them to Fiscal Year.