Volcano and earthquake hazards in the Crater Lake region, Oregon

Bacon, Charles R.; Mastin, Larry G.; Scott, Kevin M.; Nathenson, Manuel

doi:10.3133/ofr97487

Cited by 7 publications

(6 citation statements)

References 37 publications

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“…Active, generally north-south normal faults traverse the Crater Lake region (Bacon et al, 1997b. All mapped tectonic faults, except those of the east Klamath Lake fault zone, have down-to-the-east normal displacement and apparently little strike-slip motion.…”

Section: Geologic Overviewmentioning

confidence: 99%

“…6). Arant Point is cut by the Annie Springs fault (Bacon et al, 1997b, which displaces unit at a maximum of 160 m downto-the-east.…”

Section: A Ca 300 Ka Andesitetuyamentioning

confidence: 99%

“…5E); it has conspicuous microxenoliths (to 1 cm) of coarse blocky augite ± small olivine ± plagioclase. Unit bsc is offset down-to-the-east by the Sevenmile Creek fault, part of the West Klamath Lake fault zone (Bacon et al, 1997b. Basaltic andesite of Scoria Cone may be the most voluminous product of regional volcanism younger than 100 ka in age (Fig.…”

Section: Late Pleistocene Basalt and Basaltic Andesite (Ca 55-30 Ka)mentioning

confidence: 99%

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Eruptive history and geochronology of Mount Mazama and the Crater Lake region, Oregon

Bacon¹,

Lanphere²

2006

Geological Society of America Bulletin

166

133

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Geologic mapping, K-Ar, and 40 Ar/ 39 Ar age determinations, supplemented by paleomagnetic measurements and geochemical data, are used to quantify the Quaternary volcanic history of the Crater Lake region in order to defi ne processes and conditions that led to voluminous explosive eruptions. The Cascade arc volcano known as Mount Mazama collapsed during its climactic eruption of ~50 km 3 of mainly rhyodacitic magma ~7700 yr ago to form Crater Lake caldera. The Mazama edifi ce was constructed on a Pleistocene silicic lava fi eld, amidst monogenetic and shield volcanoes ranging from basalt to andesite similar to parental magmas for Mount Mazama. Between 420 ka and 35 ka, Mazama produced medium-K andesite and dacite in 2:1 proportion. The edifi ce was built in many episodes; some of the more voluminous occurred approximately coeval with volcanic pulses in the surrounding region, and some were possibly related to deglaciation following marine oxygen isotope stages (MIS) 12, 10, 8, 6, 5.2, and 2. Magmas as evolved as dacite erupted many times, commonly associated with or following voluminous andesite effusion. Establishment of the climactic magma chamber was under way when the fi rst preclimactic rhyodacites vented ca. 27 ka. The silicic melt volume then grew incrementally at an average rate of 2.5 km 3 k.y. -1 for nearly 20 k.y. The climactic eruption exhausted the rhyodacitic magma and brought up crystal-rich andesitic magma, mafi c cumulate mush, and wall-rock granodiorite. Postcaldera volcanism produced 4 km 3 of andesite during the fi rst 200-500 yr after collapse, followed at ca. 4800 yr B.P. by 0.07 km 3 of rhyodacite. The average eruption rate for all Mazama products was ~0.4 km 3 k.y. -1 , but major edifi ce construction episodes had rates of ~0.8 km 3 k.y. -1 . The longterm eruption rate for regional monogenetic and shield volcanoes was ~0.07 km 3 k.y. -1 , but only ~0.02 km 3 k.y. -1 when the two major shields are excluded. Plutonic xenoliths and evidence for crystallization differentiation imply that the amount of magma intruded beneath Mount Mazama is several times that which has been erupted. The eruptive and intrusive history refl ects competition between (1) crystallization driven by degassing and hydrothermal cooling and (2) thermal input from a regional magma fl ux focused at Mazama. Before ca. 30 ka, relatively small volumes of nonerupted derivative magma crystallized to form a composite pluton because the upper crust had not been heated suffi ciently to sustain voluminous convecting crystal-poor melt. Subsequently, and perhaps not coincidentally, during MIS 2, a large volume of eruptible silicic magma accumulated in the climactic chamber, probably because of heating associated with mantle input to the roots of the system as suggested by eruption of unusually primitive magnesian basaltic andesite and tholeiite west of Mazama. Sediment gravity-flow deposits (Hol.) Talus (Hol. and Pleist.) Landslide deposits (Hol.) Glacial deposits, undivided (Pleist.) Andesite of the E basin (Hol.) Lava Andesite of ...

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Section: Geologic Overviewmentioning

confidence: 99%

“…6). Arant Point is cut by the Annie Springs fault (Bacon et al, 1997b, which displaces unit at a maximum of 160 m downto-the-east.…”

Section: A Ca 300 Ka Andesitetuyamentioning

confidence: 99%

Section: Late Pleistocene Basalt and Basaltic Andesite (Ca 55-30 Ka)mentioning

confidence: 99%

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Eruptive history and geochronology of Mount Mazama and the Crater Lake region, Oregon

Bacon¹,

Lanphere²

2006

Geological Society of America Bulletin

166

133

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show abstract

“…Crater Lake is the collapsed caldera of Mt. Mazama from a climatic eruption about 7700-yr ago (Nelson et al, 1988;Bacon and Lanphere, 1990;Bacon et al, 1997). The floor of Crater Lake has only been mapped three times since the lake was first stumbled upon by gold prospectors in the 1853.…”

Section: Introductionmentioning

confidence: 99%

Cruise report R/V Surf Surveyor cruise S1-00-CL, mapping the bathymetry of Crater Lake, Oregon

Gardner¹,

Mayer²,

Buktenica³

2000

Open-File Report

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“…Yet even the toxic gases play a small role in overall volcanic hazards. Famine and tsunamis cause most of the deaths and suffering from volcanic disasters, followed by pyroclastic flows, mud and debris flows, falling debris, hot ash, and other physical as opposed to chemical causes (Baxter, 1990;Simkin and Siebert, 1994;Bacon et al, 1997;Myers et al, 1997;Sherrod et al, 1997;USGS, 1997USGS, , 2000a. However, ignoring CO 2 may be misguided because sudden deaths caused by CO 2 in volcanic areas appear to be common.…”

Section: Volcanic Hazardsmentioning

confidence: 99%

Lessons Learned from Natural and Industrial Analogues for Storage of Carbon Dioxide in Deep Geological Formations

Benson¹,

Hepple²,

Apps³

et al. 2002

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Volcano and earthquake hazards in the Crater Lake region, Oregon

Cited by 7 publications

References 37 publications

Eruptive history and geochronology of Mount Mazama and the Crater Lake region, Oregon

Eruptive history and geochronology of Mount Mazama and the Crater Lake region, Oregon

Cruise report R/V Surf Surveyor cruise S1-00-CL, mapping the bathymetry of Crater Lake, Oregon

Lessons Learned from Natural and Industrial Analogues for Storage of Carbon Dioxide in Deep Geological Formations

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