Publications
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Migration and rearing histories of chinook salmon (Oncorhynchus tshawytscha) determined by ion microprobe Sr isotope and Sr/Ca transects of otoliths
Strontium isotope and Sr/Ca ratios measured in situ by ion microprobe along radial transects of otoliths of juvenile chinook salmon (Oncorhynchus tshawytscha) vary between watersheds with contrasting geology. Otoliths from ocean-type chinook from Skagit River estuary, Washington, had prehatch regions with 87Sr/86Sr ratios of ~0.709, suggesting a maternally inherited marine signature, extensive fre
Authors
C. R. Bacon, P.K. Weber, K.A. Larsen, R. Reisenbichler, J.A. Fitzpatrick, J. L. Wooden
Triggered deformation and seismic activity under Mammoth Mountain in Long Valley caldera by the 3 November 2002 Mw 7.9 Denali fault earthquake
The 3 November 2002 Mw 7.9 Denali fault earthquake triggered deformational offsets and microseismicity under Mammoth Mountain (MM) on the rim of Long Valley caldera, California, some 3460 km from the earthquake. Such strain offsets and microseismicity were not recorded at other borehole strain sites along the San Andreas fault system in California. The Long Valley offsets were recorded on borehole
Authors
M.J.S. Johnston, S. G. Prejean, D. P. Hill
Debris flows: geologic process and hazard; illustrated by a surge sequence at Jiangjia Ravine, Yunnan, China
Debris flows are slurries of sediment and water that are both an important geologic process and a major hazard. They present large risks to those living in mountainous areas, as well as downstream from volcanoes in the case of the flows known as lahars that may travel 100200 kilometers (62-124 miles). The accompanying video records a series of debris flow surges at Jiangjia Ravine, in Yunnan Prov
Authors
Kevin M. Scott, Wang Yuyi
2000 volcanic activity in Alaska and Kamchatka: summary of events and response of the Alaska Volcano Observatory
No abstract available.
Authors
Christina A. Neal, Robert G. McGimsey, Olga Chubarova
Transient volcano deformation sources imaged with interferometric synthetic aperture radar: Application to Seguam Island, Alaska
Thirty interferometric synthetic aperture radar (InSAR) images, spanning various intervals during 1992–2000, document coeruptive and posteruptive deformation of the 1992–1993 eruption on Seguam Island, Alaska. A procedure that combines standard damped least squares inverse methods and collective surfaces, identifies three dominant amorphous clusters of deformation point sources. Predictions genera
Authors
Timothy Masterlark, Zhong Lu
The 26 May 1982 breakout flows derived from failure of a volcanic dam at El Chichón, Chiapas, Mexico
The eruptions of El Chichón between 28 March and 4 April 1982 produced a variety of pyroclastic deposits. The climactic phase, on 3 April at 07:35 (4 April at 01:35 GMT), destroyed the central andesitic dome and fed pyroclastic surges and flows that dammed nearby drainages, including the Magdalena River. By late April, a lake had formed, 4 km long and 300–400 m wide, containing a volume of 26 × 1
Authors
J.L. Macias, L. Capra, K. M. Scott, J.M. Espindola, A. Garcia-Palomo, J. E. Costa
Hawaiian submarine manganese-iron oxide crusts - A dating tool?
Black manganese-iron oxide crusts form on most exposed rock on the ocean floor. Such crusts are well developed on the steep lava slopes of the Hawaiian Ridge and have been sampled during dredging and submersible dives. The crusts also occur on fragments detached from bedrock by mass wasting, on submerged coral reefs, and on poorly lithified sedimentary rocks. The thickness of the crusts was measur
Authors
J. G. Moore, D. A. Clague
Rhyodacites of Kulshan caldera, North Cascades of Washington: Postcaldera lavas that span the Jaramillo
Kulshan caldera (4.5×8 km), at the northeast foot of Mount Baker, is filled with rhyodacite ignimbrite (1.15 Ma) and postcaldera lavas and is only the third Quaternary caldera identified in the Cascade arc. A gravity traverse across the caldera yields a steep-sided, symmetrical, complete Bouguer anomaly of −16 mGal centered over the caldera. Density considerations suggest that the caldera fill, wh
Authors
W. Hildreth, M. A. Lanphere, D. E. Champion, J. Fierstein
The perception of volcanic risk in Kona communities from Mauna Loa and Hualālai volcanoes, Hawai'i
Volcanic hazards in Kona (i.e. the western side of the island of Hawai'i) stem primarily from Mauna Loa and Hualālai volcanoes. The former has erupted 39 times since 1832. Lava flows were emplaced in Kona during seven of these eruptions and last impacted Kona in 1950. Hualālai last erupted in ca. 1800. Society's proximity to potential eruptive sources and the potential for relatively fast-moving l
Authors
Chris E. Gregg, Bruce F. Houghton, David M. Johnston, Douglas Paton, D. A. Swanson
The threat of silent earthquakes
Not all earthquakes shake the ground. The so-called silent types are forcing scientists to rethink their understanding of the way quake-prone faults behave. In rare instances, silent earthquakes that occur along the flakes of seaside volcanoes may cascade into monstrous landslides that crash into the sea and trigger towering tsunamis. Silent earthquakes that take place within fault zones created b
Authors
Peter Cervelli
Magmatic precursors to the 18 May 1980 eruption of Mount St. Helens, USA
Perhaps the most difficult task facing volcanologists today is that of distinguishing between low-level volcanic restlessness and activity that presages a full-scale eruption. We illustrate these difficulties by reexamining the sequence of events that led to the 18 May 1980 eruption of Mount St. Helens, activity that is often presented as a classic example of early phreatic explosions leading to a
Authors
K. V. Cashman, R. P. Hoblitt
Non-double-couple microearthquakes at Long Valley caldera, California, provide evidence for hydraulic fracturing
Most of 26 small (0.4≲M≲3.1) microearthquakes at Long Valley caldera in mid-1997, analyzed using data from a dense temporary network of 69 digital three-component seismometers, have significantly non-double-couple focal mechanisms, inconsistent with simple shear faulting. We determined their mechanisms by inverting P- and S-wave polarities and amplitude ratios using linear-programming methods, and
Authors
G. R. Foulger, B. R. Julian, D. P. Hill, A. M. Pitt, P.E. Malin, E. Shalev