Publications

Very-long-period (VLP) pulses with period of 6–7s, displaying similar waveforms, were identified in 1998 from broadband seismographs around the summit crater. These pulses accompanied most of multiphase (MP) earthquakes, a type of long-period event locally defined at Merapi Volcano. Source mechanisms for several VLP pulses were examined by applying moment tensor inversion to the waveform...

Introduction Sulfur dioxide (SO2) emission rates from Kilauea Volcano were first measured by Stoiber and Malone (1975) and have been measured on a regular basis since 1979 (Greenland and others, 1985; Casadevall and others, 1987; Elias and others, 1998; Sutton and others, 2001). A compilation of SO2 emission-rate and wind-vector data from 1979 through 1997 is available as Open-File...

A paleosecular variation (PSV) curve for western North America is presented on the basis of 94 virtual geomagnetic poles (VGPs) from dated volcanic rocks sampled at 446 sites. Approximately 60% of the paleomagnetic database has been previously published. A curve defined by “spherical smoothed splines” is fitted to the VGPs, ranked by the quality of the age determinations, where the data...

We have determined high-resolution hypocenters for 45,000+ earthquakes that occurred between 1980 and 2000 in the Long Valley caldera area using a double-difference earthquake location algorithm and routinely determined arrival times. The locations reveal numerous discrete fault planes in the southern caldera and adjacent Sierra Nevada block (SNB). Intracaldera faults include a series of...

New analytical and experimental data constrain the storage and equilibration conditions of the magmas erupted in 1912 from Novarupta in the 20th century's largest volcanic event. Phase relations at H2O+CO2 fluid saturation were determined for an andesite (58.7 wt% SiO2) and a dacite (67.7 wt%) from the compositional extremes of intermediate magmas erupted. The phase assemblages, matrix...

Kanaga Volcano is a steep-sided, symmetrical, cone-shaped, 1307 meter high, andesitic stratovolcano on the north end of Kanaga Island (51°55’ N latitude, 177°10’ W longitude) in the western Aleutian Islands of Alaska. Kanaga Island is an elongated, low-relief (except for the volcano) island, located about 35 kilometers west of the community of Adak on Adak Island and is part of the...

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 Geology and Hydrology Disciplines of the USGS and with cooperators at the Alaska Division of Geological and Geophysical Surveys, University of Alaska Fairbanks Geophysical Institute...

No abstract available.

Crater Lake was surveyed nearly to its shoreline by high-resolution multibeam echo sounding in order to define its geologic history and provide an accurate base map for research and monitoring surveys. The bathymetry and acoustic backscatter reveal the character of landforms and lead to a chronology for the concurrent filling of the lake and volcanism within the ca. 7700 calibrated yr B...

40Ar/39Ar ages were determined on the three major ash-flow tuffs of the Yellowstone Plateau volcanic field in the region of Yellowstone National Park in order to improve the precision of previously determined ages. Total-fusion and incremental- heating ages of sanidine yielded the following mean ages: Huckleberry Ridge Tuff—2.059 ± 0.004 Ma; Mesa Falls Tuff— 1.285 ± 0.004 Ma; and Lava...

A new mathematical model developed to predict behavior of debris flows and avalanches also holds promise for predicting behavior of debris-laden flash floods. The model assumes that debris flows behave as mixtures of interacting Newtonian fluids and Coulomb solids. Solid and fluid constituents obey three-dimensional mass and momentum balances, which are summed and depth-integrated to...

In southern peninsular Florida, a late-early to early-late Pliocene carbonate ramp (Ochopee Limestone Member of the Tamiami Formation) is sandwiched between underlying marine siliciclastics of the late Miocene to early Pliocene Peace River Formation and an overlying late Pliocene unnamed sand. At least three depositional sequences (DS1, DS2, and DS3), of which two contain condensed...