Publications
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Source mechanism of very-long-period signals accompanying dome growth activity at Merapi volcano, Indonesia
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 data. Sol
Authors
D. Hidayat, B. Chouet, B. Voight, P. Dawson, Antonius Ratdomopurbo
North-central Oregon Cascades; exploring petrologic and tectonic intimacy in a propagating intra-arc rift
No abstract available.
Authors
Richard M. Conrey, Edward M. Taylor, Julie M. Donnelly-Nolan, David R. Sherrod
Morphology, volcanism, and mass wasting in Crater Lake, Oregon
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.P. caldera
Authors
C. R. Bacon, J.V. Gardner, L. A. Mayer, M. W. Buktenica, P. Dartnell, D.W. Ramsey, J.E. Robinson
A Holocene paleosecular variation from 14C-dated volcanic rocks in western North America
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 density is
Authors
Jonathan T. Hagstrum, Duane E. Champion
Ancient and modern subduction zone contributions to the mantle sources of lavas from the Lassen region of California inferred from Lu-Hf isotopic systematics
Hafnium isotopic compositions have been determined on a suite of calc-alkaline and high-alumina-olivine tholeiitic lavas from the Lassen region of California and are used, in conjunction with previously published mineralogical, geochemical, and isotopic data, to constrain their petrogenesis. Positive correlation between εHf values and geochemical indices of the modern subduction component indicate
Authors
L. E. Borg, Janne Blichert-Toft, Michael A. Clynne
Very-long-period volcanic earthquakes beneath Mammoth Mountain, California
Detection of three very‐long‐period (VLP) volcanic earthquakes beneath Mammoth Mountain emphasizes that magmatic processes continue to be active beneath this young, eastern California volcano. These VLP earthquakes, which occurred in October 1996 and July and August 2000, appear as bell‐shaped pulses with durations of one to two minutes on a nearby borehole dilatometer and on the displacement seis
Authors
David P. Hill, P. Dawson, M.J.S. Johnston, A. M. Pitt, G. Biasi, K. Smith
The 12 September 1999 Upper East Rift Zone dike intrusion at Kilauea Volcano, Hawaii
Deformation associated with an earthquake swarm on 12 September 1999 in the Upper East Rift Zone of Kilauea Volcano was recorded by continuous GPS receivers and by borehole tiltmeters. Analyses of campaign GPS, leveling data, and interferometric synthetic aperture radar (InSAR) data from the ERS-2 satellite also reveal significant deformation from the swarm. We interpret the swarm as resulting fro
Authors
Peter Cervelli, P. Segall, F. Amelung, H. Garbeil, C. Meertens, S. Owen, Asta Miklius, M. Lisowski
Magmatic inflation at a dormant stratovolcano: 1996-1998 activity at Mount Peulik volcano, Alaska, revealed by satellite radar interferometry
A series of ERS radar interferograms that collectively span the time interval from July 1992 to August 2000 reveal that a presumed magma body located 6.6 ??? 0.5 km beneath the southwest flank of the Mount Peulik volcano inflated 0.051 ??? 0.005 km3 between October 1996 and September 1998. Peulik has been active only twice during historical time, in 1814 and 1852, and the volcano was otherwise qui
Authors
Zhong Lu, Charles W. Wicks, Daniel Dzurisin, John A. Power, Seth C. Moran, Wayne R. Thatcher
The Fish Canyon magma body, San Juan volcanic field, Colorado: Rejuvenation and eruption of an upper-crustal batholith
More than 5000 km3 of nearly compositionally homogeneous crystal-rich dacite (∼68 wt % SiO2: ∼45% Pl + Kfs + Qtz + Hbl + Bt + Spn + Mag + Ilm + Ap + Zrn + Po) erupted from the Fish Canyon magma body during three phases: (1) the pre-caldera Pagosa Peak Dacite (an unusual poorly fragmented pyroclastic deposit, ∼200 km3); (2) the syn-collapse Fish Canyon Tuff (one of the largest known ignimbrites, ∼5
Authors
Olivier Bachmann, Michael A. Dungan, Peter W. Lipman
Sun photometer and lidar measurements of the plume from the Hawaii Kilauea Volcano Pu'u O'o vent: Aerosol flux and SO2 lifetime
Aerosol optical depths and lidar measurements were obtained under the plume of Hawaii Kilauea Volcano on August 17, 2001, ∼9 km downwind from the erupting Pu'u O'o vent. Measured aerosol optical depths (at 500 nm) were between 0.2–0.4. Aerosol size distributions inverted from the spectral sun photometer measurements suggest the volcanic aerosol is present in the accumulation mode (0.1–0.5 micron d
Authors
J.N. Porter, K.A. Horton, P. J. Mouginis-Mark, B. Lienert, S.K. Sharma, E. Lau, T. Elias, A. J. Sutton, C. Oppenheimer
Mapping the sources of the seismic wave field at Kilauea volcano, Hawaii, using data recorded on multiple seismic Antennas
Seismic antennas constitute a powerful tool for the analysis of complex wave fields. Well-designed antennas can identify and separate components of a complex wave field based on their distinct propagation properties. The combination of several antennas provides the basis for a more complete understanding of volcanic wave fields, including an estimate of the location of each individual wave-field c
Authors
J. Almendros, B. Chouet, P. Dawson, Caleb G. Huber
Fault structure and kinematics of the Long Valley Caldera region, California, revealed by high-accuracy earthquake hypocenters and focal mechanism stress inversions
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 east/west
Authors
Stephanie Prejean, William L. Ellsworth, Mark Zoback, Felix Waldhauser