Publications
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An exact solution for ideal dam-break floods on steep slopes
The shallow‐water equations are used to model the flow resulting from the sudden release of a finite volume of frictionless, incompressible fluid down a uniform slope of arbitrary inclination. The hodograph transformation and Riemann's method make it possible to transform the governing equations into a linear system and then deduce an exact analytical solution expressed in terms of readily evaluat
Authors
C. Ancey, Richard M. Iverson, M. Rentschler, Roger P. Denlinger
Kaguyak dome field and its Holocene caldera, Alaska Peninsula
Kaguyak Caldera lies in a remote corner of Katmai National Park, 375 km SW of Anchorage, Alaska. The 2.5-by-3-km caldera collapsed ~ 5.8 ± 0.2 ka (14C age) during emplacement of a radial apron of poorly pumiceous crystal-rich dacitic pyroclastic flows (61–67% SiO2). Proximal pumice-fall deposits are thin and sparsely preserved, but an oxidized coignimbrite ash is found as far as the Valley of Ten
Authors
J. Fierstein, W. Hildreth
Dynamic stresses, Coulomb failure, and remote triggering
Dynamic stresses associated with crustal surface waves with 15-30-sec periods and peak amplitudes < 1 MPa are capable of triggering seismicity at sites remote from the generating mainshock under appropriate conditions. Coulomb failure models based on a frictional strength threshold offer one explanation for instances of rapid-onset triggered seismicity that develop during the surface-wave peak dyn
Authors
David P. Hill
Permeability of continental crust influenced by internal and external forcing
The permeability of continental crust is so highly variable that it is often considered to defy systematic characterization. However, despite this variability, some order has been gleaned from globally compiled data. What accounts for the apparent coherence of mean permeability in the continental crust (and permeability–depth relations) on a very large scale? Here we argue that large‐scale crustal
Authors
S.A. Rojstaczer, S. E. Ingebritsen, D.O. Hayba
Upper conduit structure and explosion dynamics at Stromboli
Modeling of very long period seismic data recorded during explosive activity at Stromboli in 1997 provides an image of the uppermost 1 km of its volcanic plumbing system. Two distinct dike-like conduit structures are identified, each representative of explosive eruptions from two different vents located near the northern and southern perimeters of the summit crater. Inferred volumetric changes in
Authors
Bernard A. Chouet, Phillip B. Dawson, Marcello Martini
The 2005 catastrophic acid crater lake drainage, lahar, and acidic aerosol formation at Mount Chiginagak volcano, Alaska, USA: Field observations and preliminary water and vegetation chemistry results
A mass of snow and ice 400-m-wide and 105-m-thick began melting in the summit crater of Mount Chiginagak volcano sometime between November 2004 and early May 2005, presumably owing to increased heat flux from the hydrothermal system, or possibly from magma intrusion and degassing. In early May 2005, an estimated 3.8??106 m3 of sulfurous, clay-rich debris and acidic water, with an accompanying acid
Authors
J.R. Schaefer, W. E. Scott, William C. Evans, J. Jorgenson, R. G. McGimsey, B. Wang
New episodes of volcanism at Kilauea Volcano, Hawaii
Mid‐2007 was a time of intense activity at Kilauea Volcano, Hawaii (see Figure 1). In June, the long‐lived Pu'u 'Ō'ō—Kupaianaha eruption, a dual‐vent system along the east rift zone (ERZ) that has been erupting since 1983 [Heliker et al., 2003], paused due to the outbreak of a new vent farther up the rift (see Figure 2). The Pu'u 'Ō'ō vent collapsed following that activity, and the resulting reorg
Authors
Michael P. Poland, Asta Miklius, Tim R. Orr, J. Sutton, Carl Thornber, David C. Wilson
The critical role of volcano monitoring in risk reduction
Data from volcano-monitoring studies constitute the only scientifically valid basis for short-term forecasts of a future eruption, or of possible changes during an ongoing eruption. Thus, in any effective hazards-mitigation program, a basic strategy in reducing volcano risk is the initiation or augmentation of volcano monitoring at historically active volcanoes and also at geologically young, but
Authors
R. I. Tilling
Three-dimensional P-wave velocity structure and precise earthquake relocation at Great Sitkin Volcano, Alaska
Waveform cross-correlation with bispectrum verification is combined with double-difference tomography to increase the precision of earthquake locations and constrain regional 3D P-wave velocity heterogeneity at Great Sitkin volcano, Alaska. From 1999 through 2005, the Alaska Volcano Observatory (AVO) recorded ∼1700 earthquakes in the vicinity of Great Sitkin, including two ML 4.3 earthquakes that
Authors
Jeremy Pesicek, Clifford H. Thurber, Heather R. DeShon, Stephanie G. Prejean, Haijiang Zhang
Eruptive history and tectonic setting of Medicine Lake Volcano, a large rear-arc volcano in the southern Cascades
Medicine Lake Volcano (MLV), located in the southern Cascades ∼ 55 km east-northeast of contemporaneous Mount Shasta, has been found by exploratory geothermal drilling to have a surprisingly silicic core mantled by mafic lavas. This unexpected result is very different from the long-held view derived from previous mapping of exposed geology that MLV is a dominantly basaltic shield volcano. Detailed
Authors
Julie M. Donnelly-Nolan, Timothy L. Grove, M. A. Lanphere, Duane E. Champion, David W. Ramsey
Atmospheric contribution of gas emissions from Augustine volcano, Alaska during the 2006 eruption
Airborne surveillance of gas emissions from Augustine for SO2, CO2 and H2S showed no evidence of anomalous degassing from 1990 through May 2005. By December 20, 2005, Augustine was degassing 660 td−1 of SO2, and ten times that by January 4, 2006. The highest SO2 emission rate measured during the 2006 eruption was 8650 td−1 (March 1); for CO2, 13000 td−1 (March 9), and H2S, 8 td−1 (January 19). Thi
Authors
K.A. McGee, M.P. Doukas, R. G. McGimsey, C. A. Neal, R.L. Wessels
A model for radial dike emplacement in composite cones based on observations from Summer Coon volcano, Colorado, USA
We mapped the geometry of 13 silicic dikes at Summer Coon, an eroded Oligocene stratovolcano in southern Colorado, to investigate various characteristics of radial dike emplacement in composite volcanoes. Exposed dikes are up to about 7 km in length and have numerous offset segments along their upper peripheries. Surprisingly, most dikes at Summer Coon increase in thickness with distance from the
Authors
Michael P. Poland, W.P. Moats, J.H. Fink