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Groundwater recharge at Mt. Hood, Oregon, is dominated by spring snow melt which provides a natural large-amplitude and narrow-width pore-fluid pressure signal. Time delays between this seasonal groundwater recharge and seismicity triggered by groundwater recharge can thus be used to estimate large-scale hydraulic diffusivities and the state of stress in(More)
[1] A comparison of time series of basaltic and silicic eruptions in eastern California over the last 400 kyr with the contemporaneous global record of glaciation suggests that this volcanism is influenced by the growth and retreat of glaciers occurring over periods of about 40 kyr. Statistically significant cross correlations between changes in eruption(More)
The formation of a continuous crystal network in magmas and lavas can provide finite yield strength, d y , and can thus cause a change from Newtonian to Bingham rheology. The rheology of crystal^melt suspensions affects geological processes, such as ascent of magma through volcanic conduits, flow of lava across the Earth's surface, melt extraction from(More)
We study continuum percolation of three-dimensional randomly oriented soft-core polyhedra (prisms). The prisms are biaxial or triaxial and range in aspect ratio over six orders of magnitude. Results for prisms are compared with studies for ellipsoids, rods, ellipses, and polygons and differences are explained using the concept of the average excluded(More)
We examine 20-yr data sets of seismic activity from 10 volcanic areas in the western United States for annual periodic signals (seasonality), focusing on large calderas (Long Valley caldera and Yellowstone) and stratovolcanoes (Cascade Range). We apply several statistical methods to test for seasonality in the seismic catalogs. In 4 of the 10 regions,(More)
[1] Geothermal energy offers clean, renewable, reliable electric power with no need for grid‐scale energy storage, yet its use has been constrained to the few locations worldwide with naturally high geothermal heat resources and groundwater availability. We present a novel approach with the potential to permit expansion of geothermal energy utilization:(More)
Carbonate bedrocks encompass a vast range of primary porosities and permeabil-ities, which are further modified by the addition of secondary porosities as a result of fissure, fracture, and conduit development. The wide variety of primary and initial secondary porosities found in carbonates further complicate the already difficult task of modeling(More)
Geothermal energy offers clean, consistent, reliable electric power with no need for grid-scale energy storage, unlike wind and solar renewable power alternatives. However, geothermal energy is often underrepresented in renewable energy discussions and has considerable room for growth. New technology and methods will be critical for future investment, and(More)
[1] We investigate the decrease in permeability, k, with depth, z, in the Oregon Cascades employing four different methods. Each method provides insight into the average permeability applicable to a different depth scale. Spring discharge models are used to infer shallow (z < 0.1 km) horizontal permeabilities. Coupled heat and groundwater flow simulations(More)