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Electrical structure of Newberry Volcano, Oregon

Journal Article · · J. Geophys. Res.; (United States)

From the interpretation of magnetotelluric, transient electromagnetic, and Schlumberger resistivity soundings, the electrical structure of Newberry Volcano in central Oregon is found to consist of four units. From the surface downward, the geoelectrical units are (1) very resistive, young, unaltered volcanic rock, (2) a conductive layer of older volcanic material composed of altered tuffs, (3) a thick resistive layer thought to be in part intrusive rocks, and (4) a lower-crustal conductor. This model is similar to the regional geoelectrical structure found through the Cascade Range. Inside the caldera, the conductive second layer corresponds to the steep temperature gradient and alteration minerals observed in the USGS Newberry 2 test hole. Drill hole information on the south and north flanks of the volcano (test holes GES N-1 and GEO N-3, respectively) indicates that outside the caldera the conductor is due to alteration minerals (primarily smectite) and not high-temperature pore fluids. On the flanks of Newberry the conductor is generally deeper than inside the caldera, and its deepens with distance from the summit.

Research Organization:
U.S. Geological Survey, Denver, Colorado
OSTI ID:
6874496
Journal Information:
J. Geophys. Res.; (United States), Journal Name: J. Geophys. Res.; (United States) Vol. 93:B9; ISSN JGREA
Country of Publication:
United States
Language:
English