A collaborative effort between Lawrence Berkeley National Laboratory, Sandia National Laboratorie... more A collaborative effort between Lawrence Berkeley National Laboratory, Sandia National Laboratories, Electromagnetic Instruments and the USGS Hawaiian Volcano Observatory has undertaken a three-dimensional (3D) magnetotelluric (MT) study of the Kilauea volcano in Hawaii. The survey objectives are 1): to produce a high quality 3D MT data set over the central caldera and the eastern and southwestern rift zones, 2) to
This report is preliminary and has not been reviewed for conformity with U.S Geological Survey ed... more This report is preliminary and has not been reviewed for conformity with U.S Geological Survey editorial standards and stratigraphic nomenclature. The use of trade names is solely for descriptive purposes and does not imply endorsement by the Geological Survey.
This report is preliminary and has not been reviewed for conformity with U.S. Geological Survey e... more This report is preliminary and has not been reviewed for conformity with U.S. Geological Survey editorial standards and stratigraphic nomenclature. The use of trade names is solely for descriptive purposes and does not imply endorsement by the Geological Survey, Fixed distance, horizontal loop electromagnetic (EM) soundings Mere used to define the contact between an aquifer of Alifan limestone underlain by an impervious, clayey conglomerate in Agat, Guam. A Schlumberger resistivity sounding showed that the limestone has a resistivity of approximately 15OO ohm m while the conglomerate appears to have a resistivity of less than SO ohm m. This resistivity structure presents an ideal situation for mapping by electromagnetic methods. The EM sounding measurements were not able to independently determine the resistivity of the limestone; however, they proved excellent for determining the depth to and resistivity of the conductive conglomerate beneath the limestone. After compiling the resu...
Microgravity measurements at the summit of Kilauea Volcano over the course of the Pu'u 'O... more Microgravity measurements at the summit of Kilauea Volcano over the course of the Pu'u 'O'o-Kupaianaha eruption show distinctly different trends during different periods of the eruption. Rates of mass accumulation and withdrawal during these periods, computed from excess gravity changes after correction for measured elevation changes, reveal that the rates of mass change beneath the summit were only a few percent of the total volume of magma going through the volcano plumbing system and erupting at Pu'u 'O'o. Furthermore, the rate of net mass change in the summit reservoir was not constant; indeed, the data suggest that magma was accumulating beneath the summit from 1983 to mid-1985 and from 1991 to mid-1993. The changes in excess gravity correspond to both changes in the stress regime at the summit and changes in eruptive style. Geodetic data show that the summit was extending during periods of magma accumulation and contracting during most of the period of ...
Clues to the overall structure of Kilauea volcano can be obtained from spatial studies of gravity... more Clues to the overall structure of Kilauea volcano can be obtained from spatial studies of gravity, magnetic, and seismic velocity variations. The rift zones and summit are underlain by dense, magnetic, high P-wave-velocity rocks at depths of about 2 km less. The gravity and seismic velocity studies indicate that the rift structures are broad, extending farther to the north than to the south of the surface features. The magnetic data give more definition to the rift structures by allowing separation into a narrow, highly-magnetized, shallow zone and broad, flanking, magnetic lows. The patterns of gravity, magnetic variations, and seismicity document the southward migration of the upper cast rift zone. Regional, hydrologic features of Kilauea can be determined from resistivity and self-potential studies. High-level groundwater exists beneath Kilauea summit to elevations of +800 m within a triangular area bounded by the west edge of the upper southwest rift zone, the east edge of the upper east rift zone, and the Koa'c fault system. High-level groundwater is present within the east rift zone beyond the triangular summit area. Self-potential mapping shows that areas of local heat produce local fluid circulation in the unconfined aquifer (water table). The dynamics of Kilauea eruptions are responsible for both the source of heat and the fracture permeability of the hydrothermal system. Shallow seismicity and surface deformation indicate that magma is intruding and that fractures are forming beneath the rift zones and summit area. Magma supply estimates are used to calculate the rate of heat input to Kilauea's hydrothermal systems. Heat flows of 370–820 mW/m2 are calculated from deep wells within the lower east rift zone. The estimated heat input rate for Kilauea of 9 gigawatts (GW) is at least 25 times higher than the conductive heat loss as estimated from the heat flow in wells extrapolated over the area of the summit caldera and rift zones. Heat must be dissipated by another mechanism, or the heat input rate estimates are much too high.
A collaborative effort between Lawrence Berkeley National Laboratory, Sandia National Laboratorie... more A collaborative effort between Lawrence Berkeley National Laboratory, Sandia National Laboratories, Electromagnetic Instruments and the USGS Hawaiian Volcano Observatory has undertaken a three-dimensional (3D) magnetotelluric (MT) study of the Kilauea volcano in Hawaii. The survey objectives are 1): to produce a high quality 3D MT data set over the central caldera and the eastern and southwestern rift zones, 2) to
This report is preliminary and has not been reviewed for conformity with U.S Geological Survey ed... more This report is preliminary and has not been reviewed for conformity with U.S Geological Survey editorial standards and stratigraphic nomenclature. The use of trade names is solely for descriptive purposes and does not imply endorsement by the Geological Survey.
This report is preliminary and has not been reviewed for conformity with U.S. Geological Survey e... more This report is preliminary and has not been reviewed for conformity with U.S. Geological Survey editorial standards and stratigraphic nomenclature. The use of trade names is solely for descriptive purposes and does not imply endorsement by the Geological Survey, Fixed distance, horizontal loop electromagnetic (EM) soundings Mere used to define the contact between an aquifer of Alifan limestone underlain by an impervious, clayey conglomerate in Agat, Guam. A Schlumberger resistivity sounding showed that the limestone has a resistivity of approximately 15OO ohm m while the conglomerate appears to have a resistivity of less than SO ohm m. This resistivity structure presents an ideal situation for mapping by electromagnetic methods. The EM sounding measurements were not able to independently determine the resistivity of the limestone; however, they proved excellent for determining the depth to and resistivity of the conductive conglomerate beneath the limestone. After compiling the resu...
Microgravity measurements at the summit of Kilauea Volcano over the course of the Pu'u 'O... more Microgravity measurements at the summit of Kilauea Volcano over the course of the Pu'u 'O'o-Kupaianaha eruption show distinctly different trends during different periods of the eruption. Rates of mass accumulation and withdrawal during these periods, computed from excess gravity changes after correction for measured elevation changes, reveal that the rates of mass change beneath the summit were only a few percent of the total volume of magma going through the volcano plumbing system and erupting at Pu'u 'O'o. Furthermore, the rate of net mass change in the summit reservoir was not constant; indeed, the data suggest that magma was accumulating beneath the summit from 1983 to mid-1985 and from 1991 to mid-1993. The changes in excess gravity correspond to both changes in the stress regime at the summit and changes in eruptive style. Geodetic data show that the summit was extending during periods of magma accumulation and contracting during most of the period of ...
Clues to the overall structure of Kilauea volcano can be obtained from spatial studies of gravity... more Clues to the overall structure of Kilauea volcano can be obtained from spatial studies of gravity, magnetic, and seismic velocity variations. The rift zones and summit are underlain by dense, magnetic, high P-wave-velocity rocks at depths of about 2 km less. The gravity and seismic velocity studies indicate that the rift structures are broad, extending farther to the north than to the south of the surface features. The magnetic data give more definition to the rift structures by allowing separation into a narrow, highly-magnetized, shallow zone and broad, flanking, magnetic lows. The patterns of gravity, magnetic variations, and seismicity document the southward migration of the upper cast rift zone. Regional, hydrologic features of Kilauea can be determined from resistivity and self-potential studies. High-level groundwater exists beneath Kilauea summit to elevations of +800 m within a triangular area bounded by the west edge of the upper southwest rift zone, the east edge of the upper east rift zone, and the Koa'c fault system. High-level groundwater is present within the east rift zone beyond the triangular summit area. Self-potential mapping shows that areas of local heat produce local fluid circulation in the unconfined aquifer (water table). The dynamics of Kilauea eruptions are responsible for both the source of heat and the fracture permeability of the hydrothermal system. Shallow seismicity and surface deformation indicate that magma is intruding and that fractures are forming beneath the rift zones and summit area. Magma supply estimates are used to calculate the rate of heat input to Kilauea's hydrothermal systems. Heat flows of 370–820 mW/m2 are calculated from deep wells within the lower east rift zone. The estimated heat input rate for Kilauea of 9 gigawatts (GW) is at least 25 times higher than the conductive heat loss as estimated from the heat flow in wells extrapolated over the area of the summit caldera and rift zones. Heat must be dissipated by another mechanism, or the heat input rate estimates are much too high.
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