Magnetic surveys help reassess volcanic hazards at Yucca Mountain, Nevada

Connor, Charles B.; Lane-Magsino, Sammantha; Stamatakos, John; Martin, Ronald H.; LaFemina, Peter; Hill, Brittain E.; Lieber, Steve

doi:10.1029/97eo00049

Cited by 8 publications

(5 citation statements)

References 6 publications

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“…Magnetic data are particularly useful for detecting structures in volcanic terrains, due to the high contrast in magnetic properties between basaltic lava, scoria, and alluvium [ Stamatakos et al , 1997]. Magnetic profiles and maps have been used successfully to infer geological features such as faults at a number of sites [e.g., Jones‐Cecil , 1995; Connor et al , 1997; La Femina et al , 2002], even in granitic areas where the magnetic contrast is relatively small [ McPhee et al , 2004]. On basaltic volcanoes, magnetic anomalies associated with faults are often on the order of 100–1000 nT, two to three orders of magnitude larger than the magnetic anomalies induced through electrokinetic effects associated with fluid flow [ Zlotnicki and Le Mouel , 1990; Adler et al , 1999].…”

Section: Methods For Delineating Flow Pathsmentioning

confidence: 99%

Integrated geophysical and hydrothermal models of flank degassing and fluid flow at Masaya volcano, Nicaragua

Pearson

Kiyosugi

Lehto

et al. 2012

Geochem Geophys Geosyst

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[1] We investigate geologic controls on circulation in the shallow hydrothermal system of Masaya volcano, Nicaragua, and their relationship to surface diffuse degassing. On a local scale ($250 m), relatively impermeable normal faults dipping at $60 control the flowpath of water vapor and other gases in the vadose zone. These shallow normal faults are identified by modeling of a NE-SW trending magnetic anomaly of up to 2300 nT that corresponds to a topographic offset. Elevated SP and CO 2 to the NW of the faults and an absence of CO 2 to the SE suggest that these faults are barriers to flow. TOUGH2 numerical models of fluid circulation show enhanced flow through the footwalls of the faults, and corresponding increased mass flow and temperature at the surface (diffuse degassing zones). On a larger scale, TOUGH2 modeling suggests that groundwater convection may be occurring in a 3-4 km radial fracture zone transecting the entire flank of the volcano. Hot water rising uniformly into the base of the model at 1 Â 10 À5 kg/m 2 s results in convection that focuses heat and fluid and can explain the three distinct diffuse degassing zones distributed along the fracture. Our data and models suggest that the unusually active surface degassing zones at Masaya volcano can result purely from uniform heat and fluid flux at depth that is complicated by groundwater convection and permeability variations in the upper few km. Therefore isolating the effects of subsurface geology is vital when trying to interpret diffuse degassing in light of volcanic activity.

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Section: Methods For Delineating Flow Pathsmentioning

confidence: 99%

Integrated geophysical and hydrothermal models of flank degassing and fluid flow at Masaya volcano, Nicaragua

Pearson

Kiyosugi

Lehto

et al. 2012

Geochem Geophys Geosyst

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“…orientation are similarly important to the volcanic hazard models [Smith et al, 1990;Connor et al, 1997]. Third, on a local scale the relationship between individual basaltic vents and faults is delineated, once again on the basis of detailed geologic field and magnetic data.…”

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confidence: 99%

Geologic factors controlling patterns of small‐volume basaltic volcanism: Application to a volcanic hazards assessment at Yucca Mountain, Nevada

Connor¹,

Stamatakos²,

Ferrill³

et al. 2000

J. Geophys. Res.

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152

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“…We note that the fit between observed and calculated magnetizations above anomaly G could be improved if we rotated the magnetization direction away from the nominal values used (I=-60°, D=180°). The ground magnetic survey of anomaly G shows conspicuous NE-trending linear characteristics (Connor et al, 1997;p 75) and may be part of an aligned group of volcanic centers (anomalies H, F, G, figs. 7, 8; Connor and others, 2000;p.…”

Section: Present Modeling Results: Profile Aa'mentioning

confidence: 99%

Aeromagnetic Expression of Buried Basaltic Volcanoes Near Yucca Mountain, Nevada

O’Leary¹,

Mankinen²,

Blakely³

et al. 2002

Open-File Report

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A high-resolution aeromagnetic survey has defined a number of small dipolar anomalies indicating the presence of magnetic bodies buried beneath the surface of Crater Flat and the Amargosa Desert. Results of potential-field modeling indicate that isolated, small-volume, highly magnetic bodies embedded within the alluvial deposits of both areas produce the anomalies. Their physical characteristics and the fact that they tend to be aligned along major structural trends provide strong support for the hypothesis that the anomalies reflect buried basaltic volcanic centers. Other, similar anomalies are identified as possible targets for further investigation. High-resolution gravity and ground-magnetic surveys, perhaps along with drilling sources of selected anomalies and radiometric age determinations, can provide valuable constraints in estimating potential volcanic hazard to the potential nuclear waste repository at Yucca Mountain.

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Magnetic surveys help reassess volcanic hazards at Yucca Mountain, Nevada

Cited by 8 publications

References 6 publications

Integrated geophysical and hydrothermal models of flank degassing and fluid flow at Masaya volcano, Nicaragua

Integrated geophysical and hydrothermal models of flank degassing and fluid flow at Masaya volcano, Nicaragua

Geologic factors controlling patterns of small‐volume basaltic volcanism: Application to a volcanic hazards assessment at Yucca Mountain, Nevada

Aeromagnetic Expression of Buried Basaltic Volcanoes Near Yucca Mountain, Nevada

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