Applications of the VLF induction method for studying some volcanic processes of Kilauea volcano, Hawaii

Zablocki, Charles J.

doi:10.1016/0377-0273(78)90008-2

Cited by 31 publications

(28 citation statements)

References 16 publications

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“…Geoelectrical studies during the early 1970s delineated the distribution of numerous subsurface thermal anomalies in the summit area of Kïlauea (Zablocki, 1976(Zablocki, , 1978). An electrical self-potential (SP) survey in the summer of 1972 revealed a positive SP anomaly along the southern margin of the caldera (an area of frequent historical eruptive activity) that also extended more than 2 km to the south, outside the eruptively active caldera, but above a zone of shallow (<5 km depth) earthquakes.…”

Section: Geoelectrical Surveysmentioning

confidence: 99%

“…Deformation and seismic observation showed clearly that a dike had intruded into the eastern Koa´e at this time and extended west of the surface vents (Koyanagi and others, 1983;Klein and others, 1987). Electrical Self-Potential (SP) measurements by Zablocki (1978) demonstrated the subsurface intrusion of magma extended nearly 3 km into the KFS.…”

Section: Tectonic Significance Of the December 31 Eruptionmentioning

confidence: 99%

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Magma migration and resupply during the 1974 summit eruptions of Kilauea Volcano, Hawaii

Lockwood¹,

Tilling²,

Holcomb³

et al. 1999

Professional Paper

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Section: Geoelectrical Surveysmentioning

confidence: 99%

Section: Tectonic Significance Of the December 31 Eruptionmentioning

confidence: 99%

Magma migration and resupply during the 1974 summit eruptions of Kilauea Volcano, Hawaii

Lockwood¹,

Tilling²,

Holcomb³

et al. 1999

Professional Paper

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“…As examples of application of the above theories, in the following section we fit the model to VLF tilt data measured above a magma-filled dike that intruded into the flank of Kilauea volcano in 1973 and were published by Zablocki (1976Zablocki ( ,1978 and above a dike on the south flank of Mt. Etna, Sicily, that intruded in 2001 (Bonaccorso et al, 2002).…”

Section: Numerical Comparisonmentioning

confidence: 99%

“…In Hawaii, magma intrudes into dikes that are fed by magma chambers. The location and geometry of newly formed dikes can be estimated using VLF (Zablocki 1976(Zablocki , 1978, and whether the dikes remain molten, since the conductivity decreases by several orders of magnitude on solidification. Provided measurements are not taken near the ends the problem is two-dimensional, and a single conductivity contrast between the dike and country rock is an adequate approximation.…”

Section: Introductionmentioning

confidence: 99%

“…The equations can become quite complicated. Hohmann (1971) describes a numerical method for solving twodimensional problems and an associated FORTRAN program (SCATPW.F90 Anderson et al, 1976) has been used for analysis of Hawaii data (Zablocki, 1976(Zablocki, , 1978. The program uses a collocation method to invert for currents in the conductive body and takes into account the decay of the inducing field in the surrounding conductive half-space as well as the free-surface boundary conditions.…”

Section: Introductionmentioning

confidence: 99%

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Electromagnetic induction in a conductive strip in a medium of contrasting conductivity: application to VLF and MT above molten dykes

Davis¹

2014

Geophysical Journal International

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Very low frequency (VLF) electromagnetic waves that penetrate conductive magma-filled dikes generate secondary fields on the surface that can be used to invert for dike properties. The model used for the interpretation calculates currents induced in a conductive strip by an inducing field that decays exponentially with depth due to the conductivity of the surrounding medium. The differential equations are integrated to give an inhomogeneous Fredholm equation of the second kind with a kernel consisting of a modified Bessel function of the second kind. Numerical methods are typically used to solve for the induced currents in the strip. In this paper we apply a modified Galerkin-Chebyshev method, which involves separating the kernel into source and field spectra and integrating the source terms to obtain a matrix equation for the unknown coefficients. The incident wave is expressed as a Chebyshev series. The Modified Bessel function is separated into a logarithmic singularity and a non-singular remainder, both of which are expanded in complex Chebyshev polynomials. The Chebyshev coefficients for the remainder are evaluated using a fast Fourier transform, while the logarithmic term and incident field have analytic series. The deconvolution then involves a matrix inversion. The results depend on the ratio of strip-size to skin-depth. For infinite skin-depth and a singular conductivity distribution given by τ 0 a/ √ a 2 − z 2 (where τ 0 is the conductance, a is the half-length, and z the distance from the center), Parker (2011) gives an analytic solution. We present a similar analytic series solution for the finite skin-depth case, where the size to skin depth ratio is small. Results are presented for different ratios of size to skin depth that can be compared with numerical solutions. We compare full-space and half-space solutions. A fit of the model to VLF data taken above a magma filled dikes in Hawaii 1 and Mt Etna demonstrates that while properties such as depth to top, conductivity ratio, tilt, and dip can be determined, the depth to bottom is indeterminate due to the exponential decay of the inducing field.2

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Electrical and Electromagnetic Monitoring of Volcanoes

Gailler¹,

Lénat²,

Labazuy³

2022

Hazards and Monitoring of Volcanic Activity 3

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Applications of the VLF induction method for studying some volcanic processes of Kilauea volcano, Hawaii

Cited by 31 publications

References 16 publications

Magma migration and resupply during the 1974 summit eruptions of Kilauea Volcano, Hawaii

Magma migration and resupply during the 1974 summit eruptions of Kilauea Volcano, Hawaii

Electromagnetic induction in a conductive strip in a medium of contrasting conductivity: application to VLF and MT above molten dykes

Electrical and Electromagnetic Monitoring of Volcanoes

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