Electromagnetic evidence for an ancient avalanche caldera rim on the south flank of Mount Merapi, Indonesia

Kalscheuer, Thomas; Commer, Michael; Helwig, Stefan L.; Hördt, Andreas; Tezkan, B.

doi:10.1016/j.jvolgeores.2006.12.014

Cited by 14 publications

(10 citation statements)

References 24 publications

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“…Southern flank: soil gas anomalies related to major flank collapse-related structure Using electromagnetic profiles, Kalscheuer et al (2007) postulated the existence of a major faulted structure below the southern flank that could be an ancient avalanche caldera rim connected to a deep hydrothermal reservoir. A north to south 2,500 m long traverse of 208 sampling sites (Fig.…”

Section: Resultsmentioning

confidence: 99%

“…A north to south 2,500 m long traverse of 208 sampling sites (Fig. 1c) was carried out at "Waron" for soil CO 2 measurements, along Kalscheuer et al (2007) profile. Both soil CO 2 concentration (at 50 cm depth) and surface flux were measured.…”

Section: Resultsmentioning

confidence: 99%

“…Over time, the 1911 1911 1940 1940 1984-1991 1984-1991 1906 1906 1883 1883 1954 1954 1953 1953 1956 1956 1888 1888 1911 1940 1984-1991 1906 1883 1954 1953 1956 1948 1948 1948 indicating sampling point locations, and c location of the traverse used to find the avalanche caldera major fault (Kalscheuer et al 2007). …”

Section: Summit and Lower Flank Main Structuresmentioning

confidence: 99%

“…This huge structure corresponds to the avalanche caldera rim (Camus et al 2000), which may be related to a still-active hydrothermal convective cell linked with deep levels of the volcanic pile. Recently, electromagnetic evidence for such a structure was obtained near an altitude of 825 m on the southern slope of the volcano, south of Gunung Turgo and Gunung Plawangan (Kalscheuer et al 2007). …”

Section: Summit and Lower Flank Main Structuresmentioning

confidence: 99%

“…A north-south traverse on the lower slopes of the volcano was surveyed during the fall of 2007, with a 10 m sampling interval (198 sample sites), from an altitude of 1,000 m down to an altitude of 700 m. Both CO 2 concentration and flux were measured with the addition of He and Rn determinations at specific sites where an electromagnetic anomaly occurred (Kalscheuer et al 2007). Radon was measured by alpha counting of 125 cm 3 ZnS scintillation bottles with a 600 s integration time (Baubron et al 1990.…”

Section: Summit and Lower Flank Main Structuresmentioning

confidence: 99%

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Structure and CO2 budget of Merapi volcano during inter-eruptive periods

Toutain

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Baubron³

et al. 2009

Bull Volcanol

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Soil temperature and gas (CO 2 concentration and flux) have been investigated at Merapi volcano (Indonesia) during two inter-eruptive periods (2002 and 2007). Precise imaging of the summit crater and the spatial pattern of diffuse degassing along a gas traverse on the southern slope are interpreted in terms of summit structure and major caldera organization. The summit area is characterized by decreasing CO 2 concentrations with distance from the 1932 crater rim, down to atmospheric levels at the base of the terminal cone. Similar patterns are measured on any transect down the slopes of the cone. The spatial distribution of soil gas anomalies suggests that soil degassing is controlled by structures identified as concentric historical caldera rims (1932, 1872, and 1768), which have undergone severe hydrothermal self-sealing processes that dramatically lower the permeability and porosity of soils. Temperature and CO 2 flux measurements in soils near the dome display heterogeneous distributions which are consistent with a fracture network identified by previous geophysical studies. These data support the idea that the summit is made of isolated and mobile blocks, whose boundaries are either sealed by depositional processes or Bull Volcanol (2009) 71:815-826

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Summit and Lower Flank Main Structuresmentioning

confidence: 99%

Section: Summit and Lower Flank Main Structuresmentioning

confidence: 99%

Section: Summit and Lower Flank Main Structuresmentioning

confidence: 99%

See 3 more Smart Citations

Structure and CO2 budget of Merapi volcano during inter-eruptive periods

Toutain

Sortino

Baubron³

et al. 2009

Bull Volcanol

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Crustal Structure and Ascent of Fluids and Melts Beneath Merapi: Insights From Geophysical Investigations

Lühr

Koulakov

Suryanto

2023

Active Volcanoes of the World

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Uncertainty and Resolution Analysis of 2D and 3D Inversion Models Computed from Geophysical Electromagnetic Data

Ren

Kalscheuer

2019

Surv Geophys

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A meaningful solution to an inversion problem should be composed of the preferred inversion model and its uncertainty and resolution estimates. The model uncertainty estimate describes an equivalent model domain in which each model generates responses which fit the observed data to within a threshold value. The model resolution matrix measures to what extent the unknown true solution maps into the preferred solution. However, most current geophysical electromagnetic (also gravity, magnetic and seismic) inversion studies only offer the preferred inversion model and ignore model uncertainty and resolution estimates, which makes the reliability of the preferred inversion model questionable. This may be caused by the fact that the computation and analysis of an inversion model depend on multiple factors, such as the misfit or objective function, the accuracy of the forward solvers, data coverage and noise, values of trade-off parameters, the initial model, the reference model and the model constraints. Depending on the particular method selected, large computational costs ensue. In this review, we first try to cover linearised model analysis tools such as the sensitivity matrix, the model resolution matrix and the model covariance matrix also providing a partially nonlinear description of the equivalent model domain based on pseudo-hyperellipsoids. Linearised model analysis tools can offer quantitative measures. In particular, the model resolution and covariance matrices measure how far the preferred inversion model is from the true model and how uncertainty in the measurements maps into model uncertainty. We also cover nonlinear model analysis tools including changes to the preferred inversion model (nonlinear sensitivity tests), modifications of the data set (using bootstrap re-sampling and generalised cross-validation), modifications of data uncertainty, variations of model constraints (including changes to the trade-off parameter, reference model and matrix regularisation operator), the edgehog method, mostsquares inversion and global searching algorithms. These nonlinear model analysis tools try to explore larger parts of the model domain than linearised model analysis and, hence, may assemble a more comprehensive equivalent model domain. Then, to overcome the bottleneck of computational cost in model analysis, we present several practical algorithms to accelerate the computation. Here, we emphasise linearised model analysis, as efficient computation of nonlinear model uncertainty and resolution estimates is mainly determined by fast forward and inversion solvers. In the last part of our review, we present applications of model analysis to models computed from individual and joint inversions of electromagnetic data; we also describe optimal survey design and inversion grid design as important Extended author information available on the last page of the article applications of model analysis. The currently available model uncertainty and resolution analyses are mainly for 1D and 2D problems due to the limitation...

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Electromagnetic evidence for an ancient avalanche caldera rim on the south flank of Mount Merapi, Indonesia

Cited by 14 publications

References 24 publications

Structure and CO2 budget of Merapi volcano during inter-eruptive periods

Structure and CO2 budget of Merapi volcano during inter-eruptive periods

Crustal Structure and Ascent of Fluids and Melts Beneath Merapi: Insights From Geophysical Investigations

Uncertainty and Resolution Analysis of 2D and 3D Inversion Models Computed from Geophysical Electromagnetic Data

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