Analytical volcano deformation source models

Lisowski, M.

doi:10.1007/978-3-540-49302-0_8

Cited by 79 publications

(109 citation statements)

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“…͑See the "Numerical modeling" section.͒ The limited geodetic and gravity measurements available for most volcanoes might not provide the resolution needed to discriminate clearly between simple analytical models and more-complex numerical models for sources of volcano unrest. ͑See also De Natale and Pingue, 1996;Dvorak and Dzurisin, 1997;Dzurisin, 2003;Gudmundsson, 2006;and Lisowsky, 2006.͒ Further complication arises if mass movement at depth does not cause ground deformation, such as with saturation of a permeable medium. There are cases of significant residual gravity changes without significant ground deformation and vice versa ͑Rymer et al, 1993; Carbone et al, 2003a͒, as well as of nonlinear relationships between gravity and deformation over a survey area ͑Gottsmann et al, 2006a, 2006b͒.…”

Section: Analytical Modelingmentioning

confidence: 99%

4D volcano gravimetry

Gottsmann²,

et al. 2008

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Time-dependent gravimetric measurements can detect subsurface processes long before magma flow leads to earthquakes or other eruption precursors. The ability of gravity measurements to detect subsurface mass flow is greatly enhanced if gravity measurements are analyzed and modeled with ground-deformation data. Obtaining the maximum information from microgravity studies requires careful evaluation of the layout of network benchmarks, the gravity environmental signal, and the coupling between gravity changes and crustal deformation. When changes in the system under study are fast ͑hours to weeks͒, as in hydrothermal systems and restless volcanoes, continuous gravity observations at selected sites can help to capture many details of the dynamics of the intrusive sources. Despite the instrumental effects, mainly caused by atmospheric temperature, results from monitoring at Mt. Etna volcano show that continuous measurements are a powerful tool for monitoring and studying volcanoes.Several analytical and numerical mathematical models can beused to fit gravity and deformation data. Analytical models offer a closed-form description of the volcanic source. In principle, this allows one to readily infer the relative importance of the source parameters. In active volcanic sites such as Long Valley caldera ͑California, U.S.A.͒ and Campi Flegrei ͑Italy͒, careful use of analytical models and high-quality data sets has produced good results. However, the simplifications that make analytical models tractable might result in misleading volcanological interpretations, particularly when the real crust surrounding the source is far from the homogeneous/isotropic assumption. Using numerical models allows consideration of more realistic descriptions of the sources and of the crust where they are located ͑e.g., vertical and lateral mechanical discontinuities, complex source geometries, and topography͒. Applications at Teide volcano ͑Tenerife͒ and Campi Flegrei demonstrate the importance of this more realistic description in gravity calculations.

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Section: Analytical Modelingmentioning

confidence: 99%

4D volcano gravimetry

Gottsmann²,

et al. 2008

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“…According to Lisowski (2007), strain ΔP/μ (where ΔP is internal pressure change; and μ is modulus of rigidity) ranges from 10 , and the higher value is beyond the typical elastic limit of crustal rocks. The obtained source is within the layer with a modulus of rigidity of 4.52 GPa.…”

Section: Discussionmentioning

confidence: 99%

Ground deformation source model at Kuchinoerabu-jima volcano during 2006–2014 as revealed by campaign GPS observation

Hotta

Iguchi

2017

Earth Planets Space

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We analyzed campaign Global Positioning System observation data in Kuchinoerabu-jima during 2006Kuchinoerabu-jima during -2014. Most benchmarks located around Shin-dake crater showed crater-centered radial horizontal displacements. Horizontal displacements at western rim of the Shin-dake crater were tended to be larger compared to those at eastern rim. In addition, benchmark KUC14 which locates near the cliff at Furu-dake showed westward horizontal displacement rather than crater-centered radial (southward) one. Meanwhile, small displacements were detected at the benchmarks located at the foot of Kuchinoerabu-jima. We modeled the observed displacements applying a finite element method. We set entire FE domain as 100 × 100 × 50 km 3 . We set top of the domain as a free surface, and sides and bottom to be fixed boundaries. Topography was introduced in the area within Kuchinoerabu-jima using digital elevation model data provided by Kagoshima prefecture and elevation information from Google earth, and elevation of the outside area was assumed to be sea level. We assumed a stratified structure based on a one-dimensional P-wave velocity structure. We applied a vertical spheroid source model and searched optimal values of horizontal location, depth, equatorial and polar radiuses, and internal pressure change of the source using the forward modeling method. A spherical source with a radius of 50 m was obtained beneath the Shin-dake crater at a depth of 400 m above sea level. The internal pressure increase of 361 MPa yields its volume increase of 31,700 m 3 . Taking effects of topography and heterogeneity of ground into account allowed reproduction of overall deformation in Kuchinoerabujima. The location of deformation source coincides with hypocenters of shallow volcano-tectonic (VT) earthquakes and the aquifer estimated from a two-dimensional resistivity model by audio-frequency magnetotellurics method. The obtained deformation source may be corresponding to the pressurized aquifer, and shallow VT earthquakes and demagnetization may be caused by pressure and strain accumulation in the rocks around the aquifer. Applying the obtained spherical source to the tilt change before August 3, 2014 eruption, we found that 520 m 3 of volcanic materials were supplied toward shallower in 1.5 h before the eruption. The depth and volume change of deformation source before May 2015 eruption detected by precise leveling surveys is deeper and two orders of magnitude greater compared to that before August 2014 eruption.

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“…The modeled maximum horizontal displacement is 36% of the maximum vertical displacement. Theoretical ratio of maximum horizontal to maximum vertical displacement is 38% for a single Mogi source [51]. A field based aquifer test in Nevada shows that the horizontal displacements reach 8 mm and vertical displacements reach 12 mm within the first 22 days of pumping before reaching the steady state pumping [52].…”

Section: Model Of West Subsidencementioning

confidence: 95%

“…A radius of 1 km is usually assumed for volcano cases [51]. The maximum displacement for a finite sphere is about 1 + (α/d) 3 times of that for a point sphere [51].…”

Section: Impact Of Reservoir Grid Sizementioning

confidence: 99%

Anatomy of Subsidence in Tianjin from Time Series InSAR

Liu

et al. 2016

Remote Sensing

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Groundwater is a major source of fresh water in Tianjin Municipality, China. The average rate of groundwater extraction in this area for the last 20 years fluctuates between 0.6 and 0.8 billion cubic meters per year. As a result, significant subsidence has been observed in Tianjin. In this study, C-band Envisat (Environmental Satellite) ASAR (Advanced Synthetic Aperture Radar) images and L-band ALOS (Advanced Land Observing Satellite) PALSAR (Phased Array type L-band Synthetic Aperture Radar) data were employed to recover the Earth's surface evolution during the period between 2007 and 2009 using InSAR time series techniques. Similar subsidence patterns can be observed in the overlapping area of the ASAR and PALSAR mean velocity maps with a maximum radar line of sight rate of~170 mm¨year´1. The west subsidence is modeled for ground water volume change using Mogi source array. Geological control by major faults on the east subsidence is analyzed. Storage coefficient of the east subsidence is estimated by InSAR displacements and temporal pattern of water level changes. InSAR has proven a useful tool for subsidence monitoring and displacement interpretation associated with underground water usage.

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Analytical volcano deformation source models

Cited by 79 publications

References 0 publications

4D volcano gravimetry

4D volcano gravimetry

Ground deformation source model at Kuchinoerabu-jima volcano during 2006–2014 as revealed by campaign GPS observation

Anatomy of Subsidence in Tianjin from Time Series InSAR

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