Interpretation of 1992–1994 Gravity Changes around Mayon Volcano, Philippines, Using Point Sources

2007 ◽  
Vol 164 (4) ◽  
pp. 733-749 ◽  
Author(s):  
A. G. Camacho ◽  
J. Fernández ◽  
M. Charco ◽  
K. F. Tiampo ◽  
G. Jentzsch
Keyword(s):  
Point Sources ◽  
Mayon Volcano ◽  
Gravity Changes

Analytical modelling and joint inversion of surface displacements and gravity changes at volcanoes

2021 ◽  
Author(s):  
Mehdi Nikkhoo ◽  
Eleonora Rivalta
Keyword(s):  
Source Parameters ◽  
Surface Displacement ◽  
Point Sources ◽  
Gravity Change ◽  
Density Estimate ◽  
Mass Change ◽  
Long Valley Caldera ◽  
Gravity Changes ◽  
Surface Displacements ◽  
Volcanic Reservoirs

<p>Gravity change observations at volcanoes provide information on the location and mass change of intruded magma bodies. Gravity change and surface displacement observations are often combined in order to infer the density of the intruded materials. Previous studies have highlighted that it is crucial to account for magma compressibility and the shape of the gravity change and deformation source to avoid large biases in the density estimate. Currently, an analytical model for the deformation field and gravity change due to a source of arbitrary shape is lacking, affecting our ability to perform rapid inversions and assess the nature of volcanic unrest.  </p><p>Here, we propose an efficient approach for rapid joint-inversions of surface displacement and gravity change observations associated with underground pressurized reservoirs. We derive analytical solutions for deformations and gravity changes due to the volume changes of triaxial point-sources in an isotropic elastic half-space. The method can be applied to  volcanic reservoirs that are deep compared to their size (far field approximation). We show that the gravity changes not only allow inferring mass changes within the reservoirs, but also help better constrain location, shape and the volume change of the source. We discuss how the inherent uncertainties in the realistic shape of volcanic reservoirs are reflected in large uncertainties on the density estimates. We apply our approach to the surface displacements and gravity changes at Long Valley caldera over the 1985-1999 time period. We show that gravity changes together with only vertical displacements are sufficient to constrain the mass change and all the other source parameters. We also show that while mass change is well constrained by gravity change observations the density estimate is more uncertain even if the magma compressibility is accounted for in the model.</p>

Inversion of temporal gravity changes by the method of local corrections: A case study from Mayon volcano, Philippines

2012 ◽  
Vol 241-242 ◽  
pp. 13-20 ◽  
Author(s):  
Peter Vajda ◽  
Ilya Prutkin ◽  
Robert Tenzer ◽  
Gerhard Jentzsch
Keyword(s):  
Mayon Volcano ◽  
Gravity Changes ◽  
Temporal Gravity

scholarly journals Modeling 3D Free-geometry Volumetric Sources Associated to Geological and Anthropogenic Hazards from Space and Terrestrial Geodetic Data

2019 ◽  
Vol 11 (17) ◽  
pp. 2042 ◽  
Author(s):  
Camacho ◽  
Fernández
Keyword(s):  
Numerical Solutions ◽  
Surface Deformation ◽  
A Priori ◽  
Three Dimensional ◽  
Remote Sensing Data ◽  
Point Sources ◽  
Geodetic Data ◽  
Nonlinear Inversion ◽  
Gravity Changes ◽  
Oblate Spheroids

Recent decades have shown an explosion in the quantity and quality of geodetic data, mainly space-based geodetic data, that are being applied to geological and anthropogenic hazards. This has produced the need for new approaches for analyzing, modeling and interpreting these geodetic data. Typically, modeling of deformation and gravity changes follows an inverse approach using analytical or numerical solutions, where normally regular geometries (point sources, disks, prolate or oblate spheroids, etc.) are assumed at the initial stages and the inversion is carried out in a linear context. Here we review an original methodology for the simultaneous, nonlinear inversion of gravity changes and/or surface deformation (measured with different techniques) to determine 3D (three-dimensional) bodies, without any a priori assumption about their geometries, embedded into an elastic or poroelastic medium. Such a fully nonlinear inversion has led to interesting results in volcanic environments and in the study of water tables variation due to its exploitation. This methodology can be used to invert geodetic remote sensing data or terrestrial data alone, or in combination.

Resistance Monitor and Control for Vacuum Evaporation of Metals and Carbon

1976 ◽  
Vol 34 ◽  
pp. 572-573
Author(s):  
Russell L. Steere ◽  
Eric F. Erbe ◽  
J. Michael Moseley
Keyword(s):  
Electronic Device ◽  
Point Sources ◽  
High Contrast ◽  
Variable Resistor ◽  
Quality Of Results ◽  
Low Contrast ◽  
Evaporation Source ◽  
And Control ◽  
At Will

We have designed and built an electronic device which compares the resistance of a defined area of vacuum evaporated material with a variable resistor. When the two resistances are matched, the device automatically disconnects the primary side of the substrate transformer and stops further evaporation.This approach to controlled evaporation in conjunction with the modified guns and evaporation source permits reliably reproducible multiple Pt shadow films from a single Pt wrapped carbon point source. The reproducibility from consecutive C point sources is also reliable. Furthermore, the device we have developed permits us to select a predetermined resistance so that low contrast high-resolution shadows, heavy high contrast shadows, or any grade in between can be selected at will. The reproducibility and quality of results are demonstrated in Figures 1-4 which represent evaporations at various settings of the variable resistor.

Cultured stem cells are sensitive to gravity changes

2006 ◽  
Author(s):  
L.B. Buravkova ◽  
Yu.A. Romanov ◽  
N.A. Konstantinova ◽  
N.V. Merzlikina ◽  
Yu.G. Gershovich ◽  
...  
Keyword(s):  
Stem Cells ◽  
Gravity Changes

EVALUATION OF MOUNTAIN AREA AS NON-POINT SOURCE OF NITROGEN FOR SETO INLAND SEA: THE NORTHERN SHIKOKU REGION, JAPAN

2017 ◽  
Author(s):  
Shohei Morisawa ◽  
Shohei Morisawa ◽  
Yukio Komai ◽  
Yukio Komai ◽  
Takao Kunimatsu ◽  
...  
Keyword(s):  
Average Concentration ◽  
Point Sources ◽  
Seto Inland Sea ◽  
Mountain Streams ◽  
Unit Load ◽  
Mountain Areas ◽  
Mountain Area ◽  
The Seto Inland Sea ◽  
Unit Load Method ◽  
Important Position

The northern Shikoku region is located in the Western part of Japan and faces towards the Seto Inland Sea. The forest area, which is one of the non-point sources in the Seto Inland Sea watershed, occupies 75% of the land use in the watershed of the northern Shikoku region. The amount of loadings of nutrients and COD in the Seto Inland Sea has been estimated by the unit load method but actually the data has not been investigated. It is however, necessary to know the real concentration of nitrogen in mountain streams to evaluate the role which is the mountain area plays as non-point sources. Therefore, more water samples of mountain streams in the watershed need to be taken and the concentrations of nitrogen analyzed. The mountain streams in the northern Shikoku area were investigated from April, 2015 to November, 2015. The number of sampling sites was 283, in addition to the past data by Kunimatsu et al. The average concentration of nitrate nitrogen in Ehime, Kagawa, and Tokushima was 0.61mg/L, 0.78mg/L and 0.34mg/L, respectively. The environmental standard range for nitrogen in the Seto Inland Sea is from between less than 0.2mg/L and less than 1mg/L. Therefore, the average concentration of nitrogen in these regions was over category II, and those of mountain streams in Kagawa Prefecture exceeded category III. About 20% of mountain streams were more than 1mg/L. It has become clear that mountain areas occupy an important position as non-point sources for the Seto Inland Sea.

Nitrogen and phosphorus in the Vistula River, Poland -- changes from source to mouth

1994 ◽  
Vol 30 (5) ◽  
pp. 177-186 ◽  
Author(s):  
Karin Sundblad ◽  
Andrzej Tonderski ◽  
Jacek Rulewski
Keyword(s):  
Central Region ◽  
Northern Region ◽  
Point Sources ◽  
Nutrient Loss ◽  
Phosphorus Concentration ◽  
Nitrogen And Phosphorus ◽  
Concentration Data ◽  
Diffuse Sources ◽  
Vistula River ◽  
South Central

Nitrogen and phosphorus concentration data representing samples collected once a month for nine months at 13 locations along the Vistula River are considered in a preliminary discussion of the sources of the nutrients transported to the Baltic Sea. Concentrations in relation to flow data indicated substantial differences between subbasins. Based on those differences, on the area-specific nutrient loss for a six-month period and on the wastewater discharge in each subbasin, four regions could be recognized in the river basin: i) the southern region with a large impact of point sources, ii) the south central region, where diffuse sources seemed to be of major importance, iii) the north central region with a combined effect of point and diffuse sources, and retention in two reservoirs, iv) the northern region where point sources seemed to be the dominating source, at least for phosphorus. Our results illustrate the importance of differences in phosphorus retention between the basins. Long-term retention along the course of the river, particularly in the two reservoirs, must be estimated to allow proper source apportionment in the Vistula basin. Concentration decreases in the Wloclawek Reservoir varied between 44 and 68% for P, and 11 to 37% for N, in the months with significant retention. In some months, however, concentrations increased, indicating a release of nutrients.

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