scholarly journals Deformation Source Revealed From Leveling Survey in Jigokudani Valley, Tateyama Volcano, Japan

2021 ◽  
Author(s):  
Kohei Hotta ◽  
Shigekazu Kusumoto ◽  
Hidenori Takahashi ◽  
Yuichi S Hayakawa
Keyword(s):  
Source Model ◽  
Deformation Source ◽  
Bench Mark ◽  
Interferometric Synthetic Aperture Radar ◽  
Dislocation Source ◽  
Grid Search Method ◽  
Current Maximum ◽  
Western Side ◽  
One Year ◽  
Gas Chamber

Abstract We modeled vertical deformation detected from leveling survey in Jigokudani valley, Tateyama volcano, central Japan. In Jigokudani valley, uplift of 4 cm/year was previously detected during the period from 2007 to 2010 by Interferometric Synthetic Aperture Radar (InSAR). To confirm whether this inflation has continued to the present, we conducted leveling survey in Jigokudani valley since 2015. Most bench marks showed subsidence up to 5.6 cm during the four-year period from October 2016 to September 2020, while a bench mark locates at the center of the leveling route uniquely showed uplift of 1.6 cm. We applied a dislocation source model to the deformation using a grid search method. A crack with a length of 350 m, a width of 100 m, a strike of N117°E and a dip of 61° is located at a depth of 50 m near the center of Jigokudani valley (Koya jigoku and the new fumarolic area) where highly activating recently. Closing of the crack of 344 cm yields volume decreases of 120,400 m3. Striking direction of the crack is parallel to the line of which are old explosion craters (Mikurigaike and Midorigaike ponds) and corresponds to current maximum compressive stress field in the region of Hida Mountains including Tateyama volcano. The deformation source of the previous period from 2007 to 2010 detected from InSAR was estimated to be at a depth of 50 m and a gas chamber was correspondingly found from the audio-frequency magnetotelluric (AMT) survey. The estimated crack in this study is also located at a similar position of the gas chamber which was also identified from AMT survey. During the period from 2015 to 2016, the crack opened (i.e., inflated) and the inflation stopped during the next one-year period from 2016 to 2017. During the period from 2017 to 2020, the crack turned to closing (i.e., deflation), probably because of the increase in emission of volcanic fluid or gas with a formation of a new crater at the western side of Jigokudani valley (Yahata jigoku) during the period from 2017 to 2018.

A mechanism-based homogenization of a dislocation source model for bending

2019 ◽  
Vol 164 ◽  
pp. 663-672 ◽  
Author(s):  
Severin Schmitt ◽  
Markus Stricker ◽  
Peter Gumbsch ◽  
Katrin Schulz
Keyword(s):  
Source Model ◽  
Dislocation Source

The synoptic origins of precipitation over the Antarctic Peninsula

1995 ◽  
Vol 7 (3) ◽  
pp. 327-337 ◽  
Author(s):  
J. Turner ◽  
T.A. Lachlan-Cope ◽  
J.P. Thomas ◽  
S.R. Colwell
Keyword(s):  
Antarctic Peninsula ◽  
Heavy Precipitation ◽  
Synoptic Situation ◽  
Blowing Snow ◽  
Meteorological Observations ◽  
Western Side ◽  
One Year ◽  
The One ◽  
The Uk ◽  
The Antarctic

The synoptic origins of precipitation on the western side of the Antarctic Peninsula over the one year period March 1992 to February 1993 are investigated using meteorological observations, satellite imagery and analyses produced by the UK Meteorological Office. Precipitation at Rothera Station was found to occur at 30% of the synoptic reporting time with 80% of precipitation reports being associated with cyclonic disturbances. Although three quarters of all precipitation reports were for snow, the proximity of Rothera to the zone of maximum cyclonic activity meant that incursions of mild air produced rain in all seasons. During the year 95% of all precipitation was classed as slight. Variability of precipitation on the intraseasonal timescale was highly dependent on the synoptic-scale circulation. The most common synoptic situation for precipitation was a frontal cyclone over the Bellingshausen Sea which accounted for 38% of all precipitation events and 62% of the moderate and heavy precipitation reports. Of the extra-tropical cyclones that gave precipitation 49% were found to have developed south of 60°S. None of the precipitation at Rothera was attributable to mesocyclones. Snow stake measurements from Rothera were a poor indicator of precipitation as a result of blowing snow.

Spectral discrimination between NTS explosions and Western United States earthquakes at regional distances

1988 ◽  
Vol 78 (4) ◽  
pp. 1563-1579
Author(s):  
Steven R. Taylor ◽  
Nevin W. Sherman ◽  
Marvin D. Denny
Keyword(s):  
United States ◽  
High Frequency ◽  
Source Region ◽  
Spectral Ratio ◽  
Source Model ◽  
Pressure Effects ◽  
Western United States ◽  
Dislocation Source ◽  
Overburden Pressure ◽  
Single Station

Abstract Spectral ratio disciminants are applied to 72 Western United States earthquakes and 64 NTS explosions recorded at four broadband seismic stations surrounding NTS. The ratio of the energy in the 1- to 2- and 6- to 8-Hz bands for Pn, Pg, and Lg is calculated and a simple distance correction applied to the data. The spectral ratio appears to have potential as a disciminant at relatively small magnitudes (3.0 < mb < 4.5) and single station misclassification probabilities for detected phases range from 4 to 33 per cent, with Lg showing the best performance followed by Pg and Pn. Below mb 4.5 to 5.0, the earthquakes are observed to have more high-frequency energy than the explosions for all three phases. This observation may be due to actual source differences or to depth-dependent effects of attenuation on the shallow explosions and deeper earthquakes. At higher magnitudes, the two populations merge and discrimination is poor. Overburied explosions are characterized by the existence of more high-frequency energy than those at standard containment depths and are often misclassified. The Brune dislocation source model is shown to satisfactorily fit the earthquake spectral ratios plotted as a function of mb for reasonable stress drops. However, the Mueller-Murphy explosion source model has problems predicting the decrease in the explosion spectral ratio observed at higher magnitudes (mb > 4.5 to 5.0). This may be due to uncertainties in the apparent source-time function for explosions. These complications may be due to changes in the dynamic response of the material in the near-source region as a function of overburden pressure, effects of secondary sources, or to variations in regional phase excitation with depth.

scholarly journals Computation of synthetic seismogram in real earth model by eigen function expansion

MAUSAM ◽  
2021 ◽  
Vol 67 (3) ◽  
pp. 659-668
Author(s):  
AJIT DE ◽  
A. ROY ◽  
M. MITRA ◽  
R. K. BHATTACHARYA
Keyword(s):  
Displacement Field ◽  
Source Model ◽  
Elastic Half Space ◽  
Earth Model ◽  
Dislocation Source ◽  
Transmission Coefficients ◽  
Runge Kutta Method ◽  
Function Expansion ◽  
Exact Evaluation ◽  
Eigen Function

The method of eigen function expansion has been used in the present study to compute synthetic or theoretical seismogram in layered elastic half-space of real earth model. Simple dislocation source model has been considered. The transverse (SH) or radial and vertical (P-SV) components of displacement field have been computed as summed modes and compared by using both exact and numerical techniques. The methods used in the study, include exact evaluation by propagator matrix approach using Reflection-Transmission coefficients as well as numerical computations using Runge-Kutta method of order 4. The specialty of the present study is to evaluate approximate displacement field for the earth models with homogeneous and / or inhomogeneous layers. The normalization technique has been used in the study to control the overflow errors. The study has an advantage to get an idea of earth structure or source model by an inverse iterative technique.  

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