scholarly journals A decade of GEONET: 1994–2003 —The continuous GPS observation in Japan and its impact on earthquake studies—

2004 ◽  
Vol 56 (8) ◽  
pp. xxix-xli ◽  
Author(s):  
Takeshi Sagiya
2012 ◽  
Vol 7 (1) ◽  
pp. 26-36 ◽  
Author(s):  
Masato Iguchi ◽  
◽  
Surono ◽  
Takeshi Nishimura ◽  
Muhamad Hendrasto ◽  
...  

We report methods, based on geophysical observations and geological surveys, for the prediction of eruptions and the evaluation of the activity of 4 volcanoes in Indonesia. These are Semeru, Guntur, Kelud and Sinabung volcanoes. Minor increases in tilt were detected by borehole tiltmeters prior to eruptions at the Semeru volcano depending on the seismic amplitude of explosion earthquakes. The results show the possibility of prediction of the type and magnitude of eruption and the effectiveness of observation with a high signalto-noise ratio. The establishment of background data is important for evaluating volcanic activity in longterm prediction. Typical distributions of volcanic and local tectonic earthquakes were obtained around the Guntur volcano, where geodetic monitoring by continuous GPS observation is valuable. The cumulative volume of eruptive products is valuable for evaluating the potential for future eruption. The eruptive rate of the Kelud volcano is ca 2×106m3/y (dense rock equivalent), but the volume of the 2007 eruption was only 2×107m3, suggesting a still high potential for eruption. Based on geological surveys and dating, an eruption scenario is proposed for the activity of Mt. Sinabung, where phreatic eruptions occurred in 2010 after a historically long dormancy.


2015 ◽  
Vol 10 (1) ◽  
pp. 106-112
Author(s):  
Akimichi Takagi ◽  
◽  
Kenji Fujiwara ◽  
Takahiro Ohkura ◽  
Artemio C. Luis ◽  
...  

Determining the location and the amount of volume change of the pressure source beneath a volcano during the eruption preparation stage is an important issue in monitoring the magma accumulation. To do so, we have implemented a GPS campaign survey network around the Mayon volcano and monitored ground deformation since 2005. Rapid grounddeflating deformation was detected accompanied by the 2009 eruption. The Mogi model pressure source was estimated to be 8.5 km deep beneath the summit and the amount of volume change –13 × 106 m3. In magma accumulation preceding the 2009 eruption, ground deformation showed a weak inflationary trend, but it was difficult to evaluate the source parameters definitively. After the 2009 eruption, no deformation has been detected by the Continuous GPS observation network since 2012. Trend of many baselines of continuous and campaign network turned to extension since 2014. Magma may have started accumulating beneath the Mayon volcano.


2006 ◽  
Vol 58 (2) ◽  
pp. 127-139 ◽  
Author(s):  
Manabu Hashimoto ◽  
Nithiwatthn Choosakul ◽  
Michio Hashizume ◽  
Shuzo Takemoto ◽  
Hiroshi Takiguchi ◽  
...  

2000 ◽  
Vol 52 (11) ◽  
pp. 1095-1100 ◽  
Author(s):  
Manabu Hashimoto ◽  
Shin’ichi Miyazaki ◽  
David D. Jackson

2019 ◽  
Vol 382 ◽  
pp. 173-183 ◽  
Author(s):  
Kohei Hotta ◽  
Masato Iguchi ◽  
Takahiro Ohkura ◽  
Muhamad Hendrasto ◽  
Hendra Gunawan ◽  
...  

2020 ◽  
Vol 10 (1) ◽  
pp. 136-144
Author(s):  
P.K. Gautam ◽  
S. Rajesh ◽  
N. Kumar ◽  
C.P. Dabral

Abstract We investigate the surface deformation pattern of GPS station at MPGO Ghuttu (GHUT) to find out the cause of anomalous behavior in the continuous GPS time series. Seven years (2007-2013) of GPS data has been analyzed using GAMIT/GLOBK software and generated the daily position time series. The horizontal translational motion at GHUT is 43.7 ± 1 mm/yr at an angle of 41°± 3° towards NE, while for the IGS station at LHAZ, the motion is 49.4 ±1 mm/yr at 18 ± 2.5° towards NEE. The estimated velocity at GHUT station with respect to IISC is 12 ± 1 mm/yr towards SW. Besides, we have also examined anomalous changes in the time series of GHUT before, after and during the occurrences of local earthquakes by considering the empirical strain radius; such that, a possible relationship between the strain radius and the occurrences of earthquakes have been explored. We considered seven local earthquakes on the basis of Dobrovolsky strain radius condition having magnitude from 4.5 to 5.7, which occurred from 2007 to 2011. Results show irrespective of the station strain radius, pre-seismic surface deformational anomalies are observed roughly 70 to 80 days before the occurrence of a Moderate or higher magnitude events. This has been observed for the cases of those events originated from the Uttarakashi and the Chamoli seismic zones in the Garhwal and Kumaun Himalaya. Occurrences of short (< 100 days) and long (two years) inter-seismic events in the Garhwal region plausibly regulating and diffusing the regional strain accumulation.


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