SGD23-P01

Room:Convention Hall

Time:May 27 18:15-19:30

Development of new geoid model of remote island of Japan
KOJIMA, Hideki1∗ ; MIYAHARA, Basara1 ; NEMOTO, Satoru1 ; ITOU, Jyunichi1 ; KODAMA, Tokurou1 ;KUROISHI, Yuki11

GSI of Jpan

Geospatial Information Authority of Japan released new geoid model of Japan, ”GSIGEO2011”, which consistency with survey
results is greatly improved compared with the former model, covering all Japan islands except the remote islands, on April 2014.
The GSI has developed new geoid model for the remote islands and this poster will report the result of the development.
The model has been developed for each islands by adjusting the latest gravity geoid model of Japan, ”JGEOID2008”, to fit
actually measured geoid undulations, which are determined from the results of GNSS and leveling survey. The methods for theadjustments are : 1) bias method which expresses spatial distribution of differences between the measured geoid heights andJGEOID2008 (geoid undulation) as a single offset, 2) plane adjustment method which expresses distribution of geoid undulation
in a simple inclined plane, 3) GMT method which expresses distribution of geoid undulation in a surface estimated by GMT
green spline module. The most appropriate method is selected from the three methods depending on a number and density ofinput geoid undulations.
Almost all islands have their own height origin determined for each island. Therefore, in order to keep consistency with theheight origin for the island, we have developed models for each island unless a distance between adjacent islands is too short todivide a model into two models.
Ellipsoidal heights of geoid undulation points, which are essential for calculating measured geoid heights, are recalculated if
the heights were calculated before 2004 because all of ellipsoidal heights of GNSS-based control stations, which are used as
reference stations for GNSS analysis, were recalculated on 2004. The consistency between ellipsoidal heights is improved byapplying GNSS antenna phase center variation models which were created from calibration by the GSI.
Release of the new geoid model for the remote islands enables orthometric height determination by GNSS survey in a precisionof third-order leveling over the nation including the remote islands. It is expected that this leads improvement in efficiency onsurvey work.

Keywords: GSIGEO2011, geoid, survey results, remote island

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SGD23-P02

Room:Convention Hall

Time:May 27 18:15-19:30

Improvement of the Gravity database of Kanazawa University
HONDA, Ryo1∗ ; SAWADA, Akihiro2 ; HIRAMATSU, Yoshihiro2
1Tono Research Institute of Earthquake Science, 2 Nat. Sys. College of Sci. and Eng., Kanazawa Univ.

The gravity database of Kanazawa University is now available on web (Honda et al., 2012, J. Geod. Soc. Japan). The terrain
correction for the gravity data is based on Honda and Kono (2005, J. Geod. Soc. Japan) applying 50 m gridded topography
data, which is based on various DEM, including sea data published by Japan Oceanographic Data Center, Japan Coast Gurad.
Recently, 10 m DEM published by Ministry of Land, Infrastructure, Transport and Tourism is available, which covers all overthe country. We refined our correction routine to apply the fine DEM. The terrain gravity correction, especially on mountainousregion, improved by this application. We report our new correction routine with the refined gravity anomaly map.
This research is promoted by the Grant-in-Aid for Scientific Research (C), No. 26400450.

Keywords: Gravity Anomaly, Database

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SGD23-P03

Room:Convention HallTime:May 27 18:15-19:30

Minus anomaly region of gravity in Hyuganada and place that sinking-slab-block tears
off shallow part are corresponding
MASE, Hirofumi1∗
1none(Please refer to the figure)
In convergence zones, high temperature bodies are formed diagonally-on-and-under the plate of low temp. and the bodies aredrawn each other. The mantle wedge and the plate, get on the high temp. body that heads westward from the east, head westward.
And, they are placed by the high temp. body that heads eastward from the west and compressed. I think this is the main springand structure in it. I explained in each respect of the theory, experiment, and application.(1)(2)(3),etc.
This time, I thankfully used (4) to be able to understand tomography data of 3D in seamless. And I thankfully used (5) about
gravity chart(Bouguer anomaly). I have been interested in the existence of minus anomaly region of gravity where with center inHyuganada(5). Result of the research is going out and I want to report. (the minus anomaly region of gravity:The Region)
The Region is divided roughly into the one in prefecture northern part and the prefectural boundary, and the one in Hyuganada.
The latter has the plain center like eye and the long-drawn tail to the south and is impressive. The south end of ,the subducting
slab(The SS), is exactly formed in the eye. Pulling Hot1 and Hot2 against each other is shown by black pair arrows in eachSection. (Names of high temp. bodies, etc. are naming only of here.) Bearing capacity of land and intrusive pressure generated
along with it are shown by pink arrows.
In Section 1-1’,2-2’, Hot1 invades under the land to the east to be deep and is pulled against each other again there withHot2. The black arrows are mainsprings that wring and dent or thin The SS. Pressure in the invaded part rises and The SS isdepressed(blue arrow). And the invaded part extends vertically. By the result of this calculation of going out and entering ofdensity, The Region in the prefecture northern part and the prefectural boundary might exist.
It is thought that the sinking-block is formed and separates from The SS by the above-mentioned action. On the west side,
it is divided into parts from the depth in the west due to the crack(blue broken line) and slips. On the east side, tightening andpull-tearing off(green arrow) are generated in shallow area(Hyuganada). Vertical subsidence of the sinking-block is understoodunderground in the whole area of Miyazaki Prefecture. Section 1-1’–9-9’ are like fixed point scene sending animated cartoon ofthis change.
The site of pull-tearing off and separation(The Site) is in the Miyazaki Prefecture central part offing and is corresponding to thepeak of The Region(Section 4-4’–7-7’,a-a’). By pull-tearing off action, for hanging down part of The Site, the material is pulled
out under the west, the shape is transformed into Rohto type. And, I think that the generation of the density reduction is a causeof the gravity anomaly. End of pull-tearing off and complete separation have already been generated in the southern part(Section8-8’,9-9’). However, the place is still in The Region and the tail expands to the south. The peak of the gravity anomaly came
like the shadow along with The Site that keeps going north from the south and arrives now. Even if The Site passes, the gravity
anomaly of the place remains as a track (tail) because it does not improve at once.
(1)Mase/SSJ2010/P3-47 (2)Mase/JpGU2012/SCG67-P06 (3)Mase/SSJ2014/S03-P01(4)AIST/Visualization system for subsurface structures/tomography data by Abdelwahed and Zhao (2007)dVp(5)AIST/same to (4)/gravity chart(Bouguer anomaly)

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