IAVCEI 2013 Scientific Assembly - July 20 - 24, Kagoshima, Japan
Forecasting Volcanic Activity - Reading and translating the messages of nature for society

4W_4D-P17

Date/Time: July 24 Poster

Volcanic hazard estimation using tephra GIS and geo-spatial information
Mamoru KOARAI1 , Takehiko SUZUKI2
1Geospatioal Information Authority of Japan, Japan, 2 Tokyo Merlopolitan University, Japan
E-mail: koarai@gsi.go.jp

There are many data of tephra in Japan such as ’The tephra atlas (Machida and Arai, 2003),’ however, lessdatabase of tephra in Japan, compared with Quaternary volcanoes, active faults and land slides and so on. As thedatabase of tephra is produced with location information in GIS, it is possible to identify each tephra easily in fieldworks, for the researchers of Quaternary field such as geomorphology, geology, volcanology and archeology. Inaddition, it is expected the governmental utilization for disaster prevention such as the production of hazard maps
and the estimation of environmental impact, because it is easy to analysis the distribution data of tephra combinedwith other spatial data such as DEM, NSDI and land condition map of volcano.
In this research, the authors have developed the tephra GIS data about the tephras originated from Tohoku District,
North East Japan, and middle and upper Pleistocene wide area tephras. In this presentation, the authors introduce
the results of case study for hazard map use in Kitakami Plain, Tohoku District, Japan.
The authors digitized the tephra distribution data about Iwate Volcano and Akita-Komagatake Volcano on the Tephra
Atlas and so on, and overlay thepra distribution and transportation network data of Spatial Data Infrastructure
25000 on GIS. As the results of overlay analysis, highway and national road where located on the east foot of Iwate
Volcano was covered by volcanic ashes of Iwate Volcano several times in ten thousands years, and volcanic ashesof Akita-Komagatake Volcano when the caldera of Akita-Komagatake Volcano was formed gave large influence on
the wide area near Morioka City.
Next, the authors introduce the way to open the tephra GIS database using Web-GIS. Outcrop information andtephra distribution information on the 1/25,000 topographical maps are distributed by Cyber Japan Web System.
The authors developed the trial Web GIS system about Bandai Volcano and Akita-Komagatake Volcano. At first, thelocation information of outcrops is described on topographical maps. When the users click the location of outcrops,
various data about outcrops is described such as photo of outcrop, column section, sketch of the outcrop, mineralcomposition, petrologic characteristics, index of each minerals, chemical composition and so on. Input information
about Bandai volcano is based on Suzuki et al. (1995), Koarai et al. (1995), Koarai and Soda (1995) and so on
such as the tephras originated Bandai Volcano and wide spread tephras. Input information about Akita-Komagatake
Volcano is the isopack maps of each tephras and outcrop information based on Wachi et al. (1997) and chemicalcomposition of each tephras based on Fujinawa et al. (2004). In additionally, the assumption of volcanic hazard
areas on hazard map, polygon data of landform classification, the results of automated landform classification using
50m DEM and 10m DEM are input in this database.

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