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Landslides and slope collapses triggered by Iwate-Miyagi Nairiku earthquake

A number of landslides and slope collapses were confirmed after the earthquake of magnitude 7.2 hit the southern part of Iwate on 14thJune, 2008 (seismic intensity: 6-high).  Officially requested by MLIT (Ministry of Land, Infrastructure, Transport and Tourism) and Miyagi Prefecture, Landslide Team carried out field investigation  from the 15th to 18th and gave technical advise on disaster management from the 21st to 22nd.

We express our concern about the victims of the earthquake.

Landslide -Kurihara Aratozawa- 
Landslide –Hanayama Yunokuraonsen-
Landslide -Kurihara Komanoyuonsen-
Slope collapse –Hanayama Sakashita- 
Slope collapse –Hanayama Azabu- 
Slope collapse –Hanayama Ogawara- 
Landslide and Slope collapse –Hanayama Kurikoma- 
An interview -Aratozawa dam management office on 22th June 2008- 

　

The numbers mentioned below may change following further investigation.
Landslide -Kurihara Aratozawa 

An overview of  the Aratozawa reservoir

Landslide. Width: 810m. Length: 1400m. Scarp is 140m in height.

The toe of the landslide.

A view from the top of  the slide. A  ditch on the right side was formed by the slide movement.

Cracks at the toe of the landslide.

Main scarp. Geology: welded tuff (upper) and pumice tuff (lower)

Cracks and steps on the municipal road on the ridge of the hill. Their connection with the slide is not confirmed at this stage.

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Landslide –Hanayama Yunokuraonsen-

    

Landslide debris deposited in the river. Geology of the landslide area is welded tuff.
Landslide -Kurihara Komanoyuonsen-

The landslide stopped a debris flow from the upstream, causing deposition in the river.
Slope collapse –Hanayama Sakashita-

The earthquake  enlarged  the area of the collapse (geology: alternative layer of welded tuff and pumice tuff). 

Slope collapse –Hanayama Azabu-

The collapse occurred along the slope whose angle of around 45 degrees.  

Slope collapse –Hanayama Ogawara-

Collapsed mass traveled long distance. Fine materials from the debris stuck to cedar trees downhill. 
Landslide and Slope collapse –Hanayama Kurikoma- 

Cracks and steps near the Gyoujya fall.

Little change found upstream of the Gyoujya fall.

Cracked welded tuff on the collapsed surface.

Rocks of 3〜4 m in diameter  were seen in the  mass.
Press release -Aratozawa dam management office on 22th June 2008-

Press release at the Aratozawa dam management office.

Team leader Fujisawa expounds on landslides in the area.

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Landslide Research Team, Erosion and Sediment Control Research Group, Public Works Research Institute
ＴＥＬ ： +81-29-879-6787、 FAX ： +81-29-879-6729
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