[H-DS25] Geohazards in humid, tectonically active countries and their precursors

[HDS25-P11] Relationship between the wind damage caused by the 1959 Isewan Typhoon and the landslide that occurred afterwards

3-min talk in an oral session

*Wataru MURAKAMI¹, Hitoshi SAITO², Hiromu DAIMARU¹ (1.FFPRI, 2.Kantogakuin Univ.)

Keywords:Isewan Typhoon, wind damage zone, landslide, aerial photointerpretation, granite rock

We investigated landslides caused by the later rain, on the slopes in the granite where forests were destroyed by typhoon. Investigation area is located in Nagiso town, Nagano Prefecture. In Nagiso town, large-scale forest area was destroyed by the Isewan Typhoon in 1959. First, we interpreted aerial photographs been filmed immediately after the typhoon and extracted wind damage zone. Second, we interpreted plural aerial photographs been filmed after the typhoon and extracted landslides occurred by the later rain. And then, we examined the relationship between forest damage zone by the typhoon and landslides by the later rain, in conjunction with the topographic condition.
As a result, it was revealed that a lot of landslides occurred on the forest slope where the typhoon was damaged. Furthermore, it was recognized that the slope where landslides occurred was tendency to gentle and southfacing.