Introduction to the Landforms and Geology of Japan

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Neodani Fault Museum

This is a unique museum in Motosu City, Gifu Prefecture. The Earthquake Fault Observation Museum has a trench to exhibit 6-m vertical offset of the Neodani fault. A preserved fault scarp is also outside the museum.

Neodani fault

The 1891 Nobi earthquake with magnitude 8, the largest historic inland earthquake in Japan, struck the central part of Honshu. The earthquake killed about 7300 people and greatly damaged buildings, transport systems, and industries. The Neodani earthquake fault zone (Nobi earthquake fault system), about 80 km long, appeared from Ikeda Town in Fukui Pref. through Neo Village (now Motosu City) to Kani City in Gifu Pref., faults in which are left-lateral strike-slip faults with vertical offsets. Of the faults in the zone, the Neodani fault is a prominent fault 38km in length with a maximum left-lateral offset of 8 m and a vertical offset of 6 m. These earthquake faults produced many fault-related landforms, such as offset streams and paths, fault scarps, and sag ponds, some of which can still be found in the zone.

At Midori in Motosu City, a fault scarp (6 m high, 1000 m long) of the Neodani fault was formed, a part of which is preserved as a special natural monument. Digging a trench to observe the underground area of the fault scarp revealed a 6-m offset of basement rock. The Earthquake Fault Observation Museum was constructed in 1991 to open the trench to the public. In addition to the trench, the museum has exhibits including three-dimensional models of the Neodani fault and modified landscape, and earthquake observing materials.

Fault scarp
Photo 1: Fault scarp [Another window]

Photos 2 and 3 show the northwestern wall of the trench. The black-gray bed vertically displaced by 6 m is basement rock (Middle Jurassic - earliest Cretaceous sedimentary complex with basalt) overlaid with a Holocene gravel bed deposited before the earthquake. The basement rock has been fractured by repeated faulting (crush zone). Clastic materials over the gravel bed are flood deposits, paddy field soil, and embankments, which were produced after the earthquake. It is notable that the oblong gravels deposited in horizontal position turned upright along the fault plane. Fault gouge is found in the band 20 - 30 cm wide of the bed rock along the fault plane.

Northwestern wall of the trench
Photo 2: Northwestern wall of the trench [Another window]

Fault
Photo 3: Close-up of the fault [Another window]

Photo: museum

Location: 512 Neomidori, Motosu City, Gifu Prefecture.
Midori Station on the Tarumi Railway line (transfer at Ogaki Stn. (JR Tokaido line) to the Tarumi Railway line), 2 minutes' walk from the station.
Location on Google Map
 
Admission: JPY500 (adults), JPY250 (children) Open: 9:00 a.m. - 5:00 p.m. Tue - Sun (When Monday is a public holiday, the museum is open and closed on the next day)
Tel: 0581-38-3560

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