6-11）　Enoshima Tsunami Observatory

To obtain good tsunami records without coastal noise, Miyagi-Enoshima Island, 14 kilometers off the Sanriku coast, Onagawa town, Miyagi Prefecture, about 60 km

north east of Sendai, was selected as a tsunami observation point in 1941. In 1966, a building with a tide gauge well was established, and various oceanographical and meteorological observations were started. Several types of tide gauges were designed, improved, and tested. Finally, the “ERI-V type sensor" was invented in 1974, with which micro-tsunamis generated by nuclear explosions were observed. Tests of sea bottom tide gauges began in 1985.

The Sanriku coast was hit by two huge tsunamis in 1896 and in 1933, which killed 22,000 and 3,000 persons, respectively. A tsunami detection network was planned as a joint project with municipalities on the Sanriku coast in 1992. At the beginning of February 1995, the first tsunami detection system using an ultrasonic type tide gauge was installed in Fudai village, Iwate prefecture. Up to February 1997, tsunami detection systems employing the same type of sensor were equipped at eight municipalities, including Miyako city, where the sensor is set up at Chikei fishing port, 2 km SW from the Cape of Todo, the most easterly point of Honshu.

 

Fig.1. Testing of sea bottom tide gauge.

Fig.2. The tsunami detection system installed in Fudai village.