Giant earthquakes sometimes affect deep-sea organisms. During the Hokkaido Nansei Oki earthquake (M7.8) on July 12, 1993 (hypocenter off shore Okushiri Island in Hokkaido prefecture, 1,300 ~ 1,700 m deep), the seafloor suffered extensive damage, with landslides and fissures found everywhere.

This is a cephalopod that died in the Central Japan Sea earthquake in 1983. The carcass has remained intact nine years after the earthquake.

Chionoecetes japonicus and Gorgonacea were found crushed and killed by landslides, and a ray was found buried in sediment. Similar incidents were observed near the epicenter (3,000 m deep) of the Central Japan Sea earthquake in May 1983 (M7.7). Here, we found carcasses of many mid-sea cephalopods and fish at the sea floor.

Chionoecets japonicus and Gorgonacea crushed by the landslide resulting from the Hokkaido Nansei Oki earthquake.

| INDEX | The basics of a chemosynthetic ecosystem |
| The discovery of a chemosyntheticecosystem | Mid-and Deep-sea organisms |
| The Effect of a Giant Earthquake |