The risk of a mega earthquake from a fault line off the east coast of Japan is high, with potentially devastating threats to millions of people living in the zone and to the global economy.
The warning from the Seismological Society of China comes just days after a magnitude 7.1 earthquake originating in the Nankai Trough area hit the Japanese island of Kyushu.
In a video posted online by the society, Gao Mengtan, from the Institute of Geophysics at the China Earthquake Administration, said a partial rupture in the trough could result in an earthquake above magnitude 8.5, and a complete rupture in a magnitude 9.1 earthquake.
The quake could trigger a tsunami of more than 10 metres (33 feet), destroying 2.38 million buildings and killing 320,000 people in addition to displacing up to 9.5 million people, Gao said.
“Cities near the Nankai Trough, especially in the Chugoku and Kansai clusters, are key economic centres, accounting for 70 per cent of Japan’s manufacturing,” he said.
“An earthquake in this region would not only affect Japan’s manufacturing sector but also affect the global supply chain, with potential economic losses reaching 220 trillion yen [US$1.5 trillion], twice Japan’s annual budget.”
The Nankai Trough is an area off the Japanese coast where the Pacific Plate and the Philippine Sea Plate meet and form a fault line.
The August 8 quake that hit Kyushu did not result in widespread damage but it prompted the Japan Meteorological Agency to warn of an increased chance of a significant seismic event near the trough within the following week.
In the aftermath, Japanese Prime Minister Fumio Kishida cancelled a planned trip to Central Asia and panicked travellers cancelled holiday plans for Japan.
The Japanese Cabinet Office said on Tuesday that the warning would be lifted on Thursday afternoon if no significant earthquakes occurred.
Japan’s Earthquake Research Committee estimates that an earthquake of magnitude 7 or higher could affect 151 towns across 10 prefectures, and a tsunami over 5 metres could hit more than 100 towns.
Kyushu is a hub for Japan’s semiconductor industry, with more than 200 manufacturers based on the island and about half of the national semiconductor output coming from the area, according to Shanghai-based news service The Paper.
Gao said the trough generated a major earthquake about every 117 years and the likelihood of another one remained high.
“The last significant earthquake in 1946, which resulted in a 6.9-metre tsunami, underscores the high probability of future seismic events,” he said.
03:41
Survivors of Japan’s deadly earthquake struggle to pick up the pieces over a month since disaster
Survivors of Japan’s deadly earthquake struggle to pick up the pieces over a month since disaster
He also said the Japanese government had prepared for such a disaster, making the threat of a Nankai Trough earthquake a priority in national disaster mitigation planning since 2012.
“The [Japanese] government has implemented comprehensive plans ranging from emergency response to post-disaster recovery,” Gao said.
“These include assessing the earthquake resistance of buildings, evaluating tsunami risks in low areas, and establishing evacuation plans.
“Emphasis has been placed on tsunami evacuation training and the creation of clear signage along evacuation routes.
“Additionally, businesses are encouraged to develop plans to ensure quick operational recovery after disasters.”
