Thursday, August 15, 2024

Japan ends megaquake advisory on Nankai Trough disasters


Aug 15, 2024, 

TOKYO - Japan on Thursday ended its call for higher-than-usual risks of a major earthquake, one week after a strong tremor on the edge of the Nankai Trough seabed zone caused the government to issue its first-ever megaquake advisory.

Citizens can now return to normal life as no abnormalities were observed in the seismic activity of the Nankai Trough located along Japan's Pacific coast in the past week, said Yoshifumi Matsumura, the state minister for disaster management.

A Japan Meteorological Agency (JMA) expert panel on Aug. 8 released an advisory that there was a "relatively higher chance" of a Nankai Trough megaquake as powerful as magnitude 9, after a magnitude-7.1 quake hit the country's southwest.


While the advisory was not a definitive prediction, the government asked residents of a wide range of western and central regions to review evacuation procedures in case of severe earthquake and tsunami disasters.

Prime Minister Fumio Kishida cancelled a diplomatic tour to Central Asia and Mongolia over the weekend to prioritise disaster management.

On Aug. 9, a magnitude-5.3 earthquake hit eastern Japan near Tokyo, but its epicentre was located outside of the Nankai Trough zone where the JMA signalled the chance of a megaquake, and the damage was small as only three mild injuries were reported.

Central Japan Railway ended its week-long precaution of reducing the speed of trains running near coastal areas, although the risk of another natural disaster, approaching Typhoon Ampil, forced the company to cancel high-speed trains connecting Tokyo and Nagoya on Friday.

Japan has predicted a 70%-80% chance of a Nankai Trough megaquake occurring in the next 30 years.

The government's worst-case scenario has estimated that a Nankai Trough megaquake and subsequent tsunami disaster could kill 323,000 people, destroy 2.38 million buildings and cause 220 trillion yen ($1.50 trillion) of economic damage.

Japan is one of the world's most earthquake-prone countries. More than 15,000 people were killed in a magnitude 9 quake in 2011 that triggered a devastating tsunami and the triple reactor meltdowns at a nuclear power plant in northeast Japan. 

REUTERS


Weeklong Japan megaquake alert ends


Public urged to remain vigilant and prepared



PUBLISHED : 15 Aug 2024
WRITER: Kyodo News

Signage showing evacuation routes from the shore in the event of an earthquake is put up at Shirahama beach in Wakayama Prefecture, as seen on Friday. (Photo: Kyodo)

KYODO - A weeklong government call for increased preparedness based on an advisory over a potential megaquake along the Pacific coast officially ended 5pm on Thursday, after no new major seismic activity was confirmed around the Nankai Trough.

The Nankai Trough megaquake advisory, the first since the system was implemented in 2017, prompted the central government and local communities to intensify disaster preparations over the past week. It also negatively impacted some tourism-related businesses during the summer holiday season.

Japan, a quake-prone nation, has long feared a magnitude 8 to 9 quake along the Nankai Trough within the next 30 years, with predictions that a wide area could be jolted and vast coastal regions engulfed by massive tsunami.

The megaquake advisory was issued just hours after a M7.1 quake rocked southwestern Japan on Aug 8, with its focus located in waters off Miyazaki Prefecture, on the western edge of the Nankai Trough.

The advisory is intended to inform the public of the higher-than-usual risk of a large-scale quake around the Nankai Trough for a week. The government is urging the public to remain vigilant and prepared, as the possibility of a major temblor has not been eliminated.

The Nankai Trough is an ocean-floor trench that runs along Japan's Pacific coast where the Eurasian and Philippine Sea tectonic plates meet.



The Japan Meteorological Agency stated that as of Wednesday, it had detected no seismic activity indicating any concerning changes in the presumed area where the megaquake could originate.

According to the Cabinet Office, the advisory has been applied to 707 municipalities across 29 prefectures where strong shaking and large tsunami are expected in the event of a major quake.

The government estimates that, in a worst-case scenario, a megaquake in the Nankai Trough could result in over 200 trillion yen (UScopy.36 trillion) in damage.

A M9.0 earthquake with an epicentre near land would increase the damage due to the collapse of housing and infrastructure, as well as reduced business activity.

Kuroshio in Kochi Prefecture, western Japan, where a 34-metre tsunami is expected in the event of a megaquake, responded to the advisory by establishing a disaster response headquarters and increasing the number of disaster response staff.

According to the prefecture, over 100 evacuation centres have been established, with up to 63 people having sought refuge.

Some beaches in western and southwestern Japan that were closed for swimming following last week's quake have reopened.

History shows that a major earthquake around the Nankai Trough occurs every 100 to 150 years. About 80 years have passed since the most recent.

The quake that devastated northeastern Japan on March 11, 2011, triggered massive tsunami and led to the Fukushima Daiichi nuclear power plant disaster. It registered a M9.0, the strongest earthquake ever recorded in Japan.

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