(Personnel of the Japan Maritime Self-Defense Force loading relief supplies onto the JS Hiuchi bound for the Noto Peninsula. Source: JMSDF.)
On Jan. 1, 2024, a magnitude 7.5 earthquake struck the Noto Peninsula of the West Coast of the island of Honshu at 4:00 pm JST, causing at least 94 fatalities and resulting in insured losses approaching $6.4 billion, according to a report from Karen Clark & Company (KCC, Boston).
Known initially as the 2024 Sea of Japan earthquake, the event was officially named the 2024 Noto Peninsula Earthquake by the The Japan Meteorological Agency (JMA). It included shaking and an accompanying tsunami that caused extensive damage on the Noto Peninsula and in the towns of Wajima, Suzu and Noto, according to a report from Al Jazeera. It also led to Japan’s first major tsunami warning since the 2011 Tōhoku earthquake, Sky News reported, and a tsunami run-up of 4.2 m (14 ft) was measured along the Sea of Japan coast, according to the Japan Times.
The 94 fatalities and 222 missing individuals were reported in Ishikawa while over 500 were injured across multiple prefectures, making it the deadliest earthquake in Japan since the 2016 Kumamoto earthquakes, and the largest since 2015, notes KCC.
KCC’s report specifies the cause of the earthquake as shallow reverse faulting, meaning that geological strata on one side of a fault plane are pushed up over the strata on the other side. The Noto Peninsula, while a less seismically active region than the east coast of Japan, most recently was struck by an earthquake on May 5, 2023, when a M6.2 event killed one person and damaged dozens of buildings, according to KCC.
It is more typical for Japan to have earthquakes on its east coast, where the Pacific Plate subducts beneath the country, according to KCC. This west coast event demonstrates the accommodation of crustal deformation arising from broader plate motions in shallow faults, the report says, adding that shallow earthquakes such as the Jan. 1 event tend to cause more damage than their deeper counterparts due to the proximity of the released energy to the Earth’s surface—the Noto Peninsula earthquake had a depth of 10.0 km (6.2 mi).
“While the region around the January 1, 2024 earthquake generally exhibits lower seismicity compared to the major subduction zone along the east coast, historical data reveals a notable seismic history,” the report adds. “Over the past century, 30 earthquakes with magnitudes of 6 or higher have occurred within 250 km of the event, with three of them affecting the Noto Peninsula, the location of the January 1 event. A recent M6.2 earthquake on May 5, 2023 resulted in casualties and hundreds of damaged buildings. At the time, the M6.2 earthquake was the largest earthquake to occur in an ongoing earthquake swarm in northeastern Noto Peninsula. The recent M7.5 earthquake is now the largest in this swarm.”
The Japan Times noted that the earthquake struck as Japan was marking New Year’s Day, a public holiday when many were at home and most establishments were closed, potentially minimizing casualties. All of the deaths occurred in the Ishikawa Prefecture, as well as 464 of the injured, according to reporting by Japan’s TV Asahi.
Jiji Press reported that, as of today, Jan. 5, 222 people remained missing, primarily from Wajima and Suzu. According to various source, 100 people remained trapped beneath collapsed buildings in Wajima, and some people may have been swept into the sea by the tsunami. France 24 reported that by 3 January, a total of 31,800 people were living in shelters following the earthquake, and about 27,700 sheltering in 336 evacuation centers in Ishikawa prefecture alone, according to CNN.
Extent of Impact
KCC reports that the 2024 Noto Peninsula Earthquake impacted the four prefectures of Ishikawa, Niigata, Toyama, and Fukui. Several cities and towns experienced very high ground motion, including Shika, Nanao, Wajima, Suzu, Anamizu, and Noto. KCC scientists estimate over half a trillion USD of exposure in the ground motion footprint (0.3 sec SA ≥ 0.2g), including residential, commercial, and industrial properties.
The KCC event brief reports that Machiya homes make up more than a third of the residential inventory in Ishikawa Prefecture, and they can be especially vulnerable during earthquakes because their heavy earthen walls, traditional timber construction, and tiled roofs are more prone to collapse than modern materials like steel and reinforced concrete. In addition, the long narrow layout of Machiya homes can make the structures more susceptible to lateral forces during strong shaking, the report says.
Other residential buildings, mostly one- and two-story wooden structures, have better earthquake resistance than Machiya buildings because they have wooden frames partially reinforced by light metal and are anticipated to have suffered lower levels of damage, KCC says. However, the report cautions, in the areas of significant ground motion, these wood buildings can be severely damaged.
The age of buildings can also be a significant factor, according to KCC. “Across Ishikawa, a third of all residential buildings date from before 1981,” the report explains. “Commercial and industrial buildings in the affected cities are predominantly steel construction, which has significantly higher earthquake resistance. Residential property losses are expected to exceed those of commercial and industrial properties.”