Magnitude 7.5 Earthquake Shocks Western Japan

On January 1, 2024, a powerful magnitude (Mw) 7.5 earthquake struck the Noto Peninsula in western Japan. According to the U.S. Geological Survey (USGS), the event caused significant disruption and property damage across Ishikawa Prefecture, particularly in the cities of Wajima and Suzu.

What were the seismic details of western Japan’s 2024 earthquake?

The earthquake originated at a shallow depth of 6.2 miles (10 kilometers) at 4:10 p.m. local time. Its epicenter was located roughly 71 miles (115 kilometers) northeast of Kanazawa (the capital of Ishikawa) and 187 miles (302 kilometers) northwest of Tokyo.

Intensity: Unlike magnitude, which measures the earthquake's overall energy at its source, seismic intensity describes the localized effects of shaking. Consequently, different organizations report these effects using their own scales.

Near the epicenter, the USGS reported a Modified Mercalli Intensity (MMI) of IX (Violent), which causes heavy structural damage. Concurrently, the Japan Meteorological Agency (JMA) recorded a Shindo 7 in the hardest-hit areas—the maximum possible shaking intensity on its scale. Meanwhile, the city of Kanazawa experienced a much milder MMI of VI (Strong).

In central Wajima City, post-earthquake fires destroyed more than 100 buildings.

Aftershocks: In the 24 hours following the main event, the USGS recorded more than 40 strong aftershocks ranging from Mw 4.1 to 6.2.

Estimated insured losses in Japan

Damage was caused by ground shaking, fires, tsunamis, and soil liquefication. Cotality Hazard HQ Command Central™ estimates that insured losses in Japan will range between $1 billion and $5 billion (approximately 144.6 billion to 722.8 billion yen).  

Cotality loss estimates account for damage to residential, commercial, industrial, and Kyosai structures. This includes contents, business interruption, and additional living expenses.  

Not considered for insured loss estimates are government property, infrastructure such as road and rail networks, water and electric power systems, and oil and gas pipelines.

Initial reports indicate material damage in the smaller towns and cities near the Noto Peninsula, such as Wajima and Suzu. The Mayor of Suzu stated that over 90% of the 5,000 homes in the city may have been damaged or destroyed. Meanwhile, the earthquake spared major economic centers like Tokyo, reducing the loss potential from this event.

What is the history of earthquakes in western Japan?

The west coast of Japan experiences far fewer earthquake events than the major subduction zone in the east of the country.

Since the beginning of the 20th century, there have been 30 Mw 6.0 or greater earthquakes within 155 miles (250 kilometers) of the New Year’s Day Mw 7.5 event, according to the USGS. Only three of these events were on or near the Noto Peninsula.  

Notable events:

June 16, 1964: A Mw 7.6 earthquake struck 127 miles from the 2024 event, destroying 3,500 homes.  

March 25, 2007: A Mw 6.7 earthquake struck just west of the Noto Peninsula, destroying 476 homes, half-destroying 620 homes, and partially damaging 7,000 homes.

How did building codes impact damage from the 2024 Noto earthquake?

Given the high level of seismic activity in Japan, building codes have been continuously updated since the late 19th century, and building performance in the face of earthquakes has improved. The seismic vulnerability of buildings is largely determined by Japan’s 1981 building code update:

Pre-1981 construction: High vulnerability. During the 1995 Great Hanshin Earthquake (Kobe Earthquake), nearly 97% of collapsed wooden buildings were built under older codes.

Post-1981 construction: Significantly improved performance. These structures showed significantly lower collapse rates in the 2007 and 2024 Noto events. Older wood-framed structures were damaged or destroyed with much more frequency.

Cotality continues to monitor the situation as new data emerges from the Noto Peninsula.

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