Parts of the peninsula rose by 4 meters (13 ft), changing the position of the coastline and leaving some ports dry. The first day of 2024 brought disaster to some parts of Japan. At 16:10 Japan Standard Time (07:10 UTC), the ground on the Noto Peninsula in northwestern Honshu began shaking violently for approximately 50 seconds. The main earthquake of magnitude 7.5 was followed by dozens of aftershocks in the following minutes, hours and days.

The January 1, 2024 earthquake was the strongest in Ishikawa Prefecture since 1885 and the strongest in mainland Japan since the 2011 Tohoku earthquake. Tremors were felt across much of the island of Honshu, including Tokyo, about 300 kilometers southeast of the quake’s epicenter. The strongest of the tremors were in the cities of Suzu, Noto, Wajima and Anamizu, near the epicenter on the northern Noto Peninsula.

Infrastructure damage caused fires that engulfed communities. Heavy snow following the earthquake disrupted emergency response efforts and made it difficult to deliver aid to some communities.

Scientific analysis of earthquake

While first responders responded to the disaster from the ground, several teams of scientists monitored the situation using satellites. The map above shows the number of landslides (soil displacement) caused by the earthquake. The red areas were pushed upward and to the northwest. Scattered dark blue and red areas around the airport and other cleared areas of the peninsula and populated areas are false signals caused by the way building shapes or other objects reflect radar signals.

“The surface rose 4 meters (13 feet) in parts of the northern coast of the Noto Peninsula,” said Eric Fielding, a geophysicist at NASA’s Jet Propulsion Laboratory (JPL). “The uplift is large because the fault occurred near the surface, at a depth of about 10 kilometers (6 miles). This occurred on a steeply dipping fault, and the south side of the fault moved upward; we call this a thrust earthquake.”

Earthquakes occur at different depths. Those between 0 and 70 kilometers are shallow, those between 70 and 300 kilometers are medium, and those between 300 and 700 kilometers are deep. Earthquakes that occur at shallow depths like this tend to be more destructive because the seismic waves produced have less time to lose energy on their way from the earthquake source to the surface.

Advanced satellite data and coastline changes

The map is based on data from the Advanced Rapid Imaging and Analysis (ARIA) group at JPL and the Caltech Seismology Laboratory, a group that develops state-of-the-art strain measurements, change detection methods, and physical models for use in hazard situations. Science and reaction. The ARIA team used synthetic aperture radar data from the PALSAR-2 sensor on the Japan Aerospace Exploration Agency’s Advanced Land Observation Satellite-2 (ALOS-2) and a pixel displacement tracking technique to measure surface displacements in the line-of-sight between two satellites. used. earth and satellite.

Additional analysis of ALOS-2 observations by scientists at Japan’s Geospatial Information Office shows that the earthquake lifted land along an 85-kilometer (52-mile) coastline. This shifted the coastline in Minazuki Bay, one of the areas with the largest uplift, about 200 meters seaward. They also reported a major rise and new lands in Waijma and Nafuna.

Using aerial photographs and satellite data, geomorphologist Goto Hideaki of Hiroshima University, along with colleagues from the Japan Association of Geographers, estimated that the earthquake exposed a total area of ​​4.4 square kilometers along the coast of the Nota Peninsula.

Some changes to the coastline around Minazuki Bay can be seen in the Landsat image pair above. The top image from OLI-2 (Operational Land Imager-2) on Landsat 9 was acquired on January 10, 2022, before the earthquake. The bottom image from the OLI (Operational Land Imager) on Landsat 8 was acquired on January 17, 2024, after the event. There are two small fishing shelters in the bay, which are left much higher and drier than normal. According to Asashi ShimbunMore than 15 fishing ports in Ishikawa Prefecture reported increases.

Satellite data is often useful for emergency response organizations that help respond to natural disasters in the immediate aftermath of an event, as it can be used to quickly identify the most severely damaged areas. Satellite data over a longer time period can also help authorities make more informed decisions about recovery and reconstruction in preparation for possible future events.