JAXA Developing Program to Estimate Earthquake Damage to Buildings from Satellite Images; Aims to Improve Disaster Response Capabilities

By Haruka Kohatsu / Yomiuri Shimbun Staff Writer

1:00 JST, May 2, 2025

KUMAMOTO — The Japan Space Exploration Agency (JAXA) is cooperating with the Kumamoto prefectural government to develop a program that quickly estimates damage to residential buildings by using satellite images in case of an earthquake.

The prefectural government has provided JAXA with data on 200,000 residential buildings affected by the 2016 Kumamoto Earthquake to help improve the program’s accuracy.

This is the first case in which JAXA is collaborating with a local government to develop a program. They aim to finish by the end of fiscal 2026. The program is expected to implement municipalities to take initial disaster responses in a swift manner.

JAXA uses satellites to ascertain the shape of ground surfaces, such as elevations and sinkholes, on a regular basis. A radar using radio waves obtains images of ground surfaces during the day and night regardless of the weather conditions, while the Advanced Land Observing Satellite-2 “DAICHI-2” (ALOS-2) is capable of imaging an area extending 50 kilometers east-to-west and “DAICHI-4,” a successor to Daichi-2 whose operation fully started this spring, increased the observation range to 200 kilometers.

In case of a natural disaster, JAXA plans to use these satellite images to estimate damage to buildings by comparing and analyzing the shapes of buildings and ground surfaces before and after the disaster. Then, the agency would inform municipalities concerned of the damage estimates to help them choose areas to be prioritized in rescue efforts from a wide range of areas. However, compared to damage estimates in flooded areas, creating accurate damage estimates in an earthquake has been difficult because many different patterns exist in the ways that homes collapse in an earthquake.

‘Bitter experience’ in Noto

JAXA has been developing the program to estimate earthquake damage to buildings since around 2020. However, it failed to provide accurate damage information after the Noto Peninsula Earthquake that occurred on Jan. 1, 2024, causing some municipalities to estimate only 10% of all buildings that were affected by the earthquake.

“The data on the damage to several hundreds residential buildings in certain areas were inputted into the program. However, the data was incomplete as we failed to cover all areas,” said Shiro Kawakita, a senior engineer at JAXA. “We had a bitter experience in the Noto Peninsula Earthquake.”

Learning from the experience, JAXA decided to use damage data on about 200,000 residential buildings in the Kumamoto Earthquake to improve the analytical precision of the program and proposed the idea to the prefectural government in May 2024. In January, the agency and the Kumamoto Prefecture signed an agreement.

According to JAXA, many different areas were affected by the Kumamoto Earthquake, including urban locations as well as areas surrounded by mountains that did not suffer damage caused by tsunami or fire. Data from the earthquake would show damage only from the earthquake itself, allowing JAXA to develop a highly versatile program that can be applied to disaster-affected areas across the country.

The prefectural government asked 16 municipalities where more than 1,000 residential buildings were damaged, such as Kumamoto and Mashiki, for cooperation and obtained approval from them to provide data for the JAXA program.

To issue disaster-victim certificates, municipal officials visited each individual building that was damaged in the earthquake and classified the structures into four levels: “completely destroyed,” “partially destroyed on a large scale,” “half destroyed” and “partially destroyed.”

JAXA will input satellite images from before and after an earthquake along with the location information of buildings and their damage levels into the program so that estimating the extent of damage can be done more accurately and quickly than before.

“We’re glad that the data collected one by one by municipal officials will be used nationwide,” said Taishi Wada, a Kumamoto prefectural government official in charge of the project.

Lessons applied nationwide

The prefectural government is currently making adjustments with respective municipalities to provide data to JAXA. When the program is completed, estimating the damage to buildings will reportedly be able to be done in two or three hours after an earthquake occurs.

“We want to make it possible to understand the extent of damage as quickly as possible so that we can support [municipalities] in ensuring the safety of rescue workers and people affected by a disaster,” Kawakita said.

Kumamoto Gov. Takashi Kimura said: “It is our sincere hope that the lessons from the Kumamoto Earthquake are used for disaster responses across the nation. We would like to work together with [JAXA] to improve disaster response capabilities.”