Noto Quake Evacuation Data Shows Lesson Learned from 2011 Great Earthquake

The Yomiuri Shimbun

16:45 JST, March 4, 2024

Many people fled to higher ground right after the Noto Peninsula Earthquake in order to escape the ensuing tsunami, according to people-flow data analyzed by The Yomiuri Shimbun.

The 2011 Great East Japan Earthquake prompted revisions to tsunami hazard maps in Ishikawa Prefecture, apparently raising the residents’ awareness of tsunami. Some survivors from the latest earthquake said that the 2011 earthquake served as a lesson for them, reinforcing the importance of immediate evacuation.

Agoop Corp., a Tokyo-based information service company affiliated with SoftBank Corp., used anonymized cell phone location data to show the flow of people both immediately before and after the Jan. 1 earthquake struck at 4:10 p.m.

The paper’s analysis of the data showed a visible increase in the flow from coastal residential areas to evacuation centers about five minutes after the earthquake in the Iida and Tada districts of Suzu in the prefecture. The evacuation centers — such as Iida High School — are located on hills between 15 meters and 25 meters above sea level.

The prefectural government revised its tsunami forecast after the 2011 earthquake saw extensive damage caused by tsunami, and the Suzu city government created a hazard map in 2018, predicting that a tsunami would reach the area within about 20 minutes.

Data from NTT Docomo Inc.’s Mobile Spatial Statistics that estimates the floating population based on cell phone location data also showed that the population around Iida High School between 5 p.m. and 6 p.m. was triple that seen between 3 p.m. and 4 p.m. Neighboring municipalities of Suzu also saw an increase in the floating populations at higher ground, while the figures significantly decreased in lower elevation areas along the coast.

A 68-year-old man in Suzu said: “I learned a lot from the 2011 earthquake and other disasters in the past and had urged people to escape to higher ground if there was a major earthquake. The fact that we called out to each other may have contributed to the speed of the evacuation.”

The latest quake killed 241 people. Of the 139 victims whose names were released by the prefecture with the consent of their families, two were killed by the tsunami.