More than 40 percent of all the fires spawned by the Great East Japan Earthquake were the result of the massive tsunami that followed, a recent study by an academic society has found.
More than 40 percent of all the fires spawned by the Great East Japan Earthquake were the result of the massive tsunami that followed, a recent study by an academic society has found.
The findings by the Japan Association for Fire Science and Engineering are the first detailed analysis of the 371 blazes that came in the aftermath of the magnitude-9.0 temblor that rocked northeastern Japan in March 2011.
The findings could provide implications for disaster preparedness measures against possible devastating tsunami from a giant earthquake that could strike along the Nankai Trough, an oceanic trench that stretches 700 kilometers from Suruga Bay off Shizuoka Prefecture to areas off eastern Kyushu.
It has already been well-documented that tsunami can induce fires. Such infernos demolished 199 houses after the magnitude-8.1 Showa Sanriku earthquake of 1933 in Kamaishi, Iwate Prefecture, and destroyed 190 buildings on Okushiri island after the magnitude-7.8 Hokkaido Nansei-oki earthquake of 1993.
But tsunami-induced fires have usually been perceived as atypical events. Research on such incidents gained momentum after the blazes on Okushiri island, but the focus of similar studies soon shifted to non-tsunami-induced fires that razed the city of Kobe after the Great Hanshin Earthquake of January 1995.
The Japan Association for Fire Science and Engineering studied all fires that broke out within a month of the Great East Japan Earthquake, which struck on March 11, 2011, followed by a long period of large aftershocks that affected broad areas. Workers from universities and other research institutions combed the areas inundated by the tsunami and interviewed firefighters and local residents to pinpoint the origins of the fires.
The researchers carried Global Positioning System devices as they walked the areas affected by the fires. They used Google Earth and other mapping tools to superimpose the GPS trajectories of the contours on cartographic data and determine the landmass affected by the fires.
They found that tsunami induced 159 fires across 610 kilometers straddling six prefectures from Hachinohe, Aomori Prefecture, in the north, to Asahi, Chiba Prefecture, in the south. Most of that count is associated with the breakout of initial fires, but a smaller number pertains to a secondary spread of fire.
The flames affected 78.4 hectares, 20 times the size of Hyogo Prefecture's Koshien Stadium, of urbanized areas in 12 municipalities in Iwate, Miyagi and Fukushima prefectures. That total figure exceeded the combined 64.2 hectares of areas across Kobe that were destroyed by fires after the Great Hanshin Earthquake.
By prefecture, 99 fires, or 62 percent of all cases, took place in Miyagi Prefecture, followed by 29 in Iwate Prefecture, 12 in Fukushima Prefecture, nine in Ibaraki Prefecture, and five each in Aomori and Chiba prefectures.
Fifty-five, or 35 percent, of the fires originated from buildings. The buildings were non-wooden in more than 60 percent of the cases where information on their structure was available. Some of those buildings were three or more stories high, which made them eligible for designation as tsunami evacuation sites.
Vehicles were the origin of 50 fires, or 31 percent of all cases.
Most of the fires likely originated from destroyed buildings, liquefied petroleum gas cylinders and automobiles, according to Yu Hiroi, an associate professor of urban disaster management with Nagoya University, who analyzed the data. Many of the fires spread to urbanized areas after the tsunami washed blazing debris ashore at the foot of hills and elevated ground.
In Yamada, Iwate Prefecture, and Ishinomaki, Miyagi Prefecture, residents fled to secondary evacuation sites on elevated ground after fiery debris threatened their primary shelters.
Apart from tsunami, seismic shocks caused 212 fires, including in such wide-ranging prefectures as Akita, Niigata, Yamanashi and Shizuoka.