Damage to the Railway System Along the Coast Due to the 2011 Tohoku Earthquake Tsunami
Total Page：16
File Type：pdf, Size：1020Kb
Journal of Natural Disaster Science, Volume 34, Number 1, 2012, pp105-113 Damage to the Railway System along the Coast Due to the 2011 Tohoku Earthquake Tsunami Soichiro SHIMAMURA* Fumihiko IMAMURA** Ikuo ABE*** *Department of Civil and Environmental Engineering, Tohoku University 6-6-11-1106, Aoba, Sendai, 980-8579, JAPAN **International Research Institute of Disaster Science, Tohoku University ***Department of Social Environment, Fuji Tokoha University (Received May 2, 2012 Accepted November 2, 2012) ABSTRACT The enormous Mw 9.0 earthquake with a hypocenter off Sanriku-oki that occurred at approximately 14:46 (JST) on March 11, 2011, and the subsequent tsunami, caused serious damage along the Pacific coast of Iwate, Miyagi, and Fukushima. The damage to infrastructure was remarkable, and the damage to the railway caused by the tsunami was the greatest damage ever to occur to the railway. JR-East reported that they checked the damage caused by only the tsunami along seven lines, which had a total distance of 325 km, and the form of damage varied by line. This paper summarizes the damage to the railway (including damage to vehicles) and the evacuation guidance situation for each line and investigates how the trains were damaged based on the numerical analysis of the 2011 Tohoku Earthquake Tsunami. Keyword: The 2011 Tohoku Earthquake Tsunami, Train, Numerical Analysis 1. Introduction was checked along 7 provincial routes over a total of approximately 325 km. On 2011 March 11th 14:46 (JST), an enormous Mw This paper presents an outline of the 2011 Tohoku 9.0 earthquake occurred with a seismic center on the Earthquake Tsunami, and, because the degree and coast of Sanriku. Due to a strong shake ranging from form of damage differed by route, examples of train 6 to 7 on the Japanese scale and a subsequent tsunami, damage are summarized for each route. In addition, a approximately 19,000 persons died or were missing numerical analysis of the tsunami, using the seismic (as of March, 2012) along the Pacific coast (including deformation model of the 2011 Tohoku Earthquake Iwate, Miyagi and Fukushima). Damage to the infra- Tsunami (Tohoku University model version. 1.0), was structure, such as roads, bridges, plants, water and performed to determine the flow conditions in the area sewage, was also remarkable, and the damage to the where the damage to the railway occurred. A new fall railway caused by the earthquake and tsunami was the model of the damage to trains caused by the tsunami is greatest damage ever to occur to the railway. Accord- proposed, and the mechanism of damage is discussed ing to JR East, the damage caused only by the tsunami by comparison with the results of analysis. 105 S. SHIMAMURA, F. IMAMURA, I. ABE 2. Outline of the 2011 Tohoku Earthquake Tsunami on the right (Fig. 1). These shocks caused a very high tsunami in the area along the shore, and evidence of As described above, the 2011 Tohoku Earthquake the great height of the tsunami can be seen in various Tsunami of Mw 9.0 caused enormous damage to most places (Fig. 2). In particular, along the Iwate rias areas of the Pacific Ocean coast. Within a broad flood coast, the run-up height was nearly 40 m. area (about 560 km2), the tsunami caused the collapse This tsunami, with the greatest wave force ever of reinforced concrete structures and the outbreak of and causing the greatest area of flooding also serious- fires. The waveform of the offing (Fig. 1) is an impor- ly affected the railway. Figure 3 shows damage in the tant feature of tsunami action. On March 11th, imme- JR East province. The form of damage, including diately after the main Mw 9.0 shock, three consecu- damage to electrification pillars, displacement of the tive Mw 7 aftershocks occurred, causing an increase railway track, washout and burial of bridge beams, in wave height in two stages, as shown in the graph failure of signal and communication equipment, and Fig. 1. Sea-level change recorded by the ocean floor cable seismometer off of Kamaishi (Earthquake Research Institute, The University of Tokyo) Fig. 2. The field survey result projected in the direction of latitude (The 2011 Tohoku Earthquake Tsunami Joint Survey Group) 106 DAMAGE TO THE RAILWAY SYSTEM ALONG THE COAST DUE TO THE 2011 TOHOKU EARTHQUAKE TSUNAMI Fig. 3. Damage to railway caused by the tsunami (JR East) ballast outflow, varied significantly. In this paper, to at Tsugaruishi Station, which is approximately 1 km give top priority to human life, the damage to trains is from the coast. considered and summarized. 3. Damage to the railway This chapter introduces examples of train damage caused by the tsunami. 3.1. Yamada-Line・St. Tsugaruishi (Iwate, Miyako : Photo. 1) The interrupted section of the Yamada Line is the longest in the nine main disaster-affected routes, and the route passes through areas that were enormously Photo 1. Yamada-Line・St. Tsugaruishi damaged by the earthquake disaster, such as Yamada (Provided by JR East) town and Otsuchi-Cho along the railway line. At Tsugaruishi Station, while the train for Miyako Sta- 3.2. Ofunato-Line・Ofunato-Shimofunato tion from Kamaishi Station stopped, it was affected (Iwate, Ofunato : Photo. 2) by intense shaking. As the tsunami alarm from the op- Along Ofunato Line, a train with a two-car for- eration management center was sounded promptly, mation was heading to Shimofunato Station from the passengers evacuated to nearby Tsugaruishi Ele- Ofunato Station at the time the earthquake occurred. mentary School, but, because the tsunami reached the Although the train came to an emergency stop at a lo- elementary school, they then evacuated to safety on cation that was several meters higher than the sur- the hill behind the school. According to JR staff, at rounding land, the crew who received the evacuation approximately 15:20, the train was washed along in directive helped the passengers down and proceeded the Toyomane Station direction from Tsugaruishi Sta- with evacuation. They did not evacuate to Ofunato tion, and it drifted approximately 80 m along the rail- Elementary School, which is the designated evacua- way line from where it had stopped. The tsunami nu- tion building, due to the advice of a local passenger merical analysis also shows that the tsunami arrived but rather went to Ofunato Junior High School, which 107 S. SHIMAMURA, F. IMAMURA, I. ABE is the same distance from the train as the elementary crew were safe, the train was derailed and drifted ap- school but at a higher altitude. As a result, although proximately 60 m in the direction of the tsunami. the tsunami reached the schoolyard of the elementary school, they evacuated safely to the junior high 3.4. Ishinomaki-Line・St. Onagawa school. The train, which had come to an emergency (Miyagi, Onagawa : Photo. 4 and Photo. 5) stop, was approximately 240 m from the coast and Along Ishinomaki Line (the whole line section was spared derailment and drift, but the train chassis (44.9 km)), the damaged section was only 700 m from was covered with water and the train was immobile. Onagawa Station to Onagawa Tunnel but suffered crushing damage from the shape of the bay. A train with a two-car formation was at rest and ready for departure in Onagawa Station yard when the earthquake occurred, but this train and the train used by some hot spring institutions were carried away by the tsunami. Among the trains in the two-car formation that drifted, one train drifted approximately 200 m and was completely destroyed, and the other train drifted 100 m more inland and stopped at a graveyard on a hill. In ad- dition, damage to the station building and the railway track were serious, and both were severely damaged. Photo 2. Ofunato-Line・Ofunato-Shimofunato (Provided by JR East) 3.3. Kesennuma-Line・Matsuiwa-Saichi (Miyagi, Kesennuma : Photo. 3) A train with a two-car formation to Kogota was running between Matsuiwa and Saichi when the earth- quake occurred. After the train made an emergency stop, the train driver received the tsunami alarm, had the passengers disembark and started the evacuation. It was necessary to walk approximately 200 m along the railway track, and the train driver saw the sea lev- el decrease suddenly and evacuated at a hurried pace to the Junior High School, which is situated approxi- mately 1 km inland. Although the passengers and the Photo 4, Photo 5. Ishinomaki-Line・around St. Onagawa 3.5. Senseki-Line・Tona-Nobiru (Miyagi, Hagashimatsushima : Photo. 6) Photo 3. Kesennuma-Line・Matsuiwa-Saichi Senseki Line connecting Sendai and Ishinomaki (Provided by JR East) runs approximately 200 trains a day as a route for 108 DAMAGE TO THE RAILWAY SYSTEM ALONG THE COAST DUE TO THE 2011 TOHOKU EARTHQUAKE TSUNAMI main factors included the explosion at Fukushima First Nuclear Power Plant, but the damage caused by the tsunami was too serious. In particular, a train that was stopped and the station building at Shinchi Sta- tion of Fukushima were destroyed. In addition, there was damage to a freight train on the Joban Line. Be- tween Hamayoshida to Yamashita, all of the contain- ers that had been piled up were washed away and col- lided with private houses, and they were a factor in the extent of the damage. The damage to Sendai Air- Photo 6. Senseki-Line・Tona-Nobiru port access lines and North Rias Line, South Rias Line (Provided by JR East) and Hachinohe Line were confirmed in other reports. commuters and school goers. Two trains were running when the earthquake occurred in this area, and one of them was the train to Aoba-Dori Station.