Study on Casualty and Tsunami Evacuation Behavior in Ishinomaki City – Questionnaire Survey for the 2011 Great East Japan Earthquake
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Tenth U.S. National Conference on Earthquake Engineering Frontiers of Earthquake Engineering July 21-25, 2014 10NCEE Anchorage, Alaska STUDY ON CASUALTY AND TSUNAMI EVACUATION BEHAVIOR IN ISHINOMAKI CITY – QUESTIONNAIRE SURVEY FOR THE 2011 GREAT EAST JAPAN EARTHQUAKE - H. Murakami1, S. Yanagihara2 Y. Goto3, T. Mikami4, S. Sato5, and T. Wakihama6 ABSTRACT Ishinomaki city suffered largest human loss including missing of about 4,000 mostly by tsunami in the 2011 Great East Japan Earthquake Disaster. Human loss rate reached 3.52% of population in inundated area in the city. Questionnaire survey was conducted in Ishinomaki city to clarify tsunami evacuation process, factors of success and failure in evacuation by special study group in Dec., 2011, and 797 cases of data were obtained. This paper classified evacuation mobility patterns and travel means and indicated that a half of respondents evacuated by cars, 40 % of those who evacuated on foot moved to places such as schools within 1km distance, and 40 % of those who evacuated by cars moved less than 1km. A quarter of those evacuating by cars came back to their homes, and had only 17 minutes in average left to evacuate, losing critical time for evacuation. Two fifths of those evacuating by cars faced traffic jams. 1Associate Prof., Dept. of Environmental Science and Engineering, Yamaguchi University, Ube, 755-8611, Japan 2 Civil Engineering Division, East Japan Branch, Okumura Co., Minato ward, Tokyo, 108-8381, Japan 3 Earthquake Research Institute, The University of Tokyo, Bunkyo ward, Tokyo, 113-0032, Japan 4 Tono Reearch Institute of Earthquake Science, Mizunami, 509-6132, Japan 5Geology & Geotechnology Dept., Nippon Koei Co., Chiyoda ward, Tokyo, 102-0083, Japan 6Graduate Student, Dept. of Environmental Science and Engineering, Yamaguchi University, Ube, 755-8611, Japan Tenth U.S. National Conference on Earthquake Engineering Frontiers of Earthquake Engineering July 21-25, 2014 10NCEE Anchorage, Alaska Study on Casualty and Tsunami Evacuation Behavior in Ishinomaki City - Questionnaire Survey for the 2011 Great East Japan Earthquake – H. Murakami2, S. Yanagihara2 Y. Goto3, T. Mikami4, S. Sato5, and T. Wakihama6 ABSTRACT Ishinomaki city suffered largest human loss including missing of about 4,000 mostly by tsunami in the 2011 Great East Japan Earthquake Disaster. Human loss rate reached 3.52% of population in inundated area in the city. Questionnaire survey was conducted in Ishinomaki city to clarify tsunami evacuation process, factors affecting success and failure by special study group on Great East Japan Earthquake Tsunami in Oct. Dec., 2011, and 797 cases of data were obtained. This paper classified evacuation mobility patterns and travel means, and indicated that a half of respondents evacuated by cars, 40 % of those who evacuated on foot moved to places such as schools within 1km distance, and 40 % of those who evacuated by cars moved less than 1km. A quarter of those evacuating by cars came back to their homes, and had only 17 minutes in average left to evacuate, losing critical time for evacuation. Two fifths of those evacuating by cars faced traffic jams. Introduction The 2011 Off Tohoku Pacific Coast earthquake occurred at 14h46m, March 11, Friday and caused extreme human loss of 18,493 people killed and 2,683 missing (as of Mar. 26, 2013 by Fire Defense Agency, Japanese Gov). Ishinomaki city had population of 160,826 and 57,871 households (Oct. 2010 National Census) and is the second largest city after Sendai in Miyagi prefecture. Among many cities and towns along the Pacific coast damaged in Miyagi, Iwate and Fukushima prefectures, Ishinomaki city had largest inundated area and largest human loss (Table 1). The past tsunami damages in 1896, in 1933, and in 1960 was severe along rias coast, however, they were moderate or small in urban Ishinomaki. The pre-2011 tsunami hazard maps in Miyagi prefecture was based on the scenario of off Miyagi coast earthquake (M=8.0) showing nominal inundation along the ports and Kitakami river in urban Ishinomaki. Inundation map is shown with some topography in Fig. 1. The urban area of Ishinomaki extends approximately 10km EW and 4km NS having two ports of industrial and fishing. In the central city, Kyuu-Kitakami river turns around and flows down to south and Hiyoriyama hill (55mTP in 1Associate Prof., Dept. of Environmental Science and Engineering, Yamaguchi University, Ube, 755-8611, Japan 2 Civil Engineering Division, East Japan Branch, Okumura Co., Minato ward, Tokyo, 108-8381, Japan 3 Earthquake Research Institute, The University of Tokyo, Bunkyo ward, Tokyo, 113-0032, Japan 4 Tono Reearch Institute of Earthquake Science, Mizunami, 509-6132, Japan 5Geology & Geotechnology Dept., Nippon Koei Co., Chiyoda ward, Tokyo, 102-0083, Japan 6Graduate Student, Dept. of Environmental Science and Engineering, Yamaguchi University, Ube, 755-8611, Japan elevation) densely inhabited with some schools and public places is located on the west bank of the river. Mt. Makiyama (218mTP in elevation) with mostly forest and parks as land use is located on the east bank of the river. The area of inundation depth more than 4m extends around Minamihama, Kadonowaki, Minato. As for the tsunami arrival time, JMA reported max tsunami hit Ayukawa port (Oshika), Ishinomaki city at 15h26m. According to the municipal disaster report [1], rapid increase of sea level was observed at 15h25m at Tsukihama (Kitakami), at 15h40m to 15h50m at Kadonowaki, at 15h45m at Nobiru (Higashi Matsushima city). Major tsunami seems to have hit Ishinomaki urban area around 15h 40m. At the beginning of the survey, a group was established consisting of researchers and engineers who were interested in determining facts about the people’s evacuation from the giant tsunami. The group was chaired by Prof. F. Imamura of Tohoku University. It was separated into several task teams, which were assigned to different areas to avoid further traumatizing evacuees by repeated surveys. The task team for Yamada town and Ishinomaki city consists of 22 members and coordinated by Dr. Y. Goto of the University of Tokyo. Goto et al (2012) compares evacuation characteristics and human casualty of Yamada town and Ishinomaki city [2]. The survey team first started interview survey visiting temporary housing complex in urban Ishinomaki, and then conducted the survey by posting method (Table 2). Table 1. Damage Statistics in Ishinomaki city. Table 2. Outline of the questionnaire survey. Survey period Dec. 2011 Number of Dead 3,510 Temporary housing in urban Number of Missing 447 Survey area Ishinomaki Total collapse 19,957 Distibution 3300 Partial collapse 13,114 Collection 797 Number of population 160,826 (collection rate 24%) Number of population in inundated area 112,276 Great East Japan Tsunami % of people dead or missing among population 2.46 Survey team Evacuation Joint Investigation Team % of people in inundated area 3.52 (Yamada town and Ishinomaki city Source: Statistics Beurow as of Sep. 17, 2013 Team) Makiyama (218mTP) Hiyoriyama (55mTP) Figure 1. Inundation map of urban area in Ishinomaki city. (Source GIS data of inundation [3]) The survey population is regarded as those who lost housing and faced life threat without evacuation. The number of temporary housing in urban Ishinomaki was 4302 units with probablybasedon the pastexperience of1960 the Chilean tsunami. Fig.5 shows information comedidn’t or of think tsunami. Elderlypeople tendtohave thought large willhit, tsunami tsunami willcome, but not that large.About people30%of either thought tsunamiwill not thoughtimmediateof tsunami crisis right after shakinggroups. age vs. Most people thought In this section, statistics of all questionnaire da [6]. front water from 1km within areas for serious are losses human and damage housing front,andindicated strongcorrelation between heavydamage rateandhuman lossrate, and housing damage and human loss vs.tsunami inundation depth and distance from coast and river so because tsunami would not come [5]. Sato and Tanaka (2012) analyzed distribution of do to try not did or disabilities to due evacuate not could either of those most that indicated and town Yamada cityand Ishinomaki in lives lost who people of behaviors and location investigated tsunami human casualties in Tohoku municipalities in [4].Mikamiinundated etarea (2012) al population and is littlehigher for population forgroupeach and age shows sex that3) (Fig. extremely itincreases for elderly inhabitant registered against rate loss Human people. elderly for greater isfar loss human that and 2011. Age Sep. 30, asof address and birth A List of 3483 people who lost lives was provided by Ishinomaki municipal office with date of population). of (4% cases people relocated in other places, approximate 19000 is survey population. Wecollected 797 approximately8604people assuming2 persons per household. Assuming the sameof number Figure 2. Age and sex distribution of human of distribution 2. sex Age and Figure Number of People Killed 100 150 200 250 50 0 0‐4 5‐9 Male Female loss(n=34832011)30,of Sep. as 10‐14 15‐19 20‐24 25‐29 30‐34 Travel Means of Evacuation and Warning Exposure Exposure and Warning Evacuation of Means Travel 35‐39 Age 40‐44 45‐49 Group 50‐54 55‐59 60‐64 Fatality Distribution in Ishinomaki 65‐69 70‐74 elderly Koyama males. et al (2012)analyzes ageeffectson 75‐79 80‐84 85‐89 90‐94 95‐99 100‐104 sex distributionsex of human loss (Fig.2) indicates ta from Ishinomakiis indicated. Fig.4shows human of distribution sex 3. Age Figure and for regist lossrate Fatality Rate 10% 2010) 30, Sep. of as population Sep. 30, 2011, and resistered as of loss human (n=3483 the city. 0% 1% 2% 3% 4% 5% 6% 7% 8% 9% 0‐4 5‐9 10‐14 Male Female 15‐19 20‐24 25‐29 30‐34 35‐39 Age 40‐44 45‐49 Group ered population in 50‐54 55‐59 60‐64 65‐69 70‐74 75‐79 80‐84 85‐89 90‐94 95‐99 100‐104 media to get first tsunami warning.