TSUNAMI AMANO MAI SEKIYA HIDEHIKO YAMAGUCHI HIROSHI CIVIL ENGINEERING ENGLISH 1 2007/2/6 1 CONTENTS ACCIDENTS CASE 1~3 MECHANISM CAUSES OCCURRENCE TRANSMISSION • VELOCITY • HEIGHT SUBMERGENCE MITIGATION MEASURES CONCLUSIONS 2 ACCIDENTS ~CASE 1~ 1993/07/12 Okushiri Island was damaged by tsunami. FIG. 1 Picture of tsunami Big earthquake Big tsunami 3 ACCIDENTS ~CASE 2~ Aona port was damaged by tsunami. FIG. 2 Damage of Aona port Fishing boat and the breakwater were destroyed. (http://www.bo-sai.co.jp/sub8.html) FIG. 3 Damage of breakwater 4 ACCIDENTS ~CASE 3~ Inaho elementary school was damaged by tsunami. FIG. 4 Damage of Inaho elementary school (http://www.bo-sai.co.jp/sub8.html) TSUNAMI DAMAGE A LOT OF INFRASTRUCTURE!! 5 MECHANISM ~CAUSES~ The causes of tsunami Earthquakes Volcanic activities Falls of meteors 95％ of causes is earthquakes!!!! tsunami is constructed by three parts. 1. OCCURRENCE 2. TRANSMISSON 3. SUBMERGENCE FIG. 5 Sequence of tsunami （http://ja.wikipedia.org/wiki/%E6%B4%A5%E6%B3%A2） 6 MECHANISM ~OCCURRENCE~ When earthquake occurs, the bottom of the sea raises or sinks. The reaction from changing crust lifts or pulls down seawater above that point. Mechanism of tsunami FIG. 5-a Before tsunami TSUNAMI OCCURS FIG . 5-b After tsunami 7 MECHANISM ~TRANSMISSION~ 1. VELOCITY The velocity of tsunami is only influenced by depth of water. g×d For example Depth of sea Velocity 10m 500m 4000m 36km/h 252km/h 712km/h This is that of Boeing 707!! 8 MECHANISM ~TRANSMISSION~ 2. HEIGHT The height of tsunami is influenced by depth of Water. Because depth of shore is low, height becomes too high. FIG. 6 Relationship of tsunami Too dangerous!! Maximum of height Japan 38,2m (1896, Meijisanrikutsunami) World 520m (1958, Alaska) (http://ja.wikipedia.org/wiki/%E6%B4%A5%E6%B3%A2) 9 MECHANISM ~SUBMERGENCE~ Tsunami is different from tidal wave. Concentration of tsunami Tsunami has potential energy. FIG. 7-a Potential energy can concentrate in particular topography. Ex) Saw-toothed coastline It's too dangerous!!! FIG. 7-b 10 MITIGATION MEASURES Actually, there are few provisions. 1. Build a breakwater 2. Live in a concrete building 3. Flee into the second floor if tsunami happens etc. FIG. 8 water gate “byuuo” (http://www.pref.shizuoka.jp/doboku/buchou1/talk/talk17.htm) FIG. 9 Model of “MONE’S HOUSE” (http://www.k3.dion.ne.jp/~monet/sub2zennkei.html) 11 CONCLUSIONS KNOWLEDGE REFUGE RECONSTRUCT 12