The Great Hanshin-Awaji Earthquake Hello ………. Today we are going tell you about the Great Hanshin Earthquake, which is better known as the Kobe Earthquake Tarvinder Gohel Susan Leckie

Geological Background Triple destructive plate boundary Japan is a typical volcanic island arc Area is very prone to geological activity Japan lies upon the triple junction of three tectonic plates (Pacific etc..) Because of the setting it makes the are very prone to geological events like earthquakes, volcanoes and maybe tsunamis the situation is two of the oceanic crusts are subducting under the other, rate of a few centimetres a year As these plates submerge under one another they will melt and magma rises to the surface and produces volcanoes, in the case of Japan, Mt Fiji formed. Japan is so earthquake prone because as these plates submerge further under each other, frictional forces and pressure result in the plates slipping and as a result of the high stresses earthquakes form. This caused Kobe quake…………………

Background January 17th 1995 (5.46am local time) 7.2 on Richter Scale Epicentre ~25km south of Kobe (Focus 16km) Over 5000 deaths (33000 injured + more indirect deaths) $100`s Billions Damage (Direct + Indirect costs) Kobe earthquake – happened 17th Jan 1995 - near city of Kobe in Japan First major E.Q in the area since 1916 Japan prone to earthquakes due to positioning Was so severe due to close proximity to urban area which is located along a fault line, Nojima Fault Many people died as a result –2nd largest death toll since 1900 5000 died 33000 injured or affected/later died due to the aftermath and effects… homeless etc. Huge amounts of damage 55000 structures collapsed 7000 burned Traffic networks, utilities and lifelines all effected Huge amount of money needed to rebuild businesses and restore the city ($100 - $200 billion)

Effects Kobe is built on 2 artificial islands (Port/Rokko Islands) Suffered widespread liquefaction and settlement Buildings founded on the liquefied ground resulted in leaning or toppling Kobe built on 2 artificial islands -loose, weak, saturated soil -means its prone to liquefaction -happens when loads are put on the weak ground very quickly and ground not have enough time to recover -water stays in pores, reduces particle contacts, results in soil acting like a liquid Caused huge devastation to ports/harbours etc. Damage to buildings, subsidence, collapse etc.

Effects Primary effects caused collapse of older buildings Secondary effects caused fires Collapse of an 18-span viaduct section of Hanshin Expressway Destruction of utilities and lifelines throughout city Liquefaction / seismic wave pressure from epicentre -caused Hanshin Expressway to collapse -where ground areas were softer, wetter and where shaking was stronger and longer Destruction of utilities and lifelines throughout Kobe -impossible for firefighters to reach fires started by gas lines -increased death toll/ damage etc.

General Solutions Disaster Management Disaster supplies warehouse Disaster response generators Increase land strength on reclaimed areas Land readjustment Building code amendments GPS based monitoring and prediction systems Extensive fault mapping Most of the new buildings survived………………. see http://www.freeessays.cc/db/23/gci57.shtml Ground underneath buildings shifted approx. 2 feet in less than 1 second New buildings were built with dampers at the bottom to prevent this Majority of buildings lost were older The new reinforced concrete piers for Hanshin Express-highway 3m wider than previous Continual longitudinal bars Shear reinforcement @ 12.5cm spacing through entire height Use seismic isolation bearings to distribute forces and energy Ult. Capacity of piers must be for force levels up to 2.0g Majority of failure due to brittle failure of steel bearings bearings are placed between the superstructure and the top of the substructure (piers and/or abutments) adds flexibility to the structure by elongating its period and dissipating energy A major lesson learned from Kobe was more effective emergency procedures, as a lot of the problems that occurred could have been managed better and saved lives. http://www.rms.com/Publications/KobeRetro.pdf

Engineering Solutions Building dampers Seismic isolators Bearings as energy dissipaters Reinforced concrete piers (Hanshin Highway) Concrete filled steel tube beam columns Emergency walls Most of the new buildings survived………………. see http://www.freeessays.cc/db/23/gci57.shtml http://www.moriliving.com/html/safety_security/en_earthquakes.html Ground underneath buildings shifted approx. 2 feet in less than 1 second New buildings were built with dampers at the bottom to prevent this Majority of buildings lost were older The new reinforced concrete piers for Hanshin Express-highway 3m wider than previous Continual longitudinal bars Shear reinforcement @ 12.5cm spacing through entire height Use seismic isolation bearings to distribute forces and energy Ult. Capacity of piers must be for force levels up to 2.0g Majority of failure due to brittle failure of steel bearings bearings are placed between the superstructure and the top of the substructure (piers and/or abutments) adds flexibility to the structure by elongating its period and dissipating energy A major lesson learned from Kobe was more effective emergency procedures, as a lot of the problems that occurred could have been managed better and saved lives. http://www.rms.com/Publications/KobeRetro.pdf