Tsunami

What Is It? Causes Series of traveling shallow water waves Earthquakes-(most common) Eruption of coastal and island volcanoes Submarine landslides Ocean impacts of large meteorites (rare) Series of traveling shallow water waves Hit coast in intervals Majority of tsunami occur in Pacific Ocean subduction zones

wind generated waves shallow water waves period 5 - 20 seconds wavelength 100-200 meters shallow water waves ratio between water depth and wavelength is small period of 10 minutes to 2 hours wavelength in excess 480 km 2-3 meters high in deep seas

In shallow water it loses speed and increases in height contour of the ocean floor and coast can change speed & direction Wave height can reach 30 to 50 meters Rate of energy loss of waves is inversely proportional to its wavelength Areas most at risk are less than 50 feet above sea level and within a mile of the coast.

Recent Tsunamis in Japan

1960 Chile Earthquake Magnitude 9.5 South American plate moved over the subducting Nazca plate Tsunami hit Chile then reversed 17,000 miles across the Pacific Ocean and hit Japan water level 4.5 meters 122 fatalities animation

1993 Hokkaido tsunami Earthquake-magnitude 7.8 in Sea of Japan misbeleif that a tsunami would not occur in the Sea of Japan late issue of warning water levels up to 9 meters 200 fatalities

Japan’s management seawalls breakwaters buoys linked to Global Positioning Systems forcasting centers work with Tsunami Warning System in the Pacific conduct drills once a year some villages move to higher ground Education videos Karakuwa tsunami simulation hall

Tips for survival head to higher ground after strong earthquakes Do not go to the shore to watch a tsunami cooperate with warnings and evacuation procedures abandon belongings realize roads may not be accessible do not return until the “all clear” is given