Tsunami - John Seach What is a Tsunami? A tsunami is a wave generated by physical disturbance. What Causes Tsunamis? Tsunamis can be caused by landslide, earthquake, or volcanic eruption. Asteroid or comet impact in the ocean can also create a tsunami. Tsunami Waves at Sea Tsunami waves are different from normal wind generated waves. Tsunamis produce water movement all the way to the ocean floor. Tsunamis may consist of 10 or more waves in a "tsunami wave train". Individual waves may follow from 5 to 90 minutes apart. Tsunamis Near shore Tsunami waves change as they approach the shore. Tsunami waves are larger on larger islands where there is more time for them to "feel" the bottom. Tsunami waves slow down as they approach the shore. Water levels don't always fall prior to a tsunami. A 1 m high tsunami at sea may reach 15 m in height as it reaches the shore. Tsunamis may be more dangerous at headlands and funnel shaped bays where the energy is concentrated. Seiche Effect A tsunami may produce a sloshing effect of water which can magnify the effect of the wave. Effect of Reefs An offshore reef may decrease the destructive effect of a tsunami by absorbing the energy. Tsunami Information www.volcanolive.com Copyright John Seach