Acehtsunami

The continents and sea floor that wrap the earth’s surface are part of a world-wide system of plates that are in movement. These movements are quite slow, only an inch or two per year. Earthquakes occur where the edges of plates run into one another. Such boundaries are called fault lines or faults. Sometimes the forces along faults can build-up over long periods of time so that when the rocks finally break an earthquake occurs.

Examples of features produced by forces released along plate edge faults are the Andes Mountains in South America (on land) and the Aleutian Trench near Alaska (under water). When powerful, rapid faulting occurs beneath or near the ocean, a large earthquake is produced and, possibly, a tsunami.The deep ocean trenches off the coasts of Alaska, the Kuril Islands, Russia, and South America are well prone to violent underwater earthquakes and as the source area for destructive Pacific-wide tsunamis.

The tsunami generating process is more complicated than a unexpected push against the column of ocean water. The earthquake’s magnitude and depth, water depth in the region of tsunami generation, the amount of vertical motion of the sea floor, the velocity of such motion, whether there is instantaneous slumping of sediments and the efficiency with which energy is transferred from the earth’s crust to ocean water are all part of the generation mechanism.