The hot plumes create volcanoes, while the jerky action of the movement results in seismic waves that create an earthquake. The volcanic lava flowing to the surface creates islands such as the Hawaiian Islands.
Figure 2 illustrates the seismic activity that takes place when two continental plates collide. The lithosphere floats on the asthenosphere. The lithosphere has broken up the earth's crust into ten major Figure 2 (US Geological Survey) tectonic plates. Here we see one of the crustal plates being forced under the other, producing earthquakes. A mountain range is produced at the plate boundaries as the rock formations are deformed and moved upward by the action of the shifting plates. Some of the rocks in the mountains may have been set down in an ocean environment that existed between the two continental crusts prior to collision.
Figure 3 shows the boundaries of the major tectonic plates. As these plates shift over time, earthquakes occur at the point of collision. As can be seen on this map, the boundaries are the most earthquake prone areas on earth. This Figure 3 (US Geological Survey) includes the California coast, Japan, and
The destruction and number of deaths caused by earthquakes is proportional to the magnitude of the earthquake. Measured on the Richter scale from 1 to 10, each successive number is 10x the magnitude of the previous number. A magnitude 7 is 10 times stronger than a magnitude 6, and a magnitude 8 is 100 times stronger than a magnitude 6. Obviously a stronger earthquake is capable of more destruction. More deaths will generally occur when the earthquake hits a population center. However, there have been innovations in the last 100 years that have helped minimize the destruction and reduce the death toll.
Understanding plate tectonics and mapping the world to reveal major fault lines has led to improved building construction around the world. The National Earthquake Hazards Reduction Program (NEHRP) conducts research and presents programs of public education. They have also developed standards for the safe design and construction of buildings and other structures. One major change to the Uniform Building Code involves a structure which is supported by a number of bearing pads that are located at the base of the building and the foundation. As the earth's crust moves in one direction, the pads themselves absorb the vibration and the building essentially remains stationary.
Japan and California face similar seismic activity and geological threats. Experts from these areas have been world leaders in developing safer construction methods and stricter building codes. These techniques have resulted in more earthquake resistant structures in public schools, bridges, hospitals, and dams.
Earthquake Hazards Program. 24 Oct. 2006. US Geological Service. 13 Dec. 2006 .