Earthquakes: Cumulative - 1980 - 1995
It is estimated that there are 500,000 detectable earthquakes in the world each year. Of those, 100,000 can be felt and 100 of them cause damage. Anything that causes seismic waves to radiate throughout the Earth is an earthquake. The cause of earthquakes can be natural, such as one tectonic plate slipping below another, or anthropogenic (cause by humans), such as drilling for fossil fuels, extraction of minerals, huge explosions, and the collapse of large buildings. Because most natural earthquakes occur due to slipping plates, the boundaries between tectonic plates are "hot spots" for earthquakes. In the Pacific Ocean, the Pacific Plate is referred to as the Ring of Fire because this is one of the most active plates where earthquakes and volcanoes frequently occur. In order to rate the strength and magnitude of earthquakes, the Richter magnitude scale was created. It is a base-10 logarithm scale of ground motion 100km from the epicenter. Every whole-number increase in magnitude means the amplitude of the seismic wave is ten times greater. 4.0 - 4.9 on the scale is considered light, with some shaking of indoor items and significant damage unlikely.
This dataset highlights especially well the location of the ring of fire. The cumulative earthquake events from 1980 through 1995 are plotted on a world map with ocean bathymetry. Only earthquakes with a magnitude greater than 4.2 have been plotted. A yellow dot represents 1 or 2 earthquakes, an orange dot represents about 10 earthquakes and a red dot represents 50 to 200 earthquakes. The colored lines represent tectonic plate boundaries. It is clear to see that earthquakes occur most frequently along the plate boundaries. The red lines are convergent boundaries, the green lines are divergent boundaries, the blue dashed lines are diffuse boundaries and the purple lines are transform boundaries.
- Lines are tectonic plate boundaries, dots are earthquakes
- Most earthquakes occur along the tectonic plate boundaries