This view sequentially displays earthquakes and volcanic eruptions that occurred between 1960 and 2002. These events are concentrated along the boundaries of Earth's tectonic plates. This is no coincidence; both earthquakes and volcanic eruptions result from ongoing interactions between plates. Do you notice a pattern developing soon after the program begins?
Earthquakes are represented by large white dots that shrink to small white dots following the event. The initial size of each dot reflects the magnitude of the earthquake. Earthquakes commonly occur along the four major types of plate boundaries:
--Convergent boundaries, where plates collide along subduction zones (such as most margins of
the Pacific Ocean) or continental-collision zones (such as the Alps and Himalaya),
--Divergent boundaries, where plates spread apart (such as along mid-ocean ridges and
continental rift zones),
--Transform boundaries, where plates move laterally past each other (mostly in ocean basins
but also including the San Andreas fault system in California), and
--Diffuse boundaries, where the boundary position and relative motion between two
adjacent plates are not well defined and plate interaction may be spread over a broad area.
Volcanic eruptions are displayed by red triangles that shrink to small pink triangles after the eruption ends. The size of each triangle reflects the magnitude of the eruption. The majority of eruptions occur along convergent and divergent plate boundaries. However, eruptions can also occur far from plate boundaries at locations called hot spots, where magma rises to the surface above approximately stationary sources deep in the Earth's mantle. Run EARTHQUAKES THROUGH TIME, ERUPTIONS THROUGH TIME, and SEISMIC WAVES to learn more about Earth's seismically and volcanically active regions.
Earthquake data were supplied by the United States Geological Survey, University of California at Berkeley, California Institute of Technology, and Incorporated Research Institutions for Seismology. Volcanic eruption data were supplied by the Smithsonian Institution's Global Volcanism Program.
