Earthquakes
Look at the diagram for Monday, March 13, a quiet day for seismic activity. What connection do you observe between the plate lines and earthquake activity? Along which boundary type would earthquakes occur most frequently? most violently? How are volcanic activity and earthquakes related to each other and plates? Continue reading and use the links on this page and the volcano page to answer these questions. For a real-time seismicity data display from the USGS. Click
The USGS defines "Magnitude" as "A measure of the strength of an earthquake or strain energy released by it, as determined by seismographic observations. This is a logarithmic value originally defined by Charles Richter (1935). An increase of one unit of magnitude (for example, from 4.6 to 5.6) represents a 10-fold increase in wave amplitude on a seismogram or approximately a 30-fold increase in the energy released. In other words, a magnitude 6.7 earthquake releases over 900 times (30 times 30) the energy of a 4.7 earthquake - or it takes about 900 magnitude 4.7 earthquakes to equal the energy released in a single 6.7 earthquake! There is no beginning nor end to this scale. However, rock mechanics seems to preclude earthquakes smaller than about -1 or larger than about 9.5. A magnitude -1.0 event release about 900 times less energy than a magnitude 1.0 quake. Except in special circumstances, earthquakes below magnitude 2.5 are not generally felt by humans." The Richter Scale is used to measure the magnitude of an earthquake. For a complete glossary of earthquake terms, click here. This takes you to the USGS website.
Earthquakes occur along plate boundaries. Boundary types include divergent boundaries (moving away from each other), convergent boundaries (moving toward each other), and sliding (transform) boundaries (moving past each other). To see how each boundary works click Earthquake. You will be leaving this site if you use the links on this page. To return, use your browser back button.
For a table and diagram linking earthquakes, volcanoes, and plate tectonics, click here.
