How do divergent boundaries cause earthquakes

Another form of convergent boundary is a collision where two continental plates meet head-on. Since neither plate is stronger than the other, they crumple and are pushed up. This can lead to the formation of huge, high mountain ranges such as the Himalayas.

When two tectonic plates slide past each other, the place where they meet is a transform or lateral fault. The San Andreas Fault is one of the best examples of lateral plate motion. This material is also available as a free iBooks textbook and iTunes U course. Get a new perspective on earthquakes with this rich collection of multimedia resources. You'll learn why earthquakes happen, how they've shaped the Bay Area, and what you can do to prepare for the next one. Find out what you can do right now to protect yourself in the event of an earthquake.

You'll be happy you did. Sign up for event updates and exciting announcements. Learn more. Reservations are required for the planetarium and are available on a first-come, first-served basis. More info. Donate Join Tickets. California Academy of Sciences. Toggle Close. Earthquake patterns in subduction zones are more complex. As the oceanic crust begins to descend, it begins to break into blocks because of tension stress.

Earthquakes also periodically occur as the plate continues to subduct up to a depth of about kilometers miles. Earthquakes are relatively abundant in the first kilometers miles of a subduction zone, are scarce from to kilometers to miles , and then increase slightly again from to kilometers to miles. It is possible that these deepest quakes are related to sudden mineral transformations and resultant energy releases or volume changes. It has been theorized that earthquakes do not occur at depths greater than kilometers because the subducting plate is not brittle anymore and has become hot enough to flow plastically.

The distribution of earthquake foci along a subduction zone gives an accurate profile of the angle of the descending plate. Most often, plates start subducting at a shallow angle, which becomes steeper with depth. The angle of subduction is proportional to the density of the plate material, the amount of faulting and thrusting, and the tearing or crumpling of the descending plate.

Divergent boundaries are those at which crustal plates move away from each other, such as at midoceanic ridges. These huge underwater mountains often have a central graben feature, or rift valley , that forms at the crest of the ridge. Students should also be familiar with elements of the visualization introduced in Visualization 1; i. This activity is part of a series of visualizations in a unit about plate tectonics, although each visualization could also be used in isolation.

Students will understand the following concepts: Shallow, low-magnitude earthquakes commonly occur at divergent plate boundaries. Earthquakes at divergent plate boundaries are distributed with predictable locations and depths. Earthquakes at divergent plate boundaries occur as new crust is created and other crust is pushed apart. This causes the crust to crack and form faults where earthquakes occur.

Most earthquakes at divergent plate boundaries occur at mid-ocean ridges where two pieces of oceanic crust are moving away from each other. Some earthquakes at divergent boundaries occur in the middle of continents in rift zones. Students will be able to: Synthesize large data sets to recognize naturally occurring patterns Use patterns in data sets to make predictions about the distribution and characteristics of earthquakes Visualize data in 3D that is traditionally represented in 2D. Instructors Notes Acrobat PDF 95kB Aug22 11 This document includes detailed description of the visualization and how it should be used in class, talking points that are linked to specific times in the visualization, and 'quakes questions' for evaluation during playback of the visualization.

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