GEOS-2123-Module: Structural Geology. Earthquake Anatomy. Dynamic Earth . Slip, Slide, & Collide. The magma formed at a subduction zone rises up toward the earth's surface and builds up in magma chambers, where it feeds and creates volcanoes on the overriding plate. When this magma finds its way to the surface through a vent in the crust, the volcano erupts, expelling lava and ash. An example of this is the band of active volcanoes that encircle the Pacific Ocean, often referred to as the Ring of Fire. A subduction zone is also generated when two oceanic plates collide — the older plate is forced under the younger one — and it leads to the formation of chains of volcanic islands known as island arcs. Examples include the Mariana Islands in the western Pacific Ocean and the Aleutian Islands, off the coast of Alaska.
Since the collision and subduction of plates is not a smooth process, large, powerful earthquakes are another phenomenon that result from this type of interaction. Earthquakes generated in a subduction zone can also give rise to tsunamis. Collision Zones and Mountains. Seismic-animation. 3-D Earth Structure Model. Interpreting Seismograms - A Tutorial for the AS-1 Seismograph 1 Objective: This tutorial is intended as a resource for the interpretation of seismograms recorded by educational seismographs.
The tutorial provides a description of the main features of the Earth that affect seismic wave propagation and therefore controls the character of seismic signals recorded on seismographs. A catalog of selected seismograms is also presented to illustrate the variation in signal properties with distance, magnitude, and depth of focus. After initial visual analysis of an earthquake seismogram, one can often determine additional information about the event by identifying phases (individual arrivals on the seismogram that travel a distinct path through the Earth) and measuring amplitudes to estimate the magnitude of the earthquake.
This tutorial is available for viewing with a browser (html file) and for downloading as an MS Word document or PDF file at the following locations: 1. 2. 3. 4. 5. 6. 7. 8. Faults and Faulting. Earthquakes and Volcanoes. Earth's Untamed Energy:Earthquakes and Volcanoes We discuss: The difference between the intensity and the magnitude of an earthquake? What are seismic waves and what information do they give us about earthquakes when they have been recorded by a seismograph? How does temperature change with increasing depth in the Earth? Format for printing Natural Hazards In this chapter we will focus on the origin of these phenomena and try to get some sense of their inevitability. The arrival of a new natural hazard: humans. Earthquakes Earthquakes occur every day! Watching the evening news, we regularly hear the anchorperson announce the latest occurrence of an earthquake somewhere in the world.
Some Destructive Earthquakes * Official casualty figure--estimated death toll as high as 655,000. + Note that these dates are prior to 1000 AD; no digit is missing. ** Later research has shown that this was a typhoon, not an earthquake.Data compiled from several sources. Intensity Earthquake Location and Magnitude. Animations. Each series of animations below contains text, graphics, animations, and videos to help teach Earth Science fundamentals.
Click links or scroll down to view the available animations. Check out our Earth Science Videos pages. Animations Hazards Orphan tsunami How will 3 buildings, engineered equally, on different bedrock react to an earthquake? Plate Tectonics Tectonics & earthquakes of Alaska—More than just plate boundaries NEW! GPS - Understanding Future Earthquakes in the Pacific Northwest Solomon Islands Regional Tectonics Gulf of California tectonics Sumatran Tectonics What is a hotspot? How do Earth's tectonic plates interact? Do subducting plates slide smoothly past one another? How is stress stored between tectonic plates? Do faults break all at once, or in many short segments? What are the 4 basic classes of faults? What happens when the crust is stretched? GPS -- Measuring Plate Motion Earth Structure Stratigraphy Same earthquake, different stations; why do the seismograms look different?
Volcanoes.