Poster illustrates the violence of ground shaking expected for three kinds of earthquakes: (1) Cascadia subduction zone great earthquake; (2) “deep” earthquake within subducting Juan de Fuca Plate beneath Pacific Northwest (e.g. Nisqually 2001); and (3) local magnitude 7 earthquake on the Seattle Fault.
Poster illustrates the violence of ground shaking expected for three kinds of earthquakes: (1) Cascadia subduction zone great earthquake; (2) “deep” earthquake within subducting Juan de Fuca Plate beneath Pacific Northwest (e.g. Nisqually 2001); and (3) local magnitude 7 earthquake on Portland Hills Fault.
This QuickTime animation shows how P, S, and surface seismic waves are amplified as they pass from strong bedrock areas to areas underlain by weaker layers of rocks and sediment. In loose water-saturated sediment, liquefaction can occur causing the ground to turn to “quick sand” during earthquake shaking. Animation is narrated to explain the events occurring during the animation.
QuickTime animation of 2004 Indian Ocean tsunami waves generated by the December 26, 2004 Sumatra – Andaman Islands great earthquake. The magnitude 9.2 great earthquake in the Sunda Trench occurred along the subduction zone between the India – Australia Plate and the southeastern corner of the Eurasian Plate. During the earthquake, the ocean floor in the Sunda Trench was offset and uplifted a column of ocean water producing an elongated mound of ocean water at the surface of the Indian Ocean. That mound of water then propagated to eastward toward northern Sumatra and Thailand and also westward toward Sri Lanka and India.
This animation was developed by scientists at NOAA’s Pacific Marine Environmental Laboratory in Seattle.
PowerPoint presentation introducing fundamental concepts and observations of Earthquake Seismology. May be used either as learning aid for teachers of Earth Science or edited by Earth Science teachers for classroom use. Note: When using the PowerPoint slides as a learning resource, it is important to read the notes that accompany each slide. These notes appear below the slide in PowerPoint “Normal View”.
QuickTime animation developed by Jenda Johnson to illustrate how sudden release of stored elastic energy (elastic rebound) in a subduction zone causes the leading edge of the over-riding plate to jump seaward and uplift while the near-shore land area subsides. The sudden displacement of the ocean floor generates a tsunami. The tsunami that arrives onshore near the subduction zone is the “local tsunami” that arrives 20 – 30 minutes after the displacement of the ocean floor by the earthqauke. The tsunami that travels into the open ocean will arrive hours later on distant shores. Notice that the near-shore area uplifts as elastic energy is slowly stored by deformation of the plates that are locked by friction along the plate interface. When the earthquake releases the stored energy, the near-shore area suddenly drops by a meter or more. This causes near-shore areas that were near sealevel before the earthquake to drop into the intertidal zone. This “co-seismic subsidence” kills trees in near-shore forests and results in a ghost forest of dead trees in a tidal marsh.