Geologic and earthquake displays, brochures, and other information can be used to effectively communicate interesting and important facts and concepts to park visitors. Thus, the geologic and seismic attractions of the park present an opportunity for public involvement, education, and outreach. Many visitors to our national parks are interested in how the features within the park came to be. Many national parks are located in geologically interesting areas that include earthquakes or previous plate tectonic activity. The dynamic geologic processes that result in earthquakes also create topographic relief and interesting and beautiful landscapes. Some earthquakes are caused by human activity related to filling of reservoirs, detonation of explosions, or injection of fluids into the ground. Some earthquakes occur in plate boundary or intraplate regions associated with other dynamic geologic processes such as volcanic and hydrothermal activity, reactivation of ancient faults, or crustal loading (e.g., topographic loads on the crust such as mountain ranges, water loading due to filling of a reservoir). 1) as explained above this process is best explained by the theory of plate tectonics (Kearey and Vine, 1996). The vast majority of earthquakes occur along plate boundaries (Fig. Reid (1910) a half century before the development of plate tectonic theory. This process is called elastic rebound and was discovered after the 1906 San Francisco earthquake by H.F. When the resulting stress on a segment of a fault plane increases beyond a critical threshold, the fault segment slips, creating an earthquake from the release of stored elastic energy. As the plates move, rocks are progressively deformed (strained) along the plate boundaries (often over many years or decades), thus storing elastic energy. Due to friction on fault surfaces, faults that make up the plate boundaries generally do not slip continuously. The Earth’s plates are moving at speeds of centimeters per year, which produces deformation at plate boundaries. Most earthquakes are the result of plate tectonic processes. The release of elastic energy associated with earthquakes generates seismic waves that propagate through the Earth and along the Earth’s surface across large distances. Individuals, governments, and organizations can respond to the hazard by understanding the probability and the likely effects of significant events preparing emergency response plans enhancing public knowledge about what to do in case of an earthquake and taking specific steps (such as reinforcing critical or weak structures) to reduce the risk of earthquakes.Įarthquakes are often defined as ground vibrations related to a release of elastic energy, or as the sudden slip of a section of a fault plane, releasing stored elastic energy the latter is the most common source of significant ground vibrations. When significant earthquakes occur anywhere in the world, such as the December 2004 tsunami-generating event in Indonesia that killed more than 200,000 people, or the October 2005 earthquake in Pakistan that killed more than 70,000 people, emergency response and relief efforts come from around the globe, and there is renewed interest in understanding the causes and in mitigating the devastating effects of earthquakes.Įarthquakes can be significant hazards, as evidenced by occasional damaging and deadly events. The vast majority of earthquakes are caused by sudden slip along faults, resulting in seismic waves that shake the ground, often with sufficient force to damage structures or trigger other events, such as landslides. Most earthquakes are associated with natural, dynamic processes that shape Earth’s landscape. ![]() Thus, the earthquake process can be interesting and even frightening to people. Although earthquakes happen frequently in many parts of the world, any occurrence of a moderate to large event is sudden and unexpected.
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