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Ward's World MGH Earthquake Facts with TYU questions

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Earthquake Article by: Christopher H. Scholz, Lamont-Doherty Earth Observatory, Columbia University, Palisades, New York. Kaye M. Shedlock, Geological Hazards Section, U.S. Geological Survey, U.S. Department of the Interior, Denver, Colorado Access to this content is available to Ward's World readers for free from McGraw Hill's AccessScience, an award-winning, digital STEM resource containing exclusive articles written by expert scientists and engineers; biographies of well-known scientific figures; science news, videos, and animations; and much, much more. Instructors can use AccessScience to guide students on their research project journeys, to help students understand scientific concepts, to support distance learning efforts, in flipped classroom approaches, and in countless other ways. Ward's World and AccessScience have partnered to offer educators a no-obligation, free trial subscription to AccessScience. Request your free trial today to discover how valuable AccessScience can be for you and your students! Get your free trial now. A sudden movement of the Earth caused by the abrupt release of accumulated strain along a fault in the interior. The released energy passes through the Earth as seismic waves (low-frequency sound waves), which cause the shaking. Seismic waves continue to travel through the Earth after the fault motion has stopped. Recordings of earthquakes, called seismograms, illustrate that such motion is recorded all over the Earth for hours, and even days, after an earthquake. Earth- quakes are one of the most destructive natural phenomena and occur with very little warning (Fig. 1). As a result, earthquake early warning, or seismic alert, systems are being implemented in earthquake-prone cities and regions. + ward ' s science Content • Characteristics • Cause • Stick-slip friction and elastic rebound • Classification • Sequences • Size • Effects • Prediction • Deep earthquakes Fig. 1: Destruction and debris following the magnitude 9 Japan, 2011 (Fukushima) earthquake and tsunami. (Credit: MC1 Matthew M. Bradley/US Navy) Key Concepts • Among the most destructive of Earth's natural phenomena, earthquakes are sudden ground movements caused by the abrupt release of strain along a fault in Earth's interior, resulting in the propagation of seismic waves. • The vast majority of earthquakes occur on or near lithospheric plate boundaries, which are in continuous motion. • Earthquakes often occur in well-defined sequences in time, but can range enormously in size. • Earthquake size is measured by seismic moment. An older measure of earthquake size is magnitude, which is proportional to the logarithm of moment. • The intensity of an earthquake is a measure of the severity of shaking and its attendant damage at a point on Earth's surface, and usually decreases with distance from the epicenter. • While precise forecasting of earthquakes has remained unachievable, rough forecasts can be issued based on seismic gaps and probability estimates.

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