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Which of the following events does not occur on the Earth’s surface?
Erosion and weathering are "exogenic" processes—they happen on the Earth's skin due to wind, water and ice. Volcanoes are "endogenic" but result in surface landforms. A tsunami, however, is an oceanic response to a seafloor disturbance. It is a hydraulic event triggered by a subterranean or sub-mariRead more
Erosion and weathering are “exogenic” processes—they happen on the Earth’s skin due to wind, water and ice. Volcanoes are “endogenic” but result in surface landforms. A tsunami, however, is an oceanic response to a seafloor disturbance. It is a hydraulic event triggered by a subterranean or sub-marine geological shift. Because it requires a large body of water to exist, it cannot “occur” on the dry land surface in the way a landslide or a volcanic eruption does. The tsunami only reaches the surface/coastline as a secondary effect of an earthquake that happened deep beneath the ocean floor.
See lessWhich of the following is an unpredictable natural disaster? (A) Tornado (B) Hurricane (C) Earthquake (D) Cyclone
Weather-related disasters like cyclones provide days or hours of warning through atmospheric changes. Even volcanoes often give signs like gas emissions and small tremors (harmonic tremors) before erupting. Earthquakes, however, happen deep underground without consistent "precursor" signals. DespiteRead more
Weather-related disasters like cyclones provide days or hours of warning through atmospheric changes. Even volcanoes often give signs like gas emissions and small tremors (harmonic tremors) before erupting. Earthquakes, however, happen deep underground without consistent “precursor” signals. Despite decades of research into animal behavior, radon gas and electromagnetic changes, no reliable method exists to predict an earthquake. The “stress” in the crust builds up silently over centuries and releases in seconds. Currently, our only “warning” is Earthquake Early Warning (EEW) systems, which detect the fast P-waves and send an alert seconds before the destructive S-waves arrive.
See lessWhich of the following explains the cause of earthquakes occurring on the eastern margins of Asia?
The eastern coast of Asia is a classic "convergent boundary." The Pacific Plate is moving westward and diving under the Eurasian Plate at a rate of several centimeters per year. This process, called subduction, creates the deepest parts of the ocean (like the Mariana Trench). The friction between thRead more
The eastern coast of Asia is a classic “convergent boundary.” The Pacific Plate is moving westward and diving under the Eurasian Plate at a rate of several centimeters per year. This process, called subduction, creates the deepest parts of the ocean (like the Mariana Trench). The friction between these two colossal slabs of crust is immense. When the “stuck” plates finally slip, it results in some of the most powerful earthquakes in history, such as the 2011 Tohoku earthquake. This subduction also melts the crust, feeding the chain of volcanoes that make up the islands of Japan and the Philippines.
See lessWhich seismic wave is characterized by a purely horizontal, side-to-side motion perpendicular to the direction of travel?
Named after Augustus Edward Hough Love, these waves are "trapped" at the Earth's surface. While S-waves also move perpendicular to travel, Love waves are restricted to the surface and travel slightly faster than Rayleigh waves. Their motion is purely parallel to the surface, essentially "shaving" thRead more
Named after Augustus Edward Hough Love, these waves are “trapped” at the Earth’s surface. While S-waves also move perpendicular to travel, Love waves are restricted to the surface and travel slightly faster than Rayleigh waves. Their motion is purely parallel to the surface, essentially “shaving” the ground back and forth. Because they have a high amplitude and occur at the surface where human infrastructure exists, they are the primary cause of the foundation failures and horizontal “whiplash” damage seen in high-magnitude earthquakes.
See lessThe ‘Shadow Zone’ for P-waves exists because of which physical process at the Core-Mantle Boundary (CMB)?
When P-waves hit the Gutenberg Discontinuity, the change from solid silicate rock to liquid iron-nickel causes a dramatic change in wave speed. Following Snell’s Law, the waves are refracted inward. Consequently, they are diverted away from the 103°–143° region, creating the P-wave shadow zone. UnliRead more
When P-waves hit the Gutenberg Discontinuity, the change from solid silicate rock to liquid iron-nickel causes a dramatic change in wave speed. Following Snell’s Law, the waves are refracted inward. Consequently, they are diverted away from the 103°–143° region, creating the P-wave shadow zone. Unlike S-waves, which are blocked entirely by the liquid, P-waves eventually emerge beyond 143°, but the refraction pattern leaves a definitive “silent zone.” Analyzing this specific shadow zone was crucial for scientists to calculate the exact size and depth of the Earth’s core.
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