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The ‘Elastic Rebound Theory’ fails to explain which type of seismic event?
Below 300 km, rocks shouldn't be able to store elastic strain; they should "creep" like warm wax. Seismologists believe deep-focus quakes are caused by "transformational faulting," where minerals like olivine suddenly collapse into denser forms (spinel or bridgmanite) under extreme pressure. This suRead more
Below 300 km, rocks shouldn’t be able to store elastic strain; they should “creep” like warm wax. Seismologists believe deep-focus quakes are caused by “transformational faulting,” where minerals like olivine suddenly collapse into denser forms (spinel or bridgmanite) under extreme pressure. This sudden “implosion” or volume change releases energy as seismic waves. Therefore, while Reid’s theory perfectly explains quakes near the surface, the “Deep-focus” mystery requires a more complex understanding of high-pressure mineral physics and thermodynamics.
See lessWhat is the ‘Double Benioff Zone’?
This phenomenon provides deep insight into the chemical and physical changes occurring inside a subducting plate. The upper layer of quakes is usually at the top of the slab, while the lower layer is inside the slab's "cold core." The quakes are triggered by "dehydration embrittlement"—as minerals lRead more
This phenomenon provides deep insight into the chemical and physical changes occurring inside a subducting plate. The upper layer of quakes is usually at the top of the slab, while the lower layer is inside the slab’s “cold core.” The quakes are triggered by “dehydration embrittlement”—as minerals like serpentine release water under high pressure, the water reduces friction, allowing the rock to break. Studying these zones helps scientists understand the complex water cycle of the Earth’s mantle and how fluids influence deep-seated seismic activity.
See lessWhich of the following is called the ‘safety valve of nature’?
The Earth’s interior is a high-temperature environment where radioactive decay and residual heat create intense pressure. Volcanoes act as natural pressure-release mechanisms. When the internal pressure of gases and magma exceeds the strength of the overlying crust, an eruption occurs, releasing thiRead more
The Earth’s interior is a high-temperature environment where radioactive decay and residual heat create intense pressure. Volcanoes act as natural pressure-release mechanisms. When the internal pressure of gases and magma exceeds the strength of the overlying crust, an eruption occurs, releasing this energy. This process maintains the Earth’s thermal equilibrium. By providing a controlled (albeit often violent) exit for subterranean energy, volcanoes prevent the buildup of pressure that could otherwise lead to even more massive and unpredictable global tectonic shifts. Therefore, they are essential for the geological stability of the planet over millions of years.
See lessWhich of the following statements about volcanoes is true? (A) Volcanoes are classified into three main types: active, dormant and extinct. (B) It is a conduit in the Earth’s crust through which molten rock (magma) and other materials erupt. (C) Often, a circular, funnel-shaped hill or mountainous area develops around its vent. (D) All of the above.
A volcano is more than just a mountain; it is a complex geological system. It begins as a rupture in the crust (conduit) through which magma, ash and gases escape. As this material cools and solidifies around the vent, it builds up the classic cone-shaped structure or a volcanic hill. The classificaRead more
A volcano is more than just a mountain; it is a complex geological system. It begins as a rupture in the crust (conduit) through which magma, ash and gases escape. As this material cools and solidifies around the vent, it builds up the classic cone-shaped structure or a volcanic hill. The classification into active (currently erupting or frequently), dormant (hasn’t erupted recently but could) and extinct (unlikely to erupt again) provides a framework for scientists to assess hazard levels. Together, these features define the mechanical, physical and temporal nature of volcanic activity on Earth.
See lessWhich type of volcano has not erupted since historical times?
Extinct volcanoes are essentially "dead." This happens when the tectonic plate moves away from a volcanic "hotspot" or when a subduction zone ceases to function, cutting off the source of magma. For example, Mount Kilimanjaro in Africa has three volcanic cones; while two are extinct, one is dormant.Read more
Extinct volcanoes are essentially “dead.” This happens when the tectonic plate moves away from a volcanic “hotspot” or when a subduction zone ceases to function, cutting off the source of magma. For example, Mount Kilimanjaro in Africa has three volcanic cones; while two are extinct, one is dormant. To be classified as extinct, a volcano usually must show no activity for at least 10,000 years. However, the distinction can be tricky, as some volcanoes thought to be extinct have “woken up” after millennia, technically reclassifying them as dormant.
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