On Tuesday, January 7, an earthquake with a magnitude of about 7 on the Richter scale struck Tibet, causing approximately 1,000 homes to be damaged and 100 fatalities, earthquake, Nepal

 

       

On Tuesday, January 7, an earthquake with a magnitude of about 7 on the Richter scale struck Tibet, causing approximately 1,000 homes to be damaged and 100 fatalities. Although no significant damage was reported, its epicentre was located in Nepal and roughly 75 kilometers northeast of Mount Everest.China claims that earthquakes in Tibet have left at least 126 people dead and 188 injured. Nepal earthquake: The 7.1-magnitude earthquake, according to the US Geological Survey (USGS), was centered in the Tibet region at a depth of roughly 10 kilometers.

Earthquakes 

The seismic waves that are produced by a sudden movement (sudden release of energy) in the earth's crust (shallow-focus earthquakes) or upper mantle (some shallow-focus and all intermediate and deep-focus earthquakes) are what cause an earthquake, which is the shaking or trembling of the earth's surface. A seismograph, also called a seismometer, is a device that records and detects earthquakes.

The epicentre and focus

 In an earthquake, the focus or hypocentre is the location where the energy is released. Epicentre (first surface point to encounter the earthquake waves) is the location on the surface directly above the focal. Isoseismic lines are lines that connect all locations on the surface with the same intensity.

Both aftershocks and foreshocks Many smaller earthquakes known as aftershocks typically follow a large or even moderate earthquake with shallow focus. A foreshock is a little earthquake that occurs before an earthquake's severe shaking movement.

Reasons for Earthquakes Zones of Fault Tectonics of plates Activity of volcanoes Earthquakes Caused by Humans Zones of Fault The abrupt release of tension along a fault rupture (crack) in the earth's crust is the direct source of the majority of shallow earthquakes. Because of the extreme heat and pressure in the earth's interior, the volume and density of rocks are constantly changing, which causes abrupt slippage of rock formations along fault rupture in the crust.The magnitude that results increases with the length and width of the faulted area. Along thrust faults (convergent boundaries), the longest earthquake ruptures are roughly 1,000 kilometers long. On strike-slip faults (transform faults), the longest earthquake ruptures are roughly half to one-third as long as those along thrust faults. Normal faults (divergent boundaries) experience shorter fault ruptures.

Tectonics of plates 

Earthquakes are caused by the slippage of land along the faultline along convergent, divergent, and transform boundaries. The strongest earthquakes, known as megathrust earthquakes, which include nearly all of those with a magnitude of 8 or higher, are linked to reverse faults (convergent boundaries). At subduction zones, where one tectonic plate is driven beneath another, megathrust earthquakes take place. such as the 2004 earthquake in the Indian Ocean. The magnitude of significant earthquakes produced by strike-slip faults, especially continental transformations, can reach up to 8.Earthquakes occur along the San Andreas Fault, a transform fault where the Pacific and North American plates move horizontally in relation to one another. Normal fault (divergent boundary) earthquakes are often smaller than magnitude 7.

Activity of volcanoes 

An earthquake can also be triggered by volcanic activity, albeit these earthquakes are typically less powerful and have a smaller geographic scope than those brought on by crustal rupture. Tectonic faults and the movement of magma within volcanoes both result in the subsequent release of elastic strain energy, which causes earthquakes in volcanic zones. As was the case with Mount St. Helens' eruption in 1980, these earthquakes can act as an early warning system for volcanic eruptions. Major earthquakes and the geographic distribution of volcanoes, especially along oceanic ridges and in the Circum-Pacific Belt, clearly correlate.However, many earthquake sources happen far from active volcanoes, and volcanic vents are often hundreds of kilometers away from the epicentres of the majority of significant shallow earthquakes. Earthquakes Caused by Humans

 The term "human-induced earthquakes" describes small earthquakes and tremors that are usually brought on by human activities such as nuclear testing, large-scale oil production, mining, and the creation of artificial lakes or reservoirs.

Seismicity caused by reservoirs Stresses along an existing fault or fracture are altered by the pressure provided by a column of water in a big, deep artificial lake. Additionally, water seeping through the soil lubricates the fissures and degrades the soil structure. Stress can be considerably altered by loading and unloading water. An earthquake may result from a quick movement along the fault or crack brought on by this large shift in tension.Another potential example is the 2008 Sichuan earthquake, which killed about 68,000 people. It is thought that the earthquake might have been caused by the building and filling of the Zipingpu Dam.

Anywhere from the Earth's surface to around 700 kilometers below it, earthquakes can happen. This earthquake depth range of 0 to 700 km is separated into three zones for scientific purposes: shallow, middle, and deep. Deep focus earthquakes take place in the earth's deepest subduction zones, whereas shallow focus earthquakes are found in the outer crustal layer. The depth of shallow earthquakes ranges from 0 to 70 kilometers. The depth of intermediate earthquakes ranges from 70 to 300 km. 300 to 700 kilometers is the depth of a deep earthquake. About 12–15 percent of the overall energy released during an earthquake comes from intermediate earthquakes, 3–5% from deeper earthquakes, and 70–85% from shallow earthquakes.Shallow-focus occurs in the vast majority of earthquakes. For this reason, they are often referred to as "crustal earthquakes." Smaller magnitudes (often between 1 and 5) make up the majority of shallow focus earthquakes. However, others may be more severe and have the potential to do a lot of damage. They happen randomly and rather often. They are frequently unnoticed, though, because the majority are either smaller in scale or happen along undersea ridges. Even though they are relatively minor in magnitude, shallow focus earthquakes have the potential to inflict more surface damage than their deep-focus counterparts because all of the energy is focused on a tiny area.Earthquakes that occur more than 70 kilometers below the surface are generally referred to as "deep-focus earthquakes." A subducting slab (zone of subduction) is present when deeper-focus earthquakes frequently occur in patterns known as Benioff zones that descend into the Earth. Because of this, they are also referred to as intraplate earthquakes (caused by plate collisions). Since a lot of energy is released during the violent collision of the plates, they occur as massive earthquakes with larger magnitudes (often between 6 and 8). However, because earthquake foci are located at great depths and their energy disperses over a large area, earthquakes by themselves might not do much damage.

The Wadati Benioff zone is a subduction zone where earthquakes frequently occur. This area is where the strongest earthquakes happen (the strongest earthquakes happen near the convergent border). Numerous earthquakes with foci as deep as roughly 700 kilometers are produced by differential motion along the zone. Slip on faults within the downgoing plate (O-O and C-O convergent boundary) or along the subduction thrust fault (Himalayan Region – C-C convergent boundary) can create Wadati–Benioff zones.

Major earthquakes on Earth mostly happen in bands that run parallel to tectonic plate boundaries. The Circum-Pacific Belt, which includes several populous coastal regions around the Pacific Ocean, including those of New Zealand, New Guinea, Japan, the Aleutian Islands, Alaska, and the western coasts of North and South America, is the most significant earthquake belt. There are numerous branches at different locations, and the seismic activity is by no means consistent throughout the belt. The Circum-Pacific Belt has been referred to as the "Pacific Ring of Fire" because it is frequently linked to volcanic activity. About 68% of all earthquakes occur in the Pacific Ring of Fire. The Alpine Belt (Alps and Himalayas) is a second belt.

       

Earthquake Effects One natural hazard is earthquakes. A high-magnitude earthquake has the potential to seriously harm people's lives and property. The immediate dangerous consequences of an earthquake are as follows: Shaking of the Ground Variations in ground settling Mudslides and land Fires Lurching of the ground Avalanches displacement of the ground floods caused by levee and dam collapses Collapse of structures The tsunami.