Earthquake Geophysics Essay
explanatory Essay
3184 words
EARTHQUAKE
Introduction:-
1 Definition:
An earthquake is what happens when two blocks of the earth suddenly slip past one another. The surface where they slip is called the fault or fault plane. The location below the earth’s surface where the earthquake starts is called the hypocenter, and the location directly above it on the surface of the earth is called the epicenter.
Figure 1; Showing the fault plane, point of origination and epicenter
(http://earthquake.usgs.gov/learn/kids/eqscience.php)
2 Earthquake Geophysics:
The earth has the following structure, a 30 km thick crust, a 2900 km thick mantle, and a radius of 3470 km core, which forms the total radius 6370 km. The crust mantle and core are further divided in to subtypes like core is divided in to outer core and inner core. There is elasticity present in the earth’s crust and it produces strain when it under goes some stresses. Elastic rebound theory of Reid is based on this property.
Reid suggests that ‘the crust, in many parts of the earth, is being slowly displaced, and the difference between displacements in neighboring regions sets up elastic strains, which may become greater than the rock can endure. A rupture then takes place, and the strained rock rebounds under its own elastic stresses, until the strain is largely or wholly relieved’.
The point where the earthquake is originated is called focus or hypocenter and on the earth surface directly above the focus, the point is called epicenter. Earthquakes are divided in to the following types according to their depths
1) Shallow focus (focus depth < 70 km)
2) Intermediate focus (depth 70-300 km)
3) Deep focus (depth > 300km)
Wave’s passes through earth and produce motion to the ground during an earthquake. There a...
... middle of paper ...
...akes.
7.4 Results:
The moment magnitude of KME was the smallest from the all the four earthquakes but the range of groundwater level change is highest from all the four earthquakes from -0.2m to 0.67m among the 54 wells. The short distance of study area to the hypocenter can be the reason for the big range of change. FOE had hypocenter which was located at shortest distance to the study area at the second number and this earthquake had also second strongest effect. Hypocenter for GYE was far from study area and thus it also had less effect on the water level, same case for the SCE earthquake its hypocenter was located 2500 Km from the study area.
The range of ground water level changes due to FOE earthquake was 0.01m – 0.15m which was at second number. The range of water level change for GYE earthquake was 0.01m – 0.05m while for SCE earthquake was 0.01m – 0.04m.
In this essay, the author
- Explains that an earthquake occurs when two blocks of the earth suddenly slip past one another. the surface where they slip is called the fault or fault plane.
- Explains earthquake geophysics, which consists of a 30 km thick crust, 2900 km mantle, and 3470 km core. elastic rebound theory of reid is based on this property.
- Explains that reid suggests that the crust, in many parts of the earth, is being slowly displaced and the difference between displacements in neighboring regions sets up elastic strains, which may become greater than the rock can endure.
- Explains that the point where the earthquake originated is called focus or hypocenter and on the earth surface directly above the focus, the epicenter. earthquakes are divided into the following types according to their depths
- Explains that wave's pass through earth and produce motion to the ground during an earthquake.
- Describes the effects of earthquakes, such as shaking of ground, displacement, fire, tsunami, flooding, soil liquefaction, and slope failure.
- Explains the magnitude of the tohoku earthquake, which is also called great east japan earthquake.
- Describes some major earthquakes worldwide with their damages to the life.
- Explains that soils and ground have significant role in earthquake assessment or seismic hazard assessment and helps to form earthquake resistant design.
- Explains that fluid induced seismicity is observed in oil-well stimulation, hydro thermal fields, filling of dams, and mine flooding.
- Explains that fluid induced seismicity is happening in oil field wells when there is less production from the oil well then the high pressured water is introduced underground in to stimulation well.
- Describes a well drilled by the us army in rocky mountain arsenal in the denver basin in 1961, where fluids were injected at the rate of 7.5-21 million per month.
- Explains that there was no seismicity in the area before the wellbore injection project started and after that a lot of seismic events happened.
- Explains that the malpasset dam collapsed due to rock foundation failure. water flowed in the fractures of bed rock at the bottom or toe of the dam, forcing it to lean downward.
- Analyzes the correlation between seismicity and increasing water level in the flooding area of a south african mine.
- Explains that the delay in seismic activity in mining was similar to that in dam impoundment. the delay fluid induced seismicity was observed in the rocky mountain arsenal case.
- Explains that earthquake prediction by environmental isotopes and tracing techniques has been noticed since 1980s. the mechanism of deep migration and to determine fault activity is used.
- Explains tracing techniques application of stable isotopes o18 and h2 can be measured with the help of mass spectrometer. investigation of circulation depth of geothermal water, water rock interactions and ground water recharge could evolve seismicity.
- Explains that groundwater shows abnormal changes due to observation environment changes or tectonic activity in the distant area. by tracing techniques of h2 and o18 the changes in water can be determined.
- Explains that earthquake gestation and occurrence is closely associated with the geothermal fluid's circulation depth.
- Explains that the greater the circulation depth of water more negative is the values.
- Explains that fault intensity becomes smaller and fault tends to move if the depth of circulation of geothermal water is large.
- Explains that wang studied the area south of zhangjiakou city for the seismicity and hydrothermal activity.
- Explains that water-rock interaction and fluid rock interaction change isotopic composition with rocks through which they are flowing. anomaly in ground water can be determined by long-term measurements of deep wells and hot springs.
- Explains that earthquakes and groundwater level fluctuations correlation can give us sign that how crust responses in response to tectonic stress and strain.
- Explains the effects of earthquakes on groundwater level changes in unconsolidated sedimentary basins. japan is one of the seismically active regions in the world.
- Describes the geological setting of kumamoto city, which is composed of unconsolidated sediments of upper quaternary.
- Explains that four earthquakes affected the groundwater level in kumamoto city during the study period of 10 years.
- Explains wang and manga (2010) and wang (2007) proposed a parameter (e) for the responses of seismic energy.
- Explains that the moment magnitude of kme was the smallest from all the four earthquakes, but the range of groundwater level change is highest among the 54 wells.
- Explains the range of ground water level changes due to foe earthquake was 0.01m – 0.15m which was at second number.
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- Explains merriam webster defines an earthquake as a shaking or trembling of the earth that includes volcanic, tectonic, or volcanic origin.
- Explains the four layers of the earth: crust, mantle, inner core, and the outer core. tectonic plates move in a constant motion, driving them into each other.
- Describes how scientists record earthquakes with seismographs, which have a base that sits firmly on the ground, and heavy weights that hang from strings. scientists measure the distance between the up and down in the graph.
- Explains that scientists use a tool called the richter magnitude scale to measure earthquakes. the scale records the amplitude of the waves recorded by the seismograph.
- Explains that the biggest earthquake ever recorded landed a 9.5 on the richter scale in chili in the year 1960. earthquakes on one side of the earth can shake the opposite side
- Defines volcanoes as a vent in the crust of the earth from which molten or hot rock and steam issue.
- Explains that volcanoes are classified as active, dormant, or extinct according to scientists.
- Explains that eruptions happen through fault lines when pressure in the mantle builds so strong it can collapse. magma gushes through the spaces and turns into lava when it reaches the earth’s surface.
- Describes the volcanic explosivity index, a tool made by chris newhall of the united states geological survey and stephen self at the university of hawaii in 1982.
- Explains that volcanoes are destructive and cause harm to many people and towns. lava moves fast and in any direction until it cools off and then turns back into rock.
- Explains that shield volcanoes have very fluid lava, usually from multiple vents or fractures, spreading over very large areas. mount kilauea and maunaloa in hawaii define good examples.
- Explains that lava domes produce from eruptions with less viscous lava. they don't spread all over because of this.
- Explains that cinder cones are the most common volcano, and their height depends on how long the eruption takes and how much lava comes out. paricutin volcano in mexico is an example.
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- Explains that earthquakes and volcanoes are dangerous because they burst out hot lava, and if people are not prepared, they will get burned and die.
1500 wordsRead More - Earthquake Essayexplanatory essayAn earthquake occurs when there is a shaking of the Earth, caused by a buildup of energy in volcanic or tectonic form (“Earthquakes”). Essentially, an earthquake results from sections of the Earth moving, causing slippage. When two chunks of the Earth slip past each other, the point at which this happens is called the fault plane. In fact, an earthquake begins in the hypocenter beneath the Earth’s surface. Next, located right above the hypocenter is the epicenter (Wald). And finally, the main, and most important thing to remember about earthquakes is that they are random, and extremely hard to predict (“Earthquakes”).
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- Explains that earthquakes occur when two tectonic plates touch each other, preventing any movement. rock breaking along a fault can cause the ground to shake because of the release of energy in the form of seismic waves.
- Explains that earthquakes can occur due to the stress and movement caused by the tectonic plates rubbing back and forth.
- Explains that intraplate earthquakes occur because of a fault that is pushed, as result of rocks that are compressed.
- Explains that a volcanic earthquake occurs when magma travels to the surface, breaking rocks, and causing an earthquake.
- Explains that earthquakes can cause landslides. earthquake magnitude has relations with the location of the earthquake, the distance, and the volume.
- Explains that foreshocks occur when pieces of rock crack under stress, before what is called the main shock.
- Explains that an aftershock is a tinier earthquake that might happen in the same location.
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- Explains that sendai, japan was hit by an earthquake on march 11th, 2011 — normally, the japanese are accustomed to earthquakes, but this time, people realized the earthquake was different.
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- Explains that earthquakes are important to study, since they affect so many people per year.
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- Opines that major earthquakes are inevitable in indiana's future. the quake, whose epicenter was located north of evansville, was a wake-up call reminding those who haven't paid attention to past warnings.
- Explains that earthquakes are volcanic or tectonic in origin, and that more than 8,000 earthquakes occur each day without causing damage.
- Explains that earthquakes are a natural part of the earth's evolution, and geologists believe that all land on earth was at one point in time connected.
- Explains the richter scale, which measures the "back and forth force" of an earthquake using an instrument called a seismograph.
- Explains that the largest earthquake ever recorded in the world occurred in chile and registered a 9.5 in 1960.
- Explains that large earthquakes reaching a richter scale magnitude of 6.0 in indiana are predicted to occur in approximately 2,000-year cycles, but geologists don't know when the last one occurred.
- Explains that the wabash river valley fault line runs between vincennes and terre haute. most predicted epicenters are located in southwest indiana and southern illinois.
- Explains that samuelson believes that there is a greater earthquake possibility in indiana. the new madrid fault line is the largest fault in the midwest.
- Opines that an earthquake along the new madrid fault line could be more devastating to indiana than a quake from the wabash valley
- Opines that an earthquake would destroy and damage property for miles from the epicenter, killing thousands of people who are not prepared to deal with its effects.
- Explains that there is not much concern in the muncie area about devastating earthquakes. samuelson is certain that if the seismic strength of a quake was great enough, it could do damage to buildings.
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- Suggests the american red cross prepare for an earthquake by preparing a home earthquake plan, practicing drills, and choosing an out-of-town contact. prepare disaster supplies for home and car.
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- Explains that earthquakes have been happening since the beginning of time, and the oldest recorded earthquake was recorded in china on 1177 b.c.
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- Explains the story of namazu, a giant catfish, in japanese mythology. it is supposedly guarded by the god of thunder and swords.
- Explains that earthquakes are the result of poseidon, god of the seas, oceans and earthquake. kisin, a malevolent underworld deity, would often uproot and destroy trees planted by chac.
- Explains that earthquakes are the result of sudden break along a fault in the earth's crust, which results in an overwhelming amount of energy that in turn causes the seismic waves to make the ground shake.
- Explains seismic waves are energy waves that are caused by the sudden breaking of rock in the earth's crust, or because of an explosion. earthquakes make up both surface and body waves.
- Explains that surface waves have a low frequency than body waves and are at fault for the destruction earthquakes cause.
- Explains that body waves travel in the earth's interior and arrive before surface waves, which are either p waves or s waves. primary waves are the fastest seismic wave and can move through solids and not liquids.
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In this essay, the author
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- Explains that earthquakes occur on earth's fault lines, but no part of the earth is free from them. the pacific plate collides with the eurasian plate.
- Explains that earthquakes can cause other hazards such as tsunamis, avalanches, and landslides.
- Explains that earthquakes are very common because the earth's tectonic plates are constantly moving. statistics show that over 1 million occur each year worldwide, but they can't be felt by humans.
- Describes the impacts of earthquakes on the economy, society, and environment.
- Explains that earthquakes have many impacts that affect the earth and us as humans. the 9.5 magnitude earthquake in chile killed more than 5000 people, and the 2011 christchurch earthquake left 100 000 homes needing repair.
- Explains that the earth is split into four layers: the inner and outer core, the mantle and crust, and the tectonic plates.
- Explains that earthquakes occur with the tectonic plates movements and with them colliding, sliding or doing both against each other.
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- Explains how technology can reduce the loss of life in earthquake-prone areas. engineers have developed a number of different ways to build earthquake resistant structures.
- Explains dunegan, h.l., prediction of earthquakes home what’s new about ae/ms.
- Explains that earthquakes are caused by a slippage of faults, which are located all over the earth.
- Explains that earthquakes are measured using seismographs and ground motions. seismograms reveal that seismic waves are elastic energy.
- Cites mooney, m.j. (1990). tsunami. (when the sea quakes) americas, vol. 42 issue 4.
1656 wordsRead More - Earthquake Essayexplanatory essayReview of Literature I. Introduction to Earthquakes An earthquake is the shaking of the ground caused by sudden release of energy inside the earth's crust. It's the breaking and moving of tectonic plates along a fault line. Earthquakes can range in size from weak where we don't feel them to extremely violent where they actually thow people around and destroy cities.
In this essay, the author
- Explains an earthquake is the shaking of the ground caused by sudden release of energy inside the earth's crust and the breaking and moving of tectonic plates along a fault line.
- Explains that earthquakes have three different types of shocks that are normally felt by humans: foreshocks, the main shock, and after.
- Explains that earthquakes are measured on two different types of seismometers: the richter scale and the modified mercalli intensity scale.
- Explains that earthquakes are classified as primary and secondary impacts. tsunamis, fires and landslides destroy everything in their path.
- Explains that earthquakes can't be predicted, as scientists have tried many different things to try to predict them, but all have failed.
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879 wordsRead More - The Northridge California Earthquakeexplanatory essayBefore examining the Northridge event, understanding the naturally occurring hazard that is an earthquake will help to better understand exactly what happened and why it was such an important geological event. With four distinct layers, two layers, the crust and upper portion of the mantle, compose the skin that is the surface layer of the Earth. The crust is not a single, continuous piece. It is actually several different pieces, or plates, that come together to form the puzzle that comprises the surface of the Earth. These plates are in constant motion rubbing against one another. These areas, known as fault lines, where the plates rub up against one another have spots where one plate ”gets stuck while the rest of the plate keeps moving. When the plate has moved far enough, the edges unstick and is how most of the earthquakes around the world occur” (Wald, 2012). The energy stored from the friction of the two plate...
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- Explains that humans accept a certain amount of risk when choosing to live their lives. tornadoes in the midwest, hurricanes along the gulf coast or earthquakes are all hazards that residents in those regions accept and live with.
- Explains that the northridge earthquake was an important geological event. the crust and upper portion of the mantle make up the surface layer of earth.
- Explains that the northridge earthquake left a lasting impression on anyone who survived.
- Explains that the northridge earthquake struck at 4:31 am local time. the response to the event occurred quickly.
- Explains that los angeles was prepared to respond to an earthquake and did so quickly. the recovery and reconstruction plan assigns primary responsibility for 300 separate tasks to at least one city agency or department.
- Opines that fema's response was no less important or immediate than that of the city, county or state.
- Opines that fema's assistance to displaced families didn't end there. it worked with the state of california and housing and urban development to relocate one hundred and thirty thousand families.
- Explains that the small business administration (sba) offered assistance to businesses and individuals. the sba issued loans totaling about four billion dollars to replace real estate damaged in the disaster.
- Explains that earthquakes have no early warning system unlike hurricanes or tornadoes, so no watch or warning was ever issued for the northridge earthquake.
- Analyzes how the northridge, california earthquake, the most expensive disaster in american history, left scars on the landscape and in the minds of those who lived through it.
- Summarizes the northridge earthquake: 1994 quake still fresh in los angeles minds after 20 years.
- Explains gordon, k., and emerson, j. governing through a disaster: lessons from the 1994 northridge earthquake.
1129 wordsRead More - Causes Of The 1906 San Francisco Earthquakeexplanatory essayMr. Adams describes the San Francisco earthquake as his most profound human suffering experience because the horror of shaking floors, parts of his mom’s house collapse to the floor, and got a broken nose from stumbling into a brick wall (Ansel Adams & The 1906 Earthquake 2008). Earthquakes are part of natural disasters of the earth and normally caused by shaking the ground and rapid movement of one block of rock slipping past another along fractures in the earth crust called faults. Faults are usually locked excluding abrupt movements with slippage that create earthquakes (Lutgens, F. & Tarbuck,
In this essay, the author
- Explains that the 1906 san francisco earthquake was a natural disaster that was estimated to be magnitude 7.8 and caused the casualties of 2,000 people.
- Describes the 1906 san francisco earthquake, a natural disaster that was responsible for structural damage and the lives of many people.
- Explains that the 1906 san francisco earthquake was worse due to the ruptured power lines, which became uncontrollable because the water mains were also broken.
- Explains that the 1906 san francisco earthquake killed around 3,000 people and left countless residents homeless. the army provided housing for 20, 000 refugees in military camps.
- Explains that the 1906 san francisco earthquake was caused by the san andreas fault, a zone of seismic activity due to the tectonic plates moving against each under the earth.
- Explains how to identify safe places such as under a sturdy piece of furniture or against an interior wall in your home, office, or school so that when the shaking starts, you drop to the ground, cover your head and neck with your arms, and crawl to it and hold on.
- Explains the basics of getting ready for an earthquake, such as dropping down into the floor and covering head and neck with arms, if still in danger of falling objects and crawling under a sturdy desk or table.
- Explains that the 1906 san francisco earthquake was originated like every other earthquake with shaking and violent movements, which according to photographer ansel adams lasted forever.
- Explains that the 1906 earthquake was the most destructive natural event in the history of san francisco.
- Explains that the 99.7% chance of an earthquake in california as predicted by the usgs is important because people prepare by creating a plan.
1908 wordsRead More