Hazards of Earthquakes | A Level Geography Revision Notes

An earthquake is described as the shaking or vibration of the tectonic plates which float on the mantle, and oftentimes, hazards of earthquakes accompany them. Some earthquakes are tiny in magnitude, while others can cause colossal disasters. Throughout history, earthquakes are responsible for many catastrophes, but due to our advanced technology developments, we can reduce some of the damage caused by earthquakes.

The time duration of an earthquake varies with its nature. For example, the Alsakan earthquake in 1964 lasted for more than 7 minutes; that means the ground was consistently moving for 7 minutes. The earthquake caused numerous deaths and destroyed many buildings.

How Does an earthquake happen?

Earthquakes are generally caused when rock underground suddenly breaks along a flaw. The abrupt impact of power causes seismic waves that make the ground shake. At the point when two squares of rock or plates scour against one another, they stick, pushing against one another, yet not moving.

Sooner or later, the stones break as a result of all the weight that occurs. At the point when the stones break, the earthquake happens. During the earthquake and a short time later, the plates or squares of rock begin moving, and they keep on moving until they stall once more—the spot underground where the stone breaks are known as the focal point of the earthquake.

The spot directly over the centre (on the ground) is known as the focal point of the earthquake. Earthquake-like seismic waves can likewise be brought about by blasts underground. These blasts might fracture rock while burrowing through streets, railways, metros, or mines. These blasts usually do not cause substantial seismic waves. You may not feel them. Sometimes, seismic waves happen when the rooftop or dividers of a mine break down. These can occasionally be felt by individuals close to the mine.

The biggest underground blasts from the trail of atomic warheads (bombs) can cause seismic waves resembling massive earthquakes. This reality has been used to authorize the worldwide atomic test boycott because no atomic warhead can be exploded on earth without creating such seismic waves.

Are earthquakes necessary?

Since earthquakes are unavoidable and unpredictable, researchers and architects make structures movement resistant. Places like California, where earthquakes continually happen, reinforce structures to withstand earthquakes. Architects utilize lighter, more favourable building materials that can deal with sideway stacks, as skyscrapers tend to sway during severe earthquakes. Earthquakes happen because our planet needs to adjust to maintain its legitimate harmony. Inevitably, earthquakes will happen because structural plates consistently alter and discharge pressure. Besides this standard self-revision, earthquakes also permit supplements and minerals to cycle from the sea to the world’s surface. Hugh Ross, one of the astrophysicists in the Royal Astronomical Society in Canada, said that “without an earthquake or structural action, the supplements required by living on the land would be undermined from the landmass and gathered in the seas.”

What are the Hazards of Earthquakes?

There are many hazards of earthquakes that bring destruction and death. Some of these hazards include:

Fire as Hazards of Earthquakes

Earthquakes can cause massive fires to break out. The shaking of the earth can cause structural damage to factories, powerplants and heavy machinery, which can cause a fire to break out. Sometimes pipelines and electrical distribution systems are severely damaged by earthquakes, which can also cause fires. These types of fires are complicated to control because firefighters and other relevant authorities are busy dealing with other damages caused by earthquakes, for example, finding people buried beneath buildings. Moreover, there have been cases where an earthquake burst the waterlines causing a lack of water to extinguish the fire.

Loss of Life (Humans and Animals)

Hazards of earthquakes include damaged buildings, such as in this densely populated area.

Earthquakes are responsible for many deaths; even animals are not spared. When an earthquake causes the death of animal life, the ecosystem of a forest or any other environment suffers a considerable blow. The balance of the ecosystem is hindered, and it takes time to restore that balance. When it comes to the loss of human life, even though people try their best to protect themselves during an earthquake, the loss of life is still substantial.

Landslides and Avalanches

Earthquakes can trigger massive landslides, which can cause extensive damage. There are cities situated near a mountain that are vulnerable to landslides. Moreover, earthquakes can also cause very dangerous avalanches. A mass of snow tumbling down a mountainside engulfs everything it touches. There have been many cases where an earthquake caused an avalanche, and the authorities struggled to locate survivors buried beneath the snow.

Tidal wave and flooding

Earthquakes can likewise cause waves, which thus cause massive flooding in beachfront regions. At the point when a substantial earthquake happens submerged, it changes the degree of the seabed and causes the water level to fluctuate. Regardless of whether it rises or falls, it is a risk to seaside zones due to the production of colossal rushes of water that “immerses” onshore. Immersion happens when much water goes inland in a brief timeframe, flooding beachfront zones. It can demolish vegetation, social structures and even entire beachfront networks. A case of massive demolition incorporates the torrent from 2004 that happened in the Far East, influencing large regions of Thailand and encompassing nations.

Demolition to Man-made Structures

Artificial structures, for example, man-made structures, are harmed extensively when hit by a substantial earthquake, making this one of the most evident consequences. Structures occasionally even break down because the establishment cannot deal with the power of the shaking ground. Streets, electrical structures and channelling frameworks are additional casualties. This devastation can prompt fires, destructive compound holes and enormous harm to transportation foundations, for example, spans.

Mass‐wasting

Ground movement may trigger avalanches and other quick mass‐wasting occasions that bring about a death toll and harm structures. A mass‐wasting variety is an avalanche by liquefaction wherein water‐soaked residue moves downslope in the form of a slurry. Structures based on firm silt may sink if liquefaction happens.

Rocks can be uprooted during an earthquake. Flaw squares may move vertically, framing another scarp along the shortcoming plane. Level development can destroy streets, pipelines, and whatever other structures are worked over the deficiency zone. Removal once in a while surpasses around 7 meters (25 feet).

Absence of Necessities

The absence of clean water to drink or the capacity to keep individuals warm brings about genuine hardship. Nourishment supplies come up short, and infections may spread in makeshift camps. Frequently, individuals cannot escape from the territory, as transport courses – streets and railroads – will probably be shut because of harm from the shake. The overcomers of an earthquake may have lost companions and family members, their homes and practically the entirety of their possessions. It is not very easy for us to envision how they adapt at this point. The unfortunate casualties of earthquakes urgently need assistance and good causes like Shelterbox, which help victims of earthquakes and catastrophic events spare lives.

Floods brought about by the breakdown of dam dividers.

Earthquakes can cause dam dividers to break down, sending seething waters into encompassing zones and causing extreme flooding.

Liquefaction

At the point when silt with a high-water content is exposed to delayed shaking, the weight of the water held in pores in the residue gradually increments in the long run, the dregs lose all durable quality and When silt with a high-water content is exposed to ground shaking, the weight of the water held in pores in the residue gradually increments in the long run, the dregs lose all durable quality and start to carry on as though they were fluids. Buildings and different structures sink into the ground or topple, and covered tanks and holes ascend to the surface. This is known as liquefaction. Liquefaction happened during the earthquake of 1692 in Jamaica and was responsible for the decimation of the town of Port Royal. In recent decades, numerous pieces of the Eastern Caribbean have become progressively helpless against liquefaction in light of the expanded utilization of recovered land for urban advancement.

Harm to the Economy

Everyday life for people in a country affected by an earthquake changes because of the harm the calamity causes to the economy. Areas that previously experienced natural disasters and unexpected events such as earthquakes have a detrimental effect on tourism, putting strain on governments and bringing about a financial downturn that can influence whole districts of the world.

Infection and Contamination from floods brought about by earthquakes.

After a tidal wave, degraded water and food supplies represent a hazard to the wellbeing of individuals. Rising waters can convey numerous supplies of harmful materials, for example, soil or oil. Moreover, unavoidable maladies increase after a tidal wave. Intestinal sickness and cholera can be progressively typical. Individuals may need to remain sheltered or in places that lack elbow room which makes spreading maladies simpler.

How to measure an earthquake?

The Richter Scale

The Richter magnitude scale was created during the 1930s by Dr Charles Richter, a seismologist at the California Institute of Technology, to measure the strength of an earthquake. Richter magnitude is determined by the logarithm of the amplitude of the largest wave recorded during seismic activity. The Richter scale is a base-10 logarithmic scale, implying there is no restriction on how small or huge the earthquake needs to be on the scale. The Richter scale consists of 1–10, with 1 being the smallest and 10 the biggest. Since the Richter scale is logarithmic, a 5.0 earthquake releases more energy than one measuring 4.0.

The Mercalli Scale

The Mercalli scale quantifies the power of an earthquake by evaluating its impact on the Earth’s surface. Given human responses and human-made structures, the Mercalli scale rates earthquakes on a scale of 1 to 12, with 1 meaning that nothing was observed and 12 signifying absolute pulverization. Designed in 1902 by Giuseppe Mercalli, the Mercalli scale is not considered as logical as the Richter scale. This is because the Mercalli scale depends on observers to report details of the earthquake, so the shaking power is not characterized by thorough and targeted principles, as the Richter scale gives.

Moment Magnitude Scale

The minute magnitude scale was presented in 1979 as a successor to the Richter scale. The minute magnitude scale denotes the vitality discharged by earthquakes. It depends on the total moment release of the earthquake and is a product of the distance a fault moves and the energy required to move it. The minute magnitude scale is more exact in estimating massive earthquakes than the Richter scale. It is used to appraise magnitudes for all major earthquakes by the U.S. Geographical Survey.

Frequently Asked Questions

What causes earthquakes?

Earthquakes are caused by the sudden release of energy in the Earth’s crust. Most earthquakes occur along fault lines, which are fractures in the Earth’s crust where tectonic plates interact. The release of energy during an earthquake causes the ground to shake.

How are earthquakes measured?

Earthquakes are measured using a seismograph, an instrument that records ground motion. The magnitude of an earthquake is typically determined using the Richter scale or moment magnitude scale, which quantifies the energy released by an earthquake. The intensity of an earthquake, which describes the effects felt at a particular location, is measured using the Modified Mercalli Intensity scale.

What are the hazards associated with earthquakes?

Earthquakes can pose several hazards:

Ground Shaking: The shaking of the ground during an earthquake can cause buildings, bridges, and other structures to collapse, leading to injuries or fatalities.
Surface Rupture: In some cases, earthquakes can cause the ground to rupture along fault lines, potentially damaging infrastructure and disrupting the landscape.
Landslides and Avalanches: Earthquakes can trigger landslides and avalanches on steep slopes, endangering lives and property.
Tsunamis: Underwater earthquakes or those occurring near coastlines can generate tsunamis, which are powerful ocean waves that can cause widespread destruction along coastlines.
Aftershocks: Following a main earthquake, there may be smaller aftershocks that can further damage weakened structures and hinder recovery efforts.

How can buildings and infrastructure be designed to withstand earthquakes?

Building codes and engineering practices can help mitigate the hazards of earthquakes. Some strategies include:

Designing structures to withstand ground shaking by incorporating flexible materials, reinforced foundations, and proper structural bracing.
Implementing retrofitting measures on existing buildings to improve their seismic resilience.
Ensuring adherence to local building codes and regulations that consider earthquake hazards.
Conducting site-specific assessments to account for local geology, soil conditions, and potential ground amplification effects.

What measures can individuals take to prepare for earthquakes?

Individuals can take several measures to prepare for earthquakes:

Developing an emergency plan that includes communication strategies, evacuation routes, and designated meeting places.
Securing heavy furniture and objects to prevent them from falling or causing injuries during an earthquake.
Creating an emergency kit with essential supplies, including food, water, first aid, flashlights, and batteries.
Educating themselves and their families about earthquake safety, including proper response during an earthquake and how to safely shut off utilities if necessary.
Participating in community preparedness programs and drills to enhance earthquake awareness and response skills.

References

Advantages and disadvantages of earthquake . (n.d.). Retrieved from brainly: https://brainly.in/question/4686748
Disadvantages of an earthquake:. (n.d.). Retrieved from Disadvantages of an earthquake:: https://sites.google.com/site/movesliketremor/products
Earthquakes: collateral effects. (n.d.). Retrieved from SMS Tsunami Warning: https://www.sms-tsunami-warning.com/pages/earthquake-effects#.Xmol-UpRW00
Effects of Earthquake. (n.d.). Retrieved from toppr: https://www.toppr.com/guides/evs/when-the-earth-shook/effects-of-earthquake/
Effects of Earthquakes. (n.d.). Retrieved from topex: https://topex.ucsd.edu/es10/es10.1997/lectures/lecture20/secs.with.pics/node10.html
Effects of Earthquakes. (n.d.). Retrieved from Cliffsnotes: https://www.cliffsnotes.com/study-guides/geology/earthquakes/effects-of-earthquakes
EFFECTS OF QUAKES. (n.d.). Retrieved from ODDIZZI: https://www.oddizzi.com/teachers/explore-the-world/physical-features/earthquakes/effects-of-earthquakes/
Hazardous Earthquake Effects. (n.d.). Retrieved from uwiseismic.com: http://uwiseismic.com/General.aspx?id=14
The Impacts of Earthquakes . (n.d.). Retrieved from Opentextbc: https://opentextbc.ca/geology/chapter/11-4-the-impacts-of-earthquakes/
What Are Some Positives and Negatives When Earthquakes Happen? (n.d.). Retrieved from Sciencing : https://sciencing.com/an-earthquake-happen-4564348.html
Why are earthquakes dangerous? (n.d.). Retrieved from bbc.co: https://www.bbc.co.uk/newsround/14649717
Why Do Earthquakes Happen? (n.d.). Retrieved from geo.mtu: http://www.geo.mtu.edu/UPSeis/why.html

What is an Earthquake?