Many disasters have struck the world we areliving in since creation. Many of them have lost and damaged millions of lives and property. Some of these disasters were man-made, while others do not have clear explanations as to what caused them. Man has divided disasters into two broad categories: natural disasters and man-made disasters. According to this classification, the natural ones are those resulting from natural environmental factors and earth processes; Examples are floods, volcanic eruptions, earthquakes, landslides, tsunamis, tornadoes, droughts, hurricanes and other geological processes. On the other hand, man-made events are catastrophic events, which are directly and principally caused by recognizable intentional, accidental or negligent human actions. However, some people still think that both natural and man-made disasters are caused directly or indirectly by man’s activities on earth. In this article, considering many questions that have arisen as a result of the catastrophic earthquakes in some parts of our world lately, we will deal specifically with one of these natural disasters – the earthquake! that both natural and man-made disasters are caused directly or indirectly by human activities on earth. In this article, considering many questions that have arisen as a result of the catastrophic earthquakes in some parts of our world lately, we will deal specifically with one of these natural disasters – the earthquake! that both natural and man-made disasters are caused directly or indirectly by human activities on earth. In this article, considering many questions that have arisen as a result of the catastrophic earthquakes in some parts of our world lately, we will deal specifically with one of these natural disasters – the earthquake!
What is an earthquake?
An earthquake is a sudden violent shaking of the earth, causing great destruction essentially due to the sudden release of energy in the earth’s crust, creating seismic waves. These waves are manifested by vibration, rumble, shaking, and sometimes ground shifting. Earthquakes occur along cracks in the earth’s surface, called fault lines, and are felt over large areas. Earthquakes can occur both on land and at sea. Other words for earthquakes are tremor, tremor, or shock.
Possible causes and effects of earthquakes
a) Natural causes:
Movements within the earth’s crust such as landslides are the main causes of earthquakes. These earth processes cause stress to build up at weak points and cause rocks to deform. The stored energy builds up in the same way as the energy that builds up as a watch springs as it is wound. Eventually, when the stress exceeds the strength of the rock, the rock fractures along a fault, often in a zone of existing weakness within the rock. As the edges of the bugs stick together and the rest of the block moves, the energy that would normally cause the blocks to slide past one another is stored. The stored energy is suddenly released, causing seismic waves that propagate at extremely high speeds (approx. 3 to 14 km/s) from the starting point of the quake, the focal point (ie the underground point of origin of the earthquake), spread out like waves on a pond. These waves shake the earth and can travel great distances in all directions. Near the focus, the waves can be very large, making the tremors and vibrations intense and extremely destructive – banging up cliffs and causing large cracks in the ground. Earthquakes can move a city a few meters from its original location on the map. The shift may or may not be significant depending on the magnitude of the tremor. These waves shake the earth and can travel great distances in all directions. Near the focus, the waves can be very large, making the tremors and vibrations intense and extremely destructive – banging up cliffs and causing large cracks in the ground. Earthquakes can move a city a few meters from its original location on the map. The shift may or may not be significant depending on the magnitude of the tremor. These waves shake the earth and can travel great distances in all directions. Near the focus, the waves can be very large, making the tremors and vibrations intense and extremely destructive – banging up cliffs and causing large cracks in the ground. Earthquakes can move a city a few meters from its original location on the map. The shift may or may not be significant depending on the magnitude of the tremor.
Earthquakes last only a few moments and by themselves rarely kill people or wildlife. It is usually the secondary post-events that trigger them, such as: B. Collapse of buildings, ground collapse, explosion of gas pipelines, fires, floods, tsunamis, avalanches and volcanoes, which actually lead to human disasters and deaths.
Earthquakes can be caused by human earth activities such as drilling and injecting fluid into wells, coal mining, oil drilling, explosions and nuclear testing, storing large amounts of water behind a dam, and possibly constructing an extremely heavy building. The most famous example of induced tremors is probably the Sichuan earthquake in the Chinese province of Sichuan in May 2008, which killed 69,227 people. It is the 19th deadliest earthquake of all time. The Zipingpu Dam is believed to fluctuate the pressure of the fault 503m away, causing severe tremors. The largest earthquake in Australian history to strike Newcastle, a city built over a large sector of coal mining land, is also said to have been caused by mankind through coal mining. It was reported that the earthquake was triggered by a fault being reactivated due to the millions of tons of rock removed during the quarrying process.
c) Supernatural causes
I. religion
Christians generally believe that the event of the earthquakes is in fulfillment of prophecy about the signs of the end times according to Jesus Christ the Messiah. In his gospel, Christ made it clear that other calamities that will befall the earth before his second coming are earthquakes, which he said will occur in different places. This is found in the holy book of Christians, the Bible. Aside from this prophecy, there are other events in the Bible where earthquakes occurred, such as Jesus’ death on the cross, His resurrection, and also when Paul and Silas, Jesus’ disciples, were imprisoned. All of these events were recorded for significant divine purposes.
ii. myths
According to Norse mythology, earthquakes were explained as the fierce fighting of the god Loki. When Loki, the god of mischief and strife, murdered Baldr, the god of beauty and light, he was punished by being tied up in a cave with a poisonous snake placed over his head and dripping the venom. Loki’s wife Sigyn stood beside him with a bowl to catch the poison, but whenever she needed to empty the bowl, the poison dripped onto Loki’s face, forcing him to yank his head away and bang against his bonds, causing the earth to tremble . In Greek mythology, Poseidon was the cause and god of earthquakes. When he was in a bad mood, he would hit the ground with a trident, causing earthquakes and other disasters. He also used earthquakes, to punish people as revenge and to inflict fear on them. In Japanese mythology, Namazu is a giant catfish that causes earthquakes. Namazu lives in the mud underground and is guarded by the god Kashima, who restrains the fish with a stone. When Kashima drops his guard, Namazu lashes out, causing violent earthquakes.
Source of the myths – en.wikipedia.org
Types, measurement and strength of earthquakes
Earthquake magnitude is an objective measurement of the energy radiated or released by an earthquake. The magnitude of an earthquake is proportional to the fracture area multiplied by the slip of the fault. It’s the size and intensity that determines greatness. Earthquakes are measured with an instrument known as a seismometer. According to size and intensity, earthquakes are mainly divided into three categories: pre-shock, main shock and post-shock. Scientists can hardly tell if an earthquake is a foreshock until a stronger one intervenes, the main shock occurs, and every other less powerful one that follows is usually considered an aftershock. The magnitude or intensity of an earthquake can range from one that is barely felt to one violent enough to throw people around.
Below is a table classifying the earthquakes according to their magnitude:
| class | size | effects | Estimated number of occurrences per year |
| Great | 8 or more | Big Earthquake. Can completely destroy communities near the epicenter. | Once in 5-10 years |
| Main | 7 – 7.9 | Major Earthquake. heavy damage. | 20 |
| Strong | 6 – 6.9 | Can cause major damage in heavily populated areas. | 100 |
| Moderate | 5 – 5.9 | Light damage to buildings and other structures. | 500 |
| light | 4 – 4.9 | Often felt, but does little damage. | 30 000 |
| lower | 3 – 3.9 | Same as light. | 90 000 |
| Insignificant | 2.5 or less | Not usually felt, but can be recorded with a seismograph. | unknown |
Table source: pnsn.org
Major and Recent Earthquake Events – Earthquake Prone Areas
A city is most likely to be prone to earthquakes when it is located on the junction of two tectonic plates, ie on a seismically active region.
One of the most devastating earthquakes in history was the 1556 Shaanxi earthquake that occurred on January 23, 1556 in the Chinese province of Shaanxi. More than 830,000 people died. Most of the houses in the area were yaodongs – houses hewn out of loess hills – and many victims were killed when these buildings collapsed.
The 1976 Tangshan earthquake, which killed between 240,000 and 655,000 people, was the deadliest of the 20th century.
The 1960 Chilean earthquake is the largest earthquake recorded by a seismograph, reaching magnitude 9.5 on May 22, 1960. Its epicenter was near Cañete, Chile. The energy released was approximately twice that of the next strongest earthquake, the Good Friday earthquake (March 27, 1964), located in Prince William Sound, Alaska.
Some of the most significant recent earthquakes are:
- The 2004 Indian Ocean earthquake, the thirdThe largest recorded earthquake in history with a moment magnitude of 9.1-9.3. The tsunami triggered by this earthquake killed at least 229,000 people.
- Azad Jammu & Kashmir earthquake (magnitude 6.9) and KPK province which killed or injured more than 75,000 people in Pakistan.
- The earthquake and tsunami in Pangandaran amounting to 7.7.
- The 7.9 magnitude May 12, 2008, Sichuan earthquake in Sichuan Province, China. Death toll on May 27, 2008 at over 61,150.
- The earthquake and tsunami in Chile on February 27, 2010 with a magnitude of 8.8 claimed 525 lives.
- The 2011 Tōhoku earthquake and tsunami recorded a moment magnitude of 9.0. The earthquake and tsunami killed 15,889 people and injured 6,152. By 2014, 2,609 were still missing.
- The most recent earthquake occurred on April 25 and May 12, 2015. It hit the country of Nepal in Asia and claimed the lives of more than 8,000 people.
Possible forecasts and possibilities of prevention
The occurrence of an earthquake has remaineduntil now unpredictable. Scientists have tried many different methods of predicting earthquakes, but none have been successful. Based on a city’s location and a specific error, scientists can always tell that there will be another earthquake at some point, but they can’t tell when it will happen. The only precautions that are currently possible are better building design, security systems, early warning and planning. For safety reasons, the popular phrase “drop, cover, and hold” is recommended during an earthquake, but offers very little protection.
With the rapid growth of megacities like Mexico City, Tokyo and Tehran, some seismologists in areas at high earthquake risk warn that a single tremor could claim the lives of up to 3 million people.
Diagram showing what happens in an earthquake