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Earthquake

  • What is Earthquake? Natural and artificial earthquakes. Determination of earthquake and its location, results, Earthquakes in history:
  • An earthquake (also known as a quake, tremor or temblor) is the seismic fluctuations that occur in an unexpected event in the earth’s crust and the earthquake of these waves. Seismic activity refers to the frequency, type, and size of the earthquake in the area in which it occurs. Earthquakes are measured by seismograph. Seismology is also called the science branch that studies these events. The severity of the earthquake is determined by the moment magnitude scale (or the Richter scale used in the past). According to this scale, severe earthquakes can be devastating if 3 or more severe earthquakes are not generally felt. The severity of the jerk is measured by the Mercalli violence scale. The depth of the point where the earthquake occurs is also influential to the demolition force and the earthquakes that occur near the earth face are more damaging.

 

  • The earthquakes that occur on the surface of the earth sometimes show themselves as shaking and sometimes shifting. Sometimes a strong earthquake near the earth can cause tsunami. These convulsions can also trigger landslide and volcanic activity.

 

  • In general, the term earthquake is used to refer to the seismic waves that any seismic event-produced as a natural phenomenon or caused by humans. Earthquakes usually occur by cracking fractures (fault lines). In addition, volcanic activity can also occur as a result of earthquakes, mine explosions, or nuclear tests.

 

    Fault types

    Fault types

  • Natural earthquakes
  • Types of earthquake fractures
  • There are three types of fractures. These; Inclined strike reverse fracture, normal slope inclined fracture and strike slip fractures.
  • Many earthquakes on earth are sloping and strike-slip faults occur as a result of fractures.

 

  • Aftershocks
  • After the main earthquake, it is called aftershock. The aftershocks occur at the center where the main depression is felt, but the violence is smaller than that. If aftershocks occur more intensely than the main earthquake, it should be known that the earthquake which preceded the next earthquake is not the main earthquake but the leading earthquake, and the earthquake which is called the aftershock is actually the main earthquake.

 

  • Earthquake storm
  • An earthquake is a series of events in a certain region. The difference from the aftershocks is that one depression is not connected. This is possible in earthquake storms when the main earthquake does not come to the scene of violent artifacts higher than it. An example of an earthquake storm is the 2004 seismic activity at Yellowstone National Park.

 

Quake epicenters 1963-98

Quake epicenters 1963-98

  • Size and frequency of occurrence
  • Every year around 500,000 earthquakes occur in the world, and about 100,000 of them are felt. Guatemala. Earthquakes frequently occur in countries such as Chile, Peru, Indonesia, Iran, Pakistan, Portugal, Turkey, New Zealand, Greece, Italy, Japan and the United States.

 

  • Large severe earthquakes occur less frequently. For example; Roughly 10 times per day, most of the earthquakes are larger than 4, which is larger than 5. Also for example, Every year in the UK, earthquakes between 3.7 and 4.6 magnitude, earthquakes in the size of 4.7-5.5 within 10 years are observed, and magnitude earthquakes of magnitude 5.6 and above can be seen every 100 years. It’s called the Gutenberg-Richter rule.

 

  • According to the USGS, since 1900, an average of 18 earthquakes occurred between 7.0 and 7.9 magnitudes per year, while an earthquake of 8.0 and above occurs on average only once per year.

 

    San Francisco -Sfearth quake

    San Francisco -Sfearth quake

  • In the recent past, the frequency of earthquakes with a magnitude of 7.0 or above is decreasing.

 

  • Artificial earthquakes
  • Earthquakes are measured along long distances by seismometers because seismic waves are traveling along the Earth’s interior. The absolute severity of the depression is determined by the moment magnitude scale numbering (or the Richter scale used in the past). Accordingly, 7 and above earthquakes are destructive species. The perceived violence is measured by the Mercalli violence scale. (Intensity of 2-12)

 

  • Everywhere the shaking raises the motion of different types of seismic waves at different speeds: Longitudinal (P-waves), Latitudinal (S-waves) and some surface waves. The spreading rate of seismic waves can vary between 3 km / h and 13 km / h, depending on the density and flexibility of the environment. P-waves are much faster than S-waves on Earth. The depth of the earthquake center is also roughly measured, while the difference between the distance between the observatory and the epicenter is measured.

 

  • Earthquakes are not categorized only by their severity. Besides that, it is also important where they come from. The Earth is divided geographically and politically into 754 Flinn-Engdahl zones (F-E zones), along with seismic activity. More active areas are divided into smaller areas. Very inactive generations form large F-E zones.

 

  • Results
  • Rocking and cracking of the earth
  • Damage to buildings and structures due to rocking and earth cracking is one of the most fundamental consequences of earthquakes. The consequence is the seriousness; Depression is a complex combination that increases or decreases wave propagation depending on the intensity of the Richter scale, the distance from the central exponent and the local geological and geomorphologic conditions.
  • Earthquakes are measured by ground acceleration.
  • The geological, geomorphological and structural features typical of the region can cause a strong violent sway even in low intensity earthquakes. This is called amplification effect.
  • Floor cracks are a major threat to large and large structures such as dams, bridges and nuclear facilities.

 

  • Landslides and avalanches
  • Many and constant aftershocks following earthquakes, active volcanic mountains, strong waves hitting the shore, and aftershocks of forest fires can come into play. Landslides are also a serious danger for the personnel who are there to help after the earthquake.

 

  • Fires
  • After the earthquake, electrical lines and gas pipelines may be damaged, resulting in fires. If water pipes are also damaged due to depressions, it may be difficult to intervene on the earthquakes in a timely manner. For example; Much of the deaths in the 1906 San Francisco earthquake occurred as an unstoppable fire.

 

  • Soil liquefaction
  • Soil liquefaction can be seen as the loss of firmness of the water-saturated particulate materials after shaking and the transition from solid state to liquid state. In this case, the buildings and bridges may collapse or sink into the point. For example; Many buildings in the 1964 Alaska Earthquake collapse as a result of liquefaction of the soil.

 

  • Tsunami
  • The tsunamis represent the long-period sea wave that has formed in the ocean, or the bottom of the sea, which is the result of the tsunami-like tectonic events, such as ground slides,
  • The difference of the seabed after the tsunami from other sea ripples is that the dragging of the water droplets is the result of movement. This wave, which can not be felt in the deep sea, can reach very shallow waters by climbing up to shallow water when it comes to steep slopes or climbing up to 30 meters in the V-type constricted gulfs and canyons; It can become a natural disaster for people like earthquake, typhoon, avalanche, fire or flood.
  • Earthquakes of magnitude 7.5 or higher are more likely to generate tsunami.

 

  • Floods
  • Floods is one of the hazards that can occur after an earthquake. Floods may cause overflows of rivers and lakes as well as damages or damage to dams during an earthquake.

 

  • Tidal force
  • It was also found that the earthquakes constituted tidal forces

 

  • Human influences
  • Earthquakes can cause cracks and breaks in buildings due to illness, lack of basic needs, loss of life, high insurance premiums, general property damage, roads and damage to bridges. It can cause much more than existing damage by moving volcanic activity

 

  • Major earthquakes
  • The largest earthquake measured on Earth is the earthquake of 9.5 magnitude, which took place in the city of Cañete in Chile on 22 May 1960. Looking at energy drainage, the next largest earthquake occurred in Alaska on March 27, 1964, from 9.2.
  • The biggest earthquake in the world, measured at 8.5 and over, is the earthquake that broke out in the Indian Ocean in 2004, except for the earthquakes that caused the most casualties.
  • The most important consequence of earthquakes is that people lose their lives. When a strong earthquake occurs, there are significant risks to the oceanic coasts and areas where most people live. Depending on this depression, the tsunami can reach the square and can even affect areas thousands of kilometers away. Other people in distress are people living in poor areas where depression does not matter and in uncontrolled built structures where earthquakes are rare but strong.

 

  • Historical
  • Before the Middle Ages
  • Quote of a book from - 1557

    Quote of a book from – 1557

  • From the 5th century to the 14th century, when the Greek philosopher Anaxagoras lived, earthquakes were tied to the air voids in the Earth’s cavities.
  • Thales, who lived in Milton before 625-547, claimed that earthquakes were caused by tension between earth and water. According to the official Anaksimenes, the fact that the slopes were dry or wet was the main reason for the earthquakes. Another philosopher, Demokritos, showed the water as a cause of depression. Gaius Plinius Secundus described the earthquakes as underground storms.

 

  • Culture and earthquakes
  • Mythology and earthquake
  • In Scandinavian mythology, God Loki is shown as the reason for the earthquakes.
  • In Greek mythology, Poseidon was seen as the reason and god of earthquakes. Whenever he felt bad, he stuck his 3-fork, causing earthquakes and other disasters. Apart from these, he also used the earthquake to frighten people and to revenge them.
  • In Japanese Mythology, it was believed that the giant catfish, called Namazu (鯰), caused the earthquakes. Namazu lives under the mud of the earth and is imprisoned there by God Kashima. When Kashima releases him, Namazu begins to clap and leads to major earthquakes.
  • According to ancient Turkish mythology, the Turks conceived of the earth as a rectangle. The earth was divided into four directions. The Altaic Turks believe that ‘the world is first a circle, then a square’ (Coruh 2002: 89). According to the Teleut Turks in the north of the Altai, the Earth was standing on four heavenly oxen: “Four heavenly oxen, not a world like a tabernacle, They were holding on to their sides. There was an earthquake from the moving of the oxen.

 

Earthquake
Author: wik Date: 10:55 pm
Geography

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