wht are the causes of earthquakes ?

Question

i need an answer that tells me how does development of a city like the sprouting up of buildings etc. increase the chances of earthquakes if a city which first was full of trees and now is full of buildings

Answer 1

well city has tons of buildings and the buildings have weight. so they will add more pressure to the tectonic plates and cause them to move faster i guess. There are tectonic plates which meet at one point and they either slip, slide or grind agaisnt each other. and when they slip, this causes the earthquake. so then the more weight on the plates means also more pull. so the plates move faster or something. my guess. but i doubt it has any effect

Answer 2

Earthquakes occur from the deformation of outer, brittle portions of "tectonic plates", the earth's outermost layer of crust and upper mantle. Due to the heating and cooling of the rock below these plates, the resulting convection causes the adjacently overlying plates to move, and, under great stresses, deform. The rates of plate movements range from about 2 to 12 centimeters per year. Sometimes, tremendous energy can build up within a single, or between neighboring plates. If the accumulated stress exceeds the strength of the rocks making up these brittle zones, the rocks can break suddenly, releasing the stored energy as an earthquake. An earthquake begins when the plates push against earth other and the pressure builds. Cracks start to appear in walls and roads. The ground may shiver (tremor). Where the rocks snap seismic waves (body waves) make the ground move. The first ones ( primary ) travel through rock, volcanic lava, water and even air. They take about 20 minutes to go from one side of the earth to the other. The next waves (secondary) move only through solid rock. Body waves that reach the surface make the ground move like waves on the ocean. These are the most deadly. The quake starts with a violent jolt at the epicenter followed by more tremors. Aftershocks may occur as everything is setting into a new position.

Answer 3

It does not significantly.

Earthquakes are not influenced by man. They operate on a higher plan. They are casued by relative movements of different parts 'plates' of the earths crust. The forces are immense.

This is why certain regions of the world are more affected by earthquakes. These areas are where one plate is moving against or under or over another plate. When two plates collide the earth shakes and the earth is deformed. It can cause mountains to rise and when this is under the sea a new island may appear.

Also the disturbance of the ocean either when a large gap appears deep in the ocean bed or an under water mountain is formed, can lead to large waves 'Tsunamis' ( from Japanese ) to be formed.

Japan is a country comprising several major islands with a long coast line, it is also in an earthquake prone area of the world so they get a lot of earthquakes and sometimes Tsunamis.

The link with Cities is that in earthquake zones and California is also one such area, the design of buildings needs to take account of this risk in their design. Otherwise buildings often collapse after a major quake with great loss of life in poorer areas where buildings are not designed for safety.

Earthquake magnitude is measured by a logarithmic 'Ricta' scale which measures the power. This means a 8.0 earthquake on the scale is twice the power of a 7.0 quake.

Answer 4

Erarthquakes are caused by the giant tectonic plates rubbing each other on the planet Earth. In fact they dont rub together smoothly as such, due to great forces pushing against the plates, the plates stick as they rub, and when the force is too great for the plates to stick, the plates jolt a few feet to their new position. The jolting is the earthquake.

People have built cities on fault lines which is where the plates meet, before there was a geological understanding of eaerthquakes. And cities are hard to move you know, so theres more research into earthquake resistant buildings, eg in Los Angeles, and Tokyo.

Building cities on fault lines makes no changes whatever to geological process as tectonic plate movements the forces of which are far, far, greater than humans can impose by whatever means.

Answer 5

well the planets earth-crust is broken into different shapes and sizes and they are called the earths plates now these plates move and shift about and when they collide(bump and rub ) the impact and movement sends out shock-waves causing earthquakes throughout a small or large area of the earth depending on the magnitude of the impact of the plates
the sprouting up of buildings doesn`t increase the chances of earthquakes but if acity or the progression of acity is near avault where the earths crust is divided then at some point an earth quake is going to be felt and if it is a large earth quake then some buildings are going to fall i hope i have helped you out a bit

Answer 6

Earthquakes occur on a daily basis around the world, most detected only by seismometers and causing no damage. Large earthquakes however can cause serious destruction and massive loss of life through a variety of agents of damage, including fault rupture, vibratory ground motion (shaking), inundation (tsunami, seiche, or dam failure), various kinds of permanent ground failure (liquefaction, landslides), and fire or a release of hazardous materials. In a particular earthquake, any of these agents of damage can dominate, and historically each has caused major damage and great loss of life; nonetheless, for most earthquakes shaking is the dominant and most widespread cause of damage. There are four types of seismic waves that are all generated simultaneously and can be felt on the ground. Responsible for the shaking hazard, they are P-waves (primary waves), S-waves (secondary or shear waves) and two types of surfaces waves, (Love waves and Rayleigh waves).

Most large earthquakes are accompanied by other, smaller ones that can occur either before or after the main shock; these are called foreshocks and aftershocks, respectively. While almost all earthquakes have aftershocks, foreshocks occur in only about 10% of events. The power of an earthquake is always distributed over a significant area, but in large earthquakes, it can even spread over the entire planet. Ground motions caused by very distant earthquakes are called teleseisms. The Rayleigh waves from the Sumatra-Andaman Earthquake of 2004 caused ground motion of over 1 cm even at seismometers that were located far from it, although this displacement was abnormally large. Using such ground motion records from around the world, seismologists can identify a point from which the earthquake's seismic waves apparently originated. That point is called its focus or hypocenter and usually coincides with the point where the fault slip started. The location on the surface directly above the hypocenter is known as the epicenter. The total length of the section of a fault that slips, the rupture zone, can be as long as 1,000 km for the biggest earthquakes.

Earthquakes that occur below sea level and have large vertical displacements can give rise to tsunamis, either as a direct result of the deformation of the sea bed due to the earthquake or as a result of submarine landslides directly or indirectly triggered by the quake

Answer 7

Earthquakes occur on a daily basis around the world, most detected only by seismometers and causing no damage. Large earthquakes however can cause serious destruction and massive loss of life through a variety of agents of damage, including fault rupture, vibratory ground motion (shaking), inundation (tsunami, seiche, or dam failure), various kinds of permanent ground failure (liquefaction, landslides), and fire or a release of hazardous materials. In a particular earthquake, any of these agents of damage can dominate, and historically each has caused major damage and great loss of life; nonetheless, for most earthquakes shaking is the dominant and most widespread cause of damage. There are four types of seismic waves that are all generated simultaneously and can be felt on the ground. Responsible for the shaking hazard, they are P-waves (primary waves), S-waves (secondary or shear waves) and two types of surfaces waves, (Love waves and Rayleigh waves).

Most large earthquakes are accompanied by other, smaller ones that can occur either before or after the main shock; these are called foreshocks and aftershocks, respectively. While almost all earthquakes have aftershocks, foreshocks occur in only about 10% of events. The power of an earthquake is always distributed over a significant area, but in large earthquakes, it can even spread over the entire planet. Ground motions caused by very distant earthquakes are called teleseisms. The Rayleigh waves from the Sumatra-Andaman Earthquake of 2004 caused ground motion of over 1 cm even at seismometers that were located far from it, although this displacement was abnormally large. Using such ground motion records from around the world, seismologists can identify a point from which the earthquake's seismic waves apparently originated. That point is called its focus or hypocenter and usually coincides with the point where the fault slip started. The location on the surface directly above the hypocenter is known as the epicenter. The total length of the section of a fault that slips, the rupture zone, can be as long as 1,000 km for the biggest earthquakes.

Earthquakes that occur below sea level and have large vertical displacements can give rise to tsunamis, either as a direct result of the deformation of the sea bed due to the earthquake or as a result of submarine landslides directly or indirectly triggered by the quake.

Answer 8

An earth quake is created when the rock plates under the ground moves or rub against each other. These buildings might make these plates weaker and therefor create more earthquakes.

Answer 9

Earthquakes are caused when volcanic pressure
moves the earths crust ( tectonic plates )
the magnitude of the tremors are measured on a seismic graph .
over 4 on the "riktere scale" is bad , 5-6-7.8 become catastrophes

Answer 10

By the movement of the earths tectonic plates.
As they slide under/over each other a large scale friction is caused that sends a shock wave through the earths surface.
The ending result is the earth in the area effected also shakes, sometimes with disastrous consequences....