Hazardous Effects of Earthquakes




Earthquakes cause massive vibrations in the Earth’s crust. This can cause a number of problems in the ground, which in turn becomes a hazard to all life and property. The effect depends on the geology of soil and topography of the land.

1964 Niigata earthquake

1964 Niigata earthquake

Ground Motion

The most destructive of all earthquake hazards is caused by seismic waves reaching the ground surface at places where human-built structures, such as buildings and bridges, are located. When seismic waves reach the surface of the earth at such places, they give rise to what is known as strong ground motion. Strong ground motions cause’s buildings and other structures to move and shake in a variety of complex ways. Many buildings cannot withstand this movement and suffer damages of various kinds and degrees.

Most deaths, injuries, damages and economic losses caused by earthquake result from ground motion acting on buildings and other manmade structures not capable of withstanding such movement.

Ground Failure

Strong ground motion is also the primary cause of damages to the ground and soil upon which, or in which, people must build. These damages to the soil and ground can take a variety of forms: cracking and fissuring and weakening, sinking, settlement and surface fault displacement.

One of the most important types of ground failure is known as liquefaction. Liquefaction takes place when loosely packed, water-logged sediments at or near the ground surface lose their strength in response to strong ground shaking. Liquefaction occurring beneath buildings and other structures can cause major damage during earthquakes.

Ground Sliding

Strong ground motion is also the primary cause of damages to the ground and soil upon which, or in which, people must build. These damages to the soil and ground can take a variety of forms: cracking and fissuring and weakening, sinking, settlement and surface fault displacement.

Ground Tilting

Sometimes, due to earthquake, there is tilting action in the ground. This causes plain land to tilt, causing excessive stresses on buildings, resulting in damage to buildings.

Differential Settlement

If a structure is built upon soil which is not homogeneous, then there is differential settlement, with some part of the structure sinking more than other. This induces excessive stresses and causes cracking.

Soil Liquefaction

During an earthquake, significant damage can result due to instability of the soil in the area affected by internal seismic waves.  The soil response depends on the mechanical characteristics of the soil layers, the depth of the water table and the intensities and duration of the ground shaking.  If the soil consists of deposits of loose granular materials it may be compacted by the ground vibrations induced by the earthquake, resulting in large settlement and differential settlements of the ground surface. This compaction of the soil may result in the development of excess hydrostatic pore water pressures of sufficient magnitude to cause liquefaction of the soil, resulting in settlement, tilting and rupture of structures

, , , , , ,


  1. No comments yet.
(will not be published)