EARTHQUAKE DISASTER CAUSES IN CIVIL ENGINEERING

EARTHQUAKE :

   earthquake are one of the most dangerous and destructive natural hazardous. it is a sudden shaken or vibration in the earth crust. three types of classified are focus, fault, epicenter. focus is the point of origin of an earthquake inside the earth. epicenter is the point on the surface vertical above the focus.

 causes of earthquake:

• block of rocks touch or move against each other in the semi liquid layer cause earthquake 

•  volcanic activity is another cause of earthquake and land sliders

•   earthquake which originate the sea causes great disturbance like tsunamis.
• damages of building and damages of dams on river 

 what is earthquake:

    an earthquake is a sudden shaking of the surface of the earth by the passage of the seismic waves. (first detected seismic waves R.D. OLDHAM ) through earth rocks. it is also known tremblor, tremor or quake.

     

 there are three type of seismic waves:

      p waves ( primary waves) -average speed is 8 to 14 kmps travel to medium solid liquid and gas

      s wave  (secondary waves) - so move from solid does not liquid

      l wave  ( load waves) - does solid

the strength or magnitude of an earthquake is measured by richer scale by C.F RICTHER. the vibrations caused by an earthquake are detected by a seismometer and on a seismograph.

TYPES OF EARTHQUAKE:

   there four types of earthquakes namely

• tectonic - this occurs when due to geological forces on rocks and the adjoining plate cause physical and chemical change and results in the breaking of the earth crust  
• volcanic - results from tectonic forces and occurs in conjunction with volcanic activity
• collapse - the are generally small earthquakes that occurs in underground caverns and mines caused by the seismic waves which produced from the explosion of rock on the surface
• explosion - the occurs due to the detonation of a nuclear or chemical device.

 HIGHEST MAGNITUDE SCALE:

  magnitude occurred on may 22 1960 near valdivia, it was assigned magnitude of 9.5 

   may 27 1964 prince william sound, alsaka, it was assigned magnitude of 9.2

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