"Intensity" of a quake is determined based on the damages and its effect on man and urban area. Intensity is scaled in a 12-scale system called "Mercali". This scale is qualitative from I (a weak and not sensible earthquake) to XII (a destructive earthquake). Intensity reduces a way from the hypocenter and areas with the same intensity are linked by "Isoseismocity lines".

The less depth of earthquake is, the more its damages. Even though earthquake intensity reduces in far distances from the hypocenter, it might resonance in sedimentary basins and faulted areas.

Man can construct very strong buildings against quake. Around 15,000 people lost their lives in Tabas 1978 earthquakes whereas only 104 people lost their lives five years later in Japan by an earthquake with the same magnitude.

Magnitude is determined based on the energy released during a quake. The more the strain before a quake is, the higher the magnitude. Earthquake magnitude is directly related to the rock hardness. Magnitude is determined by the recorded amplitude on a seismograph. Magnitude concept was used by "Richter" in the California earthquake (SanAnderias fault) for the first time. This definition is used in other parts of the world.

Logarithm of the amplitude based thousandth of millimeters in a seismograph located 100 Km away from hypocenter is defined as magnitude. Magnitude can be determined by any seismograph instrument in any distance from the hypocenter today. If  amplitude is multiplied ten times, magnitude changes just one unit and the released energy is multiplied 31 times. No earthquake recorded with magnitude more than nine so far. In other words, nine Richter is the limit of elastic deformation of rocks and more energy can not be stored in rocks without a rupture. Energy of the atomic bomb in Hirushima was equal to a 5-Richter earthquake energy.