GEOLOGY

Detailed explanation-1: -Most large earthquakes are followed by additional earthquakes, called aftershocks, which make up an aftershock sequence. While most aftershocks are smaller than the mainshock, they can still be damaging or deadly.

Detailed explanation-2: -When a relatively large earthquake occurs, a series of smaller earthquakes will follow continuously around the epicenter of the first earthquake. We call this first large earthquake “mainshock” and the subsequent “aftershocks”. This occurrence pattern of seismic activity is called as “mainshock-aftershock type”.

Detailed explanation-3: -Aftershocks are earthquakes that usually occur near the mainshock. The stress on the mainshock’s fault changes during the mainshock and most of the aftershocks occur on the same fault. Sometimes the change in stress is great enough to trigger aftershocks on nearby faults as well.

Detailed explanation-4: -But what is the difference? The difference is in the intensity of the quake. The initial quake always has the greatest power, or magnitude, as defined by the Richter scale. Aftershocks are smaller quakes that then occur in the general area after the main quake.