Answer:
A. By the circumference of the epicenter
Explanation:
If the Earth's lithospheric plates begin to move slowly, stresses emanate in the crust, most at times close to the plate boundaries. These stresses (compression, tension strain, and shear) accumulate in the crust until they surpass the rock's strength or the pressure around an internal fault. And there's a sudden slippage of rock around a fault.
The planet shakes and the rocks lurch to their new position in a matter of seconds as the stress energy is released. Seismic waves move away from the broken portion of the fault, just like ripples from a pebble landing on calm water.
Seismologists may estimate when the slippage started on a fault, the area of the slipping fault, the sum of slippage or fault throw (i.e. just how much the crust moved), and the length of time it takes for the slippage to happen by measuring the circumference of the epicenter which is the mapped area where the earthquake is taken place.
