Seismology

SEISMOLOGY

The study of the seismic waves constitutes the science of seismology. It deals with earthquakes and seismic wave that move through the earth.

Seismograph

A Seismograph (or a seismometer) is an instrument used to record the earth tremors or the seismic waves, to some dynamical function of which, (like displacement, velocity, acceleration etc.) they respond or react.

The record of the vibrations so obtained is called the seismogram.

Construction & working

Generally, it consists of a mass attached to a fixed base as shown in fig. 5.6(a)

During an earthquake, the base moves and the mass does not. The motion of the base with respect to the mass is commonly transformed into an electrical voltage.

The electrical voltage is recorded on paper, magnetic tape, or another recording medioum.

This record is proportional to the motion of the seismometer mass relative to the earth, which can be mathematically converted to a record of the absolute motion of the ground.

Modern Application of Seismology

The development of the modern science of seismology has application in four important fields.

(i) Investigation of the nature of the interior of the earth

(ii) Prospecting for oils and minerals

(iii) Construction of quake-proof buildings

(iv) Forecasting of the occurrence of earthquakes.