The two important components contained in a modern seismometer are Geophone and Microphone as shown the Figure 3.2, the Geophone is to measure the voltage generated by the relative motion of the ground whereas microphone measures the acoustic response of the ground vibration. They use a tri-axial design. in which three identical motion sensors are set at the same angle to the vertical but 120 degrees apart on the horizontal. Vertical and horizontal motions can be computed from the outputs of the three sensors. Seismometers unavoidably introduce some distortion into the signals they measure: later the signal measured is processed by data detection algorithms to trigger to an event. The selection of these triggering algorithms depends upon the processing capability of the seismometer to compute the algorithms in real-time.