A seismograph is an instrument for measuring earthquake (seismic) waves. They are held in a very solid position, either on the bedrock or on a concrete base. The seismometer itself consists of a frame and a mass that can move relative to it. Seismographs are equipped with electromagnetic sensors that translate ground motions into electrical changes, which are processed and recorded by the instruments’ analog or digital circuits.

1. PRESENTATION ON
SEISMOGRAPH
By
Deepanjali Sahu
Assistant Proffesor

2. TOPICS
 What are Seismograph and their Work???????
 History
 Types of Seismographs
 Seismic Station

3. WHAT ARE SEISMOGRAPH???
 Seismograph is an earthquake recording
instrument which measures, in details, the
ground shaking.
 They are the waves of energy suddenly
created by the breaking up of rock within the
earth or an explosion .They are the energy
that travels through the earth and is
recorded on seismographs.

4. HISTORY CONT
 Around 132 AD, Chinese scientist Chang Heng
invented the first seismoscope, an instrument that
could register the occurrence of an earthquake.
 They are recorded on instruments called
seismographs. Seismographs record a zigzag trace that
shows the varying amplitude of ground oscillations
beneath the instrument. Sensitive seismographs,
which greatly magnify these ground motions, can
detect strong earthquakes from sources anywhere in
the world. The time, location and magnitude of an
earthquake can be determined from the data recorded
by seismograph stations.

5. SEISMOSCOPE
 Fig : Chang Heng's seismoscope

6. SEISMOMETERS AND SEISMOGRAPHS
 Seismometers are instruments for detecting
ground motions
 Seismographs are instruments for recording
seismic waves from earthquakes.
 Seismometers are based on the principal of an
“inertial mass”
 Seismographs amplify, record, and display the
seismic waves
 Recordings are called seismograms

7. o Seismology - the Study of Earthquakes and
Seismic Waves

8. SIMPLE MASS-SPRING-DASHPOT
 Simple mass-spring-dashpot

9. TYPES OF SEISMOGRAPH
 Short-period seismographs
 Long-period seismographs

10. P-WAVE

11. S-WAVE

12. SEISMIC STATION
 An individual seismic station consists of a
seismometer for sensing ground motion, a
clock for determining time, and a recorder for
collecting data.

13. THE END
 .