Baishak 12,2072 (April 25, 2015), the black day in the history of a country as the earthquake of 7.8 magnitudes hit Nepal which resulted the death of more than 20,000 peoples and destruction of thousands buildings and houses(including Dharahara). Would you like to know about the machine, which measures the magnitude of such a great earthquake? The scientific instrument, which measures and records the vibrations, location power, magnitudes, and tracks duration of shaking of ground especially during an earthquake, is called Seismograph. Seismologists are those geologists who study about earthquakes. In simple terms, seismograph is an instrument, which measures seismic waves using sensitive detectors.
The first seismograph model was invented in 132 AD, by Chinese astronomer and mathematician Chang Heng. Numerous models were invented during 18th and 19th century but these models were called Seismoscopes (they only detect direction of tremors but not intensity of pattern). But the first true seismograph was designed in 1855 by Italian scientist Luigi Palmieri . Göttingen’s seismological station is the oldest but still fully operating seismological station since century ago. The credit for modern seismograph goes to British Geologist John Milne (father of seismology), who invented modern seismograph in 1880 in Japan (along with his friends James Alfrend Ewing and Thomas Gray).But, the first electromagnetic seismograph is invented by Russian Boris Golitsyn.
Seismograph consists of three pendulums (one for vertical reading and two for horizontal reading) which is mount on a support base- connected to the recorder (ink) in such as a way that only the recorder moves relative to the frame. When the ground vibrates, it records the movement of the earth. In advanced seismograph, pendulum is place within the magnetic field so that even minuscule movements would send electrical signals in the computer. The elements like aluminum, copper, steel, glass, and plastic are some important materials for seismograph. They are hold in a very solid position such as bedrock and concrete base.
In 1935, Charles F. Richter introduced Richter scale to measure the intensity of an earthquake. The reading less than 2.0 is considered as minor and above 4.5 is considered as major in the scale. The largest earthquake ever recorded was of magnitude 9.5, which hit Chile in 1997. World Wide Standardized Seismograph Network (WWSSN) has set up 120 seismographs over 60 countries in the world. Nepal falls under top 10 earthquake affected countries. Therefore, it has been a challenge especially to the Nepalese geologists and students to invent out the most advance seismograph, which would detect the epicenter and duration more precisely than today used seismographs.