Since the formation of the globe, the base of the surface has been constantly in motion. The earth's crust, when moving, can lead to terrible consequences in the form of such a phenomenon as an earthquake. When one plate crawls onto another, the internal stress of the continental crust accumulates, when the critical point passes, the accumulated energy is released, causing terrible destruction. To avoid victims during an earthquake and to study the phenomenon itself, a seismograph was invented. With its help, it became possible to determine the amount of energy released during the fluctuations of the earth's crust.
What is a seismograph
The very word "seismograph" comes from Greek and directly means "record", "earthquake". The oldest seismograph was made in ancient China. It was a large bronze bowl, which was held on eight dragons, in the open mouth of each dragon there was a ball. Inside the bowl wassuspended pendulum attached to the rack, which was installed rigidly on the base of the slab lying on the surface of the earth. When an oscillation occurred, the pendulum hit the wall of the bowl, and a ball fell out of the dragon's mouth, falling into the mouth of a metal toad located at the bottom of this structure. Such a device could detect fluctuations 600 km from its location.
Working principle
The principle of operation of a seismograph is based on the transmission of vibrations to objects installed on a section of the earth's crust. When one plate of the earth's crust is located on another, a huge amount of energy accumulates, when it is released, a shaking occurs.
What is a seismograph? Modern instruments consist of a pendulum suspended by a thread and fixed to a stand firmly planted on the ground. At the end of the pendulum there is a pen, which, when oscillating, will plot the amplitude of the strain value. The drum with paper, on which the earthquake process will be displayed, is also installed rigidly on the ground. When an earthquake occurs, the pendulum stays in place due to inertia, and the drum with paper oscillates, plotting the value of the energy released during the earthquake. Modern devices are able to control even minor changes that do not bring destruction.
What is a seismograph in animals? Their body is designed in such a way that the slightest changes in the atmosphere and the state of the earth's surface within a radius of several kilometers cause them anxiety. The law of self-preservation kicks in and they leavedangerous areas. The most sensitive to the earthquake phenomenon are considered to be those of amphibian and reptile species, that is, snakes, frogs, lizards.
Features
Modern seismographs are able to determine and measure the amplitude of vibrations in three planes. When measuring vibration velocity, seismographs have a measurement frequency range from 0.3 to 500 Hz, with a vibration velocity measurement range of 0.0002 to 20 mm/s. Seismographs are both portable and stationary. The latter are large in size and installed specifically once and for the entire service life. Portable ones can be reinstalled in a certain place depending on the terrain. All modern models are equipped with software interfaces and directly transfer all their measurements to a database on a computer.
Application features
What is a seismograph and where to install it? It is placed in potentially dangerous areas where manifestations of fluctuations of the earth's crust are possible. Portable seismographs are installed in mining or underground mining areas to avoid human casu alties by preventing earthquakes and evacuating workers. When installing it should be taken into account that the device can give serious errors if it is installed near roads where heavy equipment can pass.
