Seismograph (from other Greek. Σεισμός - earthquake and other Greek. Γράφω - record ) or a seismometer is a special measuring device that is used in seismology to detect and record all types of seismic waves .
A device for determining the strength and direction and measurement of an earthquake [1] .
Content
History
Seismoscope - indicates the direction to the epicenter of the earthquake. It was invented by Zhang Han in 132 in China [2] .
In most cases, the seismograph has a load mounted on a spring suspension, which remains stationary during an earthquake , while the rest of the instrument (body, support) starts moving and moves relative to the load. Some seismographs are sensitive to horizontal movements, others to vertical. Waves are recorded with a pen on a moving paper tape. There are electronic seismographs (without paper tape) with recording in storage devices.
The first seismographs were mechanical. In them, the vibrations of the body relative to the load with the help of levers were amplified and transmitted to the pen, which left marks on the drum with smoked paper [3] . In 1906, the Russian prince Boris Golitsyn invented the first electromagnetic seismograph based on the phenomenon of electromagnetic induction [4] . In such a seismograph, an inductance coil is attached to the load, which, when the case vibrates, moves relative to the magnets fixed to it. In this case, an electric current arises, the oscillations of which are recorded on photo paper instead of an arrow using a galvanometer with a mirror [5] .
Until recently, mechanical or electromechanical devices were mainly used as sensitive elements of seismographs. It is quite natural that the cost of such tools containing elements of precision mechanics is so high that they are practically inaccessible to the average researcher, and the complexity of the mechanical system and, accordingly, the requirements for the quality of its performance actually mean the impossibility of manufacturing such devices on an industrial scale.
The rapid development of microelectronics and quantum optics at present has led to the emergence of serious competitors to traditional mechanical seismographs in the mid- and high-frequency spectral regions. However, such devices based on micromachine technology, fiber optics, or laser physics have very unsatisfactory characteristics in the field of infra-low frequencies (up to several tens of Hz), which is a problem for seismology (in particular, the organization of teleseismic networks).
There is a fundamentally different approach to the construction of a mechanical system of a seismograph - replacing a solid inertial mass with a liquid electrolyte. In such devices, an external seismic signal causes a flow of working fluid, which, in turn, is converted into electric current using a system of electrodes. Sensitive elements of this type are called molecular-electronic. The advantages of seismographs with a liquid inertial mass are low cost, long-lasting, of the order of 15 years, a service life and the absence of elements of precise mechanics, which greatly simplifies their manufacture and operation.
Modern systems
With the advent of computers and analog-to-digital converters, the functionality of seismic measuring equipment has increased dramatically. There was an opportunity to simultaneously record and analyze in real time the signals from several seismic sensors, to take into account the signal spectra. This provided a fundamental leap in the information content of seismic measurements.
See also
- Seismic exploration
- Seismogeological boundary
- Hawaiian Volcanic Observatory
Notes
- ↑ A. Chudinov. Dictionary of Foreign Words Included in the Russian Language. 1910.
- ↑ Stein S., Wysession ME An Introduction to Seismology, Earthquakes, and Earth Structure. London: Wiley-Blackwell, 2002. P. 400.
- ↑ Abie, 1982 , p. nineteen.
- ↑ Abie, 1982 , p. 29.
- ↑ Abie, 1982 , p. 21.
Literature
- Kropotkin P. A. Seismometers // Transactions of the 1st Congress of Russian Naturalists: [Dec 28 1867 - Jan 4 1868]. Sep. Mineralogy and geology. St. Petersburg: typ. IAN, 1868.20-22.
- Abie J.A. Earthquakes = Earthquakes. - M .: Nedra , 1982. - 50,000 copies.
Links
- Molecular electronic seismograph. .
- Autonomous bottom seismograph. . Date of treatment November 30, 2009. Archived December 2, 2012.
- The history of early seismometers
- The Lehman amateur seismograph, from Scientific American - not designed for calibrated measurement.
- The Development Of Very-Broad-Band Seismography: Quanterra And The Iris Collaboration discusses the history of development of the primary technology in global earthquake research.
- Iris EDU - How Does A Seismometer Work?