SOME ASPECTS OF METHODS OF OBSERVATION OF ACOUSTIC NOISE

IN THE EARTH'S CRUST

Askold Belyakov [email protected]

Abstract

Measurements of acoustic noise in the crust devices that may concurrently fix the high-frequency (over 500 Hz) and low frequency (less than 20Hz), the processes do not allow it to explore the variation of the amplitude - frequency characteristics in a large dynamic range. These works must be performed magneto elastic devices feature which increases with increasing frequency, and compensates for the decline in the amplitude of the natural acoustic noise in the Earth's crust to millionths of a nanometer.

To understand what happens in the crust the day before the earthquake, it is necessary to establish causal relationships between background noise variations and their sources. This should be done in a continuous monitoring mode, comparing the actual variation with background. For the calculation of background variations using the gravitational force of the Sun, the Moon and the other major planets in the solar system.

It is essential for the successful analysis of long plots of noise and intensity of earthquakes, averaging must be carried out in the "lunar" intervals (7, 14, 28, ... days). Rhythm action of solar gravity allows any averaging interval, but the lunar gravity and all its consequences only occur when using "lunar" intervals.

Academic study of the fundamental properties and practical about the seismic hazard warning system require different registration schemes. In the first case, a simple registration scheme three broadband signals, while the second requires the prior allocation of the analog four lanes in each of the three signals prior to their registration and displayed on the monitor of a wide format 12 bands for instant expert evaluation.

Keywords:

Underground noise, solar and lunar gravity, calendars, "lunar" averaging intervals, magneto elastic instruments, band pass filters, the registration system.

SOME ASPECTS OF METHODS OF OBSERVATION OF ACOUSTIC NOISE

IN THE EARTH'S CRUST

Askold Belyakov [email protected]

Status of MS research and low-frequency acoustic noise (AN) in the earth's crust, designed to forecast earthquakes, mostly limited to the classical concepts and instruments used. Modern devices cannot capture the dynamics required for the forecast of high frequency processes, in particular, variations in the amplitude - frequency characteristics of the AN. The effectiveness of borehole investigations AN, in the vast majority, sharply limited by the actual top speed sensors used (velocimeters - 110 Hz and accelerometers - 500 Hz). In addition, the sensitivity and dynamic range of these devices are not capable of detecting high-frequency natural AN preceding earthquake, which are in the earth's crust have very low amplitude and high dynamic range.

For this kind of research is necessary to use the original magneto elastic devices, which measure the rate of acceleration offset in a solid medium. The sensor has a unique low noise level, which allows for its huge dynamic range (over 240 dB) and a relatively wide band of frequencies from a few Hz to several thousand Hz. Frequency response steeply increases with increasing frequency of the magneto elastic sensor (f3), which compensates for the decline in the amplitude of natural AN in the earth's crust and allows measurements at high enough for the earth's crust frequencies (up to 2 kHz or more) with very good resolution at amplitudes (less 10-15m). The sensor device is unique, and its rigidity and strength ensure the safety of its properties for many years.

The advent in recent years of new digital recording equipment allowing autonomous record seismic acoustic signals in a wide frequency band, each channel using the frequency up to 100 kHz sampling. The developed devices, such as in seismology and applied research: seismic prospecting, the increase in oil production by means of vibration effects on the oil reservoir and the detection of weak geoacoustic signals of artificial origin, superior in its parameters (sensitivity, frequency band, the shape characteristics and dynamic range) all known devices. This was confirmed by comparative tests and published reports on the LBNL seminar in July on the AGU conference in San Francisco in December 2010. After the test, the device was installed in the pilot borehole seismic polygon SAFOD at a depth of 1000 m:

http://earthsciences.typepad.com/blog/2012/05/listening-to-seismicity.html

Translation monitoring to a new level (of the original broadband signal registration) allows more than one order, to increase the sensitivity and, therefore, a detailed study of high-frequency signals geoacoustic whose amplitude may be less millionths of a nanometer. These earlier results as a unique continuous long-term series of data in geoacoustic third octave bands with center frequencies of 30, 160, 500 and 1000 Hz from wells with different geological conditions, averaged over one minute, were the original material for research. These data helped to develop a model of the background behavior of DB in the gravitational effects of the Sun and the Moon. In developing the model used is a fundamental concept as the action. The action is a physical quantity having a dimension of a product on time and energy expressed in   J • s (dimension [H = W • T = L2 MT-1]). The action is one of the essential characteristics of the motion and the quantum of action h = 6.626 • 10-34 J • s (Planck's constant) is its minimum value. It all begins with the action of the mechanical movement, the parameters describing such variables as displacement, velocity, acceleration and speed of the acceleration of material points of the medium (the body, the particles), where the action takes place. The dynamic range of activities in the Earth's crust is vast, it can begin the quantum of action and end with the strongest earthquakes release energy over 1.6 J • 1018.

Historically, the study of action in the crust related to the earthquake, roughly speaking, began with the registration of large displacements of the earth's crust with respect to some portions of the inertial mass. The sensitivity of such devices did not depend on the frequency of vibrations in the earth's crust (f0).

The next important step in the development of earthquake recording systems became displacement measurement speed. Register displacement speed proved to be very convenient, and it is widely used in modern seismology. The sensitivity of the instrument increases in proportion to the oscillation frequency (f1). Creating devices that convert force into an electrical signal, possible to create a registration system acceleration displacement. Such systems are also widely used, and their sensitivity increases in proportion to the square of the oscillation frequency (f2). In 1985, on the basis of ferromagnetic crystalline materials with unique magnetic properties, it was created accelerate the speed of the registration system, which in physics is called "rush." The sensitivity of the new devices is growing in proportion to the cube of the oscillation frequency (f3). This property makes the amplitude-frequency characteristics of a new unique device for measuring the earth's crust.

In the science of earthquakes - Seismology - instruments that measure the motion parameters listed are appropriate name: strain gauge, accelerometer and velocimeter. The new device is called - velaccmeter (velocimeter • accelerometer). Seismology, which studies the earthquake itself, uses mostly gauges and velocimeters. The application of geophysical investigations using velocimeters and accelerometers. Velaccmeter created relatively recently, is designed to study the Earth's crust vibrations in fundamental and applied problems of seismology and geophysics, as well as a number of other tasks that require measurement vibration displacement with frequencies up to several thousand Hz, with amplitudes less than millionths of a nanometer.

The fundamental problems, for example, include the Earth's crust monitoring solid space for the purpose of registration of changes in high-frequency DB before earthquakes, surround-depth monitoring of the ice sheet of Antarctica as part of the acoustic detectors, recording flight of neutrinos and sound recording during the motion of the crust plate in the Mariana Trench, near the bed "Moho".

To understand what happens in the crust the day before the earthquake to install the main causal relationships between background movements and sources of their actions. And this should be done in a mode of continuous monitoring and comparison need adequate dynamic model of the source of action, which can be obtained by calculation for any location on Earth. Numerous short-term experiments to study the properties of the DB in the crust, conducted since 1985 in the summer in different parts of the Earth, pointed to its instability, which had a pronounced circadian period. The main natural cause of instability detected DB can only be a gravitational force of the Sun, the Moon and the other major planets in the solar system. This was taken as an axiom. As a basis for the creation of DB variation model chosen graphic design changes over time relative volume deformation of the crust of the solid medium by gravitational influences (dimension [L2 MT-1]). Most clearly manifested DB connection with the absolute rate of change of the relative volume deformation, that is, with the option closest to the energy assessment process (dimension [L2 MT-2]). It should be borne separately by solar and lunar component of gravity in the Earth's crust, although, according to some opponents, this is contrary to the principle of superposition of fields, but nevertheless, when creating a model summarized not vector gravitational field of the Moon and the Sun, and the results of their separate action in the earth's crust in the form of scalar energy. Dedicated energy dissipated in the earth's crust in the form of heat and AN. Against the background of AN can be larger seismic events. Seismic Events, AN, in principle, anything other than the amount of energy does not differ; both are subject to the law of the Gutenberg-Richter. This gives reason to believe that AN, small and large earthquakes are a common cause-and-effect relationship with the gravitational forces. This link prominently on joint plots the intensity of earthquakes and the energy model of sufficient duration (from a few days to decades). Most convincingly demonstration the 19-year Metonic cycle.

It is essential for the successful extensive analysis graphs the intensity of earthquakes, averaging, including for model graphs must be made solely to the moon slots (7, 14, 28 ... days), rather than decimal. The fact that the rhythm of the action of solar gravity allows any averaging interval, but the lunar gravity and all its consequences are well appear only when using the "lunar" intervals. Indicative duration of the studies - over 20 years - is related to the Metonic cycle, which is in compliance with the above recommendations, allows us to observe a good synchronization schedules intensity earthquakes and energy model.

Meton, the ancient Greek astronomer who lived in 433 BC, found that every 235 lunar months (19 years), new lunar year again coincides with the spring equinox. The action of solar gravity during the spring and autumn equinoxes smoothly changes its diurnal phase by 180°. In the northern hemisphere the maximum action of solar gravity observed in summer at noon, local time, and in the winter - at midnight, and the force of gravity in the winter more than summer. This is well illustrated by the earthquake and charts on the model chart. Phases of the Moon, lunar months is a very natural unit of account. Therefore, I believe the lunar months of the year the Romans, Babylonians, Greeks, and Jews. Lived lunar calendar to the present day Muslims. But it must be said that the lunar calendar is very inconvenient. In some countries, local and preserved religious lunar calendars, but leaving the international arena, they are forced to use common Gregorian calendar, which is 12 months, while the annual revolution of the Earth around the sun. Twelve lunar months it is almost time of the annual revolution of the Earth around the Sun, but "almost" very significant. The difference is close to eleven days. The moment of the vernal equinox in one year will have the first day of the first month of the lunar calendar, the next - already on the twelfth, a year later - at the twenty-third, and so on After 19 years, all again. During this cycle, the value of the joint action of the solar and lunar gravity is changing gradually, but significantly. Also, the intensity varies considerably (number per unit time) earthquakes occurring in the local site or in locations near one meridian. This confirms the fact that the natural processes of the earth's crust are associated mainly with the movements of the Earth and the Moon, in contrast to the rhythm of our civilization, using the Gregorian calendar that is associated exclusively with the motion of the Earth around the Sun.

After many years, disjointed and episodic observations Geo Acoustic Observatory (GAO) on the basis of Vorotilovskoy Deep Well (VDW) and its satellite (SS) was created, which are located in the center of the European part of Russia. GAO established in creative collaboration of the Institute of Physics of the Earth RAS (Moscow) and the Institute of Applied Physics of the Russian Academy of Sciences (Nizhny Novgorod). VDW and SS drilled in the center of the East European platform in the junction zone of the Moscow syncline and the Volga-Ural anticline in the central part of local anomalous object - Precambrian Vorotilovskogo projection Puchezh Katunkskoy-ring structure. In relation to the foundation - is the north-eastern end of the Moscow area Archean-Proterozoic complexes at the junction of the North Dvina and the Volga-Oka Early Archean massifs. VDW and SS are free from industrial noise. And for many years they have been used successfully to study AN "in situ". However, the first detailed measurements of continuous digital AN, were made in winter 2011. Measurements made over 8 days with the 8 kHz sampling rate. They showed amazing coincidence schedule DB and the estimated schedule of theoretical energy model that adequately and before that was tested multiple times [1].

Even more surprising was the coincidence of the data charts with a frequency of 20 Hz Z-component seismograph STS-2 at the station OSW Japanese Ogasawara Station, which is located on Chichijima Island in the Philippine Sea (coordinates of the point of observation: 27.0983N, 142.1961E), for the periods from 01 to 15 July 2014, and from 01 to 15 January 2015, to speed the theoretical model [2]. Speed theoretical model has been developed and successfully applied earlier (in the summer of 1989). When at a depth of 2000m was recorded intensity AN with frequency 30Hz. Registration was carried out a pen on paper [3].

Further, in developing a computer monitoring system, the analog processing has provided the original signals (X, Y and Z), with the release of each of four frequency bands. The signals were detected in the allocated bands for computer software once per minute recorded time (GMT) and 12 positive numbers averaged data, which, in fact, were energy and spectral estimates AN. Therefore, to compare the correctness, velocity model has been replaced by energy model. The last 5 years, due to the significant progress of the available equipment, the opportunity to register the three original signals (X, Y and Z) to sampling rate to 100 kHz each mode 'eternal' monitoring. In this regard, the velocity model is again relevant for fundamental research.

To specify "research of MS and a low-frequency AN in the earth's crust, aimed at the prediction of earthquakes", as it was announced in the beginning, a priori need to know the purpose for which monitoring will be used particularly: the first - for the academic study of the fundamental properties and the second - for practical work in experimental warning system of seismic hazard. For the first objective can be used a simple registration scheme three broadband signals to removable media with the possibility of further processing and investigation.

The second goal is technically more complex and requires a pre-processing analog signals prior to their registration. Pretreatment signal is analog amplification three signals X, Y and Z (0, 20, 40 or 60dB), separation and optional gain (50dB) signals in the frequency bands of 20, 160, 500 and 1000Hz for each of the three signals and their detection. Thereafter, 12 signals (four bands in each of the three channels) are digitized and recorded on digital storage media. At the same time data in graphical form should be displayed on the big screen in near real time for instant expert evaluation.

Askold Belyakov

                           [email protected]

San Francisco

REFERENCES

1. A. S. Belyakov, V. S. Lavrov, and A. V. Nikolaev, Dokl. Earth Sci. 448 (2), 209–210      (2013).

2. A. S. Belyakov, V. S. Lavrov, V. A. Muchamedov, and A. V. Nikolaev, Dokl. Earth Sci. 467 (1), 293–294 (2016).  

3. A. S. Belyakov, G. M. Vereshchagina, and V. V. Kuznetsov, Dokl. Akad. Nauk 313 (1), 53–54 (1990).