Report at XXII General Assembly of the International Union of Geodesy and Geophysics (IUGG), Birmingham, UK, July 18 – 30, 1999
Yury A. Bragin, Oleg A.Bragin, Vasily Yu. Bragin
Novosibirsk State University, Pirogova 2, Novosibirsk 630090, Russia
This report is devoted to the experimental data obtained by means of the approaches and receivers especially developed by the Observatory of Atmospheric Electricity (OAE) of Novosibirsk State University. Details are available on the WEB site http://www.phys.nsu.ru/oae and were reported by Bragin [1996].
An initial aim of researches being conducted by DAE was to separate and to measure an electric field in the area between the Earth's surface and the upper conductive atmospheric layers. In other words we are interested in global component of geoelectrical field. The characteristic features of the field were described in the literature earlier. For example one the features is a unitary 24 -hour- variation of electric field. This variation is the same ( has a same phase) around all the Earth's surface. Unfortunately no continued instrumental monitoring of this field was performed. That is why we can not compare our data with any other independent studies.
Any measuring procedure demands to carry out analysis of sources of statistical and systematic errors of experiment One needs to show clearly the sources for the statistical data dispersion and sources whose disturbing influence on the measuring is impossible to estimate (a systematic error).
For example, a sensor, placed in DAE Novosibirsk observatory station, measures an electric (actually - quasi - electrostatic-) field that is generated simultaneously by many possible sources of electrostatic charges: Sun wind, Lunar, Earth ionosphere, stratosphere, clouds, smoke, dust and different man-caused factors. There are many methods to separate an electric field generated by sources of definite origin. The methods themselves are relatively simple and easy to use. Unfortunately multiplicity of the mentioned sources makes analysis of the measured field quite difficult. We avoid this difficulty by means of employing principally different sensors and using an original method of separation of electric fields of different origin. In this way the global component of geoelectrical field was separated.
We got a first confirmation that we measure exactly the global component of the atmosphere field while recording a response of atmosphere to an explosion made in USA (Nevada) Fig.1. The 10 m sphere with explosive equivalent 5 K tonne of TNT was officially announced. The record was made by DAE's Observatory in Novosibirsk.
Further we became able to determine a specific response of the electric field to a big rocket start, powerful explosion of ammunition depot, chemical plants, oil and gas pipelines. We recorded the responses on nuclear explosions in China, India and south region of Pacific as well.
The subject is extremely important and large but it is out of view of current report.
The selected component of the global field has large systematic error. Analysis of these records clearly showed the existing of time variation of this error but at first we had no idea about its origin. It should be noticed that we, like most of researchers, accepted as correct a possibility to study electricity of the Earth depth and atmosphere independently, supposing their mutual influence as negligible. At the end of 1994 a large perturbation of the global electric field and an accompanying systematic error were observed. It was impossible to explain the phenomena on the base of the upper atmosphere processes or any process on the Earth's surface or any precipitation effects. At the same time a series of powerful earthquakes occurred in Kuril's Islands region. The intervals between earthquakes were nearly the same as for the recorded perturbations within the 6 hour accuracy. The relationships between the signals recorded and these earthquakes seemed to be quite clear but there was one problem - the electric responses were registered well before the earthquakes occurred and the temporal displacement of these events amounted to tens hours. In other words every earthquake has got its own electric precursor.
As a first approximation the precursor's amplitude is proportional to the EQ magnitude. We use a basic magnitude Mb unit as a commonly accepted by the World seismic net.
Let us mark these relationships as a first basic attribute of earthquakes.
On the basis of this fact we were able to predict a well-known Kobe earthquake of 1995. We circulated our forecast and an alarm warning in Internet two days before this event occurred. This clearly verified that it is possible to predict earthquakes and its magnitude.
The next our statement is as follows: there are no powerful earthquakes which are not accompanied with large magnitude precursors.
We should notice that the converse is not quite correct – about 10 % of the large magnitude precursors were not followed by powerful earthquakes.
What is it? What is the origin of this exception to the second rule? At the moment we do not know. It hardly seems that the World net of seismic stations does not record the earthquakes of such magnitude. Perhaps the processes that originate the electric precursor show themselves not as usual EQs, being accompanied with the Earth crack but as a tsunami or an eruption or there may exist another still unknown way of energy release.
The third our statement is - no large precursor - no powerful EQ.
The relationship is unique. More than four years of our monitoring of the global electric field component and electric precursors observation confirms there was no powerful EQ that could not be related to a large electric precursor. This unique feature has to be used first of all to forecast a period while no powerful EQ will definitely occur.
Fig 2 (a copy of our Internet WEB page) shows an example of our forecasts. It demonstrates a clear correlation between our forecasts and the real events. One can see that the forecasted magnitude of EQ is usually larger than the one actually occurred.
Nowadays we believe the complete theory for EQ has to include a set of definite stages or phases of EQ development. At one of the first stages, namely at the process beginning, the electric precursor is generated , while the energy reaches the surface and releases itself at the final stage of EQ. It should be outlined the EQs can differ from each other in several orders of the energy released but the interval between these two stages is about the same for the different EQ's within 6 hours accuracy.
It is a great temptation to propose a complete scenario of EQ but we are not ready to make it at the moment. Let us try to consider the problem step by step. First of all we need to understand the origin of electric precursor. Up to now we can not separate a complete set of universal characteristic features for electric precursors even for those EQ's that occur in the same regions. The characteristic features of precursors can differ from each other considerably. The possible changes happen in frequency spectrum , duration of precursors, levels of steady components and so on. A lack of number of similar kind of precursors does not allow to use a "individual portrait" of precursor for determination the geographical coordinates of the following EQ. We spent a lot of time and resources trying to develop this idea but with a little result.
An interesting fact was observed - sometimes the precursor signal appeared in the registration point as a series of pulses having a definite time interval. We have no doubts that they were generated in the same time and the same point by the same source. One can suppose that these are solitons waves propagating in different ways.
During the 5 years of our experiments we observed tenths events with temporal intervals between precursors and the following occurred EQs. The EQs occurred in various points of the Earth and in different time. However, the mentioned above interval keeps the same value (within 6 hours accuracy). This interval stability can not be explained by geological reasons. That is why we have to suppose there exists an external influence which run the process of the EQ formation from the precursor appearing till the EQ demonstrate itself in usual way. We propose that most possibly this is due to the mutual attraction between the Earth and Moon. We believe that a considerable forecast improvement can be achieved using the concept of liquid Earth . Let us recall that accordingly this model in magma the flood-tides exist that affect and crack a thin solid shell of the Earth. It seems very realistic the Lunar attraction affects the magma flood-tides and in this way can initiate the EQ processes.
If this hypothesis is true a new opportunities arise for the forecasting and the fundamental rules of the celestials mechanics can be used to improve it. The first what one should make is to test if any correlation exists between EQ's coordinates and the Lunar position. And , indeed, this correlation exists. Every one can verify the above statement using the easy to access seismic databases [Home Planet for Windows by John Walker WWW home page: http://www.fourmilab.ch.] and a data for the Lunar orbit. The only exceptions are the EQ's occurred in utmost South and North regions.
Fig.1.
Dependence of the Earth electric field amplitude on time as the atmosphere response on the explosion made in USA (Nevada). The records were made from 14.051987 to 18.05.1987.
In fig2 the perturbation amplitude exceeded three times the background level. As the background level we choose the magnitude of electric signal during a calm period.
The triangles mark the time of explosion.
The shown vertical components of the electric field mainly give information about global component of electric field. It is clear seen the electric perturbations decrease during 5 days.
The further studies confirms this 5 days ring as a feature of atmosphere response to external shock.
Novosibirsk State University
Observatory of Atmospheric Electricity
Updated on 1999/05/12 @ 20:55, formated on 1999/05/12 @ 21:15 (time UTC)
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Earthquakes with Mb6.0
NONEP.S.
Vertical axis shows the strength of earthquake estimated in Mb. Horizontal lines show maximum possible strength of expected earthquakes. The prognoses are made for about two days. The dots are real events. All forecasts are resulted from data retrieving and processing in Observatory of Atmospheric Electricity of NSU. The information on real earthquakes is taken from International Data Centre
http://140.162.2.29/web-bin/recentevents.We forecast four levels of global seismic activity:
| I | II | III | IV |
| Quiet (Mb < 5.5) | Normal (Mb < 6.0) | Strong (Mb < 6.5) | Extremely strong (Mb > 6.5) |
For further information, feel free to contact us by E-mail: yubragin@phys.nsu.ru
Fig. 2
References
Yu. A. Bragin, Geoelectricity and earthquake, in 10th International Conference on Atmospheric Electricity, June 10-14, 1996, Osaka, Japan, 1996, 439 – 443.