The changes of
geophysical soil often contain measurable signs that can be studied in
order to highlight signs that, if properly interpreted, can be counted
among the seismic precursors.
Among the changes
involving electromagnetism, there are changes of conductivity, local
variations of the magnetic field and other events related to radio
frequency emissions. The ability of the rock to issue radio frequency
varies between frequencies departing from ULF up to frequencies of the UHF.
There are numerous studies in this area, and carry out some monitoring of
very specific frequencies thinking they are more promising as probable
precursors. The different characteristics of the rock layers and ipocentric
depth, pose serious limits on the research in this field, in fact different
geological characteristics of the phenomenon, can respond in different ways
also, frustrating the carrying out of the results of studies on specific
areas. The carrying out of the results of research in this field may find
difficulties or offer certainties. However, the ability to take
measurements through simple and low cost tools, and creating an amateur
experimental network, can be an excellent opportunity for applied research,
since the equipment and effort required are entirely made available to amateurs.
The opportunity,
also to use university studies, from which to start, and the possibility to
involve official bodies in the study of possible outcomes, makes
particularly good this approach in many aspects.
The proposed
study includes: monitoring the background of Banda VLF waves (between 0.03
and 300 KHz, and changes due to radio frequency emissions, caused by the
phenomenon of expansion rocks subjected to compression of seismic origin.
Introduction
The idea is, that
the working group FESN is on the implementation of a network of seismic
detection of electromagnetic precursors. Many studies, in the past, have
been done on this field, but the difficulties, of making seismic events
associated with the readings of these signals, give very limited
possibilities to use with the purpose of forewarning.
It is a known fact that the signals Banda VLF and ELF are generated from a
variety of sources that include, among others, certain interactions of the
solar wind with magneto-sphere, atmospheric electrical discharges
(lightning), civilians equipment beats of various kinds, sun.
However, a
different source is constituted by phenomena associated with earthquakes,
or rather the fracturing of crystalline layers. And well-known the fact
that the phenomenon known as expansion, may precede the beginning of a
seismic event. The above phenomenon can be summed up as follows: In the
first phase, stresses due to the movement of plates accumulate along the
critical areas (faults) causing compression of rocks. This phase usually
lasts several years and is currently monitored by official corps in the
areas most at risk. By the placement of sensors based on GPS technology can
measure even the smallest movements of the ground (see dell' OGS GPS
network).
When the
compression exceeds the elastic capacity of the rock, they form a
micro-fracture causing deformation that increase the volume of the rock
itself (expansion).
The
micro-fracture arranged generally parallel to the maximum compression. The
expansion occurs on average, with an effort that is about half of what
needed to generate the resulting fracture to the earthquake. The water in
nearby groundwater precisely because of expansion, tends to penetrate
inside the fractured rock. But the time required to saturate for the rock
is fairly long and the process that generates new micro is faster than what
is able to saturate. The continuous interaction between the two processes
makes under-saturated rocks. The water can eventually saturate the rock and
that the stress of compression is such that the rocks micro-fractured are
saturated, it is no longer able to support them because the water inside
the interstices, being almost uncompressible reduces the capacity elastic
of the rock. And at this stage it starts and spreads the fracture that
generates seismic event. The expansion then tends to delay the onset of the
earthquake increasing the elasticity of the rock while the water, when they
can saturate the rocks, restores the transmission of text compression,
reducing the time required to achieve the strength to break and thus of the
seismic event. During the phenomenon of expansion, which can last from a
few hours to several days, we can verify some measurable physical
parameters, such as electrical resistance, the height of the flap, the
emission of radon gas or hydrogen gas, can also occur swarms micro-seismic
storms.
Studies in the
ULF band (between 0.1 and 10 Hz), ELF and VLF (between 10 Hz and 30 kHz)
are currently Corsican in the United States, but do not have reported
detections correlated to earthquakes, although in the ULF the anomalies are
detected that could be considered precursors.
The detection of
changes the scale of the background noise detectable by simple radio
devices has stimulated specific studies in this field. Some evidence, also
reported by radio amateurs during the days preceding the strong shock
dell'Umbria, led the prof. Ezio Roberto Mognaschi of Pavia, Dipartimento di
Fisica "A. Volta, with amateur IW2GOO name, recently deceased, to conduct
specific studies and assume a physical mechanism for the production of
electromagnetic waves by the crystal rocks, and to verify in the laboratory
the veracity of hypothesis advanced.
In order to check
the electromagnetic emission, rocks, it is essential that they are
crystalline. In this connection it should be recalled that in Friuli, while
failing, to be present in a very limited application, the granite rocks of
volcanic origin, in addition to the basement place in depth, there are
several rocks of a lens (marbles) arising from the partial melting of
limestone . The hypothesis of prof. Mognaschi includes the following
mechanism: -- Some time (from a few hours to a few days) before the
destructive earthquake, the phenomenon of expansion increases exponentially,
causing micro-fractures which propagate as branched within the crystalline
material. -- The rupture of crystal ties, if the material is not a good
conductor (as the rock precisely), produces intense electric fields. These
are in fact generated by the imbalance caused by the breaking of molecular
crystal structures with consequent formation of ions opposite sign that
comes to the line of sight, a small distance. This condition creates small
electric dipoles that remain alive during the period of relaxation of the
rock at the fracture. The life time of electric dipoles is very limited,
about (4-10) seconds and depends on the resistance of the rock and its
dielectric constant. However, despite it being short, I fear, simply to
generate the dipoles an electromagnetic field. Atoms positioned on one side
of the rock micro-fractured, being subjected to electromagnetic forces
recall of those seats on the opposite side, a cause of electric dipoles
which in turn generate electromagnetic waves. However, the dipoles are too
small compared to the wave length Emitted, to be efficient, also the layers
of rock between the surface and ipo-center fencing partially signals, and
then the noise radiated can be detected only in the areas surrounding the
epicenter.
Software and receiving system description
With the purpose of detection the electromagnetic
and seismic precursors and to detect the area of the same issue, a software
and a receiver combined with a digitizer has been developed, by some radio
amateurs in the province of La Spezia, including: -- Roberto Violi (IK1XHH)
has developed written and compiled software;
- Giuliano Sandal (I1SAF), Bruno Grassi (IK1WVG)
and Adam Mancini (IK2SBB) have developed the receiver-digitizer. The device
has a main purpose, but not unique to GROPED predict seismic phenomenon
with some indicating advance about the area of origin of the seismic
precursor electromagnetic (PSE) and possibly also estimating the intensity
of the signal in the area origin. From the initial version of the program
to the one used currently, the features are enhanced with new and more
sophisticated functions that relate to the acquisition of data through
devices such as the dynamic threshold and butterfly cross line, displayed
in real time through graphics, the possibility to compare files from
potential PSE is automatic with manual choice, the ability to compare data
from different stations, with detection software devices for calibration of
the receiver, etc.. At the beginning, the purpose of the programme
(detection and data storage) was to run together with a more ambitious
goal, namely data processing, through appropriate mathematical models.
Thus, in order to determine the place of origin of the PSE and to estimate
the 'intensity of electromagnetic phenomenon at subscription. Its made
possible by the program management of a network of detecting potentially
unlimited number of stations in the system components.
The management of this issue and 'particularly
complex involving maps with different scales, placement of stations in the
network and their changes over time, their possible use for coupling the
forecast with mathematical models related. The program, finally, by the
drawing aspect, classification and research data in order to deepen
understanding of the phenomena PSE.
The antenna
The contribution of FESN for this type of
research, has been to study and implement a suitable antenna, easily
reproducible with materials easily accessible, but with final
characteristics adapted to expectations. Has been developed, in fact, a
made in aluminium tube in which the winding is made up of one hundred
flexible wire coils.
In order to avoid dispersion, the winding has been
outdistanced by metal shielding for static electricity through wooden
supports.
The antenna is capable of receiving the magnetic
component signal, to be sent to Banda wide receiver, and given that the
antenna directivity has positioned in the vertical plane, it was decided to
mount the antenna with horizontal polarization to avoid errors in
calculating the emission zone.
The FESN is in the process of positioning No 6
detection stations in the region in the following locations Pozzuolo del
Friuli, Manzano, Gorizia, Cabia Arta Terme, Gaiarine (TV), Malnisio. The data
collected will eventually significant first shared with the OGS of Trieste
and subsequently made available on the website of the group www.fesn.org
periodic reports.
Features and size: Profile aluminium 40x40 mm
Spacers wood thickness 10 mm Length of the inner side 75 cm apart Winding
obtained with 10 coils of flat formed by 10 coupled wires Interruption of
shielding on the side opposite to the point of taking away mm 2
The network monitoring electromagnetic precursors of FESN
The FESN is in the process of positioning No 6 detection stations in
the region in the following locations:
- Pozzuolo del Friuli
- Manzano
- Gorizia
- Cabia di Arta Terme
- Pian del Cansiglio
- Tarcento
The data collected will eventually be shared with the OGS of Trieste and
subsequently made available on this site through periodic reports.
Software and Hardware
The FESN is in the process of positioning No. 6
detection stations in the region in the following locations: Pozzuolo del
Friuli, Manzano, Gorizia, Cabia Arta Terme, Gaiarine (TV), Pian del
Cansiglio.
The data collected will eventually be first shared
with the OGS of Trieste and subsequently made available on this site
through periodic reports.
The software, manual and details of the party
hardware can be downloaded at the following address:
I. L. Nersesov e A. N. Semonova in Physical Basis
of Foreshocks, Nauka, Mosca, (1969)
P. Varotsos e K. Alexopoulos, Tectonophysics, 110, 73 (1984)
J. W. Warwick, C. Stoker e T. R. Meyer, J. Geophys. Res., 87, 2851 (1982)
A. C. Fraser-Smith et al., Geophys Res. Lett., 17, 1465 (1990)
J. Y. Dea, P. M. Hansen e W.-M. Boerner, Phys. Earth Planetary
Interiors, 77, 109 (1993)
F. Bella et al., comunicazione alla XXI General Assembly della IUGG,
Boulder, (1995)
F. Bella et al. in Electromagnetic Phenomena Related to Earhtquake
Prediction, Terra Scientific Publishing Company, Tokyo, (1994)
E. Mognaschi, Radioonde, 8, 2 (1997)
E. Mognaschi, Radiorama, 12/97, pag. 34
M. Eleuteri, comunicazione privata C. H. Scholz, J. Geophys. Res., 73, 1417 (1968)
L'Astronomia n. 287 pag. 35 - Luglio (2007)
CONSTANTINE THANASSOULAS
(B. Sc Physics M. Sc. - Ph. D. in Applied Geophysics)
La Rete Sismica Sperimentale del Friuli (F.E.S.N.)
e' una rete privata amatoriale.
I dati forniti sono provvisori e quindi suscettibili di modifiche.
Nel caso di loro utilizzo, si prega di citare la fonte.
