30 Jan 2021. Cumiana Update; "Predictive Capability Of VLF/LF Emissions"; Part 3: Discussion, Pt. A
13(First half of the Discussion portion of the research.)
Prediction Capabilities of VLF/LF Emission as the Main Precursor of Earthquake
Wordpress link: (https://vertearbustosschumannresonanceharmonics.wordpress.com/prediction-capabilities-of-vlf-lf-emission-as-the-main-precursor-of-earthquake/)
M.K.Kachakhidze1 and N.K.Kachakhidze1
[1] {Saint Andrew the First-Called Georgian University}
2 Discussion
Analogous model submitted by the authors of the present paper (Kachakhidze et al., 2011) is significant, since, on its base, by monitoring of electromagnetic emission existing in the period that 4
precedes earthquake, it becomes possible to analyze the process of preparation and occurrence of large inland earthquake M≥5.
The above referred paper admits the formula, which connects with each other analytically the main frequency of the observed electromagnetic emission and the linear dimension (the length of the fault in the focus) of the emitted body:
(1) lc
where is the characteristic coefficient of geological medium and it approximately equals to 1. Of course it should be determined individually for each seismically active region, or for a local segment of lithosphere.
Comparing analogous and avalanche-like unstable models of fault formation (Mjachkin, et al., 1975), to determine reliability rate of their conformity to real process, we rely mainly on the data of earthquake which took place in Italy (L’Aquila) on 6 April, 2009 (Contadakis et,al., 2010; Papadopoulos, et al., 2010).
It is known that avalanche-like unstable model of fault formation is divided into three main stages (Mjachkin, 1975), (Fig.1): in case large earthquakes the first stage can go on for a dozen of months (Orihara,2012). At this stage chaotic formation of micro cracks without any orientation takes place.
This stage of formation of microcracks is reversible process - at this stage not only microcracks can be formed but also their the so-called “locked” can occur. Cracks created at this stage will be small (some dozen or hundred meter order) because the weak foreshock sequence may occur spatially distributed within the entire seismogenic area. For example such process was developed in case of earthquake of Italy in 2009: By the end of October 2008 the seismicity entered in the state of weak foreshock sequence which lasted up to the 26 March 2009. It is characteristic that the weak foreshock activity which developed from 28 October 2008 to 26 March 2009 spatially did not concentrated around the mainshock epicenter but it was widely distributed within the seismogenic area. The period when foreshock magnitude more or less increases and the so-called moderate foreshock occurs in region, is attributed to this stage too. This stage was fixed in case of L’Aquila earthquake: from 25 January 2009 to 26 March 2009, including this day. (Fig.2) (Papadopoulos, G. A., et al., 2010); 5
Such foreshocks can be called conditionally the “regional foreshocks” (Kachakhidze, M. et al., 2003). Because of short length of micro cracks and process reversibility first stage in the electromagnetic emission frequency range, according to our model (Kachakhidze et al., 2011) should be expressed by the discontinuous spectrum of MHz order emission (in radio diapason), which is proved by the latest special scientific literature (Eftaxias K., et al., 2009; Papadopoulos G., et al., 2010).
Thus, on the basis of analogous model, it can be stated that having of intermittent, high value MHz electromagnetic emission refers only to weak and moderate earthquakes (foreshocks), and it is not necessary for these foreshocks to be near the epicenter of the incoming main earthquake.
The second stage of the avalanche-like unstable model of fault formation is an irreversible avalanche process of already somewhat oriented microstructures, which is accompanied by inclusion of the earlier “locked” sections. Based on the analogous model, we have to suppose that this stage in the emission frequency spectrum should be expressed by MHz continuous spectrum already. Although, the values of electromagnetic emission frequency must gradually decrease. According to the avalanche-like unstable model, this process takes place few days (at about 10-14) before earthquakes, which is proved clearly by material of observations (Papadopoulos G., et al., 2010).