Short-term Earthquake Prediction Based on Seismic Precursory Electric  Signals Recorded on Ground Surface.

 

"STRANGE ATTRACTOR LIKE" ELECTRIC EARTHQUAKE PRECURSORS

 

OBSERVED DATA  (Hyperbolas,  Ellipses)

 

 

After summarizing the related papers in Introduction, it can be concluded the following physical working model that holds for the seismogenic area.

 

-  When the seismogenic area is not seismically activated, then the monitoring sites of the earth's electric field register uncorrelated electrical noise  which generates hyperbolas of random orientation.

 

- When the seismogenic area is being activated, the generated seismogenic electrical signal prevails over the present electrical noise in both monitoring sites, thus generating ellipses being the combined result of the seismogenic and electrical noise signals. Typical examples are presented as follows:

 

- Hyperbolas:

Fig. 1. HYPERBOLA. Monitoring period:20070401-04 (yyyymmdd-dd). 

For details click on the next links: arXiv:0810.0242  [ pdf ]

 

Fig. 2. HYPERBOLA. Monitoring period:200808-11 (yyyymm-mm). 

For details click on the next links: arXiv:0901.4285  [ pdf ] 

     - Ellipses:

Fig. 3. HELLIPSE. Monitoring period:200710-200809 (yyyymm-yyyymm). 

For details click on the next links: arXiv:0901.4285  [ pdf ] 

 

Fig. 4. HELLIPSE Monitoring period:20080601-03 (yyyymmdd-dd). 

For details click on the next links:  arXiv:0810.0242  [ pdf ]

 

    Ellipses have being observed not only due to signal of T = 1 day, but due to signals with T = 14 days and T = 6 months too (important solid earth tidal components). The physical mechanism of this earthquake precursor is always the same for all T values. Consequently by using a larger value of T we obtain a better in time-depth knowledge of the stress-strain load status of the regional monitored seismogenic area. Moreover, we can follow up the status of a seismogenic area by monitoring the earth's electric field, in terms of the strange attractor precursor, by using successively from large T values to lower  T values, i.e. from T = 6 months towards T = 1 day. In practice that means that the predictive time window, determined for T = 6 months as of some months, gets shorter, a couple of days, for T = 1 day.

  The ellipses are generated by the blend of the pure earthquake electric signals and the random local electrical noise at each monitoring site. The appearance of the generated ellipse depends on the amplitude ratio of the earthquake electric signal to the noise electric signal. At this point what is really needed is a method to isolate the earthquake "strange attractor" precursor signals . The solution for this problem was  presented about 10 years ago in the paper arXiv:0907.3277 [ pdf ].

  As a test case, the following typical ellipse was selected in order to  test the signal isolation from the random noise. Remember that the earthquake signal and the noise are of the same frequency. For this purpose, an inversion technique (borrowed from applied geophysics) was used for signal to noise separation.

Fig. 5. Typical strange attractor earthquake precursor to be "cleaned" from noise.

 

Fig. 7. Filtered (circle) strange attractor of fig. 6 without electrical noise interference.

 

The shape of the "cleaned" strange attractor resembles  closely the one of a circle. The same shape of a circle is observed in the strange attractor of fig. 4. it seems that in both cases of figs. (4) and (7) although the earthquake electrical signal is quite large, a small percentage of electrical noise still exists in the filtered data, thus deforming slightly the strange attractor from being a perfect circle.