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Examination of seismo ionospheric anomalies before earthquakes of Mw ≥5.1 for the period 2008–2015 in Oaxaca, Mexico using GPS TEC

Melgarejo-Morales Angela, Vazquez-Becerra G. Esteban, Millan-Almaraz J. R., Pérez-Enríquez R., Martínez-Félix Carlos A., Gaxiola-Camacho J. Ramon

Acta Geophysica

2020

Vol. 68, no. 5

1229--1244

Earthquakes are a major danger in a constantly growing society due to their imminent impact and power of destruction. Therefore, the idea of successfully forecasting an earthquake continues to motivate the multidisciplinary study of phenomena proposed as possible earthquake precursors such as ionospheric anomalies. In that sense, total electron content (TEC) has demonstrated to be an efcient parameter for investigating the state of the ionosphere by making use of the Global Positioning System receivers. In the present study, raw vertical TEC data obtained from the standard RINEX fles of the GPS constellation are used to examine the state of the ionosphere during the occurrence of light to moderate earthquakes in Mexico from years 2008 to 2015 with the aim of search for possible ionospheric anomalies related to seismic activity. In order to evaluate the impact at the geomagnetic and ionospheric environments, the Geomagnetic Equatorial Dst index, which is considered to have a great infuence on TEC during geomagnetic storm period, and solar activity parameters, have been considered. The results indicated that 17 (74%) of the studied events presented not quiet geomagnetic conditions for the days before the earthquake. Thus, the changes in VTEC are most likely related to geomagnetic anomalies which rules out its possible seismic origin. Contrariwise, 3 (13%) of the events presented geomagnetic anomalies the days after the earthquake. For the remaining 3 (13%) events, these presented particular characteristics, such as: not quiet geomagnetic condition for the earthquake day, geomagnetic anomalies throughout the period and the opposite.

Seismic activity prediction using computational intelligence techniques in northern Pakistan

Asim K. M., Awais M., Martinez-Alvarez F., Iqbal T.

Acta Geophysica

2017

Vol. 65, no. 5

919--930

Earthquake prediction study is carried out for the region of northern Pakistan. The prediction methodology includes interdisciplinary interaction of seismology and computational intelligence. Eight seismic parameters are computed based upon the past earthquakes. Predictive ability of these eight seismic parameters is evaluated in terms of information gain, which leads to the selection of six parameters to be used in prediction. Multiple computationally intelligent models have been developed for earthquake prediction using selected seismic parameters. These models include feed-forward neural network, recurrent neural network, random forest, multi layer perceptron, radial basis neural network, and support vector machine. The performance of every prediction model is evaluated and McNemar’s statistical test is applied to observe the statistical significance of computational methodologies. Feed-forward neural network shows statistically significant predictions along with accuracy of 75% and positive predictive value of 78% in context of northern Pakistan.

Observations of electromagnetic radiation in the Central Apennines seismic region

Ernst T., Jankowski J., Teisseyre R., Meloni A., Palangio P.

Acta Geophysica Polonica

2001

Vol. 49, nr 1

43-53

In recent years, continuous radio-noise recording is in use at many geophysical observatories, in order to detect possible earthquake precursors and/or coseismic signals. The recordings obtained indicate that electromagnetic radiation (e.g., in the range of 10-40 kH) can indeed be treated as seismic precursor. We present here the examples of successful prediction observation, which we have obtained in the Central Apennines region at the l'Aquila Observatory (Polish-Italian cooperation). A short discussion on relation between the evolution of stresses (dislocation dynamics) and electromagnetic emission supplements this paper.