Short-term earthquake prediction in Kamchatka using low-frequency magnetic fields

Correlations between Earthquake Properties and Characteristics of Possible ULF Geomagnetic Precursor over Multiple Earthquakes

“…In this study, the method was further improved by introducing a new range-normalization process since means and standard deviations of both components are not directly comparable. After evaluating several range combinations heuristically, it was decided to normalize S G into the range [1,2] (between 1 and 2), and S Z into [1,3] (between 1 and 3) to give a greater weightage to the Z component, since it is the primary indicator of pre-earthquake anomalies. In addition to the µ + 2σ threshold value, the value of P Z/G must also exceed 1.5 to be considered as an anomaly.…”

“…The capability of the polarization ellipse (PE) method in estimating the direction of ULF/ELF seismo-atmospheric emission source have been shown by prior studies [3,20]. In these studies, the signals filtered in the ELF range (≥3 Hz) were found to be effective for this purpose.…”

“…Researchers have demonstrated various non-seismic approaches to detect any kind of possible precursory proxy appearing before earthquakes. One of the most popular approaches is by studying anomalous lowfrequency seismo-electromagnetic (seismo-EM) phenomena, i.e., direct lithospheric [1,2], seismo-ionospheric and seismo-atmospheric emissions [3]. In these phenomena, preearthquake seismo-EM emission is assumed to either directly or indirectly originate from the epicenter and is generated by one of these suggested mechanisms: (i) microfracture electrification [4], (ii) electrokinetic effect [5], (iii) electric current induction due to conductivity variation [6], and (iv) piezomagnetic effect [7].…”

“…Thus, the observation of ULF emission holds promising potential in earthquake prediction study. Note that the definition of ULF range used in this study is widely accepted by similar studies [1][2][3][4], which is different from the International Telecommunication Union (ITU) designation, i.e., 300-3000 Hz. Moreover, seismo-EM emission is difficult to be distinguished from the much greater background natural EM field.…”

“…Prior studies have found several possible correlations between amplitude-epicentral distance [21], lead timemagnitude and lead time-hypocentral depth [22]. Schekotov et al [3] recently showed a linear dependence of maximum ULF depression on the local seismicity index (K LS , see Equation (1)).…”