Geomagnetic field variations in seismic waves traveling across a fault

Abstract

It is known that seismic waves traveling in the Earth's crust are accompanied by electromagnetic effects [1][2][3]. The probable ways how electric and magnetic signals are generated are under discussion [4][5][6][7][8].One of the most important factors determining the electromagnetic effects in the Earth's crust is the het erogeneous structure of the crust [1,7].The present paper gives the results of regular instru mental observations over geomagnetic field variations in the zones of influence of tectonic faults during trav eling of seismic waves of varied intensity. It has been shown that seismic waves with an amplitude more than 5-10 µm/s, traveling across a fault zone, always pro duced geomagnetic field variations. At weaker seismic disturbances, geomagnetic field variations are of the "glimmer" character, and the relative frequency of appearance of the effect drops as the seismic wave amplitude decreases making up about 50% in a range of 1-5 µm/s. The quantitative dependence between the maximal value of the full vector of variations in geomagnetic field induction in the fault zone and the amplitude of the seismic disturbance has been found for the first time.The heterogeneity of the medium structure, the presence of discontinuity boundaries between rocks of varied material composition, the presence of zones where the medium is ruptured or has a different stress strain state-all these points on aggregate-provide the appearance of electromagnetic effects in the field of seismic variations [1,6,7,9].Study of magnetic signals during the movement of seismic waves through large tectonic structures in the crust (fault zones) is of great interest.The practical value of study of magnetic effects in crustal discontinuity zones is related to possible cre ation of modern methods for diagnostics and control of the physical-mechanical state in local parts of the Earth's crust when choosing construction locations and safe maintenance of objects of special importance and elevated risk.In the present work, synchronous instrumental observations over seismic signals and geomagnetic field variations were performed in faults of hard rocks in the restricted zone of Muruntau open pit (Uzbeki stan), and in the zones of tectonic faults that feather the Nelidovo Ryazan tectonic structure (NRTS), which is located within the limits of the Moscow syn eclise [9].Magnetic field induction was measured utilizing G 856 proton magnetometers (GEOMETRICS) and MIN induction magnetometers (developed by the Institute of Geosphere Dynamics, Russian Academy of Sciences) [10]. Converting sensors were placed in antivibration hangers, at a height of about 2 m above the ground. The preliminary testing of sensors at PSGU and PSVU verifying seismometric installments (developed by the experimental design office of the Institute of Physics of the Earth, Russian Academy of Sciences) had indicated the absence of seismic induc tion on magnetometers in the frequency range of 0.1-20 Hz at various amplitude of no more than 10 -2 m/s for a G 856 sensor and 10 -4 m/...

Wavelet Characterization of Seismicity and Geomagnetic Coupling at Coastal Regions of Pakistan

“…Though, the dynamic system is recognized by the full behavior of inhomogeneity, identification of proper friction functions and dynamic crack propagation. A quantitative basis for research on how a geomagnetic field disturbance occurs with seismic effects in the zones of tectonic structures and for the building of the corresponding models [31].…”