Evidencing Fluid Migration of the Crust during the Seismic Swarm by Using 1D Magnetotelluric Monitoring

Abstract

We applied multi–temporal 1D magnetotelluric (MT) surveys to identify space–time anomalies of apparent resistivity (ρa) in the upper lithosphere in the Antarctic Peninsula (the border between the Antarctic and the Shetland plates). We used time series over several weeks of the natural Earth’s electric and magnetic fields registered at one MT station of the Universidad Nacional de Colombia (RSUNAL) located at Seymour–Marambio Island, Antarctica. We associated resistivity anomalies with contrasting earthquake activity. Anomalies of ρa were detected almost simultaneously with the beginning of a seismic crisis in the Bransfield Strait, south of King George Island (approximately 85.000 events were reported close to the Orca submarine volcano, with focal depths < 20 km and MWW < 6.9). We explained the origin of these anomalies in response to fluid migration near the place of the fractures linked with the seismic swarm, which could promote disturbances of the pore pressure field that reached some hundreds of km away.

Electromagnetic Monitoring of Modern Geodynamic Processes: An Approach for Micro-Inhomogeneous Rock through Effective Parameters

“…Research on electrical parameters and related phenomena in geodynamically active zones is being conducted worldwide [24][25][26][27], including seismically hazardous regions such as Altai [28][29][30], Tien Shan [31][32][33][34], Kamchatka [35,36], and Kola [21,37]. The results of these studies indicate a correlation between changes in electrical resistivity and geodynamic processes occurring in deep layers of the Earth's crust.…”

Advanced Technology and Data Analysis of Monitoring Observations in Seismology

“…Magnetotelluric deployments (MT): Time-frequency MT techniques can be integrated into permanent monitoring systems. Surficial or even at depths near earthquake or volcanic sources, changes in electrical resistivity may serve to identify transient or precursor signals [4][5][6]. Including MT data in a comprehensive monitoring system can improve the accuracy of early warnings.…”

Special Issue on Comprehensive Research in Earthquake Forecasting and Seismic Hazard Assessment

“…The second group includes articles confirming one or another model of seismicity behaviour in anticipation of a strong earthquake [3][4][5]. Finally, the third and most numerous group of articles consists of those analysing the results of long-term observations of the behaviour of various geophysical fields (seismic noise [6], seismicity [7][8][9], magnetotelluric field [10,11], deformation field [12], infrared radiation [13], vertical electric field in the atmosphere [14]) before strong earthquakes. We are confident that each of these articles will find an interested reader, and the whole collection will deserve the attention of representatives of the scientific community dealing with the problem of earthquake forecasting and the search for their precursors.…”