Please use this identifier to cite or link to this item:
http://hdl.handle.net/2122/1218
Authors: | Makris, J. P. | Title: | Properties of the geoelectric structure that promote the detectionof electrotelluric anomalies: the case of Ioannina, Greece | Issue Date: | Apr-2001 | Series/Report no.: | 2/44 (2001) | URI: | http://hdl.handle.net/2122/1218 | Keywords: | Electrotelluric Greece magnetotelluric Mohr circle noise reduction seismic precursor tensor decomposition |
Subject Classification: | 04. Solid Earth::04.06. Seismology::04.06.02. Earthquake interactions and probability | Abstract: | The reliable detection and identification of electrotelluric anomalies that could be considered as precursory phenomena of earthquakes become fundamental aspects of earthquake prediction research. Special arrangements, in local and/or regional scale, of the geoelectric structure beneath the measuring point, may act as natural real-time "filters" on the ULF electrotelluric data improving considerably the signal to "magnetotelluric-noise" ratio of anomalies originated by probably non-magnetotelluric sources. Linear polarization, i.e. local channelling of the electric field on the surface is expected in cases where 3D-local inhomogeneities, producing strong shear distortion, are present in the vicinity of the monitoring site and/or when a 2D-regional geoelectrical setting exhibits high anisotropy. By assuming different generation mechanisms and modes of propagation for the electrotelluric anomalies that could be considered earthquake precursory phenomena, a rotationally originated residual electrotelluric field results, eliminating background magnetotelluric-noise and revealing "hidden" transient variations that could be associated to earthquakes. The suggested method is applicable in real-time data collection, thus simplifies and accelerates the tedious task of identification of suspicious signals. As an indicative example, the case of Ioannina (located in Northwestern Greece) is presented. The local polarization of the electrotelluric field varies dramatically even at neighboring points although the regional geoelectric strike direction does not change.+ |
Appears in Collections: | Annals of Geophysics |
Show full item record
Page view(s)
138
checked on Apr 17, 2024
Download(s) 50
392
checked on Apr 17, 2024