scholarly journals Sanyi-Puli conductivity anomaly in NW Taiwan and its implication for the tectonics of the 1999 Chi-Chi earthquake

2002 ◽  
Vol 29 (8) ◽  
pp. 7-1-7-3 ◽  
Author(s):  
Chien-chih Chen ◽  
Chow-son Chen
Keyword(s):  
Conductivity Anomaly

Electromagnetic images of the Trans-Hudson orogen: the North American Central Plains anomaly revealed

2005 ◽  
Vol 42 (4) ◽  
pp. 457-478 ◽  
Author(s):  
Alan G Jones ◽  
Juanjo Ledo ◽  
Ian J Ferguson
Keyword(s):  
Electrical Properties ◽  
North American ◽  
Upper Mantle ◽  
Lithospheric Mantle ◽  
Three Dimensional ◽  
Conductivity Anomaly ◽  
Central Plains ◽  
Slave Craton ◽  
The North ◽  
Kimberlite Field

Magnetotelluric studies of the Trans-Hudson orogen over the last two decades, prompted by the discovery of a significant conductivity anomaly beneath the North American Central Plains (NACP), from over 300 sites yield an extensive database for interrogation and enable three-dimensional information to be obtained about the geometry of the orogen from southern North Dakota to northern Saskatchewan. The NACP anomaly is remarkable in its continuity along strike, testimony to along-strike similarity of orogenic processes. Where bedrock is exposed, the anomaly can be associated with sulphides that were metamorphosed during subduction and compression and penetratively emplaced deep within the crust of the internides of the orogen to the boundary of the Hearne margin. A new result from this compilation is the discovery of an anomaly within the upper mantle beginning at depths of ~80–100 km. This lithospheric mantle conductor has electrical properties similar to those for the central Slave craton mantle conductor, which lies directly beneath the major diamond-producing Lac de Gras kimberlite field. While the Saskatchewan mantle conductor does not directly underlie the Fort à la Corne kimberlite, which is associated with the Sask craton, the spatial correspondence is close.

Magnetotelluric tracing of the Carpathian conductivity anomaly in the Vienna Basin

1996 ◽  
Author(s):  
L. Vero ◽  
A. Madarasi ◽  
W. Seiberl ◽  
G. Varga
Keyword(s):  
Conductivity Anomaly ◽  
Vienna Basin

The Tamar conductivity anomaly

1986 ◽  
Vol 17 (1) ◽  
pp. 34-35 ◽  
Author(s):  
W. D. Parkinson ◽  
R. Hermanto
Keyword(s):  
Conductivity Anomaly

scholarly journals Locating Seismo-Conductivity Anomaly before the 2017 MW 6.5 Jiuzhaigou Earthquake in China Using Far Magnetic Stations

2020 ◽  
Vol 12 (11) ◽  
pp. 1777
Author(s):  
Zhiqiang Mao ◽  
Chieh-Hung Chen ◽  
Suqin Zhang ◽  
Aisa Yisimayili ◽  
Huaizhong Yu ◽  
...  
Keyword(s):  
Transfer Function ◽  
Moving Window ◽  
Entire Study Period ◽  
Conductivity Anomaly ◽  
Promising Candidate ◽  
Jiuzhaigou Earthquake ◽  
Entire Study ◽  
Background Distribution ◽  
Geomagnetic Data ◽  
Magnetic Transfer

Changes in the underlying conductivity around hypocenters are generally considered one of the promising mechanisms of seismo-electromagnetic anomaly generation. Parkinson vectors are indicators of high-conductivity materials and were utilized to remotely monitor conductivity changes during the MW 6.5 Jiuzhaigou earthquake (103.82°E, 33.20°N) on 8 August 2017. Three-component geomagnetic data recorded in 2017 at nine magnetic stations with epicenter distances of 63–770 km were utilized to compute the azimuths of the Parkinson vectors based on the magnetic transfer function. The monitoring and background distributions at each station were constructed by using the azimuths within a 15-day moving window and over the entire study period, respectively. The background distribution was subtracted from the monitoring distribution to mitigate the effects of underlying inhomogeneous electric conductivity structures. The differences obtained at nine stations were superimposed and the intersection of a seismo-conductivity anomaly was located about 70 km away from the epicenter about 17 days before the earthquake. The anomaly disappeared about 7 days before and remained insignificant after the earthquake. Analytical results suggested that the underlying conductivity close to the hypocenter changed before the Jiuzhaigou earthquake. These changes can be detected simultaneously by using multiple magnetometers located far from the epicenter. The disappearance of the seismo-conductivity anomaly after the earthquake sheds light on a promising candidate of the pre-earthquake anomalous phenomena.

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