TY - JOUR
T1 - Electrical structure of the Himalaya of Central Nepal
T2 - High conductivity around the mid-crustal ramp along the MHT
AU - Lemonnier, Carole
AU - Marquis, Guy
AU - Perrier, Frédéric
AU - Avouac, Jean Philippe
AU - Chitrakar, Gyani
AU - Kafle, Basantha
AU - Sapkota, Som
AU - Gautam, Umesh
AU - Tiwari, Dilliram
AU - Bano, Maksim
PY - 1999/11/1
Y1 - 1999/11/1
N2 - Twelve broadband magnetotelluric (MT) soundings were performed across the Himalaya of Central Nepal in 1996 in order to determine the electrical structure of the crust and its relation to geological structures and active tectonics. The MT impedance tensors were obtained for frequencies between 0.001 and 500 Hz. The 2-D section, derived from joint inversion of TE- and TM mode after RRI and Groom/Bailey decomposition, shows high conductivity in the foreland basin (~ 30 Ω.m) that contrasts with the resistive Indian basement (> 300 Ω.m) and Lesser Himalaya (> 1000 Ω.m). In addition, our MT sounding reveals a major conductive feature beneath the front of the Higher Himalaya also characterized by intense microseismic activity, and the position of a mid-crustal ramp along the major active thrust fault (MHT). This high conductivity zone probably reflects metamorphic fluids, released during underthrusting of the Indian basement and pervading well connected microcracks induced by interseismic stress build-up, or distributed brittle deformation around the ramp.
AB - Twelve broadband magnetotelluric (MT) soundings were performed across the Himalaya of Central Nepal in 1996 in order to determine the electrical structure of the crust and its relation to geological structures and active tectonics. The MT impedance tensors were obtained for frequencies between 0.001 and 500 Hz. The 2-D section, derived from joint inversion of TE- and TM mode after RRI and Groom/Bailey decomposition, shows high conductivity in the foreland basin (~ 30 Ω.m) that contrasts with the resistive Indian basement (> 300 Ω.m) and Lesser Himalaya (> 1000 Ω.m). In addition, our MT sounding reveals a major conductive feature beneath the front of the Higher Himalaya also characterized by intense microseismic activity, and the position of a mid-crustal ramp along the major active thrust fault (MHT). This high conductivity zone probably reflects metamorphic fluids, released during underthrusting of the Indian basement and pervading well connected microcracks induced by interseismic stress build-up, or distributed brittle deformation around the ramp.
UR - http://www.scopus.com/inward/record.url?scp=0033226429&partnerID=8YFLogxK
U2 - 10.1029/1999GL008363
DO - 10.1029/1999GL008363
M3 - Article
AN - SCOPUS:0033226429
SN - 0094-8276
VL - 26
SP - 3261
EP - 3264
JO - Geophysical Research Letters
JF - Geophysical Research Letters
IS - 21
ER -