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Long-term growth of the Himalaya inferred from interseismic InSAR measurement

Raphael Grandin, Marie-Pierre Doin, Laurent Bollinger, Beatrice Pinel-Puyssegur, Gabriel Ducret, Romain Jolivet and Soma Nath Sapkota
Long-term growth of the Himalaya inferred from interseismic InSAR measurement
Geology (Boulder) (September 2012) 40 (12): 1059-1062

Abstract

The rise and support of the approximately 5000 m topographic scarp at the front of Indian-Eurasian collision in the Himalaya involves long-term uplift above a mid-crustal ramp within the Main Himalayan Thrust (MHT) system. Locking of the shallower portion of the flat-ramp-flat during the interseismic period also produces transient uplift above the transition zone. However, spatial and temporal relationships between permanent and transient vertical deformation in the Himalaya are poorly constrained, leading to an unresolved causal relationship between the two. Here, we use interferometric synthetic aperture radar (InSAR) to measure interseismic uplift on a transect crossing the whole Himalaya in central Nepal. The uplift velocity of 7 mm/yr at the front of the Annapurna mountain range is explained by an 18-21 mm/yr slip rate on the deep shallow-dipping portion of the MHT, with full locking of the mid-crustal ramp underlying the High Himalaya. The transient uplift peak observed by InSAR matches spatially with the long-term uplift peak deduced from the study of trans-Himalayan river incision, although models of the seismic cycle involving thrusting over a ramp of fixed geometry predict an approximately 20 km separation between the two peaks. We argue that this coincidence indicates that today's mid-crustal ramp in central Nepal is located southward with respect to its average long-term location, suggesting that mountain growth proceeds by frontward migration of the ramp driven by underplating of material from the Indian plate under the Himalaya.


ISSN: 0091-7613
EISSN: 1943-2682
Coden: GLGYBA
Serial Title: Geology (Boulder)
Serial Volume: 40
Serial Issue: 12
Title: Long-term growth of the Himalaya inferred from interseismic InSAR measurement
Affiliation: Ecole Normale Superieure, Paris, France
Pages: 1059-1062
Published: 20120918
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
References: 27
Accession Number: 2012-101256
Categories: Structural geologyGeomorphology
Document Type: Serial
Bibliographic Level: Analytic
Annotation: With GSA Data Repository Item 2012309; accessed on October 15, 2012
Illustration Description: illus. incl. sketch map
Source Medium: WWW
N27°00'00" - N29°30'00", E83°00'00" - E86°30'00"
Secondary Affiliation: Commissariat a l'Energie Atomique, FRA, FranceInstitut des Sciences de la Terre, FRA, FranceNational Seismological Centre, NPL, Nepal
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data from GeoScienceWorld, Alexandria, VA, United States. Reference includes data supplied by the Geological Society of America, Boulder, CO, United States
Update Code: 201252
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