title: Segmentation of the Himalayas as revealed by arc-parallel gravity anomalies.
abstract: Lateral variations along the Himalayan arc are suggested by an increasing number of studies and carry important information about the orogen's segmentation. Here we compile the hitherto most complete land gravity dataset in the region which enables the currently highest resolution plausible analysis. To study lateral variations in collisional structure we compute arc-parallel gravity anomalies (APaGA) by subtracting the average arc-perpendicular profile from our dataset; we compute likewise for topography (APaTA). We find no direct correlation between APaGA, APaTA and background seismicity, as suggested in oceanic subduction context. In the Himalayas APaTA mainly reflect relief and erosional effects, whereas APaGA reflect the deep structure of the orogen with clear lateral boundaries. Four segments are outlined and have disparate flexural geometry: NE India, Bhutan, Nepal &India until Dehradun, and NW India. The segment boundaries in the India plate are related to inherited structures, and the boundaries of the Shillong block are highlighted by seismic activity. We find that large earthquakes of the past millennium do not propagate across the segment boundaries defined by APaGA, therefore these seem to set limits for potential rupture of megathrust earthquakes.
authors.affiliation: Institute of Earth Sciences, University of Lausanne, Géopolis, Quartier UNIL-Mouline, 1015 Lausanne, Switzerland.|Department of Earth Sciences, ETH Zürich, Soneggstrasse 5, 8092 Zürich, Switzerland.|Laboratoire de Géologie, Ecole Normale Supérieure, CNRS - UMR 8538, 24 rue Lhomond, 75005 Paris, France.
authors.forename: György
authors.initials: G
authors.lastname: Hetényi
authors.affiliation: Laboratoire de Géologie, Ecole Normale Supérieure, CNRS - UMR 8538, 24 rue Lhomond, 75005 Paris, France.|Géosciences Montpellier, CNRS UMR5243, Université de Montpellier, Place E. Bataillon, 34095 Montpellier, France.
authors.forename: Rodolphe
authors.initials: R
authors.lastname: Cattin
authors.affiliation: Department of Earth Sciences, Uppsala University, Villavägen 16, 75236 Uppsala, Sweden.
authors.forename: Théo
authors.initials: T
authors.lastname: Berthet
authors.affiliation: Géosciences Montpellier, CNRS UMR5243, Université de Montpellier, Place E. Bataillon, 34095 Montpellier, France.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Le Moigne
authors.affiliation: Department of Geology and Mines, Ministry of Economic Affairs, PO Box 173 Thimphu, Bhutan.
authors.forename: Jamyang
authors.initials: J
authors.lastname: Chophel
authors.affiliation: Department of Earth Sciences, ETH Zürich, Soneggstrasse 5, 8092 Zürich, Switzerland.|armasuisse, Science &Technology, Federal Department of Defence, Civil Protection and Sport, Feuerwerkerstrasse 39, 3602 Thun, Switzerland.
authors.forename: Sarah
authors.initials: S
authors.lastname: Lechmann
authors.affiliation: Department of Earth Sciences, ETH Zürich, Soneggstrasse 5, 8092 Zürich, Switzerland.|SwissRe, Mythenquai 50/60, 8022 Zürich, Switzerland.
authors.forename: Paul
authors.initials: P
authors.lastname: Hammer
authors.affiliation: Department of Geology and Mines, Ministry of Economic Affairs, PO Box 173 Thimphu, Bhutan.
authors.forename: Dowchu
authors.initials: D
authors.lastname: Drukpa
authors.affiliation: Department of Mines and Geology, Lainchaur, Kathmandu, Nepal.
authors.forename: Soma Nath
authors.initials: SN
authors.lastname: Sapkota
authors.affiliation: Géosciences Montpellier, CNRS UMR5243, Université de Montpellier, Place E. Bataillon, 34095 Montpellier, France.
authors.forename: Stéphanie
authors.initials: S
authors.lastname: Gautier
authors.affiliation: National Land Commission, Kawang Jagsa, PO Box 142 Thimphu, Bhutan.
authors.forename: Kinzang
authors.initials: K
authors.lastname: Thinley