Segmentation of the Himalayas as revealed by arc-parallel gravity anomalies

International audienceLateral 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

The Fruit Flies (Diptera, Tephritidae) in Bhutan: New Faunistic Records and Compendium of Fauna

Based on a field survey from 2017, twenty-three species are reported from Bhutan for the first time: Acroceratitis ceratitina, A. hardyi, Anomoia approximata, Bactrocera connecta, B. latifrons, B. nigrifacia, B. syzygii, Campiglossa sororcula, Cecidochares connexa, Dacus jacobi, Gastrozona fasciventris, Hoplandromyia antelopa, Lenitovena ultima, Ptilona confinis, Rioxoptilona dunlopi, R. formosana, R. vaga, Spathulina acroleuca, Themara yunnana, Trypeta indica, Zeugodacus apiciflavus, Z. diversus, and Z. fereuncinatus. Four species of the genera Cornutrypeta, Hemilea, Morinowotome, and Vidalia are also recorded for the first time, but the precise determination to species needs additional study and material. As the result, 71 species is listed from Bhutan by far. Their taxonomic position and key characters are discussed. Illustrations for most of the newly recorded species are given

The GANSSER seismological network in Bhutan

Abstract HKT-ISTP 2013 A