کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
4691577 | 1636740 | 2015 | 12 صفحه PDF | دانلود رایگان |
• New GPS data evidence
• Rigid clockwise rotation of EHS with respect to India plate
• Active indentation of EHS into the Eurasian plate
• Differential shortening rate along the frontal EHS, high seismic hazard in its SE sector
Newly acquired GPS data along transects across Himalaya in Eastern Himalayan Syntaxis (EHS) reveal a clockwise rotation of rigid micro-plate comprising part of Brahmaputra valley, NE Himalaya and Northern Myanmar that rotates about a pole located at 14.5°N, 100.8°E at an angular rate of 1.75 ± 0.12°/Myr. The EHS is being torn-off from the main Indian Plate as a rigid block around which the kinematic clockwise rotation of Tibetan GPS sites toward the Sichuan-Yunnan region occurs in the Eurasia fixed frame. The residual velocity field of the newly acquired data estimated after removing the rotation that minimizes the GPS rates around EHS show a clear NE motion of the EHS sites, indentation of the rigid Indian plate into a less rigid area of the Eurasian plate. The most extensive EHS zones of compression and shortening are in the direction of indenter convergence, with average values ranging between ~ 50–100 nanostrain/year. Along the frontal segment of EHS, from NW to SE, the shortening rate is reduced from the local maximum value of 160 to ~ 80 nanostrain/year, thus indicating a possibly locked fault patch of Mishmi or Lohit thrusts, the southernmost part of segment activated during the large 1950 Assam earthquake, Mw 8.6.An elastic block-model was invoked to infer the average slip rates of sections around EHS and to estimate an average locking depth of ~ 15 km. The slip rate perpendicular to the locked sector of EHS reaches 32.4 mm/year and permits to roughly infer a recurrence time of ~ 200 year for an earthquake as energetic as the 1950 Assam event.
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Journal: Tectonophysics - Volume 655, 1 August 2015, Pages 15–26