Historical triangulation and GPS geodesyĪlthough precise geodetic measurements of India were initiated in the 1830s, few measurements extended into the Himalaya because of an 1815 treaty forbidding surveyors or others from entering Nepal territory. The valley is the surface manifestation of a 300 km-long segment of northeasternmost India that fragmented from the India Plate at c. Near Kashmir in the westernmost Himalaya, the convergence rate is ≤12 mm a −1, in the central Himalaya the rate attains 17 mm a −1 and in Assam in the east, instead of increasing, which would be anticipated from Indian's counterclockwise rotation, it reduces as a result of the clockwise rotation of the Brahmaputra Valley. Since most of the convergence dispersed in Tibet and in the mountains to the north, the convergence across the Himalaya, which is responsible for its seismic productivity, is reduced to less than 18 mm a −1. 44 mm a −1 of convergence at the longitude of Pakistan and 65 mm a −1 of convergence at the longitude of Bangladesh.
The pole defines a clockwise rotation of the Indian Plate relative to Asia with c. Previous determinations with fewer high-accuracy GPS data yielded a pole position between Ireland and London, and its east–west position remains the largest uncertainty.
The pole of rotation between the India Plate and the EuroAsian Plate is currently considered to lie at 51.70° ± 0.3° N, 11.85 ± 1.8° E (roughly 100 km SW of Berlin), with convergence specified by an angular velocity of 0.553 ± 0.006°/Ma ( Jade et al. 50 Ma BP and the onset of continent–continent collision. 2015) but rapidly slowed to 6 cm a −1 following the closure of the Tethys ocean at c. Recent studies reveal that rapid northwards motion of the Indian Plate exceeded 14 cm a −1 at 70–50 Ma BP as a result of convergence across two approximately parallel, east–west subduction zones ( Van der Voo et al. Prior to the availability of GPS geodesy, this relative velocity was known only indirectly through global plate-closure summations ( Molnar & Stock 2009), there being no spreading centre between the two plates. 2017), the collisional velocity along the Himalaya is reduced by the absorption of more than half of this convergence as internal deformation within Asia. The rate of convergence of India relative to EuroAsia is fundamental to quantifying the anticipated recurrence interval of earthquakes in the Himalaya, but although India is effectively rigid to within a few millimetres ( Paul et al.
The death toll from a future nocturnal earthquake in the Himalaya could possibly exceed 100 000 due to increased populations and the vulnerability of present-day construction methods. Fatal Himalayan earthquakes have in the past occurred mostly in the daylight hours.
Ten of these fifteen segments are sufficiently mature currently to host a great earthquake (M w ≥ 8). The 2018 slip potential for fifteen segments of the Himalaya are evaluated and potential magnitudes assessed for future earthquakes should these segments fail in isolation or as contiguous ruptures. The width of the Main Himalayan Thrust is quantified along the arc, together with estimates for the bounding coordinates of historical rupture zones, convergence rates, rupture propagation directions as constrained by felt intensities. Porcelain online shop.This article summarizes recent advances in our knowledge of the past 1000 years of earthquakes in the Himalaya using geodetic, historical and seismological data, and identifies segments of the Himalaya that remain unruptured.
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