Why do the Himalayan mountains exhibit a curved shape?

What is it about?

We illustrate that a simple mechanical model can explain the arcuate shape, as observed in map view, and the post mid-Miocene growth of the Himalayan range. Our study incorporates comprehensive field measurements of shallow deformation along the surface ruptures of the two most recent and significant earthquakes (Muzzafarabad, 2005, and Assam, 1950) near the western and eastern syntaxes of the range. These measurements support the observation that, in these regions, the directions of shortening diverge by up to 130° and shortening rates are lower by a factor of 3 compared to central Nepal (~ 6 mm/yr vs ~18 mm/yr). The return time of large earthquakes is also ≈ 3 times longer (>2,000 y) than in central Nepal (≈ 700 y). Using Discrete Element Modelling, we demonstrate that this is an outcome of the elliptical growth of the range, riding atop the subducting Indian plate since the mid-Miocene. Both syntaxes mark the endpoints of approximately orthogonal strike-slip boundaries on the eastern and western sides (Chaman and Sagaing Faults).

Featured Image

Photo by Chandan Chaurasia on Unsplash

Photo by Chandan Chaurasia on Unsplash

Why is it important?

This study uncovers how the Himalayan Mountain Arc formed, explaining why it is shaped like a half-ellipse and the relationship to large earthquakes along it. This finding has broad implications and should be of interest to a broad range of Earth scientists from various disciplines including Geodesy, Seismology, Paleo-seismology, and Quaternary Geology.

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