Himalayas: an active orogen

History of plate motions:

Simple map view of the orogen. Note the distinctive curvature of the Himalayas, and the two distinct ends. Image source: http://pubs.usgs.gov/gip/dynamic/understanding.html .

Map from USGS showing earthquake distribution in the region.

USGS showing the epicenter of an earthquake in China. Much of the topography depicted here is actively tectonically generated topography. Along with the earthquake map above, they remind the viewer that the deformation associated with the India-Asia collision penetrates deeply into the Asian continent. Image source: http://neic.usgs.gov/neis/last_event/world_china.html .

Some major components of the Himalayas:

Visible earth field trip to Himalayas:

There is about 300 km of shortening in the Himalayas plus 600-700 km to form the crustal thickness observed within the Tibetan plateau. Different workers have somewhat different numbers, but all result in a deficit considering how much plate motion has occurred between the two continents since initial collision. How was the rest accomodated?

Escape tectonics:

Gravitational collapse: pile it on and it will fail.

Summary:


Course materials for Plate Tectonics, GEOL 3700, University of Nebraska at Omaha. Instructor: H. D. Maher Jr., copyright. This material may be used for non-profit educational purposes with appropriate attribution of authorship. Otherwise please contact author.