Continental Re-Org


Scientists trace the source of May’s devastating earthquake in Sichuan Province, China, to a continuous northward motion of the Indian tectonic plate, the same tectonic energy pushing the Himalayas to new heights.

Scripps Institution of Oceanography at UC San Diego researcher Steve Cande is re-analyzing the evolution of the Indian and Eurasian plate collision in Southeast Asia, which began 50 million years ago during the Eocene epoch to better understand the tectonic history of the region.

“It’s like a tube of toothpaste,” said Cande.  By applying pressure to the tube, the paste at the end of the tube escapes to reduce the pressure inside. As the earth’s continental plates collide, they create pressure that is ultimately released in faults in the form of earthquakes. Sichuan Province is located at a junction between the Indian and Eurasian plates.

Current global plate models suggest that after continents collide, the motion stops. India defies the current theory as it continues moving on a northward path, at a rate of roughly 4 centimeters per year (1.5 inches) or about 3 meters (10 feet) in 70 years. In the past 50 million years since India and Eurasia collided, India has moved 2,000 kilometers (1,243 miles) forming the Tibetan plateau and the Himalayas.

“This ongoing convergence is actually a great tectonic puzzle”, said Cande. “Why does India continue to converge with Eurasia?”

Cande, a professor of marine geophysics at Scripps, is using new data, such as satellite radar altimetry, to re-examine the tectonic events that accompanied the initial collision of India and Asia. By incorporating new data, including magnetic anomalies and fracture zones on the ocean floor, researchers can better understand what is driving India closer to Asia.

The Eocene represents the largest global plate reorganization that has occurred in Earth’s history and is “recorded” on the ocean floor. It left one such mark in the “bend” in the Hawaiian Island chain and in the Emperor seamounts, which are a continuation of the island chain located underwater. Scientists have long thought that the Pacific plate had a major change in motion during that time, or that the Hawaiian hotspot changed its motion. Researchers are also interested in understanding if the Hawaiian event is related to the collision of India with Asia or from another force.

According to Cande, these questions represent a gap in current scientific knowledge of plate tectonics. He and his colleagues hope to have new findings later this year on what is driving the Indian plate in the tectonically active region.

“The geodynamic modelers need good constraints and we hope that by better constraining the fine details of the plate motions, we can provide input that will enable the modelers to figure out what is driving the plates,” said Cande.

-- Annie Reisewitz

Related Video: Steve Cande faculty page

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