Sediment from Himalayas may have made 2004 Indian Ocean earthquake more severe

IMAGE: Researchers carry a sediment core.
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Credit: Tim Fulton, IODP-JRSO

CORVALLIS, Ore. – Sediment that eroded from the Himalayas and Tibetan plateau over millions of years was transported thousands of kilometers by rivers and in the Indian Ocean — and became sufficiently thick over time to generate temperatures warm enough to strengthen the sediment and increase the severity of the catastrophic 2004 Sumatra earthquake.

The magnitude 9.2 earthquake on Dec. 26, 2004, generated a massive tsunami that devastated coastal regions of the Indian Ocean. The earthquake and tsunami together killed more than 250,000 people making it one of the deadliest natural disasters in history.

An international team of scientists that outlined the process of sediment warming says the same mechanism could be in place in the Cascadia Subduction Zone off the Pacific Northwest coast of North America, as well as off Iran, Pakistan and in the Caribbean.

Results of the research, which was conducted as part of the International Ocean Discovery Program, are being published this week in the journal Science.

“The 2004 Indian Ocean tsunami was triggered by an unusually strong earthquake with an extensive rupture area,” said expedition co-leader Lisa McNeill, an Oregon State University graduate now at the University of Southampton. “We wanted to find out what caused such a large earthquake and tsunami, and what it might mean for other regions with similar geological properties.”

The research team sampled for the first time sediment and rocks from the tectonic plate that feeds the Sumatra subduction zone. From the research vessel JOIDES Resolution, the team drilled down 1.5 kilometers below the seabed, measured different properties of the sediments, and ran simulations to calculate how the sediment and rock behaves as it piles up and travels eastward 250 kilometers toward the subduction zone.

“We discovered that in some areas where the sediments are…

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