When a massive earthquake hit off the coast of the Indonesian island of Sumatra earlier today, the Pacific Tsunami Warning Center issued a tsunami watch for the entire Indian Ocean. But a few hours later, when no major waves occurred, the watch was lifted.
Hermann Fritz, Georgia Tech associate professor of civil and environmental engineering, explains why this earthquake did not cause a devastating tsunami like in 2004, when a 9.1-magnitude earthquake in the Indian Ocean resulted in a devastating tsunami that killed more than 200,000 people in 14 countries.
Essentially this is a strike-slip earthquake with mostly horizontal seafloor motion. No ocean-wide tsunami is expected from such an event. Strike-slip events happening close to shore can produce local tsunamis such as the Haiti earthquake in 2010, which produced local tsunami heights of up to three meters and drowned three unaware residents. Today's Indian Ocean earthquake was close to 400 km (more than 200 miles) offshore to the west of the coast of Sumatra on reactivated fracture zones.
Because the sea floor moved horizontally instead of vertically, as it did in 2004, it displaced less water and did not send monster waves into the Indian Ocean.
A leading expert in his field, Fritz researches fluid dynamic aspects of natural hazards, their mitigation and coastal protection. He is part of the research team investigating the Indian Ocean tsunami of December 2004. He's also mapping the Japan tsunami of 2011 to prepare for future events.
Damage that resulted from the Japan tsunami of 2011. Photo taken by Fritz while doing survey work
a few weeks after the event.
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