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In Sumatra, Waiting for Big One to Hit in Next ‘30 Seconds to 30 Years’
Sydney. A massive undersea earthquake is long overdue beneath the Mentawai Islands in West Sumatra and could trigger another deadly tsunami, say scientists mapping one of the world’s most quake-prone zones.
Unlike the 2004 Indian Ocean tsunami, which killed around 226,000 people, this tsunami is expected to be smaller but may be very deadly as it would hit Sumatra’s densely populated coast.
“The size of the tsunami may not be as big, but the problem is the size of the population is about three times as great as Aceh,” said Kerry Sieh, director of the Singapore-based Earth Observatory.
A major quake measuring around 8.6 magnitude is expected beneath Siberut Island, along the Sunda megathrust, where the Indo-Australian tectonic plate butts up against the Eurasian plate — one of the world’s most active fault lines, though just when it will happen is not known.
“We say most likely in the next few decades. Thirty seconds to 30 years, somewhere in there,” said Sieh, who has studied geological records showing that for the past 700 years, major quakes have occurred along the Sunda megathrust every 200 years.
There have been three major quake cycles: the late 1300s, the 1600s and between 1797 and 1833.
“The timing between those three sequences is about two centuries,” Sieh said, adding that a section of the megathrust under Siberut has not ruptured for 200 years, so it is due to slip and cause a major quake.
Superquake Cycles
The Sunda megathrust extends from Burma in the north and sweeps in a southeast arc through Sumatra, Java and toward Timor.
The northern 1,600-kilometer section of the fault, from Burma to Aceh, ruptured in 2004 sending the deadly Dec. 26 tsunami out into the Indian Ocean.
Sydney. A massive undersea earthquake is long overdue beneath the Mentawai Islands in West Sumatra and could trigger another deadly tsunami, say scientists mapping one of the world’s most quake-prone zones.
Unlike the 2004 Indian Ocean tsunami, which killed around 226,000 people, this tsunami is expected to be smaller but may be very deadly as it would hit Sumatra’s densely populated coast.
“The size of the tsunami may not be as big, but the problem is the size of the population is about three times as great as Aceh,” said Kerry Sieh, director of the Singapore-based Earth Observatory.
A major quake measuring around 8.6 magnitude is expected beneath Siberut Island, along the Sunda megathrust, where the Indo-Australian tectonic plate butts up against the Eurasian plate — one of the world’s most active fault lines, though just when it will happen is not known.
“We say most likely in the next few decades. Thirty seconds to 30 years, somewhere in there,” said Sieh, who has studied geological records showing that for the past 700 years, major quakes have occurred along the Sunda megathrust every 200 years.
There have been three major quake cycles: the late 1300s, the 1600s and between 1797 and 1833.
“The timing between those three sequences is about two centuries,” Sieh said, adding that a section of the megathrust under Siberut has not ruptured for 200 years, so it is due to slip and cause a major quake.
Superquake Cycles
The Sunda megathrust extends from Burma in the north and sweeps in a southeast arc through Sumatra, Java and toward Timor.
The northern 1,600-kilometer section of the fault, from Burma to Aceh, ruptured in 2004 sending the deadly Dec. 26 tsunami out into the Indian Ocean.
