December 13, 2013
Global Map Pinpoints Locations Of Possible Giant Earthquakes
Rebekah Eliason for redOrbit.com – Your Universe Online
Researchers have developed a new global map of areas known as subduction zones. Pinpointing these specific locations allows researchers to determine which ones have the ability to generate giant earthquakes and which ones do not.The research, led by Monash University’s Associate Professor Wouter Schellart, comes in response to the devastating giant earthquake and tsunami in Sumatra in December 2004. This region, along with many other areas surrounding the Indian Ocean, was destroyed, and more than 200,000 people lost their lives.
Since that giant earthquake, two more have occurred at subduction zones. One occurred in Chile in February 2010 and the other in Japan in March 2011. Both resulted in large-scale destruction which killed thousands of people and caused billion of dollars of property damage.
Most earthquakes take place along the boundaries between tectonic plates that cover the Earth’s surface. The largest earthquakes have only occurred at the special subduction zones. In these plate boundaries, one plate sinks, or 'subducts,' beneath the connecting plate and into the Earth’s interior. Earthquakes specialists have so far recorded only a limited number of giant earthquakes at subduction zone segments. The earliest accurate seismological records date to around 1900, which is problematic since hundreds of years can pass between giant earthquake recurrences.
“The main question is, are all subduction segments capable of generating giant earthquakes, or only some of them? And if only a limited number of them, then how can we identify these,” Dr Schellart said.
Working with Professor Nick Rawlinson from the University of Aberdeen in Scotland, Dr. Schellart used the earthquake data and data from subduction zones as far back as 1900 to make a map showing the main characteristics for all the currently active subduction zones on Earth. The researchers examined subduction segments to determine if those that experience giant earthquakes share commonalities in physical, geometrical and geological properties.
The study discovered that the style of deformation in the plate overlying the subduction zone, the level of stress at the subduction zone, the dip angle of the subduction zone, the curvature of the subduction zone, and the rate at which it moves were the main common factors indicating the potential for giant earthquakes.
As a result of these findings, Dr. Schellart identified several areas capable of producing a giant earthquake. These regions include the Lesser Antilles in the Caribbean Sea, Mexico-Central America, Greece, the Makran area on the Arabia Sea , the Sunda Islands in the Malay archipelago , North Sulawesi in Indonesia, and Hikwurangi in New Zealand.
“For the Australian region subduction zones of particular significance are the Sunda subduction zone, running from the Andaman Islands along Sumatra and Java to Sumba, and the Hikurangi subduction segment offshore the east coast of the North Island of New Zealand. Our research predicts that these zones are capable of producing giant earthquakes,” Dr Schellart said.
“Our work also predicts that several other subduction segments that surround eastern Australia (New Britain, San Cristobal, New Hebrides, Tonga, Puysegur), are not capable of producing giant earthquakes.”
The team published the results of their study in the journal Physics of the Earth and Planetary Interiors.