Area offshore has potential for big quake, study says

An Australian researcher has studied subduction zones where one tectonic plate presses against an adjacent one. He reported that certain characteristics show which areas can produce big earthquakes and which probably will not.

He is Wouter Schellart of the Monash University  School of Geosciences. The university said he has identified the zone along México and Central America as being primed for a massive quake.

The new research, published in the journal Physics of the Earth and Planetary Interiors, comes nine years after the giant earthquake and tsunami in Sumatra in December 2004, which devastated the region and many other areas surrounding the Indian Ocean, and killed more than 200,000 people, the university noted.

Since then two other giant earthquakes have occurred at subduction zones, one in Chile in February 2010 and one in Japan in March 2011, which both caused massive destruction, killed many thousands of people and resulted in billions of dollars of damage, it said.

The news probably is no surprise to expats living here because the Pacific coast of the country is part of the so-called Ring of Fire that borders the Pacific. It is under the Pacific where the Cocos tectonic plate is struggling to work its way under the lighter Caribbean plate. Many of the country’s frequent earthquakes can be traced to this contact.

Schellart worked with Nick Rawlinson, a professor from the University of Aberdeen in Scotland, to study the world’s subduction zones.

The pair reported that they found 24 physical characteristics of 241 regions of contacts between tectonic plates. Then they studied earthquake activity since about 1900.

The pair developed a global map in which individual subduction zone segments have been ranked in terms of their predicted capability of generating a giant subduction zone earthquake using the six most indicative subduction zone parameters, they said in their paper. They said a giant quake would be of 8.5 magnitude or larger.

Such parameters include rate of deformation of the top tectonic plate, the velocity of the movement and the angle of the contact between the plates. All of these are possible to measure. They said they found similar characteristics in the three biggest recorded quakes,  Chile in 1960, Alaska in 1964 and Sumatra–Andaman in 2004.

In addition to Mexico and Central America, the subduction zones most likely to produce massive quakes are Sunda, North Sulawesi, Hikurangi, Nankai-northern Ryukyu, Kamchatka-Kuril-Japan, Aleutians-Alaska, Cascadia, South America, Lesser Antilles, western Hellenic and Makran, they said.

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