New study finds Bolivia could be struck by a 8.9 magnitude quake

May 8, 2011 – BOLIVIA — The region east of the central Andes Mountains has the potential for larger scale earthquakes than previously thought, according to a new study posted online in the May 8th edition of Nature Geoscience. Previous research had set the maximum expected earthquake size to be magnitude 7.5, based on the relatively quiet history of seismicity in that area. This new study by researchers from the University of Hawaii at Manoa (UHM) and colleagues contradicts that limit and instead suggests that the region could see quakes with magnitudes 8.7 to 8.9. Benjamin Brooks, Associate Researcher in the Hawaii Institute of Geophysics and Planetology in the School of Ocean and Earth Science and Technology at UHM and colleagues used GPS data to map movement of the Earth’s surface in the Subandean margin, along the eastern flank of the Andes Mountains. From these data, the researchers conclude that the shallow section in the east of the region is currently locked in place over a length of about 100 km, allowing stress to build up as the tectonic plates in the region slowly move against each other. Rupture of the entire locked section by one earthquake could result in shaking of magnitudes up to 8.9, they estimate. These findings came as a surprise to Brooks. “No one suspected the previous estimates were too low, it was a discovery that came out of my broader interest which is studying the way in which mountains (in this case the Andes) actively grow and deform.” Major Arturo Echalar of the Bolivian IGM says “The findings here are critical in helping us to continue to provide the most up-to-date and accurate information regarding geological hazards in Bolivia.” –Physics.org