7.6 Costa Rican earthquake did not relieve fault pressure: expect another one equal or greater, scientists warn

September 12, 2012 – COSTA RICA – After a series of analyses conducted in the northwestern province of Guanacaste, experts from the Volcanological and Seismological Observatory of Costa Rica (Ovsicori) reported Tuesday that another quake of equal or greater magnitude could occur in Nicoya Peninsula, but predicting when it would happen is “impossible.” Marino Protti, Ovsicori’s lead scientist, explained that the magintude-7.6 earthquake on Sept. 5 caused a 40 percent slip and an inclination of 1.8 meters on the fault located in Nicoya. He also said that although the quake was the “big one” experts had been expecting for Guanacaste, the fault ruptured by only 50 percent, meaning that the possibility that another earthquake of equal or greater magnitude in the area still remains. Ovsicori’s report, released Tuesday, also stated that the earthquake triggered the activation of three faults in Aguas Zarcas (in the northern region), the Guanacaste Volcanic Area and Irazú Volcano (north of Cartago). Seismologists will continue monitoring the areas. By Tuesday morning, the total count of aftershocks from the recent earthquake was 1,650. On Sept. 5  at 8:42 a.m., the 7.6-magnitude earthquake shook the country and was felt as far away as Nicaraguan and Panama. Its epicenter was located 20 kilometers northwest of Sámara in the Nicoya Península. –Tico Times