Earthquake experts came out with a troubling report Tuesday. The Observatorio Vulcanológico y Sismológico de Costa Rica said that 7.6 quake last week was expected but that another quake at the same or greater magnitude is likely.
The Observatorio estimated that the fault which generated the quake has expended 50 percent of its energy but that the joint only slipped 1.85 meters of a possible 4 meters. That is about 6 feet of a possible 13.
The Observatorio, which is affiliated with Universidad Nacional, quoted quake expert Marino Protti saying that there are three ways the remaining energy might be released. He cited aftershocks, of which there have been many. He also noted that the fault could slip without generating a quake, according to the Observatorio. The third possibility is another big quake.
The Observatorio and Protti have been trying to alert residents in the Nicoya peninsula for 15 years to the possibility of a major quake. The last big one was in 1950. The quakes are generated by the subduction of the Coco tectonic plate under the lighter Caribbean plate on which much of Costa Rica rides.
The Observatorio and other agencies have many sensors in the area that can keep track of energy liberated in the coming years.
The Observatorio said that experts are keeping track of deformations of the land due to the quake. They have determined that Playa San Juanillo rose 60 centimeters, about two feet, and that the area around Juan Díaz rose 40 centimeters (16 inches). On the east side of the peninsula and along the Río Tempisque, the land sank about 5 to 10 centimeters, perhaps 2 to 4 inches.
The faults continued to release energy Tuesday and early today with aftershocks. There was
A quake at 29 minutes after midnight today took place 48 kilometers southwest of the tip of the Nicoya peninsula. The magnitude was estimated at 4.8 and 5.2. An earlier quake in about the same location offshore took place at 10:10 p.m. Tuesday. The magnitude was 4.2.
Meanwhile, Nosara was the location of two quakes, also in the 4-point range. The first was a 8:14 p.m. and was estimated at 4.2 magnitude. Then four minutes later a 4.8 magnitude quake took place at about the same location, about 3.5 kilometers south and east of the community, according to estimates of the epicenter by the Laboratorio de Ingeniería Sísmica at the Universidad de Costa Rica.
There have been more than 1,000 aftershocks, mostly in the 2 to 3 magnitude range. The strongest have been estimated at 5.6 and 5.8.
Meanwhile repair work continues in the country by individuals and government agencies. The highway agency opened a route between Zarcero and Ciudad Quesada Tuesday where a landslide had blocked the road. But then the road was closed due to high winds in the afternoon, the agency said in an announcement. More rocks were dislodged and fell to the highway, it said.