Nicoya residents get chance to learn about quake

Map shows the direction of tectonic plates with the Mid-Atlantic trench just offshore. Green dots are epicenters of past earthquakes.

Earthquake experts are hosting another conference Friday to alert Nicoya peninsula residents to the probability of a major quake.

The event is being sponsored by the Red Sismológica Nacional, and it will be in the Cruz Roja building in the town of Nicoya at 10 a.m..  Wilfredo Rojas, a geologist associated with Universidad de Costa Rica’s Red, will be the featured speaker.

This is the latest in efforts by the scientific and government communities to prepare residents for what is considered an inevitable major earthquake.

The Nicoya peninsula rides atop the Caribe tectonic plate which is inching southwest above the Cocos Plate. The movement is estimated at about 9 centimeters per year, a bit more than 3.5 inches.

According to Cal Poly Pomona University earth scientist Jeff Marshall, the peninsula is unique because it is one of the few landmasses along the Pacific Rim located directly above the seismogenic zone of what he calls a subduction megathrust. He is one of the researchers who has been studying the peninsula in detail for years. The area even is the location of university summer programs in earthquakes.

Another expert is Marino Protti, director of Universidad Nacional’s Observatorio Vulcanológico y Sismológico de Costa Rica. He can easily be called the man who wrote the book on the coming earthquake. He authored with two others the 2001 report that evaluates the earthquake potential of the Nicoya peninsula and also Heredia. Protti, too, has been giving seminars, some sponsored by the Instituto Nacional de Seguros, the insurance company.

The reasoning behind the earthquake prediction is that major quakes in the 7.0 magnitude range have taken place in 1853, 1900 and 1950. In addition, a 7.0 quake took place just south of the Nicoya peninsula in 1990 and another took place in 1992 north of the peninsula in Nicaragua. Experts expect the new epicenter to be somewhere between these two points and the magnitude to be in the 7.6 to 7.8 range.

Both Marshall and Protti expect the western beaches of the peninsula to jerk up perhaps as much as two meters or a bit more than 6.5 feet.  Land on the east shore of the peninsula is expected to subside. That is what happened in the 1950 quake, Marshall noted in a 2008 book chapter.

The highly active peninsula is being studied in detail by monitoring sites and satellites, but there is little chance of much warning. In 1950, one witness said the howler monkeys began shouting just before the quake. There are some scientific studies that suggest animals can hear an approaching quake much better than human ears.

A.M. Costa Rica has written about the earthquake threat in the past. But scientists seem to have taken a renewed interest in warning the public. The Jan. 12 Haiti earthquake was a 7.0 magnitude and killed 230,000 persons, mainly because of lack of preparation and bad construction practices.

The prognosis is not good. Scientists say there are plenty of substandard buildings on the Nicoya peninsula and that the quake would cause considerable damage in the Central Valley. The April 12, 1991, earthquake in Limón province also caused major damage in the Central Valley. That was a 7.5 magnitude quake that killed 53 persons.

The main problems for expats would be in getting medical care and having enough water, fuel and food to survive for several weeks. The prediction is for downed bridges, blocked highways and limited access by emergency workers during the first 48 hours. The damage will be regional with the Interamericana North probably cut in several places, too. That is on the mainland.

The magnitude scale for earthquakes is geometric, so the Nicoya quake is expected to have 10 times the force of the Jan. 8, 2009, quake at Cinchona north of Heredia. That was a 6.2 magnitude event. Some 22 persons died there.

The experts from the Laboratorio Nacional de Materiales y Modelos Estructurales at the Universidad de Costa Rica have said most of the buildings on the peninsula do not comply with quake codes.

The expectations of disaster are so well known that both San José television stations had crews en route by air to the peninsula shortly after a 5.1 quake took place off Montezuma Sept. 15.

The best they could find for their viewers was minor damage and street scenes of Cóbano.

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