Strong Quake Jolts Vacationers, No Injuries Or Damage Reported
It was 9:28am when a collision, called subduction, between theCocos and Caribe tectonic plates produced a quake registering 5.1 on the Richter scale, that was felt throughout the country.

The epicentre was located in the area of Los Santos (Fila la Candelaria), about 30 kilometres northeast of Quepos.

This was the strongest earthquake this year in Costa Rica. There were no reported damage or injury, just a big scare, as the movement was short but violent. The other major jolts this year were not centred in Costa Rica.

Experts say the activity is normal. According to Marino Protti of the Observatorio Sismológico y Vulcanológico de Costa Rica (Ovsicori), this earthquake was not a shock between the oceanic tectonic plates but rather continental.

The last  "big" earthquake was on November  21 last year when a quake registering 6.2 on the Richter scale with the epicenter was located about 10km northeast of Quepos with a depth of about 30km and felt as far away as Cartago, leaving eight dead and more than 500 homes damaged.

A 6.0 earthquake was felt on December 25, 2003 in Puerto Armuelles and a 5.7 in Alajuela occurred on December 22, 1990.


MAJOR TECTONIC PLATES OF THE WORLD
The earth's surface is broken into seven large and many small moving plates. These plates, each about 50 miles thick, move relative to one another an average of a few inches a year. Three types of movement are recognized at the boundaries between plates: convergent, divergent and transform-fault.

At convergent boundaries, plates move toward each other and collide. Where an oceanic plate collides with a continental plate, the oceanic plate tips down and slides beneath the continental plate forming a deep ocean trench (long, narrow, deep basin.) An example of this type of movement, called subduction, occurs at the boundary between the oceanic Nazca Plate and the continental South American Plate. Where continental plates collide, they form major mountain systems such as the Himalayas.

At divergent boundaries, plates move away from each other such as at the Mid-Atlantic Ridge. Where plates diverge, hot, molten rock rises and cools adding new material to the edges of the oceanic plates. This process is known as sea-floor spreading.

At transform-fault boundaries, plates move horizontally past each other. The San Andreas Fault zone is an example of this type of boundary where the Pacific Plate on which Los Angeles sits is moving slowly northwestward relative to the North American Plate on which San Francisco sits.

Plate tectonics, the branch of science that deals with the process by which rigid plates are moved across hot molten material, has helped to explain much in global-scale geology including the formation of mountains, and the distribution of earthquakes and volcanoes.