Police have set up a roadblock at the community of La Central to prevent visitors to the area around the Turrialba volcano and the national park of the same name. But all geologists can do is wait and speculate on what the mountain may do.
An alert continues for the immediate area, and municipal and central government officials have met to outline plans for any major eruption.
Experts from the Red Sismológica Nacional of the Universidad de Costa Rica, the Observatorio Vulcanológico y Sismológico of the Universidad Nacional and from the Comisión Nacional de Prevención de Riesgos y Atención de Emergencias have visited the area to evaluate and monitor the mountain.
The volcano gave a large burp of ash Wednesday afternoon followed by an expulsion of vapor Thursday. Since then, quiet has prevailed.
Scientists really do not know what is going on deep underground. Their best guess is that the twin columns of material were not signals of a larger eruption to come.
They face the same problem underground in the Nicoya peninsula. Two earthquakes took place
there late last week. One was offshore in the gulf of Nicoya, and one was just north of Naranjo on the east shore of the peninsula. That was 26 minutes before midnight Thursday, and the magnitude was estimated at 3.1, according to the Laboratorio de Ingeniería Sísmica at the Universidad de Costa Rica. An earlier quake also of about 3.1 magnitude took place Thursday at 2:34 a.m. The epicenter was in the gulf east of the tip of the peninsula along a recognized fault there.
Scientists say that a major earthquake in or near the gulf is just a matter of time. They even have held local meetings to brief residents.
Meanwhile, in Turrialba, the Parque Nacional Volcán Turrialba will remain closed.
The other hotspot is south of San José near the border between the central canton and the province of Cartago. This is the area around Tobosí, San Cristóbal and Tarbaca in the southern mountains.
The Laboratorio de Ingeniería Sísmica has logged a number of quakes in that area in the last three weeks. The latest, one of 2.1 magnitude, took place right at San Cristóbal at 3:20 p.m. Sunday.
The laboratory released a mathematically study of the estimated effects of a 6.0 quake in that area based on similar quakes elsewhere.