~ Espanol ~   Translate to your Language by Clicking on Your Flag  

Costa Rica Volcano Poas

Poas is a stratovolcano with several eroded calderas, cones, and two crater lakes at or near its summit. Poas has erupted at least 39 times since 1828 and is in state of nearly continuous mild activity. Most of the eruptions are phreatic, caused by the interaction of lava and the water in the crater lake.

Explosions vary in strength. Some explosions eject material about 1,500 feet (500 m) above the lake. The lake (and steam) is very acidic, with a pH less than one. Temperatures as high as 185 F (85 C) have been measured at the crater lake.

In 1989, the crater lake at Poas gradually drained away. Later, researchers found a pool of liquid sulphur about 6 feet (2 m) in diameter. This was the first observation of a liquid sulphur lake on the surface of the Earth. The sulphur is probably remobilized fumarole deposits.

POÁS VOLCANO NATIONAL PARK

• Size: 5,599 hectares
  

• Distance from San José: 37 Kilometers
  

• Trails: Yes.
  

• Dry Season: December through April.
  

Few volcanoes allow you to drive all the way to the rim. Poas does - well, at least to within 300 meters, where a short stroll puts you at the very edge of one of the world's largest active craters (1.5 km wide). The viewing terrace gives a bird's-eye view not only 320 meters down into the hellish bowels of the volcano, with its greenish sulfuric pool, but also down over the northern lowlands.

Poas (2,708 meters) is a restless giant with a 40-year active cycle. It erupted moderately in the early 1950s and has been intermittently active ever since. The park is frequently closed to visitors because of sulfur gas emissions.

Over the millennia it has vented its anger through three craters. Two now slumber under a blanket of vegetation; one even cradles a lake. But the main crater bubbles persistently with active fumaroles and a simmering lake.

The sulfuric pool frequently changes hues and emits a geyser up to 200 meters into the steam-laden air. The water level of the lake has gone down about 15 meters during the past decade, one of several indications of a possible impending eruption.

In the 1950s a small eruption pushed up a new cone on the crater floor; the cone is now 220 feet high and still puffing.

Oft as not it is foggy up here and mist floats like an apparition through the dwarf cloud forest draped with bromeliads and mosses. Clouds usually form midmorning. Plan an early-morning arrival to enhance your chances of a cloud-free visit. Temperatures vary widely. On a sunny day it can be 21°C (70°F). On a cloudy day, it is normally bitterly cold and windy at the crater rim. Dress accordingly.

Poas is popular on weekends with local Ticos who arrive by the busload with their blaring radios. Visit midweek if possible.
Botos Lagoon is a filled-up crater in the Poas Volcano National Park.

Its deep blue waters contrast with the dense tropical forest that surround it, making it the perfect spot for the stereotypical Indian sacrifice - throwing a young maiden into the mouth of a crater or a lagoon. Just a thought, not a recommendation...;o)

Back to Top

©Copyright InCostaRicaGuide.com™ 2006 and Beyond...

All Rights Reserved