Poas volcano (Costa Rica), activity summary Feb 2012: high-temperature fumarolic activity and sporadic small phreatic explosions

During February, Poás activity consisted in strong high-temperature fumarolic activity and sporadic small phreatic explosions, reported by park rangers.
The latest monthly bulletin of Costa Rica's volcano observatory OBSICORI published a more detailed summary of Poás'activity during February summarized as follows:
The ultra-acid crater lake had a greenish-gray color with sporadic convection cells visible in the central part carrying sulfur in suspension. Lake temperature were measured at 44° C, which is a value significantly lower than those measured during most of 2009-2011. The pH value of the lake water was measured at 0.01, slightly "less" acidic than during November 2011 (pH -0.4).
The lake volume continued to decrease and its level dropped by 1.16 m between 25 Jan and 24 Feb. Concentrations of sulphate and chlorine increased.

The composite pyroclastic cone (the "dome") has high-temperature fumarolic activity and a strong emissions of blue gas (SO2). Fumarolic activity in the northwest sector of the "dome" had temperatures between 685 and 725°C. In the northern part of the "dome", temperatures were ranging between 640 and 727°C (at accessible points).
On the north wall and north of the "dome" at the shore, there are some underwater fumaroles which release a significant amount of sulfur particles. Temperatures in this area range between 74 and 90°C.