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Poas volcano
Stratovolcano 2708 m (8,884 ft)
Costa Rica, 10.2°N / -84.23°W
Current status: restless (2 out of 5)
Poas webcams / live data | Reports
Poas volcano eruptions:
1828, 1834, 1838(?), 1860, 1879(?), 1880, 1888-91, 1895, 1898-1907, 1910, 1910, 1914, 1914-15, 1925, 1929, 1941-46, 1948-51, 1952-57, 1958-61, 1963, 1964-65, 1967, 1969, 1970, 1972-73, 1974-75, 1976, 1977, 1977-78, 1978, 1979-80, 1980, 1981, 1987-90, 1991, 1992, 1992-93, 1994, 1996, 2010, 2011, 2012, 2013, 2014, 2016, 2017
Typical eruption style:
Phreatic eruptions, sometimes geyser-like ejections of water from the acid crater lake.
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Volcano news: Poás volcano, Costa Rica

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

Tue, 13 Mar 2012, 11:05
11:05 AM | BY: T
High-temperature fumaraoles from the comosite cone (the "dome") at the shore of Poás' crater lake (photo: E. Fernández, 24 Feb 2012)
High-temperature fumaraoles from the comosite cone (the "dome") at the shore of Poás' crater lake (photo: E. Fernández, 24 Feb 2012)
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.
Links / Sources:
Previous news
Wed, 4 Jan 2012, 00:01
Fieldwork at Poás on 16 December showed new geyser activity from a vent on the N flank of the lava dome that formed in 2011. A water-and-mud fountain rose 5-6 m high, flowed into the lake, and built a terrace along the S shore. ... read all
Sat, 24 Sep 2011, 09:14
Recently, a part of the lava dome inside the crater of Poas volcano has been showing areas of incandescence and flames of burning gas. read all
Wed, 10 Feb 2010, 19:22
Our correspondant from Costa Rica reports two phreatic eruptions from Poás volcano's crater lake on the morning of Feb 9. ... read all
Fri, 22 Jan 2010, 22:23
Our correspondant in Costa Rica reports a beautiful phreatic eruption at Poas volcano today at noon time. This is the second eruption (after the one on 25 Dec 09) in a short time span. ... read all
Thu, 13 Sep 2007, 06:08
Laguna Caliente, the frequently visited summit lake of Poás volcano, exhibits signs that increased fumarolic activity is happening at the bottom of the lake: now greenish-gray in color, convection cells in the lake's center and dark gray floating particles are being noted.
... read all

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