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Poás is one of Costa Rica´s most active volcanoes, and one of its most frequently visited and prominent ones. It contains a green acid crater lake and during some of its frequent phreatic eruptions, water from the lake is ejected like a geyser.
Stratovolcano 2708 m (8,884 ft) Costa Rica, 10.2°N / -84.23°W Current status: minor activity or eruption warning (3 out of 5) Poas webcams / live data Poas volcano books | Tours 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. Last earthquakes nearby Latest satellite images
Image of Poás crater on 12 July 2017 with several vents and no more crater lake (image: RSN)
As a result of the recent eruptions, the crater lake has disappeared. At the place of the old lava dome near the center of the crater, a small pyroclastic cone has formed around the main emission point. ...more
Strong sulfur gas (SO2) emission is also occurring from other vents at the crater floor, indicating the presence of magma at shallow depth. During the month of June and this first half of July, the activity consisted of intermittent, passive ash eruptions of varying duration, with sometimes smaller quantities of solid materials including incandescent rock fragments ejected. [less]
Small phreatic eruptions continue to occur from the volcano's crater lake. Ash emissions less than 1 km high and mostly drifting N were seen frequently during breaks in weather by observers near the crater: on 16 June, at 18 June at 13:40 on 18 June, and at 11:00 and 13:50 on 20 June. ...more
Most of the time, a steam plume rising less than 1 km is seen from the crater lake. [less]
Tremor levels were at low-to-moderate levels during 17-21 May and at higher levels during 22-23 May. ...more
Low-amplitude long-period earthquakes were recorded on 19 May, and some low-frequency and volcano-tectonic events were detected during 21-22 May. Plumes consisted mainly of gas and water vapor, but sometimes included solid material, and rose no more than 1 km above the vent. [less]
Beginning of the explosion at Poás last night (image: RSN)
A loud and strong explosion occurred Saturday night (22 April 2017) at 22:12 pm local time from the crater. ...more
It lasted about 1 minute and launched incandescent fragments over the entire sector of the active crater and onto its walls. As the eruption occurred at night and only 4 hours ago, not much detail is available, but it seems to have been the strongest in the ongoing crisis so far. The presence of large amounts of incandescent material suggests that the magmatic component involved has increased, i.e. magma continues to rise towards the surface. [less]
Explosion from Poás 14 April morning (image: Carlos Arguedas C. / La Nacion)
The activity of the volcano continues to increase, culminating (so far) in a moderately strong explosion at 7:57 Friday morning (local time) which was the largest recorded at the volcano in the current crisis so far. ...more
The eruption produced an steam and ash plume that rose 3 km above the crater and caused light ash falls occurred in Heredia and Alajuela. The strong explosion was preceded by several smaller and moderately sized explosions from around 6 am; the most significant one occurred at 6:59, 7:18, 7:39 and 7:57 local time.
The "dome" at the lakeshore of Poás crater with recent evidence of deformation (likely by shallow magma intrusion)
Recent activity of Poás volcano (image: OVSICORI-UNA)
The activity of the volcano has increased recently. On Saturday, several small phreatic (steam-driven) explosions occurred at the crater lake and scientists measured elevated gas emission rates and raised temperatures. ...more
According to a new article, a large group of tourists was evacuated from the volcano, some of which suffered eye and throat irritations caused by the volcanic gasses. A new degassing vent had been observed at the shore of the lake which also changed color. [less]
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