The eruption was both explosive and effusive. According to news, the eruption began at 2:45 a.m. with large explosions and lava fountains possibly up to 1 km high from the summit crater. Large incandescent bombs were ejected to considerable distances and showered the summit cone of the volcano. A 500 m long lava flow traveled down on the SW flank towards the Ceniza ravine. The eruption also produced an ash column reaching 5 km (16,000 ft altitude) and pyroclastic flows probably generated mostly by cascading lava blocks traveling down the steep cone's flank into Las Lajas, El Jute y Ceniza valleys.
Ash fall was reported from nearby villages mainly to the S and SW including Morelia, Panimaché I and II, Sangre Cristo and Yepocapa. [less]

The activity followed an increase of elevated SO2 emissions and seismic activity detected in late April. According to reports, the degassing from a crack in the main crater was accompanied by jet-like sounds, and internal rumblings can be heard at the volcano.
Latina Press mentions that scientists are closely monitoring the new activity, but so far, no emergency has been declared and the Masaya Volcano National Park remains open. [less]

During 11-15 April steam-and-gas emissions from Popocatépetl occasionally contained ash; emissions contained a substantial amount of ash on 12 April.
Seismicity increased on 13 April and at 2220 an explosion ejected incandescent blocks that landed on the NE flank as far as 500 m away from the crater rim. A larger explosion at 2236 ejected incandescent blocks that landed even further away on all flanks; an ash plume rose 2 km above the crater and drifted ENE. Ashfall was reported in San Pedro Benito Juarez (10-12 km SE), where the explosion was also heard. [less]

Local authorities are preparing for potential evacuations. The last time evacuations were ordered on a large scale was in 2000 when over 50,000 people had to leave their homes.
The major hazards of a larger eruption would be ash falls, pyroclastic flows, lahars produced by mixing of water and tephra. [less]

An 12 km exclusion zone was declared around the volcano. [less]

No further ash venting has occurred since 23 March. [less]

No more phreatic explosions and ash-venting episodes have been observed since 23 March. Seismic activity has returned to a low level as well and zone C on the island was reopened for day-time visits.
However, the volcano shows strong sulfur dioxide emission, suggesting that fresh magma might be flowing into a shallow reservoir. During 24-26 March, extremely high levels of SO2 emission rates were measured, up to 4,594 tonnes per day, the third highest value measured in 10 years. [less]

Several block lava flows are traveling down from the dome, and generate glowing avalanches. Frequent explosions produce ash plumes rising 800-900 m above the lava dome. An explosion on 26 March produced pyroclastic flow on the western flank of the cone.
Satellite images detected several plumes extending up to 33 km in south-westerly directions. Ash fall occurred in up to about 10 km distances in areas to the south at the Observatory Vulcanológico de Santiaguito (OVSAN), and to the SW at the El Faro, La Florida, and Patzulin ranches (SW), as well as in the village of Santa María de Jesús (SE). [less]

During 24-25 March, the volcano had 33 small steam and gas emissions, accompanied by small earthquakes and volcanic tremor. On Saturday night, incandescence was observed at the crater.
CENAPRED recommends a safety radius of 12 kilometers around the volcano as eruptions with higher intensity could occur any time. [less]

Die Ascheauswürfe begannen etwa 8:00 lokaler Zeit am 23 März. Sie wurden von Schwarmbeben am 22. und 23. März begleitet, wie das Vulkanobservatorium MVO berichtete.
Die Ausbruchstzentren der neuen Tätigkeit befanden sich im Einbruchstal vom 11 Februar 2010, ganz nahe am Kraterrand des old English craters und westlich der langlebigen und heißesten Fumarole, die davor entdeckt wurde. Die Tätigkeit heißer Gase stieg deutlich an und eine neue Dampf-Fumarole wurde am nordwestlichen Hang hinter dem Ganges Mountain entdeckt. [less]

San Salvador volcano is an active stratovolcano immediately northwest of the capital San Salvador City and last erupted in 1917.
[less]

The pyroclastic flow traveled about 1 km to the west towards Plymouth before its ash dissipated to form a small ash cloud rising 1.3 km and drifting towards St. Georges Hill and out to sea. MVO has published further details and photographs of this event which is significant as it occurred during a quiet phase of the volcano with no current active lava dome growth and illustrates the hazard of sudden pyroclastic flows.
"There were no precursors to this event. Although activity has generally been low, this event clearly illustrates that Soufrière Hills Volcano is still an active volcano and that pyroclastic flows can occur at any time with little to no warning." [less]

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). [less]

Am 23. Februar wachte Einwohner in Guachipelin (11 km SW) auf um Explosion zwischen 0400 und 0430 Ortszeit zu hören. Seismische Aufzeichnungen zeigte Signale typisch für Explosionen zur gleichen Zeit, obwohl andere Bewohner in anderen Bereichen nicht, jede Eruption hören.
Ähnliche seismische Signale gefunden auf 19 Feb 00:16 und 20 Feb 00:46 lokaler Zeit, was darauf hindeutet, dass auch kleinere Explosionen dann aufgetreten ist. [less]

Die Informationen der höchste wissenschaftliche Einrichtung des Landes angibt, über die Dörfer San Marcos, Buena Vista und Palajunoj und auf dem Bauernhof in der Leuchtturm, Florida, Mount klar gemeldeten fallende Asche Partikel infolge der Aktivität der Koloss.
Die wissenschaftliche Stelle des Systems des nationalen Koordinators für Disaster Reduction CONRED, berichtet, dass seit früh auf Dienstag 28. Februar beobachtet wird in den Krater Glühen und Wunderkind der Blöcke, die auf der Basis, Anhebung der Federn des Asche. Außerdem weiterhin im Netzwerk aufzeichnen seismischer Aktivität Santiaguito Explosion alle 15 Minuten. [less]

(Nachricht von J Duarte, Vulkan Monitoring Team, OVSICORI-UNA) [less]

The lava flow in the direction of Taniluyá is between 150-200 m long, and incandescent blocks detach from the front, tumbling down into the forested area. [less]

Weitere Entwicklung von der neuen Lavastrom auf der südwestlichen Flanke in Richtung der Schlucht Taniluya erreichen knapp über 200 Meter lang, Wunderkind Blöcke ankommen und Vegetation zu beobachten. [less]

Authorities recommend a safety distance from the volcano of 12 km radius, and the alert level remains at "yellow". [less]

Fels Lawinen reiste SW in die Ceniza Entwässerung und auf die W, S und SW Flanken. In der Nacht am 13. und 16. Januar wurde Glut aus dem Krater sichtbar.
(Quelle: Smithsonian / GVP wöchentlich Tätigkeitsbericht) [less]

The eruption was first noticed by park rangers and local residents.
During the previous day, numerous rumblings could be heard from the mountain. According to OVSICORI-UNA, the eruption started between 3:10 and 3:20 pm and produced an ash plume from a vent on the southeast flank of the main crater in an area known as "La Quemada". [less]

This decompression event released ash that was carried by the wind at least up to Tres Rios (27km SW from the vent). As a consequence the Comisión Nacional de Emergencias and the Turrialba Volcano National Park's administration declared a yellow alert and closed the access, which is still the case on January 17th. [less]

"There is no incandescence currently as part of the wall near the vent collapsed into it. Local people are expecting an eruption to clear it. One can hear churning and avalanches and there is quite a bit of gas you bed to put the mask on or you can only stay 10-15 min on lookout. The dormant crater next door looks like has a small lava dome in it which is slowly rising. The trees and plants don't grow properly maybe because of CO2 in this crater?" [less]

Gas-and-steam plumes rose from the lava dome.
(Smithsonian / USGS Weekly Volcanic Activity Report 28 December-3 January 2012) [less]