Smithsonian/USGS Weekly Volcanic Activity Report 28 March to 3 April 2012

The latest Smithsonian Institution and United States Geological Survey Weekly Volcanic Activity Report has been published by the Global Volcanism Program, covering the week 28 March to 3 April 2012. The report is compiled by Sally Kuhn Sennert. Among the highlights of this week:

• Alert level at Clevelandraised as a new lava dome becomes evident
• A significant increase in seismicity at Nevado del Ruiz brings a rise in the alert level
• High levels of sulphur dioxide emissions at Soufrière Hills
• Another paroxysmal eruptive episode at Etna with lava fountaining and ashfall

Click on the map for a larger version (1211 x 784 pixels).

The Smithsonian Institution/United States Geological Survey Weekly Volcanic Activity Report for 28 March to 3 April 2012 is now available on the Global Volcanism Program website. The following is a summary and not a substitute for the full report.

• The current report: Weekly Volcanic Activity Report.
• Previous reports: Weekly Reports Archive.
• The SI/USGS map of volcanoes discussed this week.

New activity/unrest: Cleveland (Alaska, USA), Fuego (Guatemala), Iliamna (Alaska, USA), Lewotobi (Indonesia), Nevado del Ruiz (Colombia), Soufrière Hills (Montserrat), Sundoro (Indonesia).

Ongoing activity: Etna (Italy), Karymsky (Russia), Kilauea (Hawaii, USA), Popocatépetl (Mexico), Puyehue-Cordón Caulle (Chile), Shiveluch (Russia), Tengger Caldera (Indonesia), Tungurahua (Ecuador).

Note: ‘a.s.l.’ = ‘above sea level’.

NEW ACTIVITY/UNREST

Cleveland (Alaska, USA). AVO reported that on 28 March the Volcano Alert Level for Cleveland was raised to Watch and the Aviation Color Code was raised to Orange due to the formation of a new lava dome, observed in satellite imagery, which extruded in the summit crater during the previous week. During 29 March-3 April cloud cover prevented observations of the crater. Elevated surface temperatures consistent with a hot lava dome were detected in infrared satellite imagery on 4 April. No seismic information was available because Cleveland does not have a real-time seismic network. [GVP: Cleveland]

Fuego (Guatemala). INSIVUMEH reported that during 31 March-1 April and 3-4 April explosions from Fuego produced ash plumes that rose 500-800 m above the crater and drifted 10 km W and NW. During the night lava fountains rose 100-150 m above the crater and formed avalanches that traveled towards the Río Cenizas drainage. Based on analysis of satellite imagery, the Washington VAAC reported that on 1 April an ash plume drifted 13 km WSW and a well-defined thermal anomaly was observed. [GVP: Fuego]

Iliamna (Alaska, USA). AVO reported that during 28 March-3 April seismicity at Iliamna remained above background levels, although just slightly, during 25-27 March. When not obscured by clouds, satellite and web camera views showed nothing unusual. The Alert Level remained at Advisory and the Aviation Color Code remained at Yellow. [GVP: Iliamna]

Lewotobi (Indonesia). CVGHM reported that seismicity at Lewotobi Lakilaki, one of two stratovolcanoes comprising Lewotobi, fluctuated but declined overall during 18 September 2011-25 March 2012. No significant changes were observed at the volcano. The Alert Level was lowered to 1 (on a scale of 1-4) on 29 March. Observers of Lewotobi Perempuan, the second stratovolcano comprising Lewotobi, noted that during January-March diffuse white plumes rose 15 m above the crater and no significant changes had occurred. After 31 August 2011 through 25 March 2012 seismicity fluctuated but declined overall. On 29 March the Alert Level was lowered to 1. [GVP: Lewotobi]

Nevado del Ruiz (Colombia). According to INGEOMINAS, the Observatorio Vulcanológico and Sismológico de Manizales reported that during 24-31 March seismicity at Nevado del Ruiz increased significantly. Earthquakes indicating rock fracturing occurred W of Arenas crater, exhibiting a pattern observed prior to the eruptions in 1985 and 1989, although less energetic. Starting at 1054 on 29 March, and lasting for about 25 minutes, more than 135 earthquakes were detected S of Arenas crater at a depth of 4 km. At 0400 on 31 March earthquake signals indicating rock fracturing and fluid movement markedly increased. The Alert Level was raised to II (Orange; “eruption likely within days or weeks”). Seismicity remained elevated during 1-3 April; earthquakes were located below Arenas crater at depths between 0.5 and 3 km. [GVP: Nevado del Ruiz]

Soufrière Hills (Montserrat). MVO reported that during 24-30 March activity at the Soufrière Hills lava dome was generally at a low level and no ash-venting episodes had been detected since 23 March. The average sulfur dioxide emission rate measured during the week was 1,320 tonnes per day with a minimum of 264 and a maximum of 4,594, which was the third-highest value recorded in the last ten years. High values occurred between 24 and 26 March, averaging 2,550 tonnes per day over the three days. The average for the rest of the week was around 400 tonnes per day. The Hazard Level remained at 2. [GVP: Soufrière Hills]

Sundoro (Indonesia). CVGHM reported that seismicity at Sundoro continued to increase into January after the Alert Level was raised from 1 to 2 (on a scale of 1-4) on 5 December 2011. After the first week of January through 27 March the number of daily earthquakes significantly decreased. The Alert Level was lowered to 1 on 30 March. [GVP: Sundoro]

ONGOING ACTIVITY

Etna (Italy). Sezione di Catania – Osservatorio Etneo reported that the twenty-third paroxysmal eruptive episode since January 2011 took place at New SE Crater (New SEC) of Etna during the morning of 1 April following two weeks of quiescence. The episode was characterized by tall lava fountains from vents within the crater and on the SE flank of its cone, a gas-and-tephra plume, and lava flows descending toward the Valle del Bove. The paroxysmal phase lasted about 1.5 hours and ended just before daybreak. Ash and lapilli fell over the SE sector of the volcano, affecting mainly the area between Monterosso and Zafferana Etnea, but also the area between Acireale and Giarre, further downslope. [GVP: Etna]

Karymsky (Russia). KVERT reported that during 23-30 March seismic activity from Karymsky continued to be detected, and indicated that possible ash plumes rose to an altitude of 2.5 km (8,200 ft) a.s.l. during 22-26 March. Satellite imagery showed a thermal anomaly on the volcano almost daily. The Aviation Color Code remained at Orange. [GVP: Karymsky]

Kilauea (Hawaii, USA). During 28 March-3 April HVO reported that the lava lake periodically rose and fell in the deep pit within Kilauea’s Halema’uma’u Crater. Almost daily measurements indicated that the gas plume from the vent continued to deposit variable amounts of ash nearby. Incandescence was visible from both a small pit on the NE edge and a small spatter cone on the SE edge of the Pu’u ‘O’o crater floor, and on the upper part of the lava-tube system on the E flank. Lava flows continued to advance down the pali and across the coastal plain, reaching about 1.6 km from the coast. On 2 April a small lava flow issued from a vent on the S edge of the Pu’u ‘O’o crater floor. [GVP: Karymsky]

Popocatépetl (Mexico). CENAPRED reported that during 27 March-3 April steam-and-gas emissions rose from Popocatépetl. Emissions contained small amounts of ash on 28 and 30 March and crater incandescence was observed at night during 31 March-3 April. [GVP: Popocatépetl]

Puyehue-Cordón Caulle (Chile). OVDAS-SERNAGEOMIN reported that during 27 March-3 April satellite and web camera observations of the Cordón Caulle rift zone, part of the Puyehue-Cordón Caulle volcanic complex, showed plumes that rose no higher than 1.2 km above the crater. Incandescence from the crater was observed every night. The Alert Level remained at Orange. [GVP: Puyehue-Cordón Caulle]

Shiveluch (Russia). KVERT reported that explosive activity at Shiveluch continued during 23-30 March. Ground-based observers and satellite imagery indicated that a viscous lava flow continued to effuse in the crater formed during a 2010 eruption. During 25-26 and 28 March ash plumes rose to an altitude of 7 km (23,000 ft) a.s.l. Satellite imagery showed a weak thermal anomaly daily on the volcano and ash plumes that drifted 192 km E and SE during 25-28 March. The Aviation Color Code remained at Orange. [GVP: Shiveluch]

Tengger Caldera (Indonesia). CVGHM reported that during 1 January-29 March white plumes from Tengger Caldera’s Bromo cone rose 50 m above the crater and seismicity declined. On 30 March the Alert Level was lowered to 1 (on a scale of 1-4). [GVP: Tengger Caldera]

Tungurahua (Ecuador). IG reported that during 28 March-3 April visual observations of Tungurahua were mostly limited due to cloud cover. A plume rose 800 m above the crater on 1 April and ashfall was reported in Pillate (7 km W), Choglontus (13 km WSW), and Motilones (W). Lahars descended the Pingullo and Achupashal (NW) drainages, carrying material 30 cm in diameter and causing a temporary road closure. [GVP: Tungurahua]

The foregoing is a summary of the Smithsonian Institution/United States Geological Survey Weekly Volcanic Activity Report covering 28 March to 3 April 2012. It is provided for information only, and is based on but not a substitute for the full report, which comes with its own criteria and disclaimers. The map base is derived from the Smithsonian Institution/USGS/US Naval Research Laboratory This Dynamic Planet website.

For all our coverage of the SI/USGS Weekly Volcanic Activity Reports: Weekly Volcanic Activity Reports « The Volcanism Blog.