This (almost) daily post intends to follow up the activity changes of volcanoes all over the world. This post is written by geologist Richard Wilson who specializes in Volcano seismicity and Armand Vervaeck. Please feel free to tell us about new or changed activity if we haven’t written about it. -
September 21, 2012 volcano activity
Mount Lokon, Sulawesi, Indonesia erupted again today
Mount Lokon had 2 strong eruptions on Friday. People living around the volcano have not received the order to evacuate. Since the volcano erupted the first time in April, a no-go zone of 2.5 km around the crater has been ordered by the government. Mount Lokon is currently on the second highest alert in Indonesia.
Apparently, the eruption happened on a crater along the slopes, just like the first eruption in April earlier this year (see pictures when clicking on the link below)
We have written an in-depth article on the first, more dangerous eruption earlier this year. Click here to read it. Our article also includes pictures and a number of video’s.
Todays activity at the Alaskan volcanoes
Seismic activity remains slightly elevated, although the general trend has been a decline in the frequency of earthquakes at the volcano over the past week. Satellite views of the volcano have been obscured by clouds throughout the past week and AVO has received no reports of unusual activity at the volcano. (see also LSSA seismograms)
Seismicity remains slightly above background, but continues to decline gradually. Satellite images of the volcano over the past week have been obscured by clouds and AVO has received no reports of unusual activity at the volcano. The seismic swarm that occurred at Iliamna Volcano in 1996-1997 also exhibited a gradual decline. The episode of elevated seismicity in 1996-1997 did not lead to any type of eruptive activity.
New Activity or unrest from the world’s volcanoes from September 12 to September 18 according to the Smithsonian Institution.
FUEGO - Guatemala
In a special bulletin on 13 September, INSIVUMEH reported that activity at Fuego increased, starting the sixth eruption in 2012. Lava flows traveled 600 m down the Taniluyá drainage (SSW) and the Las Lajas drainage (SE), producing block avalanches that reached vegetated areas. Strombolian explosions generated ash plumes that rose 3 km above the crater and drifted SW and 12 km W. Ash fell in multiple areas, including the villages of Panimaché (8 km SW), Morelia (8 km SW), Santa Sofia (12 km SE), Sangre de Cristo (8 km WSW), Palo Verde, San Pedro Yepocapa (8 km NW), Santiago Atitlan (42 km NW), San Lucas Toliman (32 km NW), Mazatenango (68 km W), Suchitepéquez, Retalhuleu (86 km W), and Santa Lucia Cotzumalguapa (23 km SW). Explosions produced degassing sounds and rumbling noises, accompanied by shock waves that vibrated structures on the SW flank. Pyroclastic flows traveled down the Las Lajas and Ceniza (SSW) drainages, producing ash plumes. CONRED increased the Alert Level to Orange (third highest on a four-color scale). About 10,600 people evacuated from nearby communities including Yepocapa, San Juan Alotenango (9 km ENE), Sacatepéquez. Evacuation shelters were set up in Santa Lucia Cotzumalguapa.
Later that day seismicity decreased, ash plumes rose 300 m above the crater and drifted W and NW, fewer pyroclastic flows were observed, and the rate of explosions slowed. Ashfall was reported in Panimaché, Morelia, and Sangre de Cristo. Lava flows in the Ceniza drainage were 1 km long and 150 m wide, and in Las Lajas were 700 m long and 100 m wide. CONRED noted that residents began to return to their homes on 14 September.
During 14-18 September explosions generated rumbling noises; ash plumes that rose 400-900 m above the crater drifted 7-8 km W and SW, causing ashfall in Sangre de Cristo, Panimaché I, and Panimaché II. Lava flows were at most 1.2 km long in the Taniluyá drainage and 200 m long in the Ceniza drainage during 14-16 September; flows were not observed during 17-18 September.
GAMALAMA - Halmahera – Indonesia
CVGHM reported that during 1-14 September cloudy weather and fog at Gamalama mostly prevented observations from the post in Marikurubu and from S Ternate (S, SE, and E part of island); white plumes were sometimes observed rising 10 m above the crater. A phreatic eruption on 15 September at 2027 produced ashfall in Ternate. An eruption at 1415 the next day was accompanied by rumbling sounds. A plume rose 1 km and drifted SE and S, producing ashfall at the Gamalama observation post five minutes later. Neither eruption was observed due to fog. The Alert Level was raised to 3 (on a scale of 1-4) on 16 September. Visitors and residents were warned not to approach the crater within a radius of 2.5 km.
GROZNY GROUP – Iturup Island – Kuril Islands – Russia
Based on visual observations and analyses of satellite imagery, SVERT reported that during 10-17 September fumarolic activity at Grozny Group was at a medium intensity. The Aviation Color Code was lowered to Green.
LITTLE SITKIN – Aleutian Islands – Alaska
AVO reported that during 11-18 September seismic activity at Little Sitkin remained elevated and satellite views were obscured by clouds. Two earthquake swarms were detected on 11 and 13 September. The Aviation Color Code remained at Yellow and the Volcano Alert Level remained at Advisory.
LOKON-EMPUNG – Sulawesi – Indonesia
According to the Darwin VAAC, ground-based observers reported that on 15 September an ash plume from Lokon-Empung rose to an altitude of 3 km (10,000 ft) a.s.l. On 15 September satellite imagery showed an ash plume drifting 185 km SE.
SAN CRISTOBAL – Nicaragua
On 10 September, INETER reported that seismicity decreased after the 8 September eruption at San Cristóbal. Sulfur dioxide emissions had decreased since the previous day. During 10-11 September steam plumes rose 200-300 m above the crater and drifted W. Three small explosions on 11 September generated ash-and-gas plumes that rose 300 m above the crater and drifted W. An explosion and ash venting was observed a few hours later; a plume drifted S and ash fell on the flanks. The seismic network detected small explosions on 13 September. Sulfur dioxide gas emissions were above normal, and similar to levels detected on 8 September. Sulfur dioxide gas emissions increased on 14 September. The next day a small explosion was observed and gas plumes drifted NE. Gas plumes drifted N on 17 September.
SOPUTAN – Sulawesi – Indonesia
Based on information from US Air Force Weather Agency (AFWA), the Darwin VAAC reported that an ash plume from Soputan rose to an altitude of 9.1 km (30,000 ft) a.s.l. on 18 September. The VAAC also noted that a sulfur dioxide alert was issued by the Support to Aviation Control Service (SACS).