Wednesday, 3 April 2013

Volcanos

Town Buried In Ash After Mount Etna Volcano Eruption


A small tourist town, Zafferana Etnea, in the province of Catania, Sicily with 9,450 residents — was blanketed by thick black volcanic dust after the eruption latest eruption of Mount Etna.


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Roundup of Global Volcanic Activity:


Stromboli (Eolian Islands, Italy): Tremor and explosion signals have further increased today, but no significant new lava overflows have occurred.


Etna (Sicily, Italy): Closer inspection of the "white lava" reported in yesterday's news revealed that these were so-called xenoliths, i.e. no lava at all, but pieces of sedimentary rock from strata underlying the volcano brought up by the rising magma. In this case, they are pieces of barely compacted beach sandstone, similar to the xenoliths ejected during the flank eruptions in 2011 and 2012, which are believed to have trapped a different (so-called eccentric) shallow magma chamber beneath the volcano. Fresh snow has now covered much of the bombs from the recent eruption.


Tjörnes Fracture Zone (North of Iceland): A strong earthquake swarm including a widely felt magnitude 5.4 earthquake at 15 km depth this morning and hundreds of pre- and aftershocks is occurring in the Tjörnes Fracture Zone in a N-S elongated area about 15 km east of the island of Grimsey.


El Hierro (Canary Islands, Spain): So far, it has been one of the calmest days during the now two-weeks-long seismic crisis. Tremor has been more or less absent today, while earthquakes (so far today: 34 quakes between magnitudes 1.6-3.2) have continued at reduced intensity. Given the past experience, it is certainly too early to draw a good conclusion whether we are near the end of the crisis (or the suspected magma intrusion) or just in a pause, while magma is potentially building up new pressure. The seismic swarm has continued to decrease and activity is currently low. So far, IGN lists about 10 quakes above magnitude 1.5 for today, the largest a magnitude 3.3 at 02:32 GMT at 20 km depth. Yesterday: 82 earthquakes between M 1.7 - 3.8.


Kizimen (Kamchatka): Lava dome growth, accompanied by moderate seismic activity, strong degassing and avalanches on the western and eastern flank of the volcano continues.


Shiveluch (Kamchatka): No changes in activity occurred. Moderate seismic activity accompanies ongoing lava dome growth, KVERT mentions.


Tolbachik (Kamchatka): KVERT reports no significant changes in the ongoing basaltic flank eruption: fluid lava flows are erupted from the southern fissure and feed two major flow fields to the west and east. Tremor levels are still relatively high.


Sakurajima (Kyushu, Japan): A relatively strong explosion occurred 2 hours ago (18:17 Japan time), sending an ash plume to 12,000 ft (3.7 km) altitude, VAAC Tokyo reported.


Batu Tara (Sunda Islands, Indonesia): A plume of volcanic ash was spotted on satellite data last night, reaching 7,0000 ft (2.1 km) altitude and drifting 15 nautical miles to the NE.


Popocatépetl (Central Mexico): Activity has again been a bit elevated during the past two days and corresponds to increased SO2 emissions and frequent small quakes and/or tremor signals on the seismogram. CENAPRED reports that during 31 Mar-1 April, Popocatépetl produced small explosions at a rate of about 2 per hour, which merged into a continuous gas and ash emission yesterday morning at 5:16 am (local time) that lasted an hour. Explosions at 8:22, 8:39 an 9:55 am produced ash plumes rising more than 2 km and drifted east, where probably light ash fall occurred.


Santa María / Santiaguito (Guatemala): Explosive activity has been weak, but INSIVUMEH reports that the lava flows are producing constant avalanches, or in other words are well alimented at the moment. A strong steam plume rises about 800 m above the lava dome.


Pacaya (Guatemala): Strombolian activity has continued and seems to be becoming slowly stronger. Incandescent material can now be seen ejected at night and lands mainly on the western flank of Mackenney crater, where INSIVUMEH advises tourists not to go.


Fuego (Guatemala): Explosive activity is on the increase again. During 31 Mar - yesterday, the observatory reported 12 small to moderate explosions with ash plumes rising up to 1100 m above the crater, accompanied by shock waves felt in up to 15 km and plenty of incandescent bombs ejected to all over the summit cone.


Telica (Nicaragua): Seismicity has remained high. INETER has not (yet) published anything about unusual activity at the volcano, which suggests that they don't expect any eruption anytime soon.


Reventador (Ecuador): IG reports surface and internal (seismic) activity at stable, moderate levels. A steam plume rising 700 m above the crater, where a lava dome continues to grow, was observed.


Tungurahua (Ecuador): Seismic activity continues to increase, mainly dominated by signals corresponding to internal fluid movements. A small earthquake of magnitude 2.5 occurred in the evening of 31 Mar NW of the volcano and was felt in the sectors of Cusúa, Baños, Pondoa and Juive.


Nyiragongo (DRCongo): Strong SO2 emissions visible on NOAA satellite data suggest that the famous lava lake continues to be active inside the crater.

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