Volcanos

Roundup of Global Volcanic Activity:

Hekla (Iceland): The Icelandic Meteorological Office has informed authorities about unusual seismicity at Hekla volcano, which could be a precursor to a new eruption, and increased the volcanic alert level to yellow. Monitoring of the volcano will be intensified, as Hekla is not only one of the most active, but also one of the potentially most hazardous volcanoes of the country. The last eruption was in March 2000. On average, the volcano has been erupting about every 10 years, and it would statistically seen be due for a new one. "Uncertainty level" was declared by Civil Protection as the lowest of 3 alert levels in case of natural hazards.

El Hierro (Canary Islands, Spain): Earthquakes (more than 120 > M2 today so far) and volcanic tremor continue to be intense, and inflation has reached 10 cm on stations (HI05) located in western El Hierro. The foci of the quakes remains at about 15 km depth 5-10 km NW off the western top of the island, i.e. at the boundary to the crust beneath the island, suggesting that the still moving magma is for now not rising siginficantly into the harder layers that compose the islands' edifice. Whether and when this changes, i.e. magma starts to move vertically towards an eruption, is impossible to day, but a real possibility. The situation has not changed much. The seismic swarm continues with pulsating medium to strong tremor and frequent earthquakes, in more or less the same area as yesterday, 5-10 km NW off the island at depths mostly between 13-20 km. The average magnitudes of quakes has continued to increase: yesterday alone, there were almost 50 earthquakes >magnitude 3 - probably a record number for El Hierro, including 2 quakes of M4 and 4.1. This trend is continuing today.

Batu Tara (Sunda Islands, Indonesia): The volcano has again become a regular visitor in today's eruption list. A new ash plume rising to 7,000 ft (2.1 km) was spotted today on satellite data by VAAC Darwin.

White Island (New Zealand): In recent days, seismic activity including volcanic tremor have risen again. In its latest statement, GNS Science reported that "a pattern of repeating minor activity has become established at White Island over the last month." "Periods of passive steaming and degassing have been accompanied by very low levels of volcanic tremor. This activity has alternated with minor mud and steam explosions from the active crater when there has been strong volcanic tremor. Tremor episodes have lasted from less than one day to over a week.

Popocatépetl (Central Mexico): Activity has been showing a weakly increasing trend. Yesterday, the rate of explosions climbs to almost 2 per hour, with the largest ejecting glowing bombs to up to 500 m distance and producing plumes of steam and some ash rising 1.5 km above the crater. Satellite data continue show significant degassing. Today's seismogram shows the strong trace of some of the regional M4-5 earthquakes that hit Mexico today.

Santa María / Santiaguito (Guatemala): INSIVUMEH reports no significant changes in activity. The lava dome has been a little bit less explosive recently but continues to effuse blocky lava flows that descend its flanks and produce weak to moderate avalanches.

Pacaya (Guatemala): Weak strombolian activity continues at the McKenney crater.

Fuego (Guatemala): Activity is characterized by occasional weak to moderate strombolian explosions producing ash plumes rising 600-1000 m above the crater. Fine ash fall has been recorded in Panimaché I y II, Morelia and Santa Sofía.

Telica (Nicaragua): The earthquake swarm, presumably caused by a magmatic intrusion at shallow depth, still continues with hundreds of tiny quakes up to about magnitude 2 each day.

Reventador (Ecuador): Activity has remained stable at fluctuating moderate levels, but can rarely be observed directly due to near-constant cloud cover. Explosions and volcanic tremor, sometimes strong as earlier today, are visible on seismic recordings.

Tungurahua (Ecuador): The volcano has continued to calm down, both internally (seismicity) and externally. IG reported only weak steaming in recent days.

Heard (Australia, Southern Indian Ocean): The Smithsonian / GVP monthly Bulletin of the Global Volcanism Network for Jan 2013 confirms that Heard Island volcano is in eruption. A series of satellite images compared side by side show that the volcano started to produce lava (over-)flows from the summit crater of the Mawson Peak on the SE flank since December past year.