January 08, 2016. EN. Puracé , Bárðarbunga , Mauna-Loa .
January 08, 2016.
Puracé, Colombia :
Alert unusual seismic activity of the volcano Puracé, Colombia.
January 7, 2016. In an extraordinary council of the Risk Management which was held on Thursday to the government of Cauca, where the unusual seismic activity that took place in recent days under the Puracé volcano, located in the central mountain range are being analysed.
The authorities confirmed that recently, three average-magnitude earthquake occurred in the volcano region of Nariño, in Huila.
Relief agencies are on alert, although they appealed to the community to stay calm, because so far no earthquakes generated damage or considerable damage.
One of the most active volcanoes of Colombia, Puracé consists of an andesitic stratovolcano with a 500-m-wide summit crater that was constructed over a dacitic shield volcano. Puracé lies at the NW end of a volcanic massif opposite Pan de Azúcar stratovolcano, 6 km to the SE. A NW-SE-trending group of seven cones and craters, Los Coconucos, lies between the two larger edifices. Frequent explosive eruptions in the 19th and 20th centuries have modified the morphology of the summit crater. The largest eruptions occurred in 1849, 1869, and 1885.
Sources : WRadio, GVP.
Photo : Ingeominas
Bárðarbunga , Iceland :
Unrest in the Bárðarbunga.
The seismic activity in the volcano Bárðarbunga has become stronger in recent months, reported visir.is. After the outbreak in the Holuhraun the seismic activity had gone equally strong, since last September, they have, however, increased steadily, writes the earthquake department of the Icelandic Meteorological Service on their Facebook page. An installed on the crater rim new GPS instrument was moved to December by 6.5 centimeters to the west and to three centimeters in height.
This example suggests that the volcano ausdehne and that again ansammle magma under the volcano. In the published graphic is to be seen, the earthquake of magnitude 3 were more frequent in recent months.
According information from the Meteorological Service of the outbreak had reduced the pressure in the volcano system in Holuhraun, but the measurements led to the conclusion that again ansammle Magma. This does not mean that in the near future are likely to have a Clear open, but will the area monitored intensively.
The geologist Art Trausti Guðmundsson Recalls that is located no conventional magma chamber under the Bárðarbunga. Rather, it is a lateral margin, which fill the subsurface chamber at the end. The lava that had fallen to the earth’s surface in the Holuhraun, but come from a lying in 10 to 12 kilometers deep chamber. At the beginning of the events of 2014, Magma was flowed toward Kistufell, have never reached the Earth’s surface there. In the region there are old cracks, where the movement of tectonic plates develop through tension.
Under the Dyngjujökull and before that there are two deep valleys have recently formed on the report geologist Ásta Rut Hjartardóttir and others in a new journal article. One can clearly see here the interaction of magma pressure, landscape and new and old plans that control the formation of a magma Ganges, explained the geologist.
Bárðarbunga has been very active between the 9th and 15th centuries, and in the 18th century. It is impossible to say when and how it happened in the volcano again to an activity, however, the transition formation and magma accumulation were signs of new unrest period.
Source : Icelandrewiew
Photos : Páll Stefánsson, Ragnar Axelsson ( archives)
Mauna Loa , Hawai :
19°28’30 » N 155°36’29 » W,
Summit Elevation 13681 ft (4170 m)
Current Volcano Alert Level: ADVISORY
Current Aviation Color Code: YELLOW
Mauna Loa is not erupting. No significant change in seismicity was recorded beneath the volcano in the past week, remaining elevated above long-term background levels. In the past week, earthquakes at Mauna Loa occurred mostly beneath the volcano’s upper Southwest Rift Zone at depths less than 5 km (3 mi). Global Positioning System (GPS) measurements continue to show deformation related to inflation of a magma reservoir complex beneath the summit and upper Southwest Rift Zone.
TOP: Mauna Loa weekly earthquake rates between 2010 and September 17, 2015. Blue bars indicate the number of earthquakes that were located by the USGS Hawaiian Volcano Observatory seismic network. Earthquakes of all magnitudes are plotted. Subtle increases in earthquake rates started in mid-2013, while more obvious changes in rates started in 2014.
BOTTOM: Change in distance across Mauna Loa’s summit caldera between 2010 and September 17, 2015. Blue dots indicate the relative distance between two stations that span the summit caldera of Mauna Loa, shown in the map on the upper left. Sustained extension across the caldera started in mid-2014. This extension is one of the indicators of magma infilling a complex reservoir system beneath the summit and upper Southwest Rift Zone.
Massive Mauna Loa shield volcano rises almost 9 km above the sea floor to form the world’s largest active volcano. Flank eruptions are predominately from the lengthy NE and SW rift zones, and the summit is cut by the Mokuaweoweo caldera, which sits within an older and larger 6 x 8 km caldera.
Two of the youngest large debris avalanches documented in Hawaii traveled nearly 100 km from Mauna Loa; the second of the Alika avalanches was emplaced about 105,000 years ago (Moore et al. 1989). Almost 90% of the surface of the basaltic shield volcano is covered by lavas less than 4000 years old (Lockwood and Lipman, 1987). During a 750-year eruptive period beginning about 1500 years ago, a series of voluminous overflows from a summit lava lake covered about one fourth of the volcano’s surface. The ensuing 750-year period, from shortly after the formation of Mokuaweoweo caldera until the present, saw an additional quarter of the volcano covered with lava flows predominately from summit and NW rift zone vents.
Source : HVO. GVP.