Overblog
Editer l'article Suivre ce blog Administration + Créer mon blog

Earth of fire

Actualité volcanique, Articles de fond sur étude de volcan, tectonique, récits et photos de voyage

Publié le par Bernard Duyck
Publié dans : #volcanic activity
Sangay - activity of 19.05.2019  - a) fissure associated with lava flow of Ñuñurcu. (b) Active lava flow from the Nucurcu. c) Central crater d) Pyroclastic flow - Doc. IGEPN

Sangay - activity of 19.05.2019 - a) fissure associated with lava flow of Ñuñurcu. (b) Active lava flow from the Nucurcu. c) Central crater d) Pyroclastic flow - Doc. IGEPN

The Sangay volcano continues its current eruptive phase that started on May 7th (190 days in total until the publication of this report). It should be noted that the activity occurs from two eruptive centers: the central crater and the Ñuñurco vent (southeast).

- The central crater has an explosive activity that generates small ash emissions up to 3.2 km high above the crater and is frequently directed to the west and southwest. Associated with these emissions, ash falls have been reported in recent days in the areas of Cebadas and Guarguallá (Chimborazo province). In addition, ballistic blocks are projected by explosions and are deposited on all the upper flanks of the volcano.

Comparison of geophysical monitoring parameters of the Sangay volcano during the 2019 period. A) Sulfur dioxide emissions recorded by the SENTINEL-SP5 satellite. b) Emission column height of ash, above the crater level, issued by the Washington VAAC and a pink chart showing wind direction and speed. c) Thermal emission power and cumulative volume estimated using the MODIS satellite sensor.

Comparison of geophysical monitoring parameters of the Sangay volcano during the 2019 period. A) Sulfur dioxide emissions recorded by the SENTINEL-SP5 satellite. b) Emission column height of ash, above the crater level, issued by the Washington VAAC and a pink chart showing wind direction and speed. c) Thermal emission power and cumulative volume estimated using the MODIS satellite sensor.

- On the other hand, the Ñuñurcu vent has an effusive activity that results in an almost continuous emission of lava flows that are deposited along the south-east flank. On the lava flow fronts, there are usually small rock falls that reach the Río Volcán basin and the upper channel. Frequently, these deposits are remobilized by precipitation, forming mudslides and debris (lahars) in the Volcan Rio. The presence of sediments in this river, which joins the downstream upstream of the Upano River, has been persistent in recent months. During a field inspection on October 19, a recent lahar deposit was discovered on the banks of the Upano River. In addition, pH values ​​of 7.91, a temperature of 17.9 ° C and a conductivity of 179 μS / cm 2 were measured in Volcán River water, normal values ​​compared with other rivers in the region. 

Photographs of the upper east and southeast flanks of the Sangay volcano. On the left, eruptive activity with steam emission from the central crater and emission of a powerful lava flow from the Ñuñurco wind (May 2019 / Photo: M. Almeida, IGEPN). On the right, emission of low ash columns from the central crater and emission of a new lava flow in the area corresponding to the surface of the lava flow observed in May, delimited by the broken yellow lines (Photos P. Ramón , IG-EPN).

Photographs of the upper east and southeast flanks of the Sangay volcano. On the left, eruptive activity with steam emission from the central crater and emission of a powerful lava flow from the Ñuñurco wind (May 2019 / Photo: M. Almeida, IGEPN). On the right, emission of low ash columns from the central crater and emission of a new lava flow in the area corresponding to the surface of the lava flow observed in May, delimited by the broken yellow lines (Photos P. Ramón , IG-EPN).

The main volcanic hazards associated with this eruptive phase are as follows: ash fall, ballistic projectiles, lava flows and subsequent collapses of up to several kilometers.

In addition, frequent rains cause remobilization of the volcanic material generating mudslides and lahars in the Volcán Rio, which can affect the waters of the Upano River. Finally, it should be mentioned that the eruptive activity recorded during this year (2019) was greater than that recorded during previous eruptive processes (eruptions 2015, 2016, 2017 and 2018).

 

Source: IGEPN

News of Sangay, Misti, Rincon de La Vieja and Poas.

The Geological, Mining and Metallurgical Institute (Ingemmet) today recorded a collapse or a fall of rocks on the southern flank of the Misti volcano, located in the region of Arequipa, near the crater of the massif.

Cameras and monitoring instruments from the Ingemmet Volcano Observatory (OVI) captured the Misti event which took place at 9:41 today and lasted three minutes.

The collapse occurred at the place where San Lázaro Creek begins; so far, no injured population has been reported.

The alert level of the Volcano remains green.

 

Source: Andina & Ingemmet Agency

Rincon de La Vieja - 31.10.2019 - Photo of Geól.Waldo Taylor from ICE via RSN

Rincon de La Vieja - 31.10.2019 - Photo of Geól.Waldo Taylor from ICE via RSN

At Rincon de la Vieja, seismic activity decreased in terms of the occurrence of long-term signals (just under two tens), recorded at the nearest station of the volcano.

Spasmodic tremor decreased in amplitude on October 31 and continues to this day.

It is recommended to stay away from drainages after the volcano in case of eruption, due to the possibility of generation of primary lahars. As in the case of rain, because secondary lahars could be generated by ashes and materials accumulated in the upper parts of the volcano.

In the above photo of the Rincon de la Vieja volcano of October 31, 2019, taken on the south flank of the crater, there is a greyish color of the acidic lake and active fumaroles of the western sector.

Floating spherules of sulfur can also be seen as a product of the chemical reaction between the gases and the lake.

 

Source: RSN

Poas - surface of the acid lake 04.11.2019 / 05:26 and 15.11.2019 / 6:56 Poas - Sources: RSN & Ovsicori
Poas - surface of the acid lake 04.11.2019 / 05:26 and 15.11.2019 / 6:56 Poas - Sources: RSN & Ovsicori

Poas - surface of the acid lake 04.11.2019 / 05:26 and 15.11.2019 / 6:56 Poas - Sources: RSN & Ovsicori

In Poas, the acidic lake maintained its surface area compared to the previous week. Its color tends to become greenish. The evaporation processes were less intense and the precipitation constant. The field of fumaroles rich in sulfur in the north-east sector maintains its activity.

Seismically, the low amplitude background tremor is maintained (2 to 4.5 Hz), as well as discrete earthquakes of type LP (long period) also of low amplitude.

 

Source: RSN & Ovsicori

Commenter cet article

Articles récents

Hébergé par Overblog