Observations and measurements from aircraft:
On September 3, with the logistical support of an aircraft MICS, an overview of the Cotopaxi volcano occurred since Tababela airport, in a Twin Otter aircraft FAE (452), commanded by Captain Byron Brown.
During the approach the volcano, you could see a column of emission rising 1000 m above the crater, heading west, due to high winds and changing course towards the north
Once in the volcano area, it was observed that it issued a steam column with a moderate to high ash content , rising to about 1000 m above the crater, moving first on the western flank, then veering north, where it reached a height of about 8500 meters, as the report of VAAC said . The coverage of ash on the volcano goes from the top edge NNE to SSW flank.
As mentioned in previous reports, in several regions of the upper part of some glaciers, we continue to observe the presence of new cracks, mainly on the flanks E and NE and on the wall Yanasacha. Areas where landslides and an accumulation of material at the foot of wall, were observed in the Yanasacha sector. Both in the north sector of the summit that the South Summit and other high parts of the cone, an accumulation of ballistic blocks was observed, with small impact craters of the same blocks when they are expelled. On this occasion, at a time when the emission intensity has decreased, it has been observed much of the crater. It was confirmed that the circular glacier inside the crater in the southern sector, due to the volcanic activity has decreased significantly in size and has large fractures , which could indicate he experienced a merger. In general, we can say that the areas of melting glaciers in the upper flanks of the volcano increased in size.
It was observed on the north side, the presence of water and humidity of the glaciers in contact with the surface of the ground, where nets of water descend downstream flank in the main drains that have been formed on the volcano.
Given the conditions and continuous emission, thermal monitoring concerned only the flanks N, E, S and S part of the inner crater. Higher temperatures were recorded from the column with a emission temperature (TMA) of 200.3 ° C , namely a temperature greater than that of the emitting column of 26 August, which was around 150 ° C. Some regions of S and E sides have increased a few degrees centigrade in temperature compared with those measured on August 26, for example, the South flank area and the eastern flank of Zone 1.
It is also interesting to note that this time no blocks were seen accompanying the emission columns, as was seen in the thermal image during the flight on August 26 In addition, it should be noted that in several places of the side walls, it was observed the presence of new thermal anomalies which had not been seen before.
Seismicity levels were maintained to seismic amplitudes lower values compared to that of a week , but their values are always much higher than the levels prior to June.
The seismic signals are characterized by episodes of tremor of moderate amplitude and occasional discrete seismic events whose locations are aligned with the duct volcanic several kilometers deep. Earthquakes in particular a volcano-tectonic and VLP on 01 and September 2 have been reported in Report No. 13.
Characteristics of analyzed ashes:
Samples of ash that fell on the western flank of the volcano Cotopaxi, between August 15-26 were analyzed in the laboratory of Dr. Peter Delmelle, University of Leuven, Belgium, a specialist in the chemistry of the ash and its effects on agriculture and human life. The results show that the ash has a relatively low pH, concentrations of sulfate (SO4), and in particular concentrations of fluorine (F) and chloride (Cl) not high.
Delmelle The specialist said that the low pH can affect the digestive system and skin of herbivores that feed on the ash-covered grass. Plants can suffer from acid and this could possibly be corrosive to metals. Fluorine (F) does not seem levels to cause problems on articulations or teeth of herbivorous animal , a condition called Flurosis and that was evident in the health of animals during the basaltic eruptions in Chile, of Lonquimay volcano.
The ash from the Cotopaxi are the product of weathering of rocks or hydrothermal conduit system of the volcano, where there is an atmosphere of rock affected by acidic conditions, particularly in light of SO4. Finally, if the eruptive system shows a higher concentration of juvenile magmatic material particles (new magma), the pH should increase (standardized) and have a lower concentration of SO4.
Every day, ashes are collected and analyzed to identify changes by members of The IGEPN.
September 07, 2015. Cotopaxi, Equateur :
Source : IGEPN