September 19 , 2016. Piton de la Fournaise , Tungurahua , Turrialba , White Island .
September 19 , 2016.
Piton de la Fournaise , La Réunion :
ALERT LEVEL: Backup Phase
After an increase in the night of 17 to 18 September 2016, the eruptive tremor fell sharply on September 18 at 4:18 (local time), meaning stopping the surface activity. The eruptive tremor (continuous signal recorded by the seismic stations) is generated by soil movement, itself generated by the gases driving the magma to the surface (engines of the eruption).
The sudden end of the tremor marks the end of a surface supply.
Between 11 and 18 September 2016, 7 million m3 of lava were emitted at the surface. Just before the cessation of the eruption, the flow front was located in the upper part of the Great Slopes.
The OVPF does not exclude any hypothesis about the evolution of the situation in the coming hours.
Evolution of the RSAM (indicator signal of the eruptive tremor and intensity of the eruption) from 7.00 (3h UTC) on September 11 and 6:30 (2:30 UTC) on September 18 for the seismic station Faujas, located on the north side of volcano. (© OVPF / IPGP)
After the eruptive crisis of Sunday, September 11, 2016 which led to the switching to alert level 2-2 of the specific device ORSEC * Volcano Piton de la Fournaise, the Volcano Observatory of Piton de la Fournaise recorded on Sunday September 18 at 4:18 local a brutal fall of the eruptive tremor (meaning the cessation of surface activity).
In these circumstances, the prefect of Reunion decided the passage to the backup phase of the specific device ORSEC * Volcano Piton de la Fournaise, at 8:30 am this Sunday, September 18, 2016.
Despite the termination of activity of the geo-physical point of view and the cessation of feeding (end of tremor, vibration associated with the path of the magma and gases it contains)an eruption remains likely in the days and hours to come up.
Consequently, the prohibition of access to the top of the Enclos and the helicopter drop in the volcano area remain in force until further notice. The prefect said that the massive volcano is a natural park , subject to weather changes very fast and sometimes violent.
The safety-related recommendations in the mountains are particularly relevant: check the weather, do not leave the marked trails, bring attention to your individual equipment. The temperature range is significant between day and night.
Source : OVPF
Photos : Fournaise info , Ilotdrones.
Tungurahua , Ecuador :
In recent months, after the last eruption, generally there was a low seismic activity, recording under 2 earthquakes volcano-tectonic type (VT) daily, no explosions or tremor of issuance. Between 1 and 20 May 2016 a slight increase in long-period type earthquakes (LP), reaching a maximum of 68 events on May 14 was recorded. These events are common during periods of quiescence and are associated with fluid movements within the volcano. Dated on September 12, significantly, the number of LP events increased, especially episodes of tremor on 16th, the following days showing the continuing trend. In addition, on 18 September, between 4:08 and 4:24, a swarm of 24 events LP type was recorded.
The station of the inclinometer Retu (Refugio Tungurahua), located on the north side under the crater rim, shows a clear inflationary trend since the end of the last eruption of both the radial axis (~ 980 mrad, microradians) and the tangential axis (~ 400 mrad). It should be noted that from September 15, this trend has changed to deflation at a rate of 21 mrad / day.
Inflationary trend was also observed in the tangential axis of inclinometer MNDR (Mandur, Northwest edge), but with a much smaller amplitude (~ 30 mrad), probably due to a larger distance between instrument and the pressure source. At the end of June, the trend changed to deflation and again in August, this trend has again become inflationary. In other stations of the network Inclinometry an apparent deformation trend is observed. However, it should be noted that with the end of the last eruptive period, the sensor Retu began recording evidence of magma movement.
Modeling (Dmodels) with the data of stations with the most evidence of deformation (Retu and MNDR), between March 12 and September 17 was performed, showing the presence of a deformation center with the presence of a body with a volume of about 5.3 million m3 and at a depth of about 1 km below the crater, between the latter and the RETU station.
no big change is observed in the degassing from the end of the last eruptive phase for the maximum daily flow of SO2 on the number of valid measures. Both indicators are at the basic level and could indicate that the channel is closed after the eruption of February-March 2016.
In recent months, visual observation conditions were variable and generally have been hampered by the almost permanent clouding of the volcano. The surface activity when the weather volcano was discovered in time, shows the fumaroles activity characterized by low intensity and absence of ash emissions since the end of the last eruption. These days, when there was heavy rain, it was noticed an increased activity fumaroles from the edge of the crater, so that they are fumaroles pulsatile nature and phreatic origin.
Over the last 8 years of activity, the volcano Tungurahua has had 15 quiet periods similar to the current period with low seismic activity, deformation inflationary trend, and surface activity characterized by low energy fumaroles. Generally, these periods of silence were followed by small volcanic eruptions ( Explosive Index VEI 0-1, the main phenomenon was ash falls) and sometimes by large eruptions (VEI 2, with pyroclastic flows). It is important to note that the vast majority (80%) of these eruptions had no warning signs of recovery in the short term (hours to days). The actual deformation of the volcano is evidence of magmatic intrusion (movement of magma from a deep tank) and has been observed several times before the eruptions of Tungurahua. The low outgassing may indicate a blockage of the channel prevents the free passage of magmatic gases. Given that the current quiet period has exceeded six months (185 days) and the sharp increase in seismic activity (LP since 12/09, tremors from 16/09 , and the swarm of LP on 18/09) it is estimated that a recovery in the short term (the next few days to weeks) is possible.
Source : IGEPN
Photos : José Luis Espinosa Naranjo , IGEPN.
Turrialba , Costa Rica :
Turrialba Volcano continues to emit ash.
18 SEPTEMBER 2016. Following weeks of moderate calm, the Turrialba volcano returned with a roar Saturday morning.
According to the National Emergency Commission (Comisión Nacional de Emergencias – CNE), the volcanic activity began at 9:57am, spewing out a plume of smoke and ash to about 500 metres from the base of the crater.
The emanation was dispersed by the wind to the northwest, says the Instituto Meteorológico Nacional (IMN), the national weather service.
Reports of ashfall was greatest in the areas surrounding the colossus, La Silvia and La Picada.
Experts say the volcano still has a lot of energy, experts maintain a constant monitoring. The Turrialba had more than a month of “relative rest”.
Source : Q COSTA RICA
White Island , New Zealand :
Volcanic Alert Bulletin WI 2016/12:
11:00am Monday 19 September 2016; White Island Volcano
Volcanic Alert Level is lowered to Level 1 (from Level 2)
Aviation Colour Code remains Yellow (no change)
No further sustained eruptive activity has been observed at White Island. As a consequence the Volcanic Alert Level has been lowered to Level 1. The Aviation Colour code remains Yellow.
Observations over the weekend suggest no further sustained ash emissions have occurred from the active vents. Occasionally images on the web camera indicate very minor amounts of ash may be present in the steam plumes, but this has not been confirmed. Such intermittent appearance of ash is likely due to shedding of debris on the fumarole walls and may be expected to continue. The seismic and acoustic activity remains low, and the gas flux from the island has not changed substantially during this minor activity.
Although Tuesday’s eruption has ceased, White Island is always capable of a new eruption at any time, without prior warning. GeoNet continues to monitor the volcano for possible renewed activity.
Source : Geonet /Brad Scott
Photo : gorentals.co.nz