September 01 , 2017. EN. Piton de la Fournaise , Bezymianny , Mauna Loa , Popocatepetl .
Piton de la Fournaise , La Réunion :
Monthly Bulletin of Thursday, August 31, 2017.
The eruption begun on July 14, 2017 (0050 local time) continued until August 28, 2017 (0300 local time), when the volcanic tremor (a shallow or surface activity) Has disappeared from the seismological records of the OVPF. Seismic activity, deformation of the volcanog and degassing recorded during the month of August 2017 were thus mainly associated with this eruption.
In August 2017 (up to 31 August, 12 noon local time), the OVPF recorded a total of:
77 earthquakes (0-2 km deep), 93% (72 events) of which have been recorded since 16 August in the south-south sector within the Enclos Fouqué (Figure 1) . 42 of these earthquakes have been recorded since the end of the eruption (between 28 and 31 August). The remaining 7% were located beneath the summit craters during the first fortnight of August;
1 deep earthquake (> 2 km deep);
97 crumbling (in the Crater Dolomieu and at the level of the ramparts of the Enclos Fouqué);
14 local earthquakes (under the island, Piton des Neiges side);
1 regional earthquake (in the Indian Ocean zone).
Figure 1: Location of the seismicity recorded in the south-south-east sector of Enclos Fouqué during the month of August 2017. Only localizable earthquakes were represented on the map. The observatory records seismic events not represented on this map because they can not be located due to their too low magnitude. The color represents the date, and the size of the circle the magnitude (see legend). (© OVPF / IPGP)
Following the magma injection into the surface during the night of 13-14 July 2017, the volcano experienced an inflation phase (swelling) during 3/4 of the eruption, depth. This inflation stopped around August 15th. Since no trend is apparent from background noise and GPS signals are relatively stable (Figure 2).
Figure 2: Illustration of the deformation since July 14, 2017. Here is represented a baseline (distance between two GPS receivers) crossing the Dolomieu crater from north to south (in black the raw data, in blue the smoothed data over a week ). An increase in the signal is synonymous with elongation and therefore swelling of the volcano; Conversely, a decrease in the signal is synonymous with contraction and thus with deflation of the volcano. (© OVPF / IPGP)
Atmospheric emissions of SO2
The fluxes and concentrations of SO2 in the atmosphere at the summit of Piton de la Fournaise decreased gradually throughout the eruption started on July 14th and therefore throughout the month of August; This is related to the continuous decrease in the amount of magma emitted by the volcano during the eruption (Figure 3). A final and short phase of moderate increase in SO2 emissions was detected on 18 August. Since then, SO2 fluxes and concentrations have remained close to the limit of detection.
Figure 3: Evolution of concentrations and fluxes of SO2 in air recorded by the OVPF MAX-DOAS network (NOVAC) located at Piton de Bert between 04/03/2017 and 31/08/2017. Also shown are the temperature in the meter housing (red) and the battery voltage (yellow) for correcting the raw data and maintaining the station. (© OVPF / IPGP)
Soil CO2 Emissions
The onset of the July 14 eruption was preceded by a phase of decreasing CO2 emissions from the soil in the nearby fields (Gîte du Volcan) and then marked by a rapid and short-term increase. Since August 8, a trend of increasing CO2 emissions by soil in the same sector is measured (Figure 4).
Figure 4: Mean CO2 concentration in soil at the Volcanic Gap between March 2016 and August 2017 (eruptions of 26-27 May 2016, 11-18 September 2016, 31 January-27 February 2017 and 14 July – 28 August 2017 are shown in red, and the magma injection of 17 May 2017 is represented by a gray bar). In blue the raw data. In red the data corrected for the effects of temperature. Values are normalized to the maximum value recorded. (© OVPF / IPGP)
Assessment of the eruption of 14 July (00h50, local time) – 28 August (03h00 local time)
During the 45 days of the eruption, from July 14 to August 28, 2017, less than 10 million m3 of lava were released on the surface (Figure 5).
After high lava flows (22-30 m3 / s) recorded on the first day of the eruption, average flows estimated by satellite thermal imaging via the MIROVA platforms (University of Turin, Figure 5) and HOTVOLC (OPGC – Clermont Ferrand, Figure 6), decreased progressively throughout the eruption from 5 to <1 m3 / s.
Figure 5: Evolution of lava flows (in m3 / s, blue) and volumes (millions of m3 red) emitted. Estimates obtained from satellite thermal imagery (MIROVA platform). (© OVPF / IPGP).
Figure 6: Evolution of the lava flows (in m3 / s) emitted. Estimates obtained from satellite thermal imagery (HOTVOLC platform). (© OVPF / IPGP)
This gradual decline in lava flows was accompanied by a decrease in SO2 flux in the air (Figure 3).
The lava field associated with the eruption changed very little during the eruption. The maximum extension was reached from the first days of the eruption, with a maximum length of 2.8 km (Figure 7). Subsequently, the flow was slightly broadened, but the growth was mainly due to thickening due to an activity mainly in lava tunnels and extremely low flows.
Figure 7: Evolution of the extension of the lava field during the eruption, deduced from the study of radar satellite images. (© OVPF / IPGP)
The deformations associated with magma migration to the eruptive site (on the night of 13-14 July) focused on the southern and eastern part of the volcano and did not exceed 30 centimeters (Figure 8). The satellite data (radar interferometry) associated with this 13 July injection show that the deformations are not propagated beyond the eruptive crack (Figure 8).
Figure 8: (left) Surface displacements associated with magma migration to the eruptive site (July 13-14 night). The vectors represent the horizontal displacements (scale in meters given by the value VECTOR MAX) and the colored circles the vertical displacements (scale in meters given by the colored bar). The eruptive crack is indicated in red, and the supposed path of the injection of the magma into depth is indicated by the black line. (Right) Interferogram covering the injection of 13 July 2017. A red-blue-yellow phase (i.e. a fringe) corresponds to a distance of the ground from the satellite position of 2.8 cm. (© OVPF / IPGP)
Deep magma migration at the end of the eruption
A number of indications show that two magma migrations occurred at the end of the eruption. Without being exceptional this is not common.
Associated with the resurgence of seismicity on the south-south sector is August 16, and at the peak of SO2 on August 18, satellite data showed in August deformation zones (in inflation) further downstream of the crack opened on July 14 (Figure 9). These deformation zones in inflation (swelling) correspond to two injections of magma.
During the first phase of the eruption (inflation until 15 August), the feeding system pressurized, allowing the magma to continue its propagation further downstream towards the south – South-east, in the form of two intrusions that occurred between 07 and 25 August (dates of acquisition of satellite images). The rapid change in SO2 emissions may indicate an initial shallow intrusion on 18 August. The second phase of intrusion certainly took place on the night of 24 to 25 August when a seismic swarm was recorded on the seismological network of the OVPF and located in this sector.
Overflights conducted by the Air Force Section and the OVPF staff on August 25 indicate that no new cracks associated with these two injections surfaced.
Figure 9: (left) Interferogram covering the period from 7 to 19 August 2017. (right) Interferogram covering the period from 13 to 25 August 2017. A red-blue-yellow phase (ie a fringe) corresponds to Distance from the ground relative to the satellite position of 2.8 cm. The lava flow is represented by a white contour and the deformation field by a black outline. The stars correspond to the location of the seismicity recorded since August 16, 2017. (© OVPF / IPGP)
Given the small spatial extension of the deformations associated with these two intrusions (arrows in Figure 9), the geodetic stations (GPS, inclinometers, extensometers) on the ground, which are outside the deformation field, Signals. On the other hand, the seismicity recorded since August 16 is located in the zone intruded by the magma (Stars in Figure 9).
In conclusion: following the cessation of the eruption, seismicity under the southeastern region of the Enclos Fouqué continues and near-field CO2 concentrations in the ground remain high. As a result, no assumption is made as to the evolution of the situation (resumption of an activity or not).
Source : OVPF
Bezymianny , Kamchatka :
55.97 N, 160.6 E;
Elevation 9453 ft (2882 m)
Aviation Color Code is ORANGE
A gas-steam activity of the volcano continues. A danger of strong ash explosions up to 32,800 ft (10 km) a.s.l. is remains. Ongoing activity could affect international and low-flying aircraft.
Explosive eruption of Bezymianny volcano on 09 March 2017.
A moderate gas-steam activity of the volcano continues. An incandescence of the lava dome was observing at night, and a lava flow continued to squeezing at the western flank of the lava dome. Satellite data by KVERT showed a thermal anomaly over the volcano on 24-25 and 28-30 August; the volcano was obscured by clouds in the other days of week.
Source : Kvert
Photo : videodata KB GS RAS (9/3/2017 )
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 Volcano is not erupting. Rates of deformation and seismicity have not changed significantly in the past week and persist at above-long-term-background levels.
Shallow, depths less than 5 km (3 miles), small-magnitude earthquakes persist beneath the summit caldera and upper Southwest Rift Zone. Additional deeper events (5-13 km or 3-8 miles) were also recorded from beneath the southeast and upper west flanks of the volcano.
Global Positioning System (GPS) and satellite radar (InSAR) measurements continue to show deformation consistent with inflation of a magma reservoir beneath the summit caldera and upper Southwest Rift Zone.
No significant changes in volcanic gas emissions or summit fumarole temperature were measured.
Source : HVO
Popocatepetl , Mexico :
Bulletin of 31 August, 11.00 (31 August, 16.00 GMT)
Over the past 24 hours, 104 exhalations of low – to medium – intensity, with steam and gas emissions, have been identified through the monitoring systems of the Popocatépetl volcano. An explosion was also recorded today at 06:10. There was also 80 minutes of harmonic tremor. Because of the cloudy weather conditions, the volcano was not observed continuously.
At the time of this report, there was no visibility on the crater due to intense cloudiness.
CENAPRED asked not to come near the volcano and especially the crater.
The Popocatépetl volcanic warning semaphore is located in Amarillo Phase 2.
Source : Cenapred
Photo : Cristobal Garciaferro