After an increase in seismicity linked to gaz emissions from July 13, 2020 (15 earthquakes of blast on July 15, 2020), an eruption started on July 16, 2020 at 13:53 local time (06:53 UTC) at Raung, on the island of Java.
The initial eruption lasted 56 seconds, recorded with an amplitude of 10 mm, with an ash plume estimated at 3,500 meters, or perhaps more by an observer on the ground. As a result, the color of the Air Alert (VONA) changed to Orange.
Flights to and from Bali and regional airports have been canceled due to the threat of ash.
A second VONA was issued at 3:37 p.m. local time, where it is reported that the eruption continues, with an ash plume moving north.
Raung - slight emissions on July 14, 2020 - Sentinel-2 L2A bands 4,3,2 nat colors - one click to enlarge
A moderate thermal anomaly was noted by Mirova this July 16 at 3 p.m. UT VRP 10MW, and from 8MW at 6:05 p.m. UT.
The seismicity of July 16 comes in:
- 60 eruption earthquakes, with an amplitude of 2-16 mm, and the duration of the earthquake 45-370 seconds.
- 23 blast earthquakes with an amplitude of 2 to 12 mm and an earthquake duration of 38 to 81 seconds.
- 15 episodes of non-harmonic tremor with an amplitude of 1 to 2 mm and an earthquake duration of 118 to 214 seconds.
- 5 distant tectonic earthquakes, with an amplitude of 3-32 mm, S-P 11-47 seconds and an earthquake duration of 60-164 seconds.
The height of the gas / ash plume and its color began to change on July 16, 2020. The color of the plume indicates the presence of ash brought to the surface.
The number of earthquakes in burst experienced a slight increase but was not followed by the appearance of other types of volcanic earthquakes (shallow volcanic earthquakes, deep volcanic or tremor), not indicating the existence of a supply of magma from the depths under the summit crater of Raung.
The activity level remains at 1, with the recommendation: The public and visitors / tourists are not allowed to descend to the crater at the top and / camp around the peak / lip of the caldera / crater G. Raung because volcanic gases coming out of the crater are dangerous for human life.
The last eruption, of VEI 3, took place from February 1 to August 22, 2015. (GVP)
Sources: Magma Indonesia & Global Volcanism Program
Raung - seismicity on July 15 and 16, 2020 - NB: the scales of the number of earthquakes are different - Doc. Magma Indonesia - one click to enlarge
The activity level of Gunung Agung, on Bali, was lowered from level 3 / Siaga to level 2 / Waspada from July 16, 2020 at 3:00 p.m. WITA. In the level II status (Waspada), it is recommended to the community around G. Agung and to climbers / visitors / tourists not to be located, not to climb and not to practice any activity in the estimated danger zone , which is in the area of G. Agung crater and everywhere within a 2 km radius of the crater.
Visually, a significant decrease in the surface activity of the crater was observed. The period from January 1, 2020 to July 16, 2020 was dominated by a plume emanating from the white crater, of low intensity with a height of about 20-150 meters above the summit. The last eruption occurred on June 13, 2019 at 1:38 a.m. WITA and the surface activity is now dominated by gusts of low to moderate intensity.
The number of volcanic earthquakes in the past year has generally decreased. This indicates that the movements of the magma still occur inside the volcano, but with a weak intensity.
The thermal anomaly at the crater surface was last detected by the Modis satellite in October 2019, then was no longer observed. This decrease in temperature at the surface of the crater indicates a decrease in the supply of surface magma. Deformation data from G. Agung over the past year shows a tendency towards the deflation pattern and in recent months, the pattern tends to be stable and does not indicate a significant build-up of magma pressure .
Source: 16 July 2020 19:10 WIB, Devy Kamil Syahbana, Dr., S.Si. / Magma Indonesia
Santiaguito - photo of Santa Maria and the Santiaguito's complex of domes, including Caliente - photo Francisco Juarez / Insivumeh
At Santiaguito, the seismicity of July 16, 2020 corresponds to explosions accompanied by ash at 3,400 meters asl. at the Caliente dome, moving for 1 km to the southwest. Some explosions generate aircraft turbine noises, under the pressure of magmatic gases.
The southern flank of the Caliente dome is marked by avalanches of boulders, and nocturnal glow is observed.