Activity of Stromboli, Etna, Santiaguito and Mt. Michael.

Back on Stromboli and the strombolian activity of July 3 :

the explosions were "spectacular and dangerous", according to Jacques-Marie Bardintzeff - in an interview with France Tv info -, "but remains in the norm for this volcano, which has behavior once every six years.This kind of activity can not be anticipated, due to constant vibrations of the volcano ".

A photo taken from an airplane shows the development of a plume of gas, ash and pyroclastic materials at least 2,000 meters high (new data to 4 km above the summit zone); A pyroclastic flow marks the Sciara del Fuoco, as well as two traces of impacts at its base (on the left of the photo)

Two INGV releases report on developments after yesterday's explosions, which left one dead and one injured.

VOLCANIC ACTIVITY COMMUNICATION of 2019-07-03 18:31:07 (UTC) - STROMBOLI.

L'Osservatorio Etneo, of the National Institute of Geophysics and Volcanology, reported that the monitoring networks had recorded the return of the parameters to normal activity at 20:31 (18:31 UTC).

After the paroxysm of 14:46 UTC, no other high intensity explosive event was observed. The seismic route returned to the levels preceding the explosive sequence and, thanks to the surveillance cameras, it was possible to observe normal strombolian activity and cooling of the relapsed material deposited along the Sciara del Fuoco, which produces continuous rolling towards the coast. The GPS network of Stromboli, for the moment, does not present any significant variations. However, it should be noted that during the paroxysmal explosion phase, the high frequency processing system measured large variations due to the GPS frequency perturbations induced by the abundant amounts of ash transients or low frequency deformations. One of the GPS stations (STDF - Timpone del Fuoco, Ginostra), a few minutes after the explosive sequence, stopped working. Further details are underway regarding the data and causes of the STDF station failure. the

The stations of the clinometric network (Punta Labronzo and Timpone del Fuoco), after the variations recorded between 14:45 and 14:49 UTC, do not show significant variations in the following hours. The dilation signal recorded at the SVO station preceded the event starting around 14 h 38 UTC approximately. Finally, the flow of SO₂ measured through the FLAME network did not show any significant variations in the days preceding the explosion and in today's day, remaining under a medium to low degassing regime compared to typical features of Stromboli.

VOLCANIC ACTIVITY COMMUNICATION of 2019-07-03 19:08:10 (UTC) - STROMBOLI.

The National Institute of Geophysics and Volcanology, Osservatorio Etneo, announced that following the improvement of the visibility of the summit area, it was possible to observe from the images of the cameras of the surveillance network, the presence of a modest lava overflow currently confined to the source, in the upper part of the Sciara del Fuoco. From the lava front, large incandescent lava blocks reach the coast.

Sources: INGV vulcani, France info / J-M. Bardintzeff, Boris Behncke, and the photographers mentioned

After the explosive activity that occurred yesterday at the North-Eastcrater of  Etna, and twenty-four hours away, a new explosion was recorded at the same crater by the CCTV cameras of the INGV.

These explosions were probably caused by pressurized steam inside a largely blocked conduit, and not by a rise of new magma, according to Boris Behncke.

In both cases, the ash emitted quickly dispersed in the summit zone. The event was not accompanied by a significant variation in the magnitude of the volcanic tremor.
 

Source: INGVvulcani & Boris Behncke.

The insivumeh issued a special bulletin concerning the Santiaguito, Guatemala, which shows since June 28, 2019 changes in its seismic activity: the number and energy of explosions has increased from 10-15 daily explosions to 35 - 40 low to moderate explosions per day, accompanied by ash plumes up to 3,500-3,800 meters asl.

The ashes are scattered to the south and southwest, with spillover effects to Horizontes, Las Larias, Loma Linda, and San Marcos Palajuno e.a.

Due to a magmatic extrusion into blocks that pile up chaotically, the domed cupola has instability, generating avalanches on the south-east and southwest flanks, currently raising only ash particles.

Due to the explosive behavior and recorded avalanches, the activity of Santiaguito could generate a collapse of the dome become unstable, and pyroclastic flows on a southern sector.

Sources: Insivumeh & Conred

In the South Sandwich Islands, Mount Michael could house a lava lake.

A study based on Sentinel-2, Landsat and Aster satellite images show thermal anomalies not associated with lava overflows from 1989 to 2018.

Short wave infrared bands (SWIR) images have been associated with a lava lake that has been present in the crater since 2003, until 2018, with temperatures between 284 and 419 ° C, comparable to those of other lava lakes. The suppression of SWIR anomalies reveals the presence of a molten lava component at basaltic temperatures, between 989 and 1279 ° C.

As thermal anomalies are detected on all the images, the study suggests the presence of a persistent lava lake.

Sources:

- Science Direct - Evidence for a lava lake on Mt. Michael volcano, Saunders Island (South Sandwich Islands) from Landsat, Sentinel-2 and ASTER imagery satellite - by D.M.Gray & al.

- BBC News - Michael's Remote Mount volcano hosts persistent lava lake

- Global Volcanism Program - Saunders