Activity of Etna, Stromboli and Semisopochnoi.

Osservatorio Etneo, of INGV, announced that moderate eruptive activity, which began on 14 July at Etna's New Southeast Crater (NSEC), is continuing and has shown a gradual intensification.

Yesterday, July 17, there was frequent ash emissions, which produced only minor anomalies in the images recorded by the thermal surveillance cameras. Since the beginning of the morning, however, the activity consists of Strombolian explosions, which occur every 1 to 2 minutes, but every 20 to 30 seconds, at the end of the morning. The explosions projected glowing pyroclastics a few tens of meters above the vent located in the eastern part of the NSEC. The ejectas frequently fell on the upper flanks of the cone.

With respect to the volcanic tremor, a gradual increase in the mean amplitude of the volcanic tremor has been recorded since 2030 UTC, from low to medium. This was accompanied by migration and superficialization of the volcanic tremor source to the NSEC region, as well as an increase in the frequency of infrasonic events.

This activity continued in the day of 18 July, and remained stable, without emitting ash or lava flow until around 23h.

On July 19, a mouth was opened around 01:07 at the NSEC's west base, in the same way as at the beginning of the May 30 eruption. (communication by Boris Behncke) A small lava flow is visible at first light of dawn.

In addition, at 05:48 UTC, an ash emission occurred in the northeastern crater, causing a plume to form that quickly dissipated into the atmosphere. The first issue was followed by other smaller issues that continued during the production of this report [but ceased thereafter]. In contrast to the NSEC activity, ash emissions from the northeast crater produced no abnormal signals in the images recorded by the thermal surveillance cameras.

Sources: INGVvulcani, Boris Behnvcke and Gio Giusa

Thermal data from satellites and cameras recorded during the last 12 hours on July 17 indicate an increase in the effusive activity of the south-west crater of Stromboli. MODIS images acquired over the last 12 hours, in favorable meteorological and satellite conditions, show elevated thermal anomalies up to 744 MW (01:50 UTC) which correspond to an increase in effusive activity, with effusive velocities (TADR) estimated at about 2 m³ / s (+/- 0.6 m³ / s).

The increase in thermal luminance measured by MODIS is confirmed by the SENTINEL image acquired at 10:00 UTC on 17/07/2019, which shows a clear increase in the casting surface. From the images, it is possible to estimate a maximum stream length of about 600 m and a maximum width of 80 m. The lava front is installed at an altitude of about 300 m.

In line with the increase in effusion activity, there is a further increase in the SO₂ flux measured by the UV Roccette camera which attests to a very high level. This increase is visible on the images of the Ginostra thermal camera, showing a well-fed and organized flow in several branches.

Source: LGS -  http://lgs.geo.unifi.it/index.php/blog/comunicato-stromboli-15-luglio-h1230

The Alaska Volcano Observatory raised the level of the Semisopochnoi to Watch / Orange Aviation Code on July 18 around 10:38.

An increase in seismic activity began during the night. A strong tremor signal, and an infrasonic signal are reported east of Adak Island at 23:39 AKDT: this event probably resulted in ash emissions and, at the current level of persistent disturbances, similar events could occur without Warning. The weather cloud is located approximately 10,000 ft (3,000 m) above Semisopochnoi and no ash signal has been detected above this height. A small plume extending 18 km from the Cerberus vent was visible in yesterday's satellite data but did not contain an ash signal.

Source: AVO