Lava overflows after major explosion at Stromboli volcano, Italy

A major explosion took place at Stromboli’s Northern crater at 19:06 UTC on August 8, 2023, leading to lava overflows on the outer slope. The eruption came with a sharp spike in tremor, and its aftermath showed a decrease in spattering activity from the North crater area.

Following a major eruption from Stromboli’s Northern crater area on August 8, 2023, incandescent lava bombs and lapilli were catapulted to the upper Sciara del Fuoco. This powerful eruption resulted in a minimum of two lava overflows onto the mountain’s outer slope.

In conjunction with the onset of the eruption, a sharp rise in seismic tremor was observed at 19:05 UTC, which subsequently peaked at high amplitude tremor values.

The intensity of the eruption can be deduced from the progressive decrease in spattering activity observed during the night of August 9. Moreover, there was a noted halt and eventual cooling of the lava flow that had commenced after the powerful explosion.

Intense Strombolian activity was reported from both the North and South Central crater areas on August 9. This activity was interspersed with sporadic instances where products fell outside the crater terrace. The accompanying seismic tremor maintained a medium intensity. However, it was still notably higher than the tremor that preceded the major explosion on August 8. Furthermore, there was a slight uptick in the occurrence rate and magnitude of explosion-quakes compared to the recordings before the explosion.

From a structural perspective, no variations in the deformation signals were measured by high-frequency and clinometric GNSS networks.

On the morning of August 12, at approximately 08:00 UTC, INGV’s Etna Observatory reported the formation of a small lava flow, originating from one of the mouths of the North crateric area. Positioned atop the Sciara del Fire, this lava stream has since expanded, spanning a length between 30 – 50 m (98.4 – 164 feet). Concurrently, weak spattering activity was observed from the same mouth fueling the flow.

Seismic data suggested that the width of the volcanic quake maintained an average range over the past few hours. Pertinent changes in the rate of occurrence and magnitude of explosion-quakes were documented. As of the latest data until 06:00 UTC, no significant changes in deformation signals were detected.

References:

¹ VOLCANIC ACTIVITY ANNOUNCEMENT for STROMBOLI VOLCANO – INGV-OE – August 8, 9 and 12, 2023

Featured image credit: Claudio Formisani (stillshot)

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