Mount Stromboli, the volcano on the small Italian island of the same name, sent a cloud of ash more than a kilometer into the sky on Wednesday, May 19, around 14:51 local time.

The “increase in explosive activity” sent a pyroclastic current down to the coast, stretching out into the sea for more than a kilometer, officials said.

According to the National Institute of Geophysics and Volcanology (INGV) in Catania, explosive activity increased from 2.47 pm local time at the northern vents (on the side of Stromboli village).

At 2.51 pm, this culminated in a pyroclastic flow that reached the coast and traveled out above water for about 1 km beyond the coastline (!).

The associated ash plume rose to 1.5-2 km (0.9 to 1.25 miles) height.

After an aerial survey of staff from the volcanological institute in Catania (INGV), scientists concluded that part of the rim of the northeast crater had collapsed, producing a landslide that turned into the observed pyroclastic flow earlier today.

Pyroclastic flows are deadly, turbulent hot avalanche of lava rock fragments of all sizes embedded in a mixture of turbulent gas and ash racing down slopes.

Mount Stromboli’s eruption coincided with Italy’s Mount Etna eruption, which sprayed lava and ash into the Sicilian sky early on Wednesday morning.

recent study investigated the long-term hazard levels at Stromboli. Their conclusion: occasional more intense eruptions can present a serious danger. Here the abstract:

Stromboli volcano (Italy), always active with low energy explosive activity, is a very attractive place for visitors, scientists, and inhabitants of the island. Nevertheless, occasional more intense eruptions can present a serious danger. This study focuses on the modeling and estimation of their inter-event time and temporal rate. With this aim we constructed a new historical catalog of major explosions and paroxysms through a detailed review of scientific literature of the last ca. 140 years. The catalog includes the calendar date and phenomena descriptions for 180 explosive events, of which 36 were paroxysms.

“We evaluated the impact of the main sources of uncertainty affecting the historical catalog. In particular, we categorized as uncertain 45 major explosions that reportedly occurred before 1985 and tested the effect of excluding these events from our analysis. Moreover, after analyzing the entire record in the period [1879, 2020], we separately considered, as sequences, events in [1879, 1960] and in [1985, 2020] because of possible under recording issues in the period [1960, 1985].