Eruption at Yasur volcano, Vanuatu

A new eruption took place at Vanuatu’s Yasur volcano at 06:09 UTC on April 4, 2023. The Volcanic Alert Level remains at Level 2 since October 28, 2016.

A new Volcanic Ash Advisory has been issued by the Wellington Volcanic Ash Advisory Center (VAAC) for the Yasur volcano in Vanuatu at 13:12 UTC on April 4, 2023.¹

The eruption was observed at 06:09 UTC on the same day, and the source of the information was a pilot report (PIREP) that detected ash below the altitude of 3 km (10 000 feet).

At the time of the advisory, the aviation color code was unknown, indicating that there may be a potential risk to aviation, but the severity is not yet known. Although the ash cloud was not identifiable on satellite imagery, the location of the ash was estimated based on the report of ash in the vicinity of the crater.

The estimated movement of the ash cloud is southwest at a speed of 8 km/h (6 mph). The forecasted ash cloud for the next 6, 12, and 18 hours is expected to move in the same direction and altitude, as described in the advisory.

The next advisory is scheduled to be issued no later than 19:12 UTC on April 4.

Volcanic activity at Yasur volcano is continuing at the major unrest state, consistent with the Volcanic Alert Level 2, the Vanuatu Meteorology and Geohazards Department said in their latest bulletin issued on March 30.²

Latest data analysis from the monitoring system show moderate to low explosions, emissions of steam, gas and ash including bombs that fall inside the crater. Some explosions remain intensified and volcanic projectiles or bombs fall in and/or around the summit crater.

With the ongoing volcanic activity and the associated hazards such as gas plumes, ash fall, possible landslides and volcanic projectiles or bombs falling in and/or around the summit crater, the danger zone is limited in the danger zone A (red circle) which is 600 m (2 000 feet) from the Permanent Exclusion Zone (See Yasur caldera safety map below).

It is a useful reminder that eruptions can occur at any level of unrest with little or no warnings, VMGD said.

At Alert Level 2, the risk for visitors accessing areas from the crater rim to the parking area remains low, however, given the unpredictable character of the volcano, all tourism agencies, local authorities, people on Tanna Island and the general public are advised to give serious consideration to potential volcanic hazards.

Geological Summary

Yasur, the best-known and most frequently visited of the Vanuatu volcanoes, has been in more-or-less continuous strombolian and vulcanian activity since Captain Cook observed ash eruptions in 1774. This style of activity may have continued for the past 800 years.

Located at the SE tip of Tanna Island, this mostly unvegetated pyroclastic cone has a nearly circular, 400 m (1 312 feet) wide summit crater.

Yasur is largely contained within the small Yenkahe caldera and is the youngest of a group of Holocene volcanic centers constructed over the down-dropped NE flank of the Pleistocene Tukosmeru volcano.

The Yenkahe horst is located within the Siwi ring fracture, a 4 km (2.5 miles) wide, horseshoe-shaped caldera associated with eruption of the andesitic Siwi pyroclastic sequence.

Active tectonism along the Yenkahe horst accompanying eruptions has raised Port Resolution harbor more than 20 m (65 feet) during the past century.³

References:

¹ Yasur VAA – Wellington VAAC – 12:15 UTC on April 4, 2023

² VANUATU VOLCANO ALERT BULLETIN N°3 – TANNA ACTIVITY – VMGD – March 30, 2023

³ Yasur – Geological summary – GVP

Featured image credit: Copernicus EU/Sentinel-2, The Watchers. Acquired on March 16, 2023