The Vanuatu Meteorology and Geohazards Department (VMGD) reported that activity at Yasur continued at a level of “major unrest,” as defined by the Alert Level 2 status (on a scale of 0-5) during July. Satellite and webcam images from 1, 3-17, 20-23, 25-26, and 28-31 July showed that explosive activity continued, producing gas, steam, and/or ash emissions. Sulfur dioxide emissions were detected in satellite images from 2-14 and 17-30 July. Low-to-moderate thermal anomalies were observed in satellite images on 5, 11-13, 15, 21, 24-25, and 27-29 July. Seismic data confirmed ongoing volcanic activity, with explosions that were occasionally strong. The public was advised to maintain a minimum distance of 600 m from the eruptive vents, designated as Danger Zone A on the Yasur Caldera Safety Map.

Geological Summary. Yasur has exhibited essentially continuous Strombolian and Vulcanian activity at least 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 in Vanuatu, this pyroclastic cone has a nearly circular, 400-m-wide summit crater. The active cone 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-wide open feature 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 during the past century.

Source: Vanuatu Meteorology and Geohazards Department (VMGD)