Report on Yasur (Vanuatu) — 29 April-5 May 2020
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 29 April-5 May 2020
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2020. Report on Yasur (Vanuatu). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 29 April-5 May 2020. Smithsonian Institution and US Geological Survey.
19.532°S, 169.447°E; summit elev. 361 m
All times are local (unless otherwise noted)
On 30 April the Vanuatu Meteorology and Geo-Hazards Department (VMGD) reported that recent visual observations at Yasur confirmed that gas-and-ash emissions were ongoing. The report noted that some of the explosions could be intense and eject bombs outside of the summit crater. Data from the seismic network indicated a decrease in activity as compared to March data. The Alert Level remained at 2 (on a scale of 0-4). VMGD had increased the radius of the permanent exclusion zone to 600 m in mid-March and that remained in effect; residents and tourists were reminded that volcanic ash and gas could reach areas impacted by trade winds.
Geologic Background. 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-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, 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 during the past century.