Vanuatu

Vanuatu Volcano Alert Bulletin n°7 - Ambrym Activity (September 24th 2020)

Format
Situation Report
Source
Posted
Originally published
Origin
View original

AMBRYM VOLCANO
16°15’00”S 168°07’00”E Summit Elevation 4377ft (1334m)
Current Vanuatu Volcano Alert Level: Level 1

Ambrym volcano is continuing in the minor unrest state. The Volcanic Alert Level remains at Level 1.

The volcano activity at Ambrym is continuing at the low unrest level, consistent with the Volcanic Alert Level 1. New scientific analysis suggest that the Ambrym volcano activity is likely to continue at this level of minor unrest. Volcanic hazards remain about the summit craters area and the South East part of Ambrym Island (e.g. major cracks from 2018).

Some volcanic hazards do remain on Ambrym specifically at the summit and eastern part of the Island. These are related to the presence of cracked areas. In addition to the summit hazards, the presence of active rifts and faults (major ground cracking) at the South-East area of Ambrym are also hazardous, they will continue to be eroded and affected by earthquake activity. The danger zone for life safety at the summit area remains limited inside the Permanent Exclusion Zone at Benbow and Danger Zone A at Marum (See Ambrym caldera safety map below). These danger zones are about 1 km around Benbow and 2 km around Marum craters including Maben-Mbwelesu, Niri-Mbwelesu and Mbwelesu. An additional danger zone at the South-East of Ambrym remains within 500 meters from major cracks.

Latest observations and daily analysis of the Ambrym seismic data from the volcano monitoring system confirm that the Ambrym volcano activity conditions remains stable and its activity is continuing at the low level of unrest. The lava lakes that used to appear in Benbow and Marum craters have disappeared since the December 2018 eruption. The remaining activity inside both craters consists of ongoing steam emissions. People from Ambrym and neighbouring islands will not see the volcanic glow at nights.

Open cracks in the South-East Ambrym that formed during the December 2018 eruption may continue to open due to erosion. Major earthquake activity could continue to affect these cracks and weak layers or areas around the actives craters.

The Volcanic Alert Level (VAL) for Ambrym has been at the Level 1 since 10th October 2019. Observations of the current activity are consistent with the activity of the Volcanic Alert Level 1. Level 1 indicates ‘Minor level of unrest. Danger zone remains at 1 km around Benbow, 2 km around Marum and 500 meters from major cracked areas in the South-East part of Ambrym’. With this current volcanic activity, it is a useful reminder that eruptions can occur at any level of unrest with little or no warning.

Ambrym volcano is a very active volcano in Vanuatu with large caldera of 12 km in diameter and 2 active craters, Marum and Benbow. The volcano has been active during historical time at both summit and flank vents, producing moderate explosive eruptions and lava flows that have reached the coast. The larger events include eruptions in 1820, 1894, 1913 or 1929. Over the last seventy years (before the 2018 eruption), there have been no eruptions that extended beyond the summit caldera. The eruption of 1988 and 2015 are focused in the caldera. The December 2018 eruption was focused in the summit caldera, and also affected the Eastern Fracture or Rift Zone with ground deformation, rifting, faulting and uplift, but no eruption occurred there.

All tourism agencies, local authorities, people of Ambrym and the general public are reminded that due to the presence of cracked areas at the caldera, the danger zone remains at the Permanent Exclusion Zone **at Benbow and the **Danger Zone A at Marum which are set about 1 km radius from Benbow and 2 km radius from Marum. There are life safety hazards within these hazard zones. Due to the presence of active rifts and faults at the South-East area of Ambrym, communities concerned are advised not to access within 500 meters from major cracks (Danger Zone). There is a possibility (low) that earthquake or volcanic activity may start from this area. More information about the volcanic hazards can be found on the website:
https://www.vmgd.gov.vu/vmgd/index.php/geohazards/volcano/volcano-info/r....

The Vanuatu Meteorology and Geohazards Department continues to closely monitor this volcano activity. More information will be provided when necessary.

For further information, please contact Geohazards Division at the Vanuatu Meteorology and Geohazards Department at geohazards@meteo.gov.vu or 24686.