Volcanos

Roundup of Global Volcanic Activity - New activity for the week 29 March - 4 April 2023

Ambae - Vanuatu : On 30 March the Vanuatu Meteorology and Geo-Hazards Department (VMGD) reported that the cone in Ambae’s Lake Voui continued to produce emissions consisting of steam, volcanic gases, and possibly occasional ash that drifted downwind. Volcanic earthquakes were recorded by the seismic network. According to the Wellington VAAC a low-level ash plume rose to an altitude of 2.4 km based on satellite imagery on 5 April. The Alert Level remained at 2 (on a scale of 0-5) and the public was warned to stay outside of the Danger Zone, defined as a 2-km radius around the active vents in Lake Voui, and away from drainages during heavy rains. Source: Vanuatu Meteorology and Geo-Hazards Department (VMGD), Wellington VAAC

Kikai - Ryukyu Islands (Japan) : JMA reported that minor eruptive activity was recorded at Satsuma Iwo-jima, a subaerial part of Kikai’s NW caldera rim, during 27 March-3 April. White gas-and-steam plumes rose 700 m above the crater rim. Surveillance cameras observed nightly incandescence.

Laguna del Maule - Central Chile-Argentina : SERNAGEOMIN reported that increased seismicity at Laguna del Maule was first registered around 1800 on 30 March. The seismic monitoring stations recorded a swarm of 300 volcano-tectonic earthquakes that occurred in an elongated area in a NW-SE direction approximately 10 km SW of the crater at a depth of up 8 km. These events were associated with rock fracturing processes. Starting on 3 April there was an increase in the magnitude of the earthquakes at M 2.5, M 2.8, and M 2.9 at depths of 4.5-8 km.

Nevado del Ruiz - Colombia : Servicio Geológico Colombiano’s (SGC) reported that thermal anomalies, persistent in Arenas Crater at Nevado del Ruiz since October 2022, were low-to-moderate in intensity. Seismicity increased significantly on 24 March, characterized by rock-fracturing earthquakes mainly located 2-5 km SW of Arenas crater at depths of 2-4 km. On 28 March there were 6,500 of these events, the highest daily count since 2010. The number of daily events continued to increase and on 29 March the seismic network recorded 11,000 earthquakes, the highest daily count since seismic monitoring began in 1985; on 30 March there were 11,600 earthquakes. The maximum magnitudes per day were also increasing, with a M 2.6 on 24 March, a M 2.7 on 29 March, and a M 3.1 on 30 March. The earthquake locations migrated towards Arenas Crater, though the depths remained within the same range. The Alert Level was raised to Orange, Level II (the second highest level on a four-level scale) on 30 March. In addition to the swarm, seismic signals indicating fluid movement continued to be recorded and some were associated with ash emissions; the tallest plume on 30 March rose 1.8 km above the summit and drifted NW and SW. The number of earthquakes on 31 March totaled 8,800 with a maximum magnitude of 2.6 event at 1236. The number of signals indicating fluid movement increased during 31 March-1 April and were likely associated with ash emissions. Gas-and-ash plumes rose as high as 1.3 km above the summit and drifted SW and SE. A total of 10,400 earthquakes were recorded on 1 April with the largest event, a M 3.1, recorded at 1040. On 2 April a total of 5,400 earthquakes were recorded and the largest event (M 2.3) occurred at 1122 and was located 4.3 km SW of the crater. Ash-and-gas emissions persisted and rose to 1.2 km above the summit and drifted SW and NW. Ashfall was reported in Brisas y de Potosí by Parque Nacional Natural Los Nevados officials. The Gestión del Riesgo de Desastres (UNGRD) reported that there were 57,000 people living in 22 municipalities in the departments of Tolima, Caldas, Risaralda, Valle del Cauca, Quindío, and Cundinamarca who could be impacted by Nevado del Ruiz. Preparations and coordination for a possible evacuation of residents were centered on areas in high-risk zones including the municipalities of Villamaría in the department of Caldas, Casabianca, Herveo, Murillo, and Villahermosa in Tolima, and the sector of the Gualí River in the municipality of Guaduas, Cundinamarca.

Ubinas - Peru : Instituto Geofísico del Perú (IGP) reported that at 1713 on 28 March a moderate-volume lahar descended the Volcánmayo drainage on Ubinas’s SE flank. The town of Tonohaya (7 km SSE) is located along the drainage and the town of Ubinas is 2 km E of the drainage.