Evacuations ordered after increase in activity from Mount Ibu on Halmahera Island, Indonesia.

Authorities in North Maluku Province, Indonesia, have ordered the evacuation of six villages close to Mount Ibu, a 1325 m stratovolcano on the northwest coast of Halmahera Island, following a series of eruptions in the first two weeks of 2025. Mount Ibu began its current eruptive cycle in June 2024, but January has seen a significant rise in activity, with more than a thousand eruptions have been recorded on the volcano this year, with the largest producing ash columns reaching as high as 4 km over the summit of the volcano. However, to date only one village, with a population of 517 people, has been evacuated, with about 2500 people in the remaining five villages reluctant to leave without first harvesting crops.

An eruption on Mount Ibu, Halmahera Island, on Wednesday 15 January 2024. Azzam/AFP.

The Halmahera Island chain is a volcanic arc formed where the Halmahera Plate, a northeaster extension of the Molucca Sea Plate is being subducted beneath Philippine Plate from the east and the Eurasian Plate from the west, with the underlying plate being melted by the heat of the Earth's interior, and lighter minerals bubbling up through the overlying plate to form volcanoes. The Halmahera volcanoes are located where the Philippine Plate is overriding the Molucca Sea Plate; to the west the Sangihe Islands lie where the Molucca Sea Plate is being overridden by the Eurasian Plate.

Diagrammatic representation of the subduction zones beneath Halmahera (middle), plus the Philippines (top) and Sulawesi (bottom), with the Eurasian Plate to the left, the Molucca Sea Plate in the middle, and the Philippine Plate to the right.  Hall & Wilson (2000).

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Magnitude 5.8 Earthquake in the Afar Region of Ethiopia linked to activity on Mount Dafan.

The Ethiopian Geological Institute has reported a Magnitude 5.8 Earthquake at a depth of 10.0 km, in the Awash Fentale Woreda (District) of the Afar Region of Ethiopia, about 150 km to the northeast of Addis Ababa, slightly after 4.50 am local time (slightly after 0.50 am GMT) on Saturday 4 January 2025. There are no reports of any damage or injuries arising from this quake, but it was felt as far away as Addis Ababa, and it is possible that some minor damage has occurred.

The approximate location of the 4 January 2024 Ethiopian Earthquake. USGS.

This is the latest in a series of Earthquakes in the Central Ethiopia, which began in the third week of December 2024. Clusters of Earthquakes are concerning in northern or central Ethiopia, as the area is volcanic, and seismic movements can be linked to magma moving into chambers beneath volcanoes from deeper in the Earth, which in turn can be a predictor of future volcanic eruptions. On this occasion the Ethiopian Geological Institute has suggested that the Earthquakes may be linked to a fissure eruption on Mount Dafan, a shield volcanoe in the Dulacha Woreda, which opened on 2 January producing a sustained jet of steam and hot water. Residents of the area have been evacuated as a precaution against a future, larger eruption.

A vent which opened on Mount Dafan in the Dulacha Woreda of Ethiopia on 3 January 2024, producing a sustained jet of steam and hot water. Ethiopian Geological Institute/Facebook.

The deserts of Northern Ethiopia and Southern Eritrea are extremely volcanically active, with dozens of volcanoes fed by an emerging divergent margin along the East African Rift. The African Plate is slowly splitting apart along the Ethiopian Rift and the East African Rift to the south (which is splitting the Nubian Plate to the West from the Somali Plate to the East). Arabia was a part of Africa till about thirty million years ago, when it was split away by the opening of the Red Sea Rift (part of the same rift system), and in time the Ethiopian and East African Rifts are likely to split Africa into a number of new landmasses. This rifting exerts pressure on the rocks around the margin of the sea, slowly pushing them apart, not smoothly but in fits and starts as the pressure overcomes the tendency of the rocks to stick together, creating shocks that we experience as Earthquakes.

Rifting in East Africa. The Danakil Microplate is the red triangle to the east of the Afar depression at the southern end of the Red Sea. Università degli Studi di Firenze.

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Eruption and lahar on Mount Kanloan, Negros Island, the Philippines.

Mount Kanlaon, a 2465 m stratovolcano (cone shaped volcano made up of layers of ash and lava) on northern Negros Island in the central Philippines, erupted on Monday 3 June 2024, producing a 5km high column of ash, and subsequent ashfalls in the area around the volcano. On Wednesday 5 June heavy rainfalls in the area produced a series of lahars (mudslides of volcanic ash) which swept down watercourses in some cases entering villages. There are no reports of any casualties, but the Philippine Institute of Volcanology and Seismology has warned that the mud is likely to be toxic, raising concerns about the availability of safe water in the effected villages.

An eruption on Mount Kanloan, Negros Island, the Philippines on Monday 3 June 2024. Dollet Demaflies/AFP/Getty Images.

The geology of the Philippines is complex, with the majority of the islands located on the east of the Sunda Plate. To the east of this lies the Philippine Sea plate, which is being subducted beneath the Sunda Plate (a breakaway part of the Eurasian Plate); further east, in the Mariana Islands, the Pacific Plate is being subducted beneath the Philippine Sea Plate. This is not a smooth process, and the rocks of the tectonic plates frequently stick together before eventually being broken apart by the rising pressure, leading to Earthquakes in the process. Material from the subducting Philippine Plate is heated by the temperature of the Earth's interior, causing lighter minerals to melt and the resultant magma to rise through the overlying Sunda Plate, fuelling the volcanoes of the Philippines.

Subduction beneath the Philippines. Yves Descatoire/Singapore Earth Observatory.

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Town of Grindavik evacuated again as new eruption begins on the Reykjanes Peninsula, Iceland.

Eruptive activity on the Reykjanes Peninsula, Iceland began again on 29 May 2024, according to the Icelandic Met Office, the first such eruption since activity on a fissure which opened in March petered out three weeks ago. The activity is thought to have started when magma flowing from the magma reservoir beneath Svartsengi into the area beneath the Sundhnúkur crater row. At about 4.00 pm on 29 May the magma encountered groundwater penetrating through a fissure from a previous eruption, leading to a phreatic explosion as a large volume of the water was turned into steam instantly. This led to the formation of a new fissure running southwest to northeast (parallel to previous fissures on the peninsula) for about 2.4 km. This fissure has produced lava fountains up to 50 m high, and is extruding lava at a rate of about 1500-2000 m³ per second. The eruption has prompted the evacuation of the town of Grindavik, and the nearby Blue Lagoon Geothermal Spa. The fissure is further from the town than the eruption in January which saw lava entering the streets of the settlement and several buildings destroyed, but is also significantly larger, and is evolving significant amounts of toxic gasses.

A volcanic fssure on the Reykjanes Peninsula, Iceland, which opened on 29 May 2024. Marco Di Marco/AP.

Although dramatic, lava flows are not usually considered particularly dangerous, as their advancing fronts are quite slow and can quickly be outpaced by an able-bodied Human being. The more deadly volcanic events are pyroclastic flows, such as the one which engulphed the Roman town of Pompeii, in which clouds of superheated gas and ash move downhill at high speeds in an avalanche-like motion, and phreatic explosions, caused by bodies of lava encountering bodies of water, which evaporate almost instantly, causing huge explosions.

The size and position of the new fissure on the Reykjanes Peninsula, Iceland. Icelandic Met Office/BBC.

Iceland lies directly upon the Mid-Atlantic Ridge, a chain of (mostly) submerged volcanoes running the length of the Atlantic Ocean along which the ocean is splitting apart, with new material forming at the fringes of the North American and European Plates beneath the sea (or, in Iceland, above it). The Atlantic is spreading at an average rate of 25 mm per year, with new seafloor being produced along the rift volcanically, i.e. by basaltic magma erupting from below. The ridge itself takes the form of a chain of volcanic mountains running the length of the ocean, fed by the upwelling of magma beneath the diverging plates. In places this produces volcanic activity above the waves, in the Azores, on Iceland and on Jan Mayen Island. All of this results in considerable Earth-movement beneath Iceland, where Earthquakes are a frequent event.

The passage of the Mid-Atlantic Ridge beneath Iceland. NOAA National Geophysical Data Center.

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Exclusion area around Mount Ibu, Halmahera Island, extended following new eruption.

The Indonesian Center for Volcanology and Geological Hazard Mitigation has extended the exclusion zone around  Mount Ibu, a 1325 m stratovolcano on the northwest coast of Halmahera Island, following a new eruption on 18 May 2024. A two kilometre exclusion zone had already been put in place after the volcano began erupting on 28 April, but this has been increased to seven kilometres following the most recent eruption, which produced an ash column which rose to 4 km above the volcano's summit, resulting in seven villages needing to be evacuated. 

An ash column and lava fountain above Mount Ibu on the Indonesian island of Halmahera on 18 May 2024. Several lightning discharges can be seen within the ash column; ash columns can build up considerable charge variations leading to frequent electrical discharges. Indonesian Center for Volcanology and Geological Hazard Mitigation/Reuters.

The Halmahera Island chain is a volcanic arc formed where the Halmahera Plate, a northeaster extension of the Molucca Sea Plate is being subducted beneath Philippine Plate from the east and the Eurasian Plate from the west, with the underlying plate being melted by the heat of the Earth's interior, and lighter minerals bubbling up through the overlying plate to form volcanoes. The Halmahera volcanoes are located where the Philippine Plate is overriding the Molucca Sea Plate; to the west the Sangihe Islands lie where the Molucca Sea Plate is being overridden by the Eurasian Plate.

Diagrammatic representation of the subduction zones beneath Halmahera (middle), plus the Philippines (top) and Sulawesi (bottom), with the Eurasian Plate to the left, the Molucca Sea Plate in the middle, and the Philippine Plate to the right.  Hall & Wilson (2000).

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