Showing posts with label Negros Island. Show all posts
Showing posts with label Negros Island. Show all posts

Friday, 20 February 2026

Eruption on Mount Kanloan causes ashfall events across Negros Island.

Mount Kanlaon, a 2465 m stratovolcano (cone shaped volcano made up of layers of ash and lava) on the northern part of Negros Island in the central Philippines, erupted slightly before 3.40 pm local time on Thursday 19 February 2026, according to the Philippines Volcano Observatories. The eruption comprised a series of explosions which lasted about two minutes and produced an ash column about 2 km high, and followed by a longer period of gas emissions. 

An eruption on Mount Kanloan, Negros Island, the Philippines, on Thursday 18 February 2026. Philippines Volcano Observatories.

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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Wednesday, 5 November 2025

At least 116 dead as Typhoon Kalmaegi sweeps across the Philippines.

At least 116 people are now known to have died, with many more still missing, after Typhoon Kalmaegi swept across the central Philippines on Tuesday 4 November 2025. The majority of the deaths occurred in the city of Cebu, and surrounding metropolitan area, with 35 people having apparently drowned in a single incident in the town of Liloan, with 76 people having died in the greater metropolitan area, despite over 400 000 being evacuated from areas deemed to be at risk ahead of the storm. On Mindanao Island a military helicopter taking part in relief efforts crashed during the storm, leading to the deaths of all six crewmembers.

Damage in the city of Talisay on Cebu Island following the passage of Typhoon Kalmaegi on 4 November 2025. Jam Sta Rosa/AFP/Getty Images.

On Negros Island at least 12 people have died and 12 more are still missing after heavy rains triggered a lahar, which buried a number of homes in Canlaon City. Lahars are ash-laden flash floods associated with volcanoes. They can be caused directly by volcanic eruptions, for example when hot lava encounters a glacial lake rapidly destroying an ice dam, but are also common in areas of high seasonal rainfall, where ash deposits from a volcano can build up during the dry season, creating dams on seasonal waterways, which temporarily halt the flow of water, then give way rapidly leading to dramatic flash floods. The Negtos lahar was caused by heavy rains associated with Typhoon Kalmaegi falling onto unconsolidated ash from an eruption on Mount Kanloan last year.

Tropical storms are caused by the warming effect of the Sun over tropical seas. As the air warms it expands, causing a drop in air pressure, and rises, causing air from outside the area to rush in to replace it. If this happens over a sufficiently wide area, then the inrushing winds will be affected by centrifugal forces caused by the Earth's rotation (the Coriolis effect). This means that winds will be deflected clockwise in the northern hemisphere and anti-clockwise in the southern hemisphere, eventually creating a large, rotating Tropical Storm. They have different names in different parts of the world, with those in the northwest Pacific being referred to as typhoons.

The structure of a tropical cyclone. Wikimedia Commons.

Despite the obvious danger of winds of this speed, which can physically blow people, and other large objects, away as well as damaging buildings and uprooting trees, the real danger from these storms comes from the flooding they bring. Each drop millibar drop in air-pressure leads to an approximate 1 cm rise in sea level, with big tropical storms capable of causing a storm surge of several meters. This is always accompanied by heavy rainfall, since warm air over the ocean leads to evaporation of sea water, which is then carried with the storm. These combined often lead to catastrophic flooding in areas hit by tropical storms. 

The formation and impact of a storm surge. eSchoolToday.

Typhoon Kalmaegi, known as Typhoon Tino in the Philippines, deposited 183 mm of rain onto Cebu Island in the 24 hours before making landfall. When it arrived, it brought with it sustained winds of more than 130 km per hour, with gusts exceeding 180 km per hour. Storms such as this are becoming more frequent due to global warming which is warming the oceans faster than the land, with the Philippines, which typically suffers about 20 storms per year, having been hit by twelve major storms since the typhoon season began in June this year: Tropical Storm Wutip in June, Typhoon Danas, Severe Tropical Storm Wipha, and Severe Tropical Storm Co-May in July, Tropical Depression Fabian and Typhoon Kajiki in August, Tropical Storm Mita, Typhoon Ragasa, and Typhoon Bualoi in September, and Typhoon Matmo, Severe Tropical Storm Fengshen, and Tropical Depression Salome in October. Furthermore, it is thought likely that a system currently known as Tropical Depression Thirty Two, which is currently crossing the central Pacific, will increase in strength and become a Typhoon-strength storm before making landfall in the Philippines this weekend.

A rescue team in the Talamban District of Cebu City following the passage of Typhoon Kalmaegi on 4 November 2025. Philippine Red Cross/Reuters.

As well as leading to larger and more frequent storms, warmer seas can enable them to change course rapidly, making it harder to predict where and when they will make landfall. However, this does not appear to have been the issue in the Philippines this week, where over half a million people were evacuated in advance from areas considered vulnerable to the storm. Instead, the storm has contributed to a growing corruption scandal in the country, with approximately 26.6 billion Philippine Pesos (about US$452 million) having been spent on flood defences which were found to be insufficient, incomplete, or simply absent as the storm approached.

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Thursday, 10 April 2025

Eruption on Mount Kanlaon.

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, underwent an explosive eruption at 5.51 am local time on Tuesday 8 April 2025, producing an ash column 4 km high which drifted to the west and southwest, according to a bulletin issued by the Philippine Institute of Volcanology and Seismology. The sound of the eruption was heard about 20 km away, and pyroclastic flows were observed on the southern flanks of the volcano, and debris is reported to have set fire to vegetation close to the summit of the volcano. Ash falls were reported up to 50 km from the eruption.

An ash column over mount Kanlaon on 8 April 2025. Philippine Institute of Volcanology and Seismology.

No injuries have been associated with the eruption, but the Philippine Institute of Volcanology and Seismology has recommended that communities within 6 km of  the volcano evacuate the area, and has placed a ban on aircraft overflying the area.

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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Wednesday, 5 June 2024

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.

See also...

Wednesday, 11 March 2020

Warnings issued after seismic activity on Mount Kanlaon, a volcano on northern Negros Island in the central Philippines

The Philippine Institute of Volcanology and Seismology has raised the alert level on 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, following a series of seismic events thought likely to have been caused by phreatic eruptions (explosions caused by magma or other hot volcanic material coming into contact with water) within the volcano's crater. People are being 'strongly advised' not to go withing four kilometres of the volcano, due to the possibility of an imminent eruption; planes are also being advised to keep clear of the area.

Mount Kanloan on northern Negros Island, the Philippines. Wikimedia Commons.

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.

See also...

https://sciencythoughts.blogspot.com/2020/01/evacuations-after-eruptions-on-mount.htmlhttps://sciencythoughts.blogspot.com/2019/12/magnitude-69-earthquake-in-davao-del.html
https://sciencythoughts.blogspot.com/2019/12/typhoon-kammuri-causes-at-least.htmlhttps://sciencythoughts.blogspot.com/2019/11/magnitude-65-earthquake-in-cotabato.html
https://sciencythoughts.blogspot.com/2019/10/magnitude-66-earthquake-beneath.htmlhttps://sciencythoughts.blogspot.com/2019/10/magnitude-63-earthquake-beneath.html
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