PHIVOLCS reported that seismicity at Taal began to increase on 28 March 2019 and fluctuated between moderate and high levels throughout the year and into 2020. A seismic swarm beneath Taal began at 1100 on 12 January and a phreatic eruption commenced at 1300. The initial eruptive activity was characterized by increased steaming from at least five vents in Main Crater and phreatic explosions that generated 100-m-high plumes. PHIVOLCS raised the Alert Level to 2 (on a scale of 0-5) and reminded the public that the entire Volcano Island (the main cone of Taal) is in a Permanent Danger Zone (PDZ).

Booming was heard at 1400 in Talisay, Batangas (4 km NNE, all distances are measured from the center of Main Crater lake). Activity escalated at 1404; volcanic tremor and earthquakes felt locally were accompanied by an eruption plume that rose 1 km. Ash fell in the SSW part of Taal. The Alert Level was raised to 3 and the evacuation of high-risk barangays was recommended. Activity again intensified around 1730, prompting PHIVOLCS to raise the Alert Level to 4 and recommend a total evacuation of the island and high-risk areas within a 14-km radius. The eruption plume of steam, gas, and tephra significantly intensified and rose 10-15 km (32,800-49,200 ft) a.s.l., producing frequent lightning. Wet ash fell in areas downwind, including as far N as Quezon City (75 km). According to news articles schools and government offices were ordered to close and the Ninoy Aquino International Airport (56 km N) in Manila suspended flights. About 6,000 people had been evacuated but the number was expected to rise. Residents described heavy ashfall, low visibility, and fallen trees.

Ashfall was reported in a wide area; in a statement issued at 0320 on 13 January PHIVOLCS noted that ashfall was reported in Tanauan (18 km NE), Batangas; Escala (11 km NW), Tagaytay; Sta. Rosa (32 km NNW), Laguna; Dasmariñas (32 km N), Bacoor (44 km N), and Silang (22 km N), Cavite; Malolos (93 km N), San Jose Del Monte (87 km N), and Meycauayan (80 km N), Bulacan; Antipolo (68 km NNE), Rizal; Muntinlupa (43 km N), Las Piñas (47 km N), Marikina (70 km NNE), Parañaque (51 km N), Pasig (62 km NNE), Quezon City, Mandaluyong (62 km N), San Juan (64 km N), Manila; Makati City (59 km N) and Taguig City (55 km N). Lapilli (2-64 mm in diameter) fell in Tanauan and Talisay; Tagaytay City (12 km N); Nuvali (25 km NNE) and Sta. Rosa, Laguna. Felt earthquakes (Intensities II-V) continued to be recorded in local areas.

The eruption progressed to a magmatic eruption during 0249-0428 on 13 January, characterized by weak lava fountaining accompanied by thunder and flashes of lightning. Activity briefly waned then resumed with sporadic weak fountaining and explosions that generated 2-km-high, dark gray, steam-laden plumes. New lateral vents opened on the N flank, producing 500-m-tall lava fountains. Heavy ashfall impacted areas SW including in Cuenca (15 km SSW), Lemery (16 km SW), Talisay, and Taal (15 km SSW), Batangas. News articles noted that more than 300 domestic and 230 international flights were cancelled as the Manila Ninoy Aquino International Airport was closed during 12-13 January; some flights could depart in the early afternoon of 13 January. Some roads from Talisay to Lemery and Agoncillo were impassible and electricity and water services were intermittent. Ashfall in several provinces caused power outages. Authorities continued to evacuate high-risk areas within a 14-km radius of Taal; by 13 January more than 24,500 people had moved to 75 shelters out of a total number of 460,000 people within 14 km.

In a bulletin posted at 0800 on 14 January PHIVOLCS noted that lava fountaining continued and steam plumes rose form Main Crater. Fissures on the N flank produced 500-m-tall lava fountains. Sulfur dioxide emissions averaged 5,299 tonnes/day on 13 January. By 1300 lava fountaining generated 800-m-tall, dark gray, steam-laden plumes that drifted SW. New ground cracks were observed in Sinisian (18 km SW), Mahabang Dahilig (14 km SW), Dayapan (15 km SW), Palanas (17 km SW), Sangalang (17 km SW), and Poblacion (19 km SW) Lemery; Pansipit (11 km SW), Agoncillo; Poblacion 1, Poblacion 2, Poblacion 3, Poblacion 5 (all around 17 km SW), Talisay, and Poblacion (11 km SW), San Nicolas. A fissure opened across the road connecting Agoncillo to Laurel, Batangas.

At 0800 on 15 January PHIVOLCS stated that activity was generally weaker; dark gray, steam-laden plumes rose about 1 km and drifted SW. Since 1300 on 12 January the seismic network had recorded a total of 446 volcanic earthquakes, with 156 of those felt with Intensities of I-V. New ground cracking was reported in Sambal Ibaba (17 km SW), and portions of the Pansipit River (SW) had dried up. Satellite images showed that the Main Crater lake was gone and new craters had formed inside Main Crater and on the N flank. According to the Disaster Response Operations Monitoring and Information Center (DROMIC) there were a total of 53,832 people dispersed to 244 evacuation centers by 1800 on 15 January.

Geological Summary. Taal is one of the most active volcanoes in the Philippines and has produced some powerful eruptions. The 15 x 20 km Talisay (Taal) caldera is largely filled by Lake Taal, whose 267 km2 surface lies only 3 m above sea level. The maximum depth of the lake is 160 m, with several submerged eruptive centers. The 5-km-wide Volcano Island in north-central Lake Taal is the location of all observed eruptions. The island is composed of coalescing small stratovolcanoes, tuff rings, and scoria cones. Powerful pyroclastic flows and surges have caused many fatalities.

Sources: Bloomeberg, The National Disaster Risk Reduction and Management Council (NDRRMC), Disaster Response Operations Monitoring and Information Center (DROMIC), Philippine Institute of Volcanology and Seismology (PHIVOLCS), ReliefWeb