THREAD: After a few hours of minor phreatic and then phreatomagmatic explosions, #Taal volcano on the Philippine island of Luzon has entered into a major explosive eruption. Taal has been quiescent since a small phreatic eruption in October 1977.
#Taal, one of the most active and notorious volcanoes of the Philippines, lies on an island in a large caldera lake (Lake Taal, formerly also referred to as Lake Bombon), about 50 km south of the Philippine capital, Manila. It is often called "the lowest volcano on Earth" ...
... because it is only about 300 m high, which is indeed a rather modest height considering #Taals frequent and mostly violent eruptions. Taal island has multiple vents: a large central crater (Main Crater), which is filled with a lake (and had, until now, a small island inside)
Many historical eruptions through 1911 have occurred from Main Crater; eruptions in the 1960s and 1970s, on the other hand, took place near Mt. Tabaro, on the southwest side of the island. (Map from Delos Reyes et al., Earth Science Reviews v. 177, p. 565-588, 2018). 
Most eruptions of #Taal are violently explosive, and therefore many historical eruptions have been destructive and deadly. The most powerful historical eruption seems to have been that of 1754, which lasted from May until November and killed dozens of people.
The most deadly historical eruption of #Taal was that of 30 January 1911, which resulted in the death of 1335 people (most of them on Taal island, which was then inhabited, and was completely ravaged by pyroclastic flows). Gruesome photo from National Geographic April 1912
#Taal then remained silent for more than 54 years, and suddenly became active again on 28 September 1965. This eruption started with basaltic lava fountaining from a new vent near Mt. Tabaro, on the southwest side of the island (which was again populated at the time).
Apparently, water from #Taal lake soon gained access to the vent, and the activity turned violently phreatomagmatic (photo from Moore et al., Science, v. 151, p. 955-960), generating diluted but devastating and deadly pyroclastic flows, killing about 190 people.
The 1965 eruption opened a huge chasm in the southeast side of the island, which formed a narrow bay. The final weakening activity on 30 September created a small, ring-shaped island within that bay (photo by Jim Moore, commons.wikimedia.org/wiki/File:Taal…)
Less than a year later, in August 1966, renewed eruptive activity started at the island formed at the end of the 1965 eruption (photo by Jim Moore, from the book "Volcanic Landforms and Surface Features", edited by Green & Short, 1971, plate 103A).
*The 1966 eruption of #Taal started on 5 July and lasted one month
During the 1966 eruption of #Taal, phreatomagmatic activity built a broad cone of light colored material typical for magma-water interactions (such cones are called tuff cones), which filled much of the embayment formed by the 1965 eruption.
The crater of the 1966 tuff cone of #Taal subsequently filled with a lake. A rather small, still phreatomagmatic eruption occurred on 16-18 August 1967 and built a 40-m-diameter cone within the 1966 crater lake (photo from Ruelo, Philippine Journal of Volcanology, v. 1, 1983)
In 1968, #Taal decidedly changed its eruptive character. On 2 February, lava started flowing from a new cone growing within the 1966 tuff cone, and the explosive activity became Strombolian. This was the first time in recorded history that Taal produced a lava flow.
After filling the 1966 tuff cone, lava overflowed, reached the shore of Taal island, & began to fill what remained of the 1965 embayment. Photo (from Rittmann "Vulkane in Farbe", 1976) shows 1966 tuff cone in foreground, growing 1968 cone in center, and new lava field at left.
The 1968 eruption ended on 2 April, but another Strombolian-effusive eruption started on 29 October 1969, adding more lava to the island and enlarging the Strombolian cone. This eruption ended on 10 December 1969. A small phreatic eruption occurred on 9-12 November 1970.
#Taal erupted again on 3 September 1976, but this time with phreatic explosions from several vents near the site of the 1965-1970 eruptions. This activity lasted until mid-October. Photo from the cover of EOS, v. 61, 5 February 1980.
The 1976 eruption of #Taal volcano produced small, probably relatively cool pyroclastic flows, as is seen in this historical video footage from Associated Press:
Finally, on 3 October 1977, a very small phreatic eruption occurred within the largest of the vents formed during the 1976 eruption of #Taal, which lasted only 2 days.
None of the eruptions following the deadly 1965 event caused human fatalities, the island remained uninhabited.
None of the eruptions following the deadly 1965 event caused human fatalities, the island remained uninhabited.
Now a few notes about the ongoing 2020 eruption.
The eruption seems to have started rather abruptly, although slight unrest may have preceeded it. Episodes of unrest at #Taal have been repeatedly observed since the early 1990s. A possible magmatic intrusion occurred in 2010-2011
The eruption seems to have started rather abruptly, although slight unrest may have preceeded it. Episodes of unrest at #Taal have been repeatedly observed since the early 1990s. A possible magmatic intrusion occurred in 2010-2011
I erroneously said in a previous tweet that #Taal island remained uninhabited after 1965, but it seems that by 2010, ~3700 people lived there (Arpa et al., Bulletin of Volcanology, v. 75, 747, 2013). I have no information whether people were on the island at the time of eruption
In any case, the 2020 eruption is the first activity at #Taal's Main Crater since the 30 January 1911 eruption. However, that eruption was preceded by many minor eruptions in previous years and a dramatic increase in unrest (Worcester, in National Geographic, April 1912).
This time, the volcano went from alert level 1 to alert level 4 (by @phivolcs_dost ) in a few hours, as eruptive activity went from steam emission to phreatic and phreatomagmatic explosions to (presumably) fully magmatic. This is not much time for emergency response.
@phivolcs_dost While we all hope that this eruption will not become another disaster in the eruption record of #Taal, we must also be careful about the spread of false information (volcanoes do NOT emit "smoke"), and there seems to be no lava in this eruption, thus far.
@phivolcs_dost Photos circulating on the Internet that show brightly incandescent jets of molten rock are - once again - photos of other eruptions at other volcanoes, one showing #Momotombo (Nicaragua) in 2015, and another that seems to be Ibu (Indonesia) or Kirishima (Japan), but not #Taal.
