Volcano Spouting off in my neighborhood

[Alan Mighty]

Active geological faults (in red) in the immediate vicinity of Taal

[Alan Mighty]

Settlements in the vicinity of Taal destroyed by historic eruptions:

[Alan Mighty]

Looking back through recorded history (which is never very long), the 1754 eruption was the most hazardous recorded.


That's when Old Taal etc (see map above) were destroyed. According to the eyewitnesses of 1754, the destruction was from pyroclastic flows reaching at least 16 km from the volcano.

The 1754 eruption is classified as 'Plinian', meaning of the style described by Pliny. And we all know what happened to the folks at Pompei, when Vesuvius erupted in the Plinian style.

Best to monitor Philvolcs' reports. And stay at least 16 km away.

[Alan Mighty]

Most of the historically recorded eruptions of Taal were of the Strombolian style. Apparently not nearly so destructive and hazardous to humans as the Plinian eruptions.

[Sand crab]

Taal lake fills in the caldera for a much bigger volcano but it hasn't gone off in 7000 years. I noticed that right away from the aerial pic previously posted and then looked it up. So to expand on a previous posting we have a lake (now probably gone) filling the crater of a volcano which is an island in a lake (which may be gone someday) which fills the crater of a much larger volcano which is on an island.

Did I get that right?

[delmarrey]

Close enough.

The ash clouds Have slowed down and the crater lava is bubbling away but no flow yet. It could still blow up. The center island is completely dead if all life now, plants and animals.

In upper Cavite we only got a light sprinkle of ash, so far.

The nice thing is Taal is one of the smallest active volcanos on earth.

https://news.abs-cbn.com/news/01/14/...eming-slowdown

[Alan Mighty]

Originally Posted by Sand crab

Taal lake fills in the caldera for a much bigger volcano but it hasn't gone off in 7000 years. I noticed that right away from the aerial pic previously posted and then looked it up. So to expand on a previous posting we have a lake (now probably gone) filling the crater of a volcano which is an island in a lake (which may be gone someday) which fills the crater of a much larger volcano which is on an island.

Yes, Taal lake is a caldera, or perhaps two caldera joined together, from pre-historic eruptions. The best dating of the most recent big eruption responsible for the caldera pointed to 5.4 K to 6.8 K years ago.

But the size of the caldera - which is close to 30 km across - is perhaps also limited (or expanded) by other geology. Look at the graphic showing the active faults, and you'll note that the caldera has expanded to those faults (and the Tagaytay ridge).

What we do know is that since 1572, when Spanish priests started writing notes about the volcanic activity, the eruptions have been limited to fissures and craters on Volcano Island. That of course leaves unsaid the big questions:

* how do the big eruptions, of the size that created the Taal Lake caldera, relate to the small eruptions seen on Volcano Island since 1572? Do lots of small Volcano Island eruptions add up to one Taal Lake size eruption? Or is there a Taal Lake size eruption waiting around the corner?

Looking at where, on Volcano Island, the fissures and eruptions are occurring is possibly important (or not). In the 1960-70s, small eruptions came from the SW corner of Volcano Island, away from the Crater Lake on Volcano I. In the past decade, the location of fissuring and eruption has wandered a little.

That wandering is a source of concern.

As for the volcano on an island in a lake on an island in a lake on an island in an ocean thingie, that's just the product of a geographer's classification of islands - making the island at the centre of the Volcano Island crater lake a third order island.

What's more important is that most all of the islands of the Philippines are the result of subduction of continental plates and volcanic activity. Ring of Fire and all that.

[Alan Mighty]

Attached is the reconstructed map of the area affected by the 1754 eruption of Taal volcano. This is the map that Renato U Solidum, director of Philvolcs, discussed on an ABS-CBN program today as representing something of a 'worst case' eruption.

Vulcanologists have had a couple of attempts at reconstructing the 1754 eruption. The death toll is unknown, but assumed to be big. The historical records do name towns and barangays destroyed, but not a lot of detail.

The attached map has two panes.

In the left-hand pane you see the reconstructed surge of hot gases at ground level. In solid red, is the extent of surge that was accepted up until about 1990. Note the addition of the red dashed line - that is the westward extent of the surge accepted since about 1990 as having happened in 1754.

In the right hand pane are lines representing the depth of ash fall, in centimetres. Sort of like isohyets for rainfall, but this time ash fall. So Pulo (Volcano Island) had 1 metre to 2 metres of ash. The current location of Tagaytay City likely received 10 centimetres of ash fall.

[delmarrey]

The ash fall chart on the right shows the direction of the true wind for this area. If opposite, the whole lower section of Luzon would be covered in ash.

If Taal and the Xmas typhoon would have came at the same time, it’d be a real mess here.

[delmarrey]

Well, the volcano has settled down now and just steaming. But the danger still exists. Here’s a Utube of what some areas have experienced...... cracks.

https://youtu.be/e8oAqtu2Z_0

[delmarrey]

If interested here are some videos. They’re mostly in the Tagalog language but there’s plenty of scenes for eye candy.
Btw the warning today went back up to 4. There were lots of earthquakes this morning south of the crater.

https://youtu.be/gdIFWoLH7gU Witnesses who actually seen the first vent start

https://youtu.be/n_n6BC_2360

https://youtu.be/KCTm1G4BUWY

https://youtu.be/vgZuVeXmttU

https://youtu.be/b9aqVBbhgPw

https://youtu.be/2D2xDyPUVcA

Enjoy.....