I mentioned Jo had posted something earlier about some of the differences in volcanoes and their spew, but I realize now it might've been you.
Quoting: KickinIt It was jo
I was just trying to find some info on pyroclastic flows specifically to share. : )
Quoting: Simple27 Here is some more info..... (btw my major 40 years ago in college was geology but I think that I have said that before.)
from USGS - complete article is here: [
link to volcanoes.usgs.gov (secure)]
Klauea Volcano Erupts in Explosive and Effusive CyclesCaldera collapse 2,200 years ago ushered in 1,200 years of explosive eruptionsSince Klauea's surface is dominantly covered by young deposits, only the eruption record of the past 2,500 years is suitably well-known. Effusive lava flows were the norm until about 2,200 years ago, when the Powers caldera formed—the precursor to the present-day summit caldera. The caldera collapsed to a depth of at least 620 m (2030 ft), where magma and external water interacted to trigger powerful phreatomagmatic (water plus magma) eruptions.
Caldera formation marks transition from effusive to explosive phaseThe present-day Klauea caldera formed by collapse just after the ‘Ail‘au eruption ended (about 1470 CE) and before the Keanak;ko‘i eruptions began (about 1510 CE). The caldera floor dropped to a depth of about 600 m (1970 ft), with diameters of 3.5 km (2.2 mi) by 3 km (1.9 mi), which is estimated to be a collapse volume of 4 to 6 km3 (1 to 1.4 mi3).
Klauea's most recent explosive period lasted 300 years Towering lava fountains, likely more than 600 m (2,000 ft) high, roared from Klauea caldera just after it formed and began 300 years of explosive eruptions that ended in the early 19th century. During that time, at least four strong explosive eruptions sent tephra high into the jet stream,
Current effusive period has lasted about 200 years, but it will switch back againOnly a few lava flows were erupted during the 300 years of explosive activity, but that changed in 1823, when the volcano reverted to an effusive interval that continues to this day.
snip:
The first explosive eruption on the volcano since the early 19th century took place in 1924 within Halema‘uma‘u Crater on the floor of Klauea's summit caldera. The eruption occurred days after the active lava lake drained away, with the magma probably intruding into the volcano's East Rift Zone. For 17 days, rocks, ash, and dust erupted in dramatic clouds rising from the crater. Rocks weighing many tons were hurled as far as a kilometer (0.6 mi) from the crater. There was some subsidence within Halema‘uma‘u, but the caldera did not deepen appreciably.
Having pieced together the recent geologic past of Klauea, scientists conclude that the volcano will eventually return to a long period of mostly explosive activity, just as it did around 1500 CE.
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Remember that the ash that a volcano pushed up into the air has mass or weight. What goes up will come down. And if it is still hot the ash that comes down in a pyroclastic flow it can be be as hot as lava. Most of the time when it falls back down it follows the valleys on the sides of the volcano.
Run don't walk to the nearest exit.
Last Edited by joinca on 06/05/2018 09:29 PM"The government will one day be corrupt and full of liars, and the people will flock to the one that tells the truth." - “Tyranny is defined as that which is legal for the government but illegal for the citizenry.” - "The democracy will cease to exist when you take away from those who are willing to work and give to those who would not." - "I predict future happiness for Americans if they can prevent the government from wasting the labors of the people under the pretense of taking care of them." - "A Country with no Border, is not a country" -- Thomas Jefferson
We MUST NEVER forget what Kamala Harris did to Justice Kavanaugh & his family!