Volcanic Products Flashcards
What are the four types of volcanic products?
- Lava flow
- Pyroclastic materials
- Glass
- Pyroclastic density currents (PDCs)
-Streams of lava pouring from a fissure or a vent during an eruption which have different forms due to the different composition and environment of deposition.
What are its four classifications?
Lava flow
1. ‘A’a flow
2. Pahoehoe flow
3. Block Lava
4. Pillow Lava
Pronounced as Ah-ah, is a type of lava flow characterized by its rough, jagged surface that have spiky and sharp edges, and are often associated with fluid basaltic flows.
‘A’a flow
Pronounced as Pa-hoy- hoy, is a type of lava flow that form relatively smooth surfaces that often resembles twisted ropes and are often products of basaltic flows.
Pahoehoe flow
Short, detached, vesicle-free, proximal lava that are often produced by viscous lava, such as andesitic and rhyolitic lava.
Block Lava
Lava flows that formed as - structures composed of numerous smooth, tube-like protuberances, which are good indicators for the surrounding environment as they form underwater.
Pillow Lava
Volcanic material of varying sizes produced from volcanic eruptions.
Pyroclastic Materials
Pyroclastic material ejected into the atmosphere.
Tephra/Bombs
What are the different Pyroclastic rocks? Differentiate according to size.
Block - >64mm
Lapili - 2-64mm
Ash - <2mm
A fractured textured surface texture formed when bombs cool
Breadcrust Texture
Lapilli-sized pyroclastic deposits that are good indicators for environment during deposition as they formed due to saturation from water
Accretionary-Lapilli
A lung disease caused by inhaling fine pyroclastic materials.
pneumonoultramicroscopicsilicovolcanoconiosis
-Naturally occurring solids that lacks an orderly crystalline structure, which formed due to quenching or rapid cooling of lava.
Glass
What are two examples of glassy volcanic products?
-Pele’s tears - black, glassy, streamlined particles that formed as lava droplets that quenched in flight.
-Pele’s hairs - golden, acicular glassy strands that formed as lava droplets were propelled through the air. being partially stretched into shape.
Generally hot flows made up of a mixture of pyroclastic materials and hot gases that can travel at rapid speeds.
Pyroclastic density currents (PDCs)
A blanket of pyroclastic
material and tephra that fall to the ground due to gravity, which is identified to have a good sorting of angular juvenile clasts.
Pyroclastic Fall
A dense, “ground- hugging” flow of pyroclastic materials that moves at speeds up to 150 km/h that can reach over to a 1000 °C and develop poorly sorted beds with rounded clasts that can produce block-and-ash flows.
Pyroclastic Flow
A more dilute and mobile current which have low concentrations of particles mixed with gases that can travel up hills and valleys at high velocity and horizontally from the eruption site, usually associated with phreatic and phreatomagmatic eruptions, and identified to have a “pinch and swelling” beds with moderate sorting of moderately rounded clasts.
Pyroclastic surge
Differentiate Pyroclastic fall, flow, surge.
Pyroclastic Fall- equally distributed, good sorting of angular clasts
Pyroclastic Flow - ground hugging, poorly sorted rounded clasts
Pyroclastic Surge -‘pinch and swelling’ beds, moderately sorting of moderately rounded clasts
- Siliceous, low to moderate density, hot vesiculated flows.
Pumice Flows
Andesitic to basaltic, hot vesiculated flows.
Scoria Flows
Compacted or “welded” pumice and tuff
Ignimbrites
Flattened or compacted pumice in ignimbrites.
Fiamme
French for “fiery
clouds,” are fluidized mixtures of hot, incandescent rock fragments and gases that flow along the surface as a “glowing avalanche” of pyroclastic debris.
Nuées ardentes
Thick mudflows, composed of volcanic materials, that can be up to tens of meters thick with the consistency of wet cement.
Lahar
What are the two types of Lahar?
Syn-eruption Lahar
- Lahar directly associated with active volcanic activity.
Post-eruption Lahar -
Lahar indirectly associated with active volcanic activity and occurs as remobilization of volcanic deposits.
When was the recent eruption of Mt. Pinatubo and what typhoon coincided with it?
-June 15, 1991
-Typhoon Yunya
Mass wasting of large volumes of volcanic materials along volcanic flanks.
Give an Example
Debris Avalanche
-1980 Mt. Saint Helens Eruption
Debris avalanche associated with movement of magma beneath volcanic edifice.
Bezymianny-type
Debris avalanche associated with seismicity.
Bandai-type
What are the two origins of volcaniclasts?
Juvenile clasts/cognate clasts - derived directly from the magma from the volcanic activity.
Accidental clasts - Rock inclusions from the vent walls or brought from the surface by lava or pyroclastic walls.
What are the three fragmentation process?
- Pyroclastic process
- Autoclastic process
- Epiclastic process
Fragmentation through explosive ejection and aerial dispersal of pyroclasts of rock and magma from a volcanic vent.
Pyroclastic process
Fragmentation as a result of breaking up the cooler and rigid exterior of the lava as it continuously moves that can include block-sized autoclasts.
Autoclastic process
Fragmentation brought by the weathering and disintegration of volcanic rocks.
Epiclastic process
What are the different parts of the transport of pyroclasts?
Mass flow transport - A group of clasts with interstitial fluid that interact and move together. (as a whole)
Traction transport - Clasts within the mass flow behaving independently in moving interstitial fluids.
Suspension transport - Fully suspended clasts in interstitial fluid
