Volcanic Products

Question 1

What are the four types of volcanic products?

Answer 1

1. Lava flow
2. Pyroclastic materials
3. Glass
4. Pyroclastic density currents (PDCs)

Question 2

-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?

Answer 2

Lava flow
1. ‘A’a flow
2. Pahoehoe flow
3. Block Lava
4. Pillow Lava

Question 3

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.

Answer 3

‘A’a flow

Question 4

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.

Answer 4

Pahoehoe flow

Question 5

Short, detached, vesicle-free, proximal lava that are often produced by viscous lava, such as andesitic and rhyolitic lava.

Answer 5

Block Lava

Question 6

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.

Answer 6

Pillow Lava

Question 7

Volcanic material of varying sizes produced from volcanic eruptions.

Answer 7

Pyroclastic Materials

Question 8

Pyroclastic material ejected into the atmosphere.

Answer 8

Tephra/Bombs

Question 9

What are the different Pyroclastic rocks? Differentiate according to size.

Answer 9

Block - >64mm
Lapili - 2-64mm
Ash - <2mm

Question 10

A fractured textured surface texture formed when bombs cool

Answer 10

Breadcrust Texture

Question 11

Lapilli-sized pyroclastic deposits that are good indicators for environment during deposition as they formed due to saturation from water

Answer 11

Accretionary-Lapilli

Question 12

A lung disease caused by inhaling fine pyroclastic materials.

Answer 12

pneumonoultramicroscopicsilicovolcanoconiosis

Question 13

-Naturally occurring solids that lacks an orderly crystalline structure, which formed due to quenching or rapid cooling of lava.

Answer 13

Glass

Question 14

What are two examples of glassy volcanic products?

Answer 14

-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.

Question 15

Generally hot flows made up of a mixture of pyroclastic materials and hot gases that can travel at rapid speeds.

Answer 15

Pyroclastic density currents (PDCs)

Question 16

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.

Answer 16

Pyroclastic Fall

Question 17

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.

Answer 17

Pyroclastic Flow

Question 18

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.

Answer 18

Pyroclastic surge

Question 19

Differentiate Pyroclastic fall, flow, surge.

Answer 19

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

Question 20

• Siliceous, low to moderate density, hot vesiculated flows.

Answer 20

Pumice Flows

Question 21

Andesitic to basaltic, hot vesiculated flows.

Answer 21

Scoria Flows

Question 22

Compacted or “welded” pumice and tuff

Answer 22

Ignimbrites

Question 23

Flattened or compacted pumice in ignimbrites.

Answer 23

Fiamme

Question 24

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.

Answer 24

Nuées ardentes

Question 25

Thick mudflows, composed of volcanic materials, that can be up to tens of meters thick with the consistency of wet cement.

Answer 25

Lahar

Question 26

What are the two types of Lahar?

Answer 26

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.

Question 27

When was the recent eruption of Mt. Pinatubo and what typhoon coincided with it?

Answer 27

-June 15, 1991
-Typhoon Yunya

Question 28

Mass wasting of large volumes of volcanic materials along volcanic flanks.
Give an Example

Answer 28

Debris Avalanche
-1980 Mt. Saint Helens Eruption

Question 29

Debris avalanche associated with movement of magma beneath volcanic edifice.

Answer 29

Bezymianny-type

Question 30

Debris avalanche associated with seismicity.

Answer 30

Bandai-type

Question 31

What are the two origins of volcaniclasts?

Answer 31

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.

Question 32

What are the three fragmentation process?

Answer 32

1. Pyroclastic process
2. Autoclastic process
3. Epiclastic process

Question 33

Fragmentation through explosive ejection and aerial dispersal of pyroclasts of rock and magma from a volcanic vent.

Answer 33

Pyroclastic process

Question 34

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.

Answer 34

Autoclastic process

Question 35

Fragmentation brought by the weathering and disintegration of volcanic rocks.

Answer 35

Epiclastic process

Question 36

What are the different parts of the transport of pyroclasts?

Answer 36

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