Week 8: Volcanic Hazards

Question 1

It is an opening in the earth’s
crust where lava, pyroclastics and
gases are ejected onto the surface during eruptions.

Answer 1

Volcano

Question 2

This part of the volcano is a steeped-wall depression at the peak of the volcano and the volcanic vent.

Answer 2

Crater

Question 3

This part of the volcano a very large crater that can exceed for about 1 km in diameter; they are formed when the summit of the volcano collapses during violent or explosive eruptions.

Answer 3

Caldera

Question 4

This part of the volcano is the most prominent part of a volcano.

Answer 4

Cone

Question 5

This part of the volcano formed by the mountainous accumulation of volcanic materials

Answer 5

Cone

Question 6

This kind of volcano has a recent history of eruptions (within the last 10,000 years); they are also likely to erupt again.

Answer 6

Active volcano

Question 7

Identify the different parts of a volcano.

Answer 7

1. Ash cloud
2. Main/Primary vent
3. Magma chamber
4. Crater
5. Lava flow
6. Conduit
7. Cone
8. Dome
9. Secondary vent

Question 8

This kind of volcano have not erupted in a long time but are expected to erupt again in the future (has not erupted in the past 10,000 years).

Answer 8

Dormant/Inactive Volcano

Question 9

This kind of volcano are not expected or are unlikely to erupt again (30,000-40,000 years of no eruption).

Answer 9

Extinct volcano

Question 10

Occurs when lava is ejected to the surface through an opening in the earth’s crust.

Answer 10

Volcanic eruption

Question 11

This type of eruption is non-explosive or quiet. It is dominated by flow of lava and formation of fountains and lakes.

Answer 11

Effusive eruption

Question 12

This type of eruption is also called violent or Plinian eruption. It ejects ash and larger fragments of broken up pyroclastic materials, forming ash clouds that eventually collapse and cover the slope of the volcano.

Answer 12

Explosive eruption

Question 13

Identify if it is effusive or explosive eruption: Less Silica/Higher Temperature/More Gas/Less Viscous

Answer 13

Effusive eruption

Question 14

Identify if it is effusive or explosive eruption: More Silica/Lower Temperature/Less Gas/More Viscous

Answer 14

Explosive eruption

Question 15

This type of eruption is magma-driven.

Answer 15

Magmatic eruption

Question 16

This type of eruption is steam-driven; it is due to the heating of surface or groundwater near a magma chamber.

Answer 16

Phreatic eruption

Question 17

This type of eruption involves the interaction of magma and water.

Answer 17

Phreatomagmatic eruption

Question 18

This phreatomagmatic eruption involves volcanic eruptions of volcanoes on shallow waters.

Answer 18

Surtseyan eruption

Question 19

This phreatomagmatic eruption involves volcanic eruptions of volcanoes under the water.

Answer 19

Submarine eruption

Question 20

This phreatomagmatic eruption involves volcanic eruptions of ice-covered volcanoes.

Answer 20

Subglacial eruption

Question 21

This magmatic eruption type is effusive, with streams of molten basaltic lava that flow from long, parallel fissures. These often build lava plateaus.

Answer 21

Icelandic eruption

Question 22

This magmatic eruption type is also effusive. However, fluid lava flows from a volcano’s summit and radial fissures to form shield volcanoes, which are quite large and have gentle slopes.

Answer 22

Hawaiian eruption

Question 23

This magmatic eruption type involve moderate bursts of expanding gases that eject clots of incandescent lava in cyclical or nearly continuous small eruptions.

Answer 23

Strombolian eruption

Question 24

This magmatic eruption type is characterized by moderate explosions of gas laden with volcanic ash–which together form dark, turbulent, rapidly ascending eruption clouds.

Answer 24

Vulcanian eruption

Question 25

This magmatic eruption type is noted for its explosive outburstst that produce pyroclastic flows, dense mixtures of hot volcanic fragments and gas that roll down slopes at high speeds.

Answer 25

Pelean

Question 26

This magmatic eruption type is an intensely violent in which the uprushing gases and volcanic fragments resemble a gigantic rocket blast directed vertically upward.

Answer 26

Plinian eruption

Question 27

This volcanic shape has a narrow base and a steep slope. It is made up of loose fragments called cinders (pyroclasts and tephra).

Answer 27

Cinder cone volcano

Question 28

This volcano shape is formed from explosive eruption

Answer 28

Cinder cone volcano

Question 29

This volcanic shape has a wide base with gently sloping sides. It is made up purely of solidified lava.

Answer 29

Shield cone volcano

Question 30

This volcanic shape is formed from effusive eruption.

Answer 30

Shield cone volcano

Question 31

This volcanic shape is composed of alternating layers of lava and cinders.

Answer 31

Composite volcano

Question 32

This volcanic shape is formed when volcanic eruptions vary between quiet and violent and explosive.

Answer 32

Composite Volcano

Question 33

This volcanic hazard refers to hot dry masses of fragmented volcanic materials that move along the slope and in contact with ground surface. This includes: pumice flow, ash flow, block-and-ash flow, nuee ardente and glowing avalanche.

Answer 33

Pyroclastic flow

Question 34

This volcanic hazard is a glowing eruption cloud characterized by extreme heat (about 500 °C or higher).

Answer 34

Nuee ardente

Question 35

This volcanic hazard is a highly elongated mass of molten rock materials cascading downslope from an erupting vent. The lava flow being extruded has low silica and low water contents.

Answer 35

Lava flow

Question 36

This volcanic hazard involves rocks that an erupting volcano sends into the air. The rocks can vary in size and density– some can be as small as ash, others are as big as boulders. Examples are lapilli, cinders, blocks and bombs.

Answer 36

Ballistic projectile

Question 37

This volcanic hazard is dangerous due to their temperature and toxicity. This contains water vapor, carbon monoxide, carbon dioxide, hydrogen sulfide, hydrogen chloride, hydrogen fluoride and helium.

Answer 37

Volcanic gases

Question 38

When this gases mix with water, they form an acidic solution.

Answer 38

Volcanic gases

Question 39

It is made of small jagged pieces of rocks, minerals, volcanic glass less than 2 mm in diameter (about the size of sand)

Answer 39

Ash fall

Question 40

This volcanic hazard involves fine, silica-rich particles that are extremely abrasive, mildly corrosive, conducts electricity when wet and does not dissolve in water.

Answer 40

Volcanic ashfall

Question 41

This volcanic hazard is sometimes called mudflows or volcanic debris flows; are flowing mixtures of volcanic debris and water.

Answer 41

Lahar

Question 42

Lahar that is associated directly with volcanic eruption.

Answer 42

Primary or hot lahar

Question 43

Lahar that is caused by heavy rainfall.

Answer 43

Secondary or cold lahar

Question 44

TRUE OR FLASE: Lahar in tropical areas can be produced by: * sudden draining of a crater lake, caused by either an explosive eruption or collapse of a crater fall (e.g. Agua, Kelut, Ruapehu) * movement of a pyroclastic flow into a river or lake, displacing and mixing with water * avalanche of water-sustained rock debris, where water can be from heavy rain, hydrothermal activity or other sources

Answer 44

TRUE

Question 45

TRUE OR FLASE: Lahar in tropical areas can be produced by: * torrential rainfall on unconsolidated deposits on slope of a volcano (e.g. Pinatubo) * collapse of a temporary dam, where recent volcanic deposits have blocked a steam channel (e.g. Asama, Pinatubo

Answer 45

TRUE

Question 46

Earthquake is caused by the movement of magma beneath the surface of the Earth.

Answer 46

Volcanic earthquake