EQ1:Volcanoes

Question 1

What are volcanoes and why do they erupt?

Answer 1

-a volcano is a rupture in the earth’s crust which allows magma and gas to escape from beneath the surface
-Magma collects in the chamber and pressure is built, when the pressure exceeds the space in the chamber the magma and gas content increases and magma is forced through the vent

Question 2

What is the VEI, and what is it used for?

Answer 2

-it is the volcanic explosivity index and is used to measure volcanic eruptions
-they are calculated using the amount of material ejected from the volcano

Question 3

What is a shield volcano?

Answer 3

A shield volcano is a broad, gently sloping volcanic structure that is prone to effusive eruptions, where low-viscosity lava flows out steadily and smoothly.

Question 4

What is a composite/stratovolcano?

Answer 4

A large steep volcano made of alternating layers of lava and ash prone to violent, explosive eruptions due to high silica content in the magma

Question 5

What determines the shape of a volcano (4)?

Answer 5

-the volume of volcanic products (volcanoes with a larger volume of volcanic products such as magma tend to be be larger such as composite volcanoes)
-the interval length between eruptions (shorter interval lengths/ frequent eruptions usually indicate that the volcano has more of a symmetrical; continuous shape like shield volcanoes while longer interval lengths mean more explosive)
-the composition of volcanic products(lava that is low in silica like basalt is less viscous and more fluid forming broad gently sloping shield volcanoes while higher silica content = more explosive steeper composite volcanoes )
-the variety of volcanic eruptions types(effusive eruptions=Shield explosive eruptions= composite)

Question 6

what are the different types of lava?

Answer 6

1) Basaltic lava- low viscosity lava often associated with shield volcanoes and effusive eruptions, it is the hottest type at 1000-1200 degrees
2) Andesitic lava- intermediate viscosity often associated with composite volcanoes at subduction zones and violent/moderately explosive eruptions, it is the second hottest type at 800-1000 degrees
3)Rhyolitic lava- High viscosity lava often associated with super volcanos and composite cone volcanoes as well as very violent and cataclysmic eruptions, it is the coolest lava type at 650-800 degrees

Question 7

What determines the type of lava(4)?

Answer 7

-temperature (the higher the temperature the less viscous)
-silica content (the higher the silica content the more explosive)
-gas content (the lower the gas content the less viscous the lava is)
-location (basaltic lava is at hot spots, andesitic lava is at subduction zones and rhetoric lava is found at super volcanoes)

Question 8

What determines the explosivity of lava(3)?

Answer 8

1)temperature (the cooler the more explosive)
2)silica content (the more silica the more explosive)
3)gas content (the higher the more explosive)

Question 9

What is the magma chamber?

Answer 9

A large pool of magma below surface

Question 10

What are layers of ash?

Answer 10

These cool and harden and build up over time to create the volcano

Question 11

What is an ash cloud?

Answer 11

A picture of lava, ash and hot gases ejected from the volcano

Question 12

What is tephra?

Answer 12

Pieces of volcanic rock that blast into the air

Question 13

What is a conduit?

Answer 13

A main pipe which magma wells up to reach the surface

Question 14

What is a vent?

Answer 14

The exact point of eruption

Question 15

What is a carter?

Answer 15

A circular depression at the top of a volcano

Question 16

What is a side vent?

Answer 16

A smaller vent that can erupt volcanic material

Question 17

What are primary hazards (in terms of volcanoes)?

Answer 17

Direct hazards from eruption (ejected from volcano)

Question 18

What are the 4 primary hazards associated with volcanoes?

Answer 18

1)pyroclastic flows
2)lava flows
3)tephra and ash flow
4)gas eruptions

Question 19

What is pyroclastic flow?

Answer 19

A fast moving current of hot gas, tephra and volcanic material ejected during an eruption, capable of travelling at high speeds and causing widespread destructions ( can be far deadlier than the other hazzards due to their high speed, heat and unpredictability)

Question 20

What is lava flow?

Answer 20

-A stream of lava that moves (usually quite slowly) across the surface of land
-usually associated with shield volcanoes
-Due to their slow-moving nature, lava flows tend to be less deadly compared to other volcanic hazards like pyroclastic flows or lahars.

Question 21

What is tephra and ash flow?

Answer 21

Tephra and Ash Fall refer to volcanic materials ejected during an eruption, with tephra encompassing all fragmental volcanic material ejected such as lapilli and atomic bombs and ash fall specifically referring to the ash that settles on the ground.

Question 22

What are gas eruptions?

Answer 22

refers to the release of volcanic gases such as carbon dioxide, water vapour and sulphur dioxide from a volcano, that often occur as a result of magma movement beneath the Earth’s surface.

Question 23

What are the 2 secondary hazards of volcanoes?

Answer 23

1)Lahars
2)Jokulhlapups

Question 24

What are Jokulhlapus?

Answer 24

Flooding from glaciers or ice sheets melting due to geothermal heat

Question 25

What are Lahars (mudflow)?

Answer 25

-Fast moving mixtures of volcanic ash, rock, water and debris triggered by heavy rainfall, rivers or melting snow

Question 26

what are some factors that influence why some volcanoes are more hazardous than other?

Answer 26

-viscosity
-type of plate margin
-explosiveness
-distance to populated area
-frequency
-prediction technology
-type of volcano
-county development/eduaction

Question 27

What is an example of a volcanic erruption that led to pyroclastic flow?

Answer 27

-an eruption in 2018 with Volcano de Fuego, a composite volcano, in Guatemala produced pyroclastic flow that rolled down the flank of the volcano at speeds of 62mph

Question 28

What were the impacts of the volcan de fuego Erruption In Guatemala 2018 (4)?

Answer 28

-it buried villages like El Rodeo under scorching debris resulting in 159 faculties
-approximately 8,500 hectares of agricultural land were damaged, translating to losses of around $219 million
-Despite scientists warning the government eight hours before the main eruption, evacuation orders were only given when some communities were already covered in ash and debris. This indicates that the hazard can be exacerbated by governmental inefficiencies and corruption
-following the eruption heavy rainfall mixed with the ash and volcanic debris deposited from the pyroclastic flow creating lahars (a secondary hazard) that further damaged infrastructure

Question 29

What are examples of volcanic eruptions that led to lava flows?

Answer 29

-Kīlauea Volcano, Hawai’i, June 2014 – early 2015 caused by an effusive eruption from a volcanic hotspot, VEI 0
-The 2021 Nyriagongo eruption in the democratic republic of congo, VEI 2

Question 30

What were the impacts of lava flow in the Kīlauea Volcano, Hawai’i (3)?

Answer 30

-lava advanced toward the town of Pāhoa at around 200 meters per day, threatening homes and infrastructure, including Highway 130, a key roadway
-However, the flow’s gradual pace gave residents ample time to evacuate and allowed authorities to implement preventive measures, such as rerouting traffic and reinforcing defenses, resulting in zero deaths
-overall damage was limited, demonstrating how well-developed early warning systems and infrastructure in high-income countries

Question 31

What were the impacts of lava flow in the Democratic Republic of Congo Nyriagongo 2021(3)?

Answer 31

-lava flows reached speeds of up to 60 kilometers per hour due to low viscosity, leading to approximately 32 fatalities.
-The Goma Volcano Observatory, responsible for monitoring the volcano, faced resource limitations due to inadequate funding, resulting in ineffective warning systems
-Consequently, residents received minimal time to evacuate. Thus, while the hazard itself may be predictable, the response capacity and development levels significantly impact the overall damage caused.