GeoHaz quiz 3 Flashcards
1
Q
- It is the process where the early-formed minerals are denser (heavier) than the liquid (melt) and sink toward the magma chamber.
A
Crystal settling
2
Q
- What are the three types of magma?
A
- Basaltic
- Andesitic
- Rhyolitic
3
Q
- What is the percentage of Silica (SiO2) in andesite and Dacite rocks?
A
52% to 68%
4
Q
- What has the least mobility between Basalatic, Andesitic, and Rhyolitic magma?
A
Rhyolitic
5
Q
- What are the two main factors that affects the viscosity of a magma?
A
- Temperature
- SiO2 content
6
Q
- It is the process through which a single homogeneous magma is able to produce two or more fractions (daughter magmas) of different composition, which ultimately forms diverse rock types.
A
Magma Differentiation
7
Q
- This process occurs during the ascent of two chemically distinct magma bodies as the more buoyant mass overtakes the more slowly rising body.
A
Magma Mixing
8
Q
- This event occurs when the surrounding rocks breaks and is incorporated in the magma up-welling.
A
Assimilation
9
Q
- It is the process that generates a magma that is nearer the felsic (granitic) end of the compositional spectrum than the parent rock from which it was derived.
A
Partial Melting
10
Q
- Minerals with the _______ ________ ______ are the first to melt.
A
lowest melting temperatures
11
Q
- Most magma that erupts on the Earth’s surface is basaltic in
composition and has a temperature of?
A
1000 C to 1250 C
12
Q
- Basaltic (mafic) magmas that originate from partial melting of
mantle rocks are called ____________ magmas because they
have not yet evolved.
A
primary or primitive
13
Q
- As basaltic magma solidifies, the silica-poor ferromagnesian minerals crystallize first. If these iron-rich components are separated from the liquid by crystal settling, the remaining melt will have an ______________.
A
Andesitic Composition
13
Q
- True or False:
Two magma bodies with the same composition and temperature undergoes magma mixing, the resulting magma is now considered as an evolved magma.
A
False, A change in composition is needed to be considered as an evolved magma.
13
Q
- This phenomenon occurs when hot rock of the mantle rises upward and spontaneously melts, turning into magma.
A
Decompression Melting
14
Q
- What is the term used for evolved(changed) magma?
A
Secondary Magma
14
Q
- This type of magmas are mostly generated by the partial melting of continental crust.
A
Granitic
15
Q
- True or False: Higher content of dissolved gases within a magma will result to a more explosive volcanic eruption.
A
True
16
Q
- It occurs whenever magma reaches the surface and begins to move across the landscape.
A
Lava Flow
17
Q
- These are steep-sided mounds that were formed from
viscous lava (rhyolitic lava). It can also act like a plug when
it begins to solidify and thus allow pressure to build in the
magma chamber and result in a more explosive eruption.
A
Lava Domes
18
Q
21.This volcanic landform is formed when large volumes of basaltic
lava will flow onto the surface along large fracture zones.
A
Continental flood basalt
19
Q
- What are the three types of volcanic cones.
A
- Cinder
- Composite
- Shield
20
Q
- A volcanic vent can coincide with a fault or fracture, resulting in a linear extrusion known as a?
A
Fissure Eruption
21
Q
- What type of volcanic cone does Mt. Taal belongs to?
A
Cinder Cone
22
Q
- Composite cone volcanoes are also known as ________. What is the most popular composite volcano in the Philippines?
A
a. Stratovolcano;
b. Mt. Mayon
23
Q
- True or False: Shield volcanoes have quiescent eruptions because basaltic magma contains large amounts of dissolved gases and has a low viscosity.
A
False,
Basaltic magma contains small amounts of dissolved gases
24
Q
- This is a circular depression where lava and pyroclastic
material is being ejected.
A
Crater
25
Q
- This is a a circular depression that forms after an eruption
when large volumes of magma are ejected from a shallow
magma chamber, leaving it relatively empty and thus causing it
to subside/collapse.
A
Caldera
26
Q
- This is a zone of molten material where magma accumulates and occurs at a considerable depth.
A
Magma Chamber
27
Q
- Eruptions create pulverized rock that is ejected along with the lava which is collectively known as?
A
Pyroclastic Material
28
Q
- True or False: Tephra are solidified lava and pulverized rock.
A
True
29
Q
- How does pyroclastic deposits and rocks classified?
A
by:
1. Grain Size
2. Grain Size Mixture
3. Components
30
Q
- What is the Volcanic Explosivity Index or VEI?
A
It is a relative measure of the explosiveness of
volcanic eruptions.
31
Q
- The way in which humans respond to potential volcanic threats depends on several factors, in particular the ________ at which eruptions occur and the _______________ .
A
frequency;
availability of habitable living space
32
Q
- What volcano erupted that resulted to global cooling of 3 degrees Celsius?
A
Mt. Tambora in Indonesia
33
Q
- Another name for volcanic mudflow.
A
Lahar
34
Q
- It occurs whenever steep flanks of a volcano become unstable and results rapid downslope movement of rocks, debris, and/or snow/ice. It is often triggered by heavy rains or earthquakes.
A
Volcanic landslide
35
Q
- In volcanic mudflow, ash and rock may comprise ___ to ___%
by weightand may resemble a river of wet concrete.
A
60% to 90%
36
Q
- Volcanic gas is mainly composed of three gases: _______; _________; and _________. Together they account for 95% of all volcanic gases.
A
- Water Vapor(H2O)
- Carbon Dioxide (CO2)
- Sulfur Dioxide (SO2)
37
Q
- Volcanic gas cloud is hazardous to humans, this is simply because it contains no ___________ .
A
free oxygen (O2)
38
Q
- True or False: Volcanic gases are typically cool and not a hazard.
A
False,
Volcanic gases are typically quite hot, severely burned skin and lung tissue is another life-threatening hazard.
39
Q
- True or False: Release of toxic volcanic gases may happen even with the absence of any volcanic activity.
A
True
40
Q
- It is also formed when volcanoes explode violently in an oceanic setting and may subsequently strike coastal communities far from the volcano itself
A
Tsunami
41
Q
- What primary volcanic hazard caused the most death in Krakatau, Indonesia? When did it occured and what was the average mortality of that event?
A
- Tsunami;
- 1883;
- 36, 000
42
Q
- It is an excellent tool for predicting eruption as earthquake activity invariably increases as magma moves toward the surface.
A
Seismic Monitoring
43
Q
- This is a predictive tool that makes use of of the size, shape, composition, and layering characteristics of the particles of a volcanic deposit to infer the history of a particular volcano and subsequently device mitigating measures should there be a nearby exposed population to volcanic hazards.
A
Geologic History
44
Q
- What is the biggest con of Monitoring of Volcanic Gases?
A
Volcanic gases do not always originate from fresh magma moving up from depth. Other sources include heated groundwater and older magma leftover from a previous eruption.
45
Q
- Based on PHIVOLCS, what are the alert levels?
A
Alert Levels:
0 - No Alert
1 - Abnormal
2 - Increasing Unrest
3 - Increased Tendency Towards Hazardous Eruption
4 - Hazardous Imminent Eruption
5 - Hazardous Eruption
46
Q
A
