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
25. Composite cone volcanoes are also known as ________. What is the most popular composite volcano in the Philippines?
a. Stratovolcano;
b. Mt. Mayon
23
26. True or False: Shield volcanoes have quiescent eruptions because basaltic magma contains large amounts of dissolved gases and has a low viscosity.
False,
Basaltic magma contains small amounts of dissolved gases
24
27. This is a circular depression where lava and pyroclastic
material is being ejected.
Crater
25
28. 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.
Caldera
26
29. This is a zone of molten material where magma accumulates and occurs at a considerable depth.
Magma Chamber
27
30. Eruptions create pulverized rock that is ejected along with the lava which is collectively known as?
Pyroclastic Material
28
31. True or False: Tephra are solidified lava and pulverized rock.
True
29
32. How does pyroclastic deposits and rocks classified?
by:
1. Grain Size
2. Grain Size Mixture
3. Components
30
33. What is the Volcanic Explosivity Index or VEI?
It is a relative measure of the explosiveness of
volcanic eruptions.
31
34. The way in which humans respond to potential volcanic threats depends on several factors, in particular the ________ at which eruptions occur and the _______________ .
frequency;
availability of habitable living space
32
35. What volcano erupted that resulted to global cooling of 3 degrees Celsius?
Mt. Tambora in Indonesia
33
36. Another name for volcanic mudflow.
Lahar
34
37. 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.
Volcanic landslide
35
38. In volcanic mudflow, ash and rock may comprise ___ to ___%
by weightand may resemble a river of wet concrete.
60% to 90%
36
39. Volcanic gas is mainly composed of three gases: _______; _________; and _________. Together they account for 95% of all volcanic gases.
1. Water Vapor(H2O)
2. Carbon Dioxide (CO2)
3. Sulfur Dioxide (SO2)
37
40. Volcanic gas cloud is hazardous to humans, this is simply because it contains no ___________ .
free oxygen (O2)
38
41. True or False: Volcanic gases are typically cool and not a hazard.
False,
Volcanic gases are typically quite hot, severely burned skin and lung tissue is another life-threatening hazard.
39
42. True or False: Release of toxic volcanic gases may happen even with the absence of any volcanic activity.
True
40
43. It is also formed when volcanoes explode violently in an oceanic setting and may subsequently strike coastal communities far from the volcano itself
Tsunami
41
44. What primary volcanic hazard caused the most death in Krakatau, Indonesia? When did it occured and what was the average mortality of that event?
1. Tsunami;
2. 1883;
3. 36, 000
42
45. It is an excellent tool for predicting eruption as earthquake activity invariably increases as magma moves toward the surface.
Seismic Monitoring
43
46. 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.
Geologic History
44
47. What is the biggest con of Monitoring of Volcanic Gases?
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
48. Based on PHIVOLCS, what are the alert levels?
Alert Levels:
0 - No Alert
1 - Abnormal
2 - Increasing Unrest
3 - Increased Tendency Towards Hazardous Eruption
4 - Hazardous Imminent Eruption
5 - Hazardous Eruption
46
