| What is the temperature of Pahoehoe lava? | >1250 degrees |
| What are volcanoes? | Openings or wents where lava, ashes and steam erupt onto the earth's surface. |
| Name 7 hazards of a volcanic eruption. | Lava flow
Hot debris
Avalanches
Lahars
Gas release
Tsunamis
Small earthquakes |
| On what scale are volcanic eruptions ranked on? What is the range of this scale? | VEI scale, from 1 to 8 |
| Name the 2 strongest volcanic eruptions ever recorded in history. | Mount Tambora 1815
Krakatau volcano 1883 |
| What is a volcanic Hotspot? | Hotspots are volcanic zones within a tectonic plate fromed by mantle diapirs that merge from the core-mantle intersurface where lava flows like a river. |
| What is the mechanism behind a Hotspot? | -A pressure increase in the core-mantle interface creates a mantle diapir (bubble of magma).
-The diapir propogates through the mantle up to the crust
-The diapir ermerges on the surface -> Hotspot. |
| What is the phenomenon that occurs at a hotspot? | Tectonic plates can move over the hotspot and form long chains of previously extinct volcanoes -> reconstructs the plate movement and velocity. |
| Where are the majority of volcanoes located? | 75% in the Pacific Ring |
| Name 6 active volcanoes in Vietnam. | Bas Dong Nai (Xuan Loc Plateau)
Cu-Lao Re Group
Haut Dong Nai (Djiring Plateau)
Ile des Centres [submarine volcano]
Toroeng Prong [balsatic cone volcano]
Veteran [submarine volcano] |
| How is a volcano formed? | At a subduction zone, water enters the mantle -> lithostatic change in pressure/the addition of water -> Mantle rock melts -> semi-liquid and gaseous that rise through the crust. |
| What type of rock is cooled magma? | Igneous rock |
| What are the components of a volcano? | Volcanic cone
Lava
Crater
Secondary crater
Vent
Secondary vent
Lagergang
Magma chamber |
| What is a volcanic cone? | The "mountain" part of a volcano, formed of cooled solidified lava. |
| What is a crater and secondary crater of a volcano? | The opening on the top and in the side of the volcano where lava and ash is ejected. |
| What are is a vent and secondary vents in a volcano? | The channels that connect the magma chamber to the surface. |
| What is the lagergang of a volcano? | A small lava reservoir inside a volcano. |
| What is a magma chamber? | A chamber filled with magma inside the earth's crust. |
| What are volcanic materials? | Pyroclastic materials
Volcanic gases
Lava |
| What are pyroclastic materials? Name them. | Ejected fragments of volcanic rock and ash during an eruption.
+Ash (2 mm diamter)
+Lapilli (2 - 64 mm diameter)
+Bombs (>64 mm diameter) |
| What are volcanic gases? | They are disolved gases in magma that forces the magma to rise to the surface. |
| What is lava? | Lava is molten rock that flows to the surface after a volcanic eruption. |
| What are the positive and negative affects of pyroclastic materials? | -Positive: Soil improvement (+new minerals)
-Negative: Ecosystem destruction, forest fires, contamination of groundwater, health problems, etc. |
| What is an ash column? | A vertical column of gases and pyroclasts ejected into the atmosphere. |
| What happens when an ash column reaches high altitude? | Convection currents form at the top due to temperature differences -> creates an umbrella. The umbrella is displaced by wind and dispersed thousands of km. |
| What is a volcanic plume? | The general term to describe the cloud of pyroclastic materials ejected into the atmosphere during an eruption, can extend horizontally or vertically. |
| Name the gases that a volcanic eruption can create. | H2O
CO2
SO2
H2S |
| What is the most important element in lava and pyroclastic material? | SILICA |
| What element determines how lava flows? Explain how this element affects lava flow. | SILICA.
High silica -> dense flow (viscous)
Low silica -> more fluid |
| True or False: Hotpot chains have lower silicic acid content. | True |
| True or False: Subduction zones have lo silicic acid content. | False |
| Name 4 kinds of volcanic stones. | Basalt
Andesite
Dacite
Rhyolite |
| True or False: Magma with high silicic acid is more vicous. | True |
| True or False: Magma with high silicic acid is less dense. | False |
| True or False: Magma with high silicic acid is less hot. | True |
| True or False: Magma with high silicic acid is more gaseous. | True |
| True or False: Magma with high silicic acid is less explosive. | False |
| What is pahoehoe lava flow (pillow lava)? How long is the stream of this lava? | Very fluid lava, made of basalt, lowest SiO2 content. 20km long. |
| What is AA lava flow? How long is the stream of this lava? | Fluid lava, made of andesite, 60% SiO2. 10 km long. |
| What are the 2 types of block lava flow? How long are the streams of each kind of flow? | Type 1: Viscous flow, made of dacite, 66% SiO2. 6 km long.
Type 2: Viscous flow, made of rhyolite, 75% SiO2. 3 km long. |
| What is the temperature of Pahoehoe lava? | >1250 degrees C. |
| What is the temperature of AA lava? | 700 - 1000 degrees C. |
| What temperature is block lava? | <850 degrees C. |
| Name the types of volcanoes. | Fissure volcano
Shield volcano
Lava dome volcano
Fragmental volcano
Caldera
Stratovolcano
Cinder cone/Ash cone volcano. |
| What are the characteristics of a cinder cone/ash cone volcano? | -The cone is made of pyroclastic material, smallest and simplest type of volcano
-High silica content lava (dacite and andesite), explsove eruption
-Frequently on converging plate boundaries |
| What are the characteristics of a Stratovolcano? | -High cone made of pyroclasts and lava, most common type
-Medium silica content
-Frequently occur in subduction zone of a volcanic arc |
| What are the characteristics of a Fissure volcano? | -Lava comes out of a fissure
-VERY FLUID lava, not that explosive with little to no ash
-Frequently occur on divergent plate boundaries and hotspots. |
| What are the characteristics of a Shield volcano? | -Large, flat flanks like a shield
-Very fluid basaltic lava that comes out in a thin layer but spreads widely
-Frequently occur on divergent plate boundaries |
| What are the characteristics of a Lava dome volcano? | -Circular dome made of lava
-Viscous lava, very violent explosion
-Common in the Andes, CAribbean and Java, The Moon, Mars and Venus |
| What are the characteristics of a Caldera? | -Large crater (hole in the ground, sometimes with water)
-Liquid basalt and andesite lava, fast flow, no explosion
-Frequently occur on converging and diverginf plate boundaries |
| What are the characteristics of a Fragmental volcano? | -Similar to caldera - but with ejector ring (Hole in the ground, the sides of the hole are raised, often with water)
-Varying silica content, very explosive eruption due to interaction with water
-Frequently occur on diverging plate boundaries and hotspots |
| What are the phases of a volcanic eruption? | 1) Earthquake swarms and gas emissions
2) Ejection of ash and steam through newly opened vents
3) Formation of lava dome and eruption |
| What are the types of volcanic eruptions? | 1) Explosive
2) Effusive |
| What are the characteristics and types of an effusive eruption? | -High basalt lava, fluid and not gaseous
-No pyroclastic material
-2 types: Icelandic eruption (Long and narrow hole in the ground) and Hawaiian eruption (Tiny cone with hole in the ground). |
| What are the characteristics and types of explosive eruptions? | -Medium to low silica content, vicous, lots of gas and pyroclastic materials.
-5 types: Strombolian, Vulcanian, Pelean, Plinian, Phreatomagmatic [Free-ah-toe-mag-mah-tic] |
| What are the characteristics of Strombolian eruptions? | -Ejection of gases and hot-red lava fragments, occurs in a cycle (Oval shaped eruption column) |
| What are the characteristics of Vulcanian eruptions? | -Explosions of gas and ash, spiral clouds (Upsidedown triangle shape eruption column) |
| What are the characteristics of Pelean eruptions? | -Highly explosive, streams of hot pyroclasts and gas (eruption column follows the shape of the cone) |
| What are the characteristics of Plinian eruptions? | -Extremely iolent eruption with gas and pyroclasts with a lot of pressure (GIANT ERUPTION COLUMN, upsidedown triangle shape) |
| What are the characteristics of Phreatomagmatic eruptions? | -Extremely explosive eruption (because of contact with water) with fragments and ash, forms a maar (a new rim made of ash and fragments). (LOTS OF STEAM) |
| On the VEI scale, what range (from 0 to 8) do effusive eruptions fall under. | 0 to 1 |
| (2 - 3)
(2 - 4)
(4 - 8)
(6 - 8)
(0 - 1)
Out of these VEI index ranges,which belongs to Vulcanian and Pelean eruptions? | 2 - 4 |
| (2 - 3)
(2 - 4)
(4 - 8)
(6 - 8)
(0 - 1)
Out of these VEI index ranges,which belongs to Phretomagmatic eruptions? | 6 - 8 |
| (2 - 3)
(2 - 4)
(4 - 8)
(6 - 8)
(0 - 1)
Out of these VEI index ranges,which belongs to Plinian eruptions? | 4 - 8 |
| (2 - 3)
(2 - 4)
(4 - 8)
(6 - 8)
(0 - 1)
Out of these VEI index ranges,which belongs to Strombolian eruptions? | 2 - 3 |
| What is Lahare? | Pyroclastic material transported away by melting snow or rain, dries to cement-like solid. |
| What aftermath of a volcanic eruption is used to classify risk areas? | Lava flow paths
Lahare flow paths
Ballistic blocks (Large fragments that are blown away)
Ash distribution maps |
| What are the types of models used to predict volcanic eruptions? What are they used for? | -Spatial model: Model the consequences and affected area
-Probabilistic model: The same as above, with time variable
-These models are used to estimate the probability of a location being affected by a volcanic eruption. |
| What are the most recently active volcanoes in Vietnam? | Iles des Cendres
Cu-Lao Re
Chu Dang Ya |
| Which is correct as the reason Vietnam has volcanic activity?
1) Vietnam is located at a plate boundary
2) Vietnam is located on a hotspot | 2) is correct |
