1. What is the most viscous and most explosive lava? 2. What is the least viscou
ID: 232185 • Letter: 1
Question
1. What is the most viscous and most explosive lava? 2. What is the least viscous and least explosive lava? 3. What geologic features result from rifting volcanism? 4. What type of volcano is the most explosive? 5. What type of volcano is symmetrical in shape? Cinder cone volcano 6. What is the most common type of volcano? Cinder cone volcano 7. What type of volcano results from Hot Spot volcanism? Caldera volcano 8. What type of volcano forms from subduction volcanism? 9. What type of volcano is Olympus Mons? 10. What are the dark areas on the Moon? 11. What are the benefits and dangers of volcanoes? 12. What is the difference between a crater and caldera? 13. How did the island of Surtsey form? 14. What is a lahar? 15. What is a cinder? 16. What is a nuée ardente? 17. What is the difference between aa lava and pahoehoe lava? 18. What is the largest volcano on Earth? 19. What type of volcanism produced the volcano pictured below?
Explanation / Answer
1. An example of high viscos and most explosive lava is felsic lava, like rhyolite or dacite. It erupts at lower temperatures, and can flow for tens of kilometers.
2.An example of a low viscosity or fast flowing lava is basaltic lava. It flows quickly out of a volcano at a temperature of about 950 degrees Celsius. It travels great distances creating shield volcanoes or flood basalt fields.
3.Mountains are formed due to rifting volcanism.
4.Composite or strato volcanoes are more explosive
5.Cinder cone volcanoes are symmetrical in shape.
6.Cinder cone volcanoes are most common type of volcanoes.
7.Caldera volcanoes results from Hot Spot volcanism.
8. Strato volcanoes form from subduction volcanism
9.Olympus Mons is a shield volcano.
10. The dark areas on the surface of the moon are actually craters filled with basalt, which is a very dense material.
11.
Volcano Benefits
The major resource from volcanoes is the land formed from the materials they explode. Volcanic activity has created many of the most scenic and productive regions on earth.
The geothermal energy of volcanic systems gives a nearly pollution-free source of thermal and electric energy. The steam from the Geysers located in Northern California, which is the world’s largest geothermal field, is enough for the electrical needs of the city of San Francisco.
The rocks associated with volcanoes- Volcanic rocks and magmatic rocks contain precious ore deposits, such as copper, lead, zinc, gold, and silver.
Crushed lava rocks, pumice, cinders, and other eruptive products are a source of raw materials for the road-building, constructing, manufacturing and landscaping industries.
Volcano Hazards
Volcanic eruptions cause a direct and indirect hazard to people, and property.
Pyroclastic flows, lava flows, falling ash, and debris flows are examples of direct flows. Pyroclastic flows are mixtures of hot ash, rock fragments, and gas. They are deadly because of their high temperatures of 850oC or higher and can reach speeds of 250 km/h or greater.
Lava flows can create massive property damage. Volcanic ash comes in contact with rain, it can collapse roofs and damage crops.
Debris flows travel quickly through valleys, destroying everything in their paths.
During the 20th century pyroclastic and debris flows caused the most eruption related deaths. Indirect hazards usually accompany or follow eruptions. Earthquakes, tsunamis, rainfall caused debris flow, and after eruption disease are main examples of indirect hazards.
12.
These are two different kinds of depressions.
A caldera is created when a large eruption of magma or lava, makes a gigantic empty hollow underground. The volcanic material above the hollow usually made of volcanic rock and tuff, fall down into the empty magma chamber.
On the other hand a crater is a vent for volcanic activity. Large volcanoes form when magma and other material are expelled from a vent, which creates a cone around the vent, and as more material expells over time, a mountain is ultimately formed.
13.
Surtsey is a volcanic island off the southern coast of Iceland, southwest of the Vestmanna Islands. It emerged from the Atlantic Ocean in a fiery eruption in November 1963 in a volcanic eruption which dragged it up out of the waters 18 km south-west of Heimaey; 32 km off the south coast of Iceland.
14.
Lahars are hot or cold mixture of water and rock fragments which flows down the slopes of a volcano and typically enters a river valley. These are similar to pyroclastic flows but hold more water. Lahars form 1) from debris avalanches which consists water from snow and ice and when released it mixes with loose debris to form a lahar, 2) from pyroclastic flows and surges, it release water and it mixes with debris, 3) from pyroclastic flows which mixes with river water as they travel downslope, 4) from natural dam failure and 5) from rainfall on slack material such as ash. Lahars which consists of 20 to 60 percent sediment are usually very turbulent.
15.
Cinders are pyroclastic materials which are extrusive igneous rocks. Cinders are similar to pumice, it has so many cavities and is such low-density that it can float on water. Cinder is usually brown, black, or red depending on its chemical content. A more modern name for cinder is Scoria.
16. These are highly destructive, fast-flowing, incandescent mass of gas covered particles associated with some types of volcanic eruptions.
17.
The pahoehoe flows are very smooth or ropy surface. These flows are relatively thin, from a few inches to a few feet thick. But the surface of the aa flow comprise of large and angular pieces of materials. Aa is characterized by a rough, jagged and generally clinkery surface. Aa lava flows tend to be relatively thick compared to pahoehoe flows. This difference in form reflects flow dynamics. Aa lava forms when lava flows rapidly.
18. Tamu Massif on the Shatsky Rise in the northwest Pacific Ocean has the greatestmass and the largest volcano on earth.
19. Picture is missing in the question
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