But most importantly, highly viscous lava is associated with explosive eruptions and dangerous pyroclastic flows. An example of a low viscosity (fast flowing) lava is basaltic lava.It can also clog up the volcanic vent and form blocks that resist the flow of lava.
Full Answer
Are basaltic lava flows dangerous?
Lava flows rarely threaten human life because lava usually moves slowly -- a few centimeters per hour for silicic flows to several km/hour for basaltic flows.
Which type of lava is the most dangerous?
Pelean and Plinian eruptions are the most dangerous and explosive of the eruption types. Pelean eruptions are named for the catastophic eruption on the island of Martinique in the Carribean Sea in 1902. The eruption and the pyroclastic flow that followed killed 29,000 people almost instantly.
Do basaltic volcanoes explode?
The ... Basaltic volcanoes are characterized by persistent periods of activity ranging from effusive lava flows to explosive eruptions with variable intensity (i.e., lava fountains to high-intensity, short-lasting paroxysmal events), each posing different types of potential threats to the local population.
Is basaltic an explosive lava?
Basaltic eruptions are the most common form of volcanism on Earth and planetary bodies. The low viscosity of basaltic magmas inhibits fragmentation, which favours effusive and lava-fountaining activity, yet highly explosive, hazardous basaltic eruptions occur.
Which lava is least explosive?
The lava, still molten when it returns to the surface flows away down slope as a lava flow. Hawaiian Eruptions are considered non-explosive eruptions. Very little pyroclastic material is produced.
What happens if lava touches a human?
Lava won't kill you if it briefly touches you. You would get a nasty burn, but unless you fell in and couldn't get out, you wouldn't die. With prolonged contact, the amount of lava "coverage" and the length of time it was in contact with your skin would be important factors in how severe your injuries would be!
How explosive is basalt?
Basaltic magmas have lower viscosities, higher temperatures, and lower volatile contents than silicic magmas, and therefore generally have a lower potential for explosive activity. However, basaltic eruptions display great variability, from mild lava flows to more energetic explosions with large plumes.
Which volcano is more likely to explode?
Height: 11,380 ft. Researchers at Oregon State University call Mount Nyiragongo "the most dangerous volcano in the world." This isn't just because of the sheer amount of lava it regularly spews out of its lava lake, but because of the poisonous gases it releases.
Which type of volcano is most likely to explode?
Stratovolcanoes are more likely to produce explosive eruptions due to gas building up in the viscous magma. Andesite (named after the Andes Mountains), is perhaps the most common rock type of stratovolcanoes, but stratovolcanoes also erupt a wide range of different rocks in different tectonic settings.
What type of lava is most explosive?
Explosive eruptions are favored by high gas content & high viscosity magmas (andesitic to rhyolitic magmas).
What is basaltic lava called?
Basaltic lava is another term for mafic lava. Mafic lava is molten rock that is enriched in iron and magnesium and low in silica. When mafic lava cools on the earth's surface, it forms basalt, which is why mafic lava is commonly called 'basaltic lava.
What is basaltic lava like?
Basalt is erupted at temperatures between 1100 to 1250 ° C. Volcanic rock (or lava) that characteristically is dark in color (gray to black), contains 45 to 53 percent silica, and is rich in iron and magnesium. Basaltic lavas are more fluid than andesites or dacites, which contain more silica.
What type of lava is most explosive?
Explosive eruptions are favored by high gas content & high viscosity magmas (andesitic to rhyolitic magmas).
Why is thick lava more dangerous?
Lava domes form when high-viscosity lava is slowly erupted from a volcano. Because of the high viscosity of the lava, it cannot travel far from the vent and a dome of lava builds up. These lava domes are particularly hazardous as they tend to be unstable and can collapse, causing pyroclastic density currents.
Is low or high viscosity lava more dangerous?
But most importantly, highly viscous lava is associated with explosive eruptions and dangerous pyroclastic flows.
Is viscous lava more dangerous?
More viscous lava is a bigger threat. Viscous lava causes gas to be stored in rock. Highly viscous lava is also more likely to come from volcanoes that erupt with more energy and explosive force.
Is basalt lava thick or thin?
The thickness of basalt depends on the type. Pahoehoe sheetflows are typically thin to start, with thicknesses of only 20-30 centimeters. A'a lava...
What are the types of basaltic lava?
There are two specific morphologies for basaltic lava flows: pahoehoe and a'a. Pahoehoe lavas have a lower viscosity and are often smooth and ropey...
Is basaltic lava runny?
Most basaltic lavas have lower viscosity than other more felsic lavas, which means they flow more easily. However, they are typically slower moving...
Basaltic Lava
Lava is defined as hot molten or semi-molten rock that has erupted from a volcano or fissure in the Earth's surface or as the solidified rock that resulted from the cooling of said molten material. Basalt is a type of lava that is more mafic. Mafic is defined as being rich in dark-colored minerals, such as pyroxene and amphibole.
Basalt Characteristics
As previously mentioned, basalt is a mafic lava. It has the following mineral composition:
Basaltic Lava Research
In this activity, students will be creating a poster about one example of basaltic lava. Students will choose a location where basaltic lava is found, usually released from a shield volcano, and research how the volcano looks, when it has erupted and how it affects humans.
Where are basalts found?
The Columbia River basalts, erupted 15 to 17 million years ago, cover most of southeastern Washington and regions of adjacent Oregon and Idaho. Basalticmagmais commonly produced by direct melting of the Earth's mantle, the region of the Earth below the outer crust.
What is the volcanic shield made of?
Shield volcanoes, such as those that make up the Islands of Hawai‘i, are composed almost entirely of basalt.
What is the most common rock type in the world?
Education. Multimedia. Glossary - Basalt. Basalt. Volcanic rock (or lava) that characteristically is dark in color (gray to black), contains 45 to 53 percent silica, and is rich in iron and magnesium. Basalticlavas are more fluid than andesitesor dacites, which contain more silica. Basaltis the most common rock type in the Earth's crust(the outer ...
What is the most common rock in the Earth's crust?
Basaltis the most common rock type in the Earth's crust(the outer 10 to 50 km). In fact, most of the ocean floor is made of basalt. Huge outpourings of lavacalled "flood basalts" are found on many continents.
What causes lava to become viscous?
Cooling, gas loss, and crystallization of the lava will cause it to become increasingly more polymerized and viscous as it advances farther downslope. Although the downslope increase in viscosity can convert pahoehoe to a'a, a higher rate of shear can also cause the conversion.
What type of lava flows are erupting from shield volcanoes?
Basaltic lava flows erupt primarily from shield volcanoes, fissure systems, scoria cones, and spatter cones . These fluid lava flows can be subdivided into two end-member structural types, based primarily on the nature of lava flow surfaces:
What is lava surface?
A'a lava -- Surfaces are fragmented, rough, and spiny, with a "cindery" appearance
Does shear increase as lava advances?
The rate of shear can also increase as lava advances down increasingly steeper slopes. This is demonstrated, for example, by the conversion of pahoehoe to a'a in recent lava flows that have advanced down the Hilina Pali escarpment during the ongoing eruption of the Pu'u O'o Volcano , Hawaii.
How hot is a lava?
These are the hottest lavas, about 1,000 °C and are highly fluid.
What is the hottest lava?
Basic or Basaltic or Shield lava. These are the hottest lavas, about 1,000 °C and are highly fluid. They are dark coloured basalt, rich in iron and magnesium but poor in silica. They flow out of volcanic vent quietly and are not very explosive.
Where is magma stored?
Magma is composed of molten rock and is stored in the Earth’s crust . Lava is magma that reaches the surface through a volcano vent.
Which island is the active volcano?
Barren Island in the Andaman and Nicobar Islands, Anak Krakatoa are active volcanoes
Which gases pose the greatest potential hazard to people, animals, agriculture, and property?
The volcanic gases that pose the greatest potential hazard to people, animals, agriculture, and property are sulphur dioxide, carbon dioxide, and hydrogen fluoride.
Which country has the most volcanoes?
The 5 countries with the most volcanoes ( Source) United States – 173 (most of them are in Alaska) Russia – 166. Indonesia – 139.
Do sandstones travel far before solidifying?
They flow slowly and seldom travel far before solidifying.
Which volcanic rock has course crystals?
It is high in the rock andesite, which is the most common volcanic rock after basalt. It has course crystals.
How do volcanoes affect the weather?
Volcanic eruptions have many effects they can change the weather. They can cause rain, thunder and lightning. Volcanoes can also have long-term effects on the climate, making the world cooler; this happened when Mt. Pinatubo erupted in 1991, global temperatures dropped by 0.5 Celsius the following year.
Why do volcanoes rise above hot spots?
Magma rises to eat through the plate but when lava breaks the surface , active volcanoes occur above the hot spot. The hotspot is stationary so as the Pacific plate moves over it, a line of volcanoes is created. The one above the hotspot is active and the rest form a chain of islands of extinct volcanoes.
Why do volcanoes erupt?
Volcanoes erupt when magma rises to the surface of the earth, which causes bubbles of gas to appear in it. This gas can cause pressure to build up in the mountain, and it eventually explodes. When the magma bursts out of the earth, it is called lava. The type of magma in the earth can create different volcanoes.
How many animals did the Mount St Helens volcano kill?
Lava can kill plants and animals too. The Mount St Helens volcano in 1980 killed an estimated 24,000 animals including 11,000 hares, 6,000 deer, 300 bobcats, 200 black bears and 15 mountain lions.
What happens when magma is thick and sticky?
But, if the magma is thick and sticky, the gas cannot escape, so it builds up and up until it explodes. This can cause landslides and sends out huge clouds of burning rock and gas, which devastate everything around them, like the famous eruptions at Mount St Helens and Montserrat.
Which type of lava flows more readily, andesitic or rhyolitic?
Andesitic lava flows more readily than rhyolitic lava, but not as easily as basaltic. Eruptions tend to form composite volcanoes. Composite volcanoes are what most andesitic volcanoes look like, they are the classic shape volcano, looking like a cone. Rhyolite volcanoes are the most complex and are the most explosive of Earth’s volcanoes ...
Why do lavas have different silica contents?
Both lavas are formed at different plate boundaries which is why they have different silica contents: the basaltic lava forms from the hot mantle material at constructive plate boundaries and hotspots whereas the andesitic lava forms at destructive plate boundaries from melting crust.
What word should be used when describing different lava types?
The key word that should be used when describing different lava types is viscous, which essentially means how thick the lava is, with a high viscosity describing a very thick, slow-moving lava.
What caused a huge steam eruption?
A. Melting snow caused a huge steam eruption.
What caused part of the island to collaspe?
D. The volcano was so heavy that it caused part of the island to collaspe
