Start Searching the Answers
The Internet has many places to ask questions about anything imaginable and find past answers on almost everything.
The Question & Answer (Q&A) Knowledge Managenet
The Internet has many places to ask questions about anything imaginable and find past answers on almost everything.
Silfra (Icelandic pronunciation: [ˈsɪl(v)ra]) is a rift formed in the divergent tectonic boundary between the North American and Eurasian plates and is located in the Þingvallavatn Lake in the Þingvellir National Park in Iceland.
The vent is often a few metres wide and may be many kilometres long. Fissure vents can cause large flood basalts which run first in lava channels and later in lava tubes. After some time the eruption builds up spatter cones and may concentrate on one or some of them.
Fissure swarms are areas with high density of fractures, often extending in opposite directions from central volcanoes (Einarsson and Sæmundsson, 1987, Saemundsson, 1978). The extent of some of the fissure swarms is well known.
We propose that magmatic fissures have vertical feeders with lateral offshoots extending along the rift zone. Their inflation/deflation during an eruptive cycle causes subsidence. Such magmatically generated faults can be subsequently modified by tectonic extension.
Fissure eruptions are quiescent, and the height of the airborne eruptive material is small, often only a few tens of meters. The basaltic fragments in the curtain of fire thus remain largely liquid when they hit the ground. These coherent lumps of hot, fluid lava are called spatter.
The Great Rift is the deepest and longest volcanic fissure in the continental United States. It begins at the base of the Pioneer Mountains (north of the park’s visitor center), extends for over 50 miles to the southeast, and has been measured to be more than 600 feet deep in places.
Fissure eruptions occur when magma flows up through cracks in the ground and leaks out onto the surface. These often occur where plate movement has caused large fractures in the earth’s crust, and may also spring up around the base of a volcano with a central vent.
Taal Lake was formed by a series of catastrophic volcanic eruptions and other geologic processes whose character slowly evolved as the large basinal depression and the lake took form. These phreatic eruptions created smaller circular depressions that later coalesced to form the present caldera.
There, a type of material called kimberlite magma forces its way up from deeper in Earth’s mantle, cracking the solid rock. As it rises, the magma collects fragments of rocks, like floodwaters picking up silt and gravel. Some of these fragments contain diamonds.