Lava flows are the least hazardous of all processes in volcanic eruptions. How far a lava flow travels depends on the flows temperature, silica content, extrusion rate, and slope of the land. A cold lava flow will not travel far and neither will one that has a high silica content. Such a flow would have a high viscosity<span> (a high resistance to flow). A basalt flow like those in Hawai'i have low silica contents and low viscosities so they can flow long distances. Such a flow can move as far away as 4 km from its source and have a thickness of 10 m (Bryant, 1991). These flows can move at rates of several kilometers per hour (Scott, 1989). </span><span>More silica-rich flows can move as far away as 1.3 km from their sources and have thicknesses of 100 m (Bryant, 1991). These flows can move at rates of a few to hundreds of meters per hour (Scott, 1989). If a lava flow is channelized or travels underground in a lava tube then the distance it travels is greatly extended.</span>
Answer:
Density is one of the most factors that play a key role in plate tectonic activities. Some of the ways in which density is important in the field of plate tectonics are as follows-
- The convergent plate boundaries are responsible for the creation of a subduction zone, where the high-density lithospheric plate subducts below the less dense one. It is because the heavier plate is comprised of heavy minerals thereby forming heavier rocks as a result of which its density increases. Due to these differences in density, there occurs a subduction zone.
- The divergent plate boundary forms where two plates move away from one another. This type of plate motion is responsible for the eruption of magma on the seafloor. As the plates diverge, the lithosphere becomes eventually thin, and with more progressive spreading, the magma comes out to the seafloor. This is because the hot magma is less dense, and forms convection cells as they rise upward. This is how the density helps in the upwelling of magma at the mid-oceanic ridge in a divergent plate boundary.
- When there collide two plates of equal densities, then it gives rise to the formation of huge mountains, because neither of them is heavy to get sink. So it uplifts the crust, forming a sandwich-type pattern.
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Answer:
Some, but not all, earthquakes are related to volcanoes. ... However, most earthquakes are caused by the interaction of the plates not the movement of magma . Most earthquakes directly beneath a volcano are caused by the movement of magma. The magma exerts pressure on the rocks until it cracks the rock.
