Where is there a dormant volcano

How violent the eruption is depends on the amount of silica present in the magma. Silica produces a thicker magma that is better at trapping gasses. The more gas present the greater the pressure. Therefore the more silica present in the magma the more violent the eruption will be. Types of lava and their effect on the volcano structure There are two types of lava, acidic and basic.

Acidic lava has a high silica content and this makes it thicker. Combined these cause the volcano to have a steep sided cone. These are known as Cone Volcanoes. Basic lava contains less silica, this allows the gasses to escape and gives a runny lava. Eruptions of this type of lava a gentler and this along with it being runny allows the lava to flow further. Volcanoes of this type of lava will have gently sloping sides. They are known as Shield volcanoes. For more information on the types and shapes of volcanoes see Tulane University website How can we forecast volcanic activity?

By studying the type of materials and distribution of deposits geologists can learn a lot about the activity of volcanoes. Eruptions can be predicted in a number of ways: Tiltmeters are very sensitive devices that are used to identify any bulging of the sides of a volcano.

Gases or steam coming out of vents in the volcano or the appearance of geysers could suggest an eruption will soon follow. Seismometers are used to detect vibrations in the rock. This is the tallest volcano on the island of Hawaii, which is made up of five volcanoes in total. Mauna Kea has not erupted for about 4, years, but volcanologists believe it has the potential to wake up again. Some 6, to 4, years ago, this volcano erupted about seven times, and based on its history, scientists think it has a recurrence interval of about 1, years.

This makes it sound like Mauna Kea is well overdue to erupt, but experts say this simply indicates it is likely that eruptions will take place sporadically as time goes on. The peaks were not built at the same time, and are made of different kinds of rock. They caught the attention of the general public and volcanologists when it was discovered that part of this cluster was lifting upwards in the late s.

Field studies done by the US Geological Survey showed uplift taking place and gradually swelling from late to December of , with the swelling slowing from that point. The Arenal volcano, Costa Rica. Mount Rainier is considered to be one of the most dangerous volcanoes in the US, even though it has not erupted for over years.

Volcanoes can lie sleeping for thousands of years, and experts study ground movements among other things to try and predict when an eruption will take place again. Victoria Simpson July 22 in World Geography.

Sometime more than 10, years before present marks the beginning of the Holocene epoch, which is used as an arbitrary cutoff because it marks roughly the point in time when the last ice age ended worldwide. But what does historical time even mean? Whose history are they referring to? Do they count myths and legends as historical records, or do they have to be written? What about areas of the world that have no written records, but may still have oral histories going back thousands of years?

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