A volcanic eruption is a process through which the earths crust releases pressure and heat. During this process, various poisonous gases, ash, tephra, and lapilli expels from the volcanic fissure or vent. Volcanologists categorized the eruptions based on a volcanos activity. There is a chance that few volcanoes’ exhibit only one character of eruption. However, the behavior changes according to the period and other environmental factors.
The eruptions of the volcano have different meta-types. The most observed are magmatic eruptions, which involves decompression of the gas. On the other hand, Phreatomagmatic eruptions are eruptions driven by the compression of the gas within the magma. Within the wide defining eruptive categories lie several subgroups. The stronger eruptions are Pelean eruptions followed by the Plinian eruptions. The weakest are the submarine, Hawaiian, Vulcanian, Strombolian, and Surtseyan. Volcanic Explosivity Index defines the measurement of the eruptive strength. It ranges between zero and eight and co-relates to the eruptive types.
The eruption mechanism is due to three constituents - gas released due to decompression, thermal counteraction from chilling, and ejection of entrained particles during steam eruptions. Outbreaks occur in either explosive activity or effusive activity. Explosive activity is gas driven explosions that push tephra and magma. Effusive activity is the outpouring of lava without a particular explosive eruption.
The measurement index, volcanic the explosivity index, measures the strength of the eruptions. The Smithsonian Institution’s, Global Volcanism Program uses the index in order to study the prehistoric and historic lava flows. It is very much similar to the Richter scale that measures the strength of the earthquakes. Magmatic eruptions produce juvenile clasts due to the explosive the compression created during the gas release. The intensity ranges from small volume to grander volumes. An example of the relatively small intensity is the lava fountains found in Hawaii. An example for the Ultra-Plinian eruption column is the eruption of Mount Vesuvius that buried Pompeii in 79.
Hawaiian volcanoes are calmest types of volcanic events characterized due to the effusive eruption of lava that have small gaseous content. The uniform generation of small amounts of lava forms the shield volcano. Eruptions are not at the centre but occur along the vents and fissures.
Strombolian eruptions are continuous and are active for centuries. The eruption is a mixture of gas bubbles within the magma. The bubbles accumulate within the magma and merge into a large bubble called as the gas slug. They rise through the lava column to reach the surface. Upon reaching the surface, the magma bubble bursts with a loud pop due to the difference in air pressure. The explosion causes the magma to spread in different directions. These blasts occur every few minutes.
The eBook provides information on surviving these catastrophic events. It is impossible to predict a volcanic eruption and, therefore; it is essential to prepare for one that offers food, medical assistance, and security. Taking the time to understand the importance of being prepared with volcanology and its potential events, provides you with the best opportunity to protect your family. The protection draws a line between life and death. More importantly, the information will help you to protect property and health from volcanic ash, shoot of stones, and poisonous gases.