Active Volcanoes

The Earth is full of activity. Mother nature is unpredictable and wild. From tornados to earthquakes, there is always something going on. Volcanoes, however, may pose the most serious threat around the world. When a volcano erupts it not only affects the immediate area, but it can cause long-term problems globally.

Throughout history, volcanic eruptions have been a part of life. There are very few ways to know whether or not a volcano is going to erupt or how much damage it might cause, even with modern-day technology. This was proven during the 1980 explosion of Mount Saint Helens in Washington state. What can be done for sure is to have an evacuation route and plan ready in case of an impending eruption.

About Volcanoes

There have been many eruptions throughout Earth’s history. Some have been mild and caused little or no damage. Other volcanoes have caused chaos, destroyed structures, and food supplies, changed temperatures, and killed many people.

One of the first recorded volcanic eruptions was Mount Vesuvius in 79 A.D. Although there have been over 550 recorded eruptions in Earth’s history, there are up to 60 active volcanoes at any one time. Very few are as destructive as was Krakatau which erupted in 1883. The collapse of the mountain caused a tsunami that was responsible for over 34,000 deaths.

Many of the volcanic eruptions in the last few hundred years have had a dramatic impact on the geological face of the Earth. Volcanoes like Mount Saint Helens in Washington, Mount Lassen in California, Mount Redoubt in Alaska, Kilauea Mountain in Hawaii and Eyjafjallajokull in Iceland, are still considered active threats. What these all have in common is recent activity and the fact that the land around them changed and continues to change dramatically.

Types of Volcanoes

According to the United States Geological Survey website on “PrincipalTypes of Volcanoes” maintained by John Watson, “Geologists generally group volcanoes into four main kinds–cinder cones, composite volcanoes, shield volcanoes, and lava domes.” However, some scientists would say that supervolcanoes would create a fifth group all of its own.

Cinder Cones

These are considered the most simple of volcanoes. They are made from blobs of lava and rock particles that erupt from a single vent. All volcanoes form a cinder cone at some point during their active life. The Paricutin Volcano that formed in Mexico in 1943 and evolved until 1952, was the first volcano that scientists were able to study from birth until extinction.

Composite Volcanoes

These are also called a stratovolcano. “They are typically steep-sided, symmetrical cones of large dimension built of alternating layers of lava flows, volcanic ash, cinders, blocks, and bombs and may rise as much as 8,000 feet above their bases,” according to the USGS. Some of the most famous composites are Mount Fiji in Japan, Mount Saint Helens in Washington, and Mount Shasta in California.

Shield Volcanoes

In these, there is a central vent of lava that flows up and branches off creating many vents. These have sides that are sloping and broad. The biggest shield volcano in the world is Mauna Loa in Hawaii. It rises only 13,000 feet above the ocean, but from its base on the ocean floor, it is over 33,000 feet tall.

Lava Domes

These are exactly how they sound. These domes have no real rhyme or reason. They can spring up from a single vent or many vents. They can be found on the side of stratovolcanoes like Mount Saint Helens and Mount Shasta. Lava domes form from slow eruptions

Super Volcanoes

The Yellowstone caldera is the most famous of the supervolcanoes. If it erupted it could change the face of the Earth. The event could be tens of thousands of times stronger than just a regular eruption. Ash might cover the Earth and affect everything from the temperature to the food supply to overall air and health quality. The last super explosion was Toba in Sumatra over 75,000 years ago. It caused three-quarters of all plants in the northern hemisphere to die.

Volcanologists spend their lives studying volcanoes to try and collect information about them and the risks that they may pose. It is true science, but not foolproof. Quick and fast eruptions would give people very little time to get out of the way and find safety or shelter. The after-affects can cause health problems, kill off species of animals and plants, or even wipe out towns depending on the type of eruption. There is no way to stop an eruption, only to be aware and have a plan in case of one.

Sources:

• Geology Department of San Diego State University, “How Volcanoes Work”, Geology.sdsu.edu Accessed June 2010
• Pacific Disaster Center, “Deadliest Eruptions.” Pdc.org Accessed June 2010.