Volcanoes Long Eruptive History And Recent Activity example essay topic

Viewing an erupting volcano is a memorable experience; one that has inspired fear, superstition, worship, curiosity, and fascination throughout the history of mankind. The active Hawaiian volcanoes have received special attention worldwide because of their frequent spectacular eruptions, which can be viewed and studied with a relative ease and safety. The island of Hawaii is composed of five volcanoes, three of which have been active within the past two hundred years. Kilauea's latest eruption still continues as of today. Mauna Loa's latest activity was in 1984 and Hualalai's in 1800-1801, but is likely to erupt again within the next one hundred years.

East Maui, or Haleakala, one of the oldest volcanoes, has a long eruptive history and recent activity indicates that the volcano will erupt in the near future. Last but not least, the Loihi Seamount, sometimes known as the "youngest volcano" is an undersea mountain this is still active. Scientists now believe that the hot spots lie in the ocean, deep beneath the volcanoes. These hot spots spew out of molten rock that rises to the water's surface and hardens. After doing this for a long time, the hardened lava forms an island, like the Hawaiian islands (Volcanoes Online). The Kilauea volcano is one of the most active volcanoes on earth.

It's current eruption started in January 1983, and there is no signs that the current eruption is slowing or will come to an end anytime soon. The U.S. Geological Observatory monitors the daily activities of the volcano, for example-movement of lava flows, earthquakes, surface deformation, and gas production. Kilauea has been monitored ever since, making it one of the better-studied volcanoes. Still there is much we don't understand about the inner workings of this volcano. Unlike most other volcanoes though, Kilauea is approachable. It has been called the "drive up " volcano because of the ease of access to many of its volcanic activity.

On February 24, 2000, an article came out, which was entitled Breakouts result from tube blockages. It stated: The intrusion of magma into the upper east rift zone of Kilauea on February 23 caused minor but noticeable changes in the opening eruption. Lava continued to enter the tube system at Pu'u'O'o, but blockages in the tube above the pali resulted in many breakouts on the active flow field. (Hawaii Center forVocanology) Kilauea shares the hot spot with its larger active sibling Mauna Loa, and with the Loihi Seamount.

Mauna Loa or "Long Mountain" is the largest active volcano in the world. In fact its one of the tallest mountains in the world. The Mauna Loa and other active volcanoes on the island have tended to erupt on an average of every two to three years, placing them among the most frequently active volcanoes in the world. Mauna Loa like all the volcanoes in Hawaii are called shield volcanoes.

This means it is a gently sloping mountain produced from a large number of generally very fluid lava flows. The volcano has been erupting for at least one hundred thousand years, possibly more, from a primary volcanic center at the mountain summit (The Knowledge Adventure Homepage). Hualailai is the third youngest and third most historically active volcano on the island of Hawaii. Though Hualalai is not nearly as active as Mauna Loa or Kilauea, our recent geologic mapping of the volcano shows that eighty- percent of Hualalai's surface has been covered by lava flows in the past five thousand years. Hualailai is considered a potentially dangerous volcano that is likely to erupt again in the next one hundred years. When asked about the Hawaiian volcanoes, most people imagine the big island and its eruption at Kilauea or Mauna Loa volcanoes.

But East Maui, or Haleakala, has witnessed eruptions in the past ten thousand years. Thus, the volcanoes long eruptive history and recent activity indicate the East Maui will erupt in the near future (Hawaii Center for Volcano logy). Loihi Seamount, sometimes known as the "youngest volcano" in the Hawaiian chain, is an undersea mountain rising more then three thousand meters above the floor of the Pacific Ocean. Before the 1970's, Loihi was not known to be an active volcano.

Instead, it was thought to be a fairly common old seamount volcano of the type that surrounds the Hawaiian Islands. Later, it was revealed that the Loihi was a young, active volcano. In August 1996, the Loihi volcano rumbled to life again and has been active ever since (Volcanoes Online). The Hawaiian volcanoes are called shield volcanoes, which are the largest volcanoes on earth. The Hawaiian shield volcanoes are the most famous examples.

Shield volcanoes are large volcanoes that are built almost entirely of fluid lava flows. It has broad sloping sides and is usually surrounded by gently sloping hills in a circular fan shaped pattern. The volcano is produced by the action of the gas with heat from the earth's core. This action melts rock turning it into magma. The pressure from the heat of the gas pushes the magma upwards until it explodes.

Molten magma shoots upward from deep below the ocean floor and breaks through the drifting plates to form shield volcanoes (Hawaii Center for Volcano logy). There are many volcanic hazards, which threaten the island of Hawaii. Lava flows are the most common of the direct hazards created by the Hawaiian eruptions and pose the greatest threat to property. Flows may endanger people's property, livelihood, and peace of mind, but seldom their lives. In addition to destroying homes, the flows cover highways and some residents are forced to move from their homes.

The speed of lava flow is determined not only by the steepness of the terrain, but also by the volume of the lava that has erupted, because large flows tend to advance more rapidly then do small flows. Other hazards include airborne particles of ash, cinder, and fragile strands of volcanic class called Pele's hair, and corrosive volcanic gasses. Volcanic gasses are emitted during all types of eruptions. A common gas produced during Hawaiian volcanoes that is potentially harmful to human health is sulfur dioxide. Even small concentrations of sulfur dioxide can combine with water to form sulfuric acid, which can attack skin, cloth, metal and other materials. The greatest danger associated with the explosive eruptions is their potential to produce pyroclastic surges.

These surges are highly destructive, turbulent gas clouds that flow rapidly along the ground carrying hot ash and rock fragments. These eruptions are generally caused by the interaction of magma and ground water. The magnitude of the resulting steam explosion varies from harmless to catastrophic. Ground cracks and settling is also commonly associated with volcanic activity; both generally occur near active or recently active volcanic vents as the result of shallow underground movement of magma. Cracking of the ground precedes the beginning of an eruption as magma is forcefully injected into the area. The hazard presented by ground cracks and settling associated with eruptions, is usually limited to areas near the activity.

Man-made structures that escape other damages from an eruption, however, can be damaged or destroyed by cracking, tilting, or setting of the ground beneath them. Ground cracks will remain after the eruption is over and can pose a threat to unwary people and animals if the cracks are obscured by heavy vegetation (USGS). In conclusion, the Hawaiian Islands are made up of a chain of volcanoes that began to from more then seventy million years ago. Many of these volcanoes formed the islands that have subsided and eroded beneath sea level, and some of the old volcanoes probably never reached sea level. Each Hawaiian Island is made up of one or more volcanoes, which first erupted on the sea floor and only emerged above the ocean surface after countless eruptions.

If not for these destructive volcanoes we wouldn't have the beautiful island of Hawaii today. It makes me think twice now about going on vacation there, because I am afraid of being stuck there when a volcano erupts.