The shield volcano gets its name from its appearance. Though not very impressive in height, it covers a very wide circumference, resembling a warrior’s shield. It is characterized by its gently sloping sides. The shield volcano is an accumulation of a large number of very fluid lava flows which cannot pile up to form steep sides. Here are some impressive facts about the shield volcano.
Fact 1: Shield volcanoes are almost exclusively made of basalt, as opposed to an alternating layer of ash and lava found in other types of volcanoes.
Fact 2: Unlike other types of volcanoes, shield volcanoes are very rarely explosive during eruption. They are characterized by low-explosivity fountaining. Eruptions are explosive only if water finds its way into the vent of the volcano.
Fact 3: The tallest active volcano in the world is a shield volcano – Mauna Loa Volcano in Hawaii. It dwarfs the Everest by about 4000 feet, considering that it rises more than 13,000 feet above sea level and extends to about 19,700 feet below the ocean floor.
Fact 4: Volcanism is a common feature on most terrestrial bodies, making the occurrence of volcanoes very common in the solar system. It has also been found that basaltic effusions are the most common on all the planets in the inner solar system. This means that many of these volcanoes are shield volcanoes. Such formations have been observed on Mars, Venus, perhaps even Mercury and Io. The Earth’s moon also reveals small shields on its surface.
Fact 5: The largest volcano in the solar system is found on Mars. The Olympus Mons is a gigantic shied volcano, roughly the size of the state of Arizona, USA. Owing to lower surface gravity and the stationery nature of the crust, Martian shield volcanoes here can be anywhere between 10 to 100 times the size of the volcanoes on Earth.
Fact 6: Volcanoes are geological formations that have been in a process of continuous formation since ancient times. Geological study of these surfaces reveal facts about the ancient world to a large extent. Glacial terrane remnants have been found on the Mauna Kea, dating back to the last global ice age – about 20,000 years old.
Fact 7: Shield volcanoes are typified by those found on the Hawaiian and Galapagos islands, as well as some found in Iceland. Many myths and legends evolved around the fiery activity of these volcanoes before the advancement of Science. The early Hawaiian settlers greatly feared the volcanic activity in and around Kilauea. They believed that the fire goddess Pélé was the cause of the fiery eruptions and lava flow from the volcano.
Fact 8: The entire surface of the Hawaiian Islands consists of a series of shield volcanoes that began to form about 70 million years ago. The main island of Hawaii itself is made up of five distinct volcanoes, all at various levels of growth and activity.
Fact 9: Shield volcanoes are some of the most active volcanoes in the world. A volcanic eruption that began in the Kilauea Volcano in Hawaii in January of 1983 still shows no signs of abating. The Mauna Loa has also displayed a very active history. In 1868 an eruption from the Mauna Loa caused the largest recorded earthquake in Hawaii. This has also been the sight of one of the greatest concentration of lava flows ever seen by modern observers.
Fact 10: Lōʻihi, the youngest shield volcano, is still about 1000 meters below the surface of the ocean. Studies have shown that the continuous movement of the Earth’s crust will eventually level the existing volcanoes, and in due time push up newer volcanoes, like the Lōʻihi.