Which volcanoes are most likely to explode and why

Rising silica levels in magma also give way to pyroclastic flows, a quick-moving mixture of lava, ash, gas and rock pieces that can be deadly because they cause asphyxiation, Mertzman says. It poses little danger to people, unless they get in the way — thousands of people have been evacuated in the last month and Kilauea has destroyed several homes.

Regions where volcanic eruptions can be deadly include Indonesia, the Philippines, parts of South America and various volcanoes in the U. The Italian government has multiple plans prepared for a possible eruption in the future. At least six million people live in the vicinity of Vesuvius, according to the database. A number of factors make Mount Rainier one of the most dangerous volcanoes in the U. More than two million people would be affected by an eruption, according to the Global Volcanism Program.

While the immediate area surrounding Novarupta is not populous, the eruption formed an ash cloud that rained sulfurous ash across southern Alaska and parts of Canada. After three days, people in nearby Kodiak had succumbed to eye soreness and respiratory issues caused by ash fall, according to the USGS.

The eruption that created Novarupta is not typical of the types of eruptions in the region, the National Park Service for Katmai said on its website. However, more than a dozen active volcanoes at remain under watch by volcanologists at Katmai in an effort to protect the public from harm. Mount Pinatubo, situated in a populated region of the Philippines, became notorious after a major eruption that was the second largest eruption of the twentieth century, closely following Novarupta.

Click here to learn more. A leading-edge research firm focused on digital transformation. Ben Mack. The volcano is far from the only potentially dangerous one around the world, with Japan's Mount Fuji, Oregon's Mount Hood, and others in the Philippines, Indonesia, and New Zealand also posing a threat. Here are 13 volcanoes that could erupt at any time — or are already oozing lava — ranked by the last time they blew, from oldest to most recent.

Visit Insider's homepage for more stories. Mount Paektu, North Korea. Mount Shasta, California. Mount Fuji, Japan. Mount Hood, Oregon. Mount Ruapehu, New Zealand. Tungurahua, Ecuador. Anak Krakatoa, Indonesia. Taal Volcano, Philippines. Mount Yasur, Vanuatu. Eruptions of these volcanoes are not generally explosive, but are more like liquid overflowing around the edges of a container.

The world's largest volcano, Mauna Loa in Hawaii , is a shield volcano, according to the U. Mauna Loa is about 55, feet 17, meters from its base beneath the ocean to the summit, which is 13, feet 4, meters above sea level. It is also one of the Earth's most active volcanoes and is carefully monitored.

The most recent eruption was in Lava domes are built up when the lava is too viscous to flow , according to the U. A bubble or plug of cooling rock forms over a fissure. This cooler, thick lava usually rises near the end of an explosive eruption and lava domes often form within the craters of stratovolcanoes.

Helens has several well-defined lava domes inside the crater , according to NASA. Besides well-known symmetrical volcanoes such as Mount Fuji in Japan and Kilimanjaro in Tanzania, volcanic activity is responsible for several other distinctive landforms. Calderas : A caldera is a bowl-shaped depression formed when a volcano collapses into the void left when its magma chamber is emptied.

There are three types , according to San Diego State University. The first type is a crater lake caldera. This is the result of a stratovolcano collapsing into its magma chamber during a violent eruption. Basaltic calderas have a concentric ring pattern resulting from a series of gradual collapses rather than a single event. They are often found at the summit of shield volcanoes such as the craters at the tops of Mauna Loa and Kilauea. Resurgent calderas are the largest volcanic structures on Earth.

They are the result of catastrophic eruptions that dwarf any eruptions ever recorded by human beings. Yellowstone caldera, sometimes called a "super volcano," is one example. Volcanic plugs : When magma solidifies in the fissure of a volcano the hard dense rock may form a " neck " that remains when softer surrounding rock has been eroded away, according to the U. Sometimes these calderas can fill up with water to produce beautiful lakes such as Mount Mazama Crater Lake , in Oregon.

Shield volcanoes get their name from their shape. Although shield volcanoes are not steep, they may be very large. In fact, Mauna Loa, Hawaii is the tallest mountain in the world. From sea level, Mount Everest is the tallest, but when you consider from the ocean floor to the top of the island, Mauna Loa wins.

Shield volcanoes are common at spreading centers or intraplate hot spots. The lava that creates shield volcanoes is fluid and flows easily and creates the shield shape. Shield volcanoes are built by many layers over time and the layers are usually of very similar composition. The low viscosity also means that shield eruptions are non-explosive. Eruptions tend to be mild in comparison to other volcanoes, but lava flows can destroy property and vegetation.

The low viscosity magma can flow not only on the surface as lava, but also underground in lava tubes. The most well known shield volcano is Hawaii. There are two types of lava flows, pahoehoe which is a ropy type of lava that flows easily low viscosity. The other type is called aa and is a blocky type of lava and has a higher viscosity and does not like to flow well.