Another period of unrest began in 2005 that is still ongoing.
The volcano has been stirring since the mid-20th century, with bursts of heightened activity in the 1950s, 1970s and 1980s. More than 1.5 million people live above the vast underground volcano complex, and half a million people have their homes inside its 7 mile (11 kilometer) long caldera, which was formed after an enormous eruption 39,000 years ago. Fourth slide details.An aerial image of the Campi Flegrei volcano, a cluster of more than 20 calderas, volcanic cones and hydrothermal vents. Thingvellir Valley and Lake Thingvallavatn, Thingvellir National Park, Thingvellir, Iceland.įirst slide details. They also tend to be shield volcanoes with gently sloping slides. Rift volcanoes generally issue nonviolent streams of lava, instead of explosively erupting. For example, Iceland was formed where the mid-ocean ridge met with a mantle plume – a ‘hotspot’ of abnormally hot rock in the mantle – and eruptions of lava built volcanoes and filled rift valleys. This process can also form volcanic islands. The tectonic plates are spreading apart allowing soft molten rock to bubble up between the plates. It stretches all around the globe and is more than 64,000 kilometers (40,000 miles) long. The mid‐ocean ridge is a continuous, underwater seam of mountains and volcanoes that form where divergent tectonic plates meet. Hills covered by volcanic ashes, Great Rift Valley, Tanzania, East Africa. Spreading may have created East Africa's volcanic Great Rift Valley.
When spreading centers develop within continents, they form new plate boundaries and trigger volcanic activity. Spreading centers can be found under the sea or on land. In these zones, plates move away from each other, decreasing the pressure on the underlying mantle, allowing it to rise and melt, forming magma. Volcanoes called rift volcanoes are formed in spreading centers.
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