Earlier today we covered the initiation of an eruption in Iceland. On the other side of the world, an eruption that is much more serious also is unfolding as I type this. This ash cloud is pouring out of the volcano known as Tavurvur on the island of New Britain, in the nation of Papua New Guinea.
Tavurvur is part of a much larger volcanic complex known as the Rabaul Caldera that sits at the far northeastern tip of New Britain. This caldera is the remnants of several large volcanic explosions, the most recent of which took place 1400 years ago. A caldera is a giant hole in the ground; when a large magma chamber beneath the Earth’s surface empties during an eruption, it leaves empty space and the rocks above the magma chamber collapse downward, forming a huge crater in the ground.
The Rabaul caldera is about 8 x 14 kilometers in size. On its southeastern slope, the rim of this caldera has been breached by the Pacific Ocean, flooding the caldera center and creating a natural harbor, protected from the open ocean by the eastern and northern walls of the caldera.
This setup, a protected harbor, is a solid place for economic activity. By the early 1990’s, about 50,000 people lived on the coastline of this harbor, but the volcano had something to say about that.
Calderas don’t die when they erupt. It can take thousands of years for their magma chambers to rebuild, but the magma supply doesn’t shut off after large eruptions. Typically, small volcanoes will begin growing on the edges of the caldera what is known as the resurgent phase of caldera activity. Tavurvur is one of these volcanoes. In 1994 it erupted simultaneously with another cone known as Vulcan on the volcano’s rim, decimating the area. Thankfully, the population was mostly evacuated the night before the eruption as earthquakes gave an early warning, leading to only 5 deaths, but today the population of the area today is a small fraction of what it was before these eruptions.
Tavurvur rumbled to life again today, sending ash clouds high into the air and producing fountains of lava. There is video of the eruption up at our blog,http://the-earth-story.com/
This volcano is a direct hazard to many more people on the ground than the current eruption in remote Iceland, and has also caused aviation alerts and forced the redirection of some flights due to ash in the air.
In 2009, the International Space Station flew over the Sarychev Volcano on the Kamchatka Peninsula just as it was erupting and punching a spectacular hole in the clouds. The photos and videos of it are some of the best we’ve ever seen of an erupting volcano from above. Take a look at the pyroclastic flows streaming down the sides of the peak as the station passes (shaking is the camera position adjusting as the ISS moves).