Changbaishan volcano (China / North Korea): signs of unrest
Saturday Sep 29, 2012 11:18 AM | BY: T
Changbaishan is one of China's few active volcanoes and one that has attracted special attention for having produced one of the planet's major eruption within the past 2,000 years.
Around the year 1000, the volcano had a massive VEI 6-7 eruption and ejected about 100 cubic km of tephra (almost 100 times than during the eruption of Mt St. Helens in 1980), and sent an ash plume to a calculated height of 50 km into the stratosphere. The eruption, known as the "Millennium Eruption", removed the summit cone of the volcano and left a 5 km-wide caldera which is now occupied by a scenic lake. It probably caused wide spread global climatic effects which are the subject of current research.
Since the Millennium eruption, Changbaishan has had 3 smaller eruptions, the most recent of which took place in 1903. According to the article, signs of activity resumed in 1999, and scientists established the Changbaishan Volcano Observatory.
Data collected over the past 12 years suggest that changes in seismic activity, ground deformation and gas emissions increased between 2002 and 2006. Researchers think this suggests the magma chamber beneath Changbaishan has started to refill. From 2002 to 2006, seismic activity increased to 72 earthquakes per month. It peaked in November 2003 with 243 quakes, mostly located at shallow 4.5 km depth beneath the caldera that that has risen slowly over the years.
Gas emissions from hot springs near the volcano show increased carbon dioxide, hydrogen, helium and nitrogen gas emissions, the article continues. According to researchers, this would be caused by degassing of freshly injected magma.
Although Changbaishan seems not to be in state of imminent eruption, the researchers are quoted that "an explosion could be expected in the next couple of decades."
Thanks to the monitoring set up on Changbaishan, geologists know that something is moving, most likely magma is ascending and COULD erupt. In the end, this is what an active volcano like Changbaishan is expected to do, and eventually will. The question WHEN is always difficult to answer.
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