Although Mount Rainier is an active volcano, as of 2016 seismic monitors within Mount Rainier National Park and on top of the mountain appear to show that it is indeed very much alive, but very soundly asleep.[39] However, an eruption could be deadly for all living in areas within the immediate vicinity of the volcano and an eruption would also cause trouble from Vancouver, Canada to San Francisco[40] because of the massive amounts of ash blasting out of the volcano into the atmosphere.
Mount Rainier is located in an area that itself is part of the eastern rim of the Pacific Ring of Fire. This includes mountains and calderas like Mount Shasta and Lassen Peak in California, Crater Lake, Three Sisters, and Mount Hood in Oregon, Mount Saint Helens, Mount Adams, Glacier Peak, and Mount Baker in Washington, and Mount Cayley, Garibaldi, Silverthrone, and Mount Meager in British Columbia. All of the above are dormant, but alive, and scientists on both sides of the border gather research of the past eruptions of each in order to predict how mountains in this arc will behave and what they are capable of in the future, including Mount Rainier.[41][42] Of these, only two have erupted since the beginning of the twentieth century: Lassen in 1915 and St. Helens in 1980 and 2004. However, past eruptions in this volcanic arc have multiple examples of sub-plinian eruptions or higher: Crater Lake's last eruption as Mount Mazama was large enough to cause its cone to implode,[43] and Mt. Rainier's closest neighbor, Mount St. Helens' had a huge chunk of the side of the mountain blow up in a phreatic explosion caused by a mix of gas and water; where St. Helens was once perfectly symmetrical there is now, thirty five years later, a huge crater at the top of one face. Statistics place the likelihood of a major eruption in this range at 2-3 per century.[44]
Mount Rainier is currently listed as a Decade Volcano, or one of the 16 volcanoes with the greatest likelihood of causing great loss of life and property if eruptive activity resumes.[45] If Mt. Rainier were to erupt as powerfully as Mount St. Helens did in its May 18, 1980 eruption, the effect would be cumulatively greater, because of the far more massive amounts of glacial ice locked on the volcano compared to Mount St. Helens,[37] the vastly more heavily populated areas surrounding Rainier, and the simple fact that Mt Rainier is a much bigger volcano, almost twice the size of St. Helens.[46] Lahars from Rainier pose the most risk to life and property,[47] as many communities lie atop older lahar deposits. According to the United States Geological Survey (USGS), about 150,000 people live on top of old lahar deposits of Rainier.[7] Not only is there much ice atop the volcano, the volcano is also slowly being weakened by hydrothermal activity. According to Geoff Clayton, a geologist with a Washington State Geology firm, RH2 Engineering, a repeat of the Osceola mudflow would destroy Enumclaw, Orting, Kent, Auburn, Puyallup, Sumner and all of Renton.[36] Such a mudflow might also reach down the Duwamish estuary and destroy parts of downtown Seattle, and cause tsunamis in Puget Sound and Lake Washington.[48] Rainier is also capable of producing pyroclastic flows and expelling lava.[48]
One of many emergency evacuation route signs in case of volcanic eruption or lahar around Mt. Rainier
"A home built in any of the probabilistically defined inundation areas on the new maps is more likely to be damaged or destroyed by a lahar than by fire...For example, a home built in an area that would be inundated every 100 years, on the average, is 27 times more likely to be damaged or destroyed by a flow than by fire. People know the danger of fire, so they buy fire insurance and they have smoke alarms, but most people are not aware of the risks of lahars, and few have applicable flood insurance."[49]The volcanic risk is somewhat mitigate
No comments:
Post a Comment