Mount Rainier, Washington’s snowcapped peak that stands 4.3 kilometers (2.7 miles) above sea level, has not had a significant volcanic eruption in the last 1,000 years. More than Hawaii’s exploding lava fields or Yellowstone’s vast supervolcano, Mount Rainier has many US volcanologists concerned.
“Mount Rainier keeps me awake at night because it poses a significant threat to the nearby villages. “Tacoma and South Seattle are built on 100-foot-thick (30.5-meter) ancient mudflows from Mount Rainier eruptions,” said Jess Phoenix, a volcanologist and ambassador for the Union of Concerned Scientists, on an episode of CNN’s “Violent Earth With Liv Schreiber.”
Why Mount Rainier Is The US Volcano Keeping Scientists Up At Night
The sleeping giant’s deadly potential does not stem from flaming lava flows, which, in the case of an eruption, are unlikely to spread more than a few miles beyond the boundary of Mount Rainier National Park in the Pacific Northwest. According to the US Geological Survey, most volcanic ash will likely drift downwind to the east, away from populated centers.
Instead, many scientists are concerned about a lahar, a fast-moving slurry of water and volcanic rock formed when ice or snow is rapidly melted by an eruption. Lahars gather debris as they run down valleys and drainage channels.
According to Seth Moran, a research seismologist at USGS Cascades Volcano Observatory in Vancouver, Washington, Mount Rainier’s tall height and ice and snow cover make it resilient to eruptive activity. “Hot stuff … will melt the cold stuff and a lot of water will start coming down,” he explained.
“And there are tens, if not hundreds of thousands of people who live in areas that potentially could be impacted by a large lahar, and it could happen quite quickly.”
A lahar is a rapidly flowing debris flow.
The deadliest lahar in recent memory occurred in November 1985, when Colombia’s Nevado del Ruiz volcano erupted. Just a few hours after the eruption began, a flow of mud, rocks, lava, and freezing water surged over the village of Armero, killing over 23,000 people in minutes.
In an episode of CNN’s “Violent Earth,” Bradley Pitcher, a volcanologist and Columbia University lecturer in Earth and environmental sciences, described a hardened, concrete substance that can be difficult to escape.
Pitcher stated that Mount Rainier had approximately eight times the amount of glaciers and snow Nevado del Ruiz had when it erupted. “There’s the potential to have a much more catastrophic mudflow.”
According to the US Geological Survey’s 2018 threat assessment, Hawaii’s Kīlauea volcano is the most dangerous in the US, which is unsurprising given its proximity to the population and periodic eruptions. Mount St. Helens exploded violently in May 1980 and was voted second most dangerous, followed by Mount Rainier in third.
Lahars are most commonly associated with volcanic eruptions, but landslides and earthquakes can also create them. Moran said geologists have discovered evidence that at least 11 massive lahars from Mount Rainier have reached the surrounding area, known as the Puget Lowlands, over the last 6,000 years.
Scientists have not linked the most recent of these lahars, which occurred approximately 500 years ago, to any volcanic activity. According to analysts, the flow event could have been the result of a huge landslide on the mountain’s west face.
The loose, weak rock remains in that location, and Moran and other volcanologists are particularly concerned about the possibility of a similar, spontaneous landslide-induced lahar.
Why Mount Rainier Is The US Volcano Keeping Scientists Up At Night
“We now know that the volcano can do it again. “And then we’re in this world where anything can happen at any time,” Moran explained.
“If it were the same size, it would be 10 minutes to the nearest places where people live and 60 minutes to the nearest significant settlements. “And those are very short time frames,” he added.
A 2022 study considered two worst-case scenarios. In the first scenario, a 260 million cubic meter, 4 meter deep (9.2 billion cubic feet, 13-foot deep) lahar would form on Mount Rainier’s west slope. According to Moran, the debris flow would be equivalent to 104,000 Olympic-size pools and could reach the heavily populated lowlands of Orting, Washington, roughly an hour after an eruption, moving at a rate of 13 feet (4 meters) per second.
According to the simulation, a second “pronounced hazard” area is the Nisqually River Valley, where a major lahar may displace enough water from Alder Lake to allow the 100-meter-tall (330-foot-tall) Alder Dam to spill over.
Mount Rainier’s neighbor, Mount St. Helens, farther south in the Cascade Range, erupted four decades ago, causing a disastrous lahar that did not reach any highly populated regions.
Venus Dergan and her then-boyfriend, Roald Reitan, were trapped in the Mount St. Helens lahar while on a camping vacation and are among the few persons known to have survived being swept up in a debris flow.
“I tried to cling on as we were swept downstream, but the tree bark was scraping. … During an interview for CNN’s “Violent Earth,” she recounted feeling it on her legs and arms.
“At one point, I went under the logs and dirt and accepted that this was the end. I was not going to get out of this, and I was going to die.
Why Mount Rainier Is The US Volcano Keeping Scientists Up At Night
Following the explosion of Mount St. Helens, the US Geological Survey established a lahar detection system on Mount Rainier in 1998, which has been modified and expanded since 2017.
About 20 places on the volcano’s slopes and the two paths identified as most at risk of a lahar now have broadband seismometers that send real-time data and additional sensors such as trip wires, infrasound sensors, web cameras, and GPS receivers.
Moran explained that the device is designed to identify both a lahar if the volcano erupts in the future and a lahar caused by a landslide.
Because of the constraints of 1990s technology, the original system had limited bandwidth and power requirements, resulting in data transmission every two minutes.
In March, 45,000 kids from Puyallup, Sumner-Bonney Lake, Orting, White River, and Carbonado, Washington, took part in a lahar evacuation simulation. According to the USGS, this was the first time numerous school districts exercised on the same day, making it the world’s largest lahar drill.
Approximately 13,000 pupils walked up to 3.2 kilometers (2 miles) to specified areas outside of the defined lahar zone, while the remaining schools outside the lahar zone practiced sheltering in place.
Moran stated that the fail-safe components of the Lahar detection system are roughly 45 minutes away from the next significant community; thus, that was the time window within which communities had to work.
“Most of what happens at volcanoes is close by, and that’s why you try to keep people away because things happen fast, but lahars can travel a long way from the volcano and have a big impact.”
SOURCE – (CNN)
