900 earthquakes hit major US volcano – but will it erupt?
More than 900 earthquakes have rumbled beneath Mount Rainier, in Washington State, in the last two weeks, according to the US Geological Survey (USGS). This comes after experts revealed an earthquake swarm began under the volcano on July 8, sparking worries of an eruption. So, what is going on with Mount Rainier? (Picture: Getty)
In July, officials noted that most of these earthquakes seemed to have occurred on July 11 2025, with 716 so far located and the rest to be analysed in time. The Pacific Northwest Seismic Network is in the process of looking at each earthquake to determine its location, depth and size. The USGS reveals that although most of them measured less than one magnitude, 10 shakes were between 2-3 magnitude (Picture: Getty)
Mount Rainier
Mount Rainier is a stratovolcano sitting at almost 4,500m high. The volcano is the highest peak in the Cascade Range in Washington, as it looms over nearby towns Orting, Seattle, Tacoma and Yakima. The volcano has erupted before. Around 5,600 years ago, part of Mount Rainier collapsed to form a larger crater at the northeast, like Mount St Helens after 1980. But the last magmatic eruption occurred around 1,000 years ago (Picture: Getty)
Will Mount Rainier erupt?
The USGS is not particularly worried, and says the current tremors are likely caused by hot fluids, not magma, so there is no indication there will be an eruption any time soon. During a statement after the swarm started on July 8, the USGS said: ‘Currently, there is no indication that the level of earthquake activity is cause for concern, and the alert level and color code for Mount Rainier remain at GREEN / NORMAL’ (Picture: Getty)
Why are experts worried about Mount Rainier erupting?
According to the National Volcano Early Warning System, Mount Rainier’s threat potential is high. This is assessed by the risk posed by a volcano to people and property by looking at volcanic hazards, such as the materials that are produced from a volcano, as well as exposure to people and property. Since Mount Rainier is a large volcano close to many cities, it is considered high risk (Picture: Getty)
Seth Moran, a research seismologist at USGS Cascades Volcano Observatory in Vancouver, Washington told CNN: ‘The thing that makes Mount Rainier tough is that it is so tall, and it’s covered with ice and snow, and so if there is any kind of eruptive activity, hot stuff … will melt the cold stuff and a lot of water will start coming down. 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’ (Picture: Getty)
Lahar is a huge concern. They usually happen during volcanic eruptions, but also can be caused by landslides and earthquakes. A lahar is a swiftly moving slurry of water and volcanic rock which came from ice or snow that has been rapidly melted by an eruption that picks up debris as it flows through valleys and drainage channels. The deadliest one in recent history was in November 1985, when Colombia’s Nevado del Ruiz volcano erupted. Just a few hours after the eruption started, a river of mud, rocks, lava and icy water swept over the town of Armero and killed over 23,000 people in a matter of minutes. In relation to Mount Rainier, geologists have found evidence that at least 11 large lahars from Mount Rainier have reached into the surrounding area, known as the Puget Lowlands, in the past 6,000 years (Picture: Getty)
