Mount Rainier rocked by 800 earthquakes in 30 days

Nearly 800 earthquakes have shaken Mount Rainier de Washington in the past 30 days, arousing fears that one of the most dangerous volcanoes in America comes to life. More than half of the earthquakes, around 512, struck in July only, with an intense swarm unlocking more than 400 tremors in just 12 hours. This imposing stratovolcano looms more than 3.3 million people in the metropolitan region of Seattle-Tacoma, threatening to paralyze entire communities with falls of ash, floods and catastrophic mud flows if it bursts.

Although Rainier has not produced a major rash in more than 1,000 years, swarms of earthquakes like this are often linked to volcanic disorders. Such a seismic activity is generally triggered by the magma rising towards the surface, fracturing those around the rock under intense pressure. However, the US Geological Survey (USGS) has minimized fears of immediate eruption, saying that current tremors are probably caused by hot fluids, not magma.

Be that as it may, volcanologists have said that it is only a matter of time until Rainier, undoubtedly the most dangerous volcano in the United States, is unleashed in the northwest of the Pacific. “Mount Rainier stands at night because it represents such a great threat to the surrounding communities,” said Jess Phoenix, volcanologist and ambassador of the Union of Scientists concerned at CNN.

When this volcano ultimately blows, it will not be lava flows or ash stifling clouds that threaten the surrounding cities, but the Lahars: violent and fast mud flows that can tear whole communities in minutes. Great Lahars can crush, abrader, bury or take almost everything on their way, according to the USGS.

“Tacoma and South Seattle are built on old 100 feet thick mud flows from Mount Rainier eruptions,” said Phoenix. But for the moment, the USGS has found “no indication that the level of activity of the earthquake is worrying, and the alert level and the color code for Mount Rainier remain green / normal”.

The USGS published an opinion on July 9, informing the public that a major swarm had rocked Mount Rainier, who saw hundreds of earthquakes in half a day. “Earthquakes are too small to be felt on the surface and will probably continue for several days. There would be no damage caused by such small events, “said the USGS. From the swarm of the earthquake, scientists have detected hundreds more until a magnitude of 2.3.

The USGS Cascades Volcan Observatory (CVO) has added: “The instruments show no deformation on the soil detectable while driving, and no abnormal signal has been seen in the infer surveillance stations. Volcanic eruptions generally cause Lahars by quickly melting the snow and the ice that cover the slopes of the volcano, which then destabilizes dirt, rock and volcanic debris and makes it flow quickly.

But you don’t always need an eruption to trigger a Lahar, according to the Society Seismological of America. Rarely, these powerful slopes of mud can form following a progressive weakening of the slopes of the volcano due to past eruptions, or strong precipitation after an eruption.

Lahar’s most deadly in recent history results from a 1985 eruption of Nevado del Ruiz Stratovolcano in Tolima, Columbia. In the hours following the eruption, a torrent of mud, melted snow and rock flooded the city of Armero and killed around 25,000 people. This event, now known as Tragedy Armero, was the most expensive volcanic disaster in history, according to the international disaster database. The total economic impact was estimated at $ 1 billion.

The 1980 eruption of Mont Saint Helens, located in Washington, just 80 kilometers from Mount Rainier, also produced a dangerous Lahar which destroyed more than 185 miles of roads and contributed to the total number of deaths of 57 people. These tragic events have helped scientists better understand the threat that Lahars represent human communities around active volcanoes, and experts are currently preparing for the terrifying possibility of a Lahar forming Mount Rainier.