A recent study of Letters on Earth and Planetary Sciences is the first to directly link earthquakes to climate change-induced glacier melt. Scientists analyzed 15 years of seismic activity on the Grandes Jorasses, a peak that is part of the Mont Blanc massif between Italy and France, to better understand this association. This massif is one of the most seismologically active areas in the region, and examining how climate change may affect earthquakes there could be useful in preparing for them.
“Researchers had long observed seasonal fluctuations in seismic activity and proposed several external factors. [as causes]”said Verena Simon, one of the lead authors of the study and a postdoctoral researcher at the Swiss Seismological Service. In an interview with GlacierHub, she explained that changes in snow and ice load, heavy precipitation, and changes in atmospheric pressure have previously been proposed as triggers for seismic activity.
“Fluids of various types are very involved in fault movements,” he said. John Murmulloseismologist at Columbia University’s Lamont-Doherty Earth Observatory, part of the Columbia Climate School. “Where two pieces of rock meet, there is a fault plane. That fault plane usually contains something called a cleft, which is a soft material that has been caused by the milling of one crystalline rock against the other. If there is liquid in those cleft sediments, that facilitates movement.”
Additionally, water seeping through porous rocks can also increase pressure between tectonic plates, causing landslides. Imagine a glacier melting on the Earth’s surface with meltwater rushing downstream. Some of this water will seep into the rock beneath it, trickling down through the Earth’s crust. As it descends, it fills the pores of the rock, changing the pressures between the plates. Mutter explained that it is possible that if “the stress regime is changed, that could trigger a failure,” although he was unsure if meltwater could do so given the depth it would have to reach. The study postulates that if enough meltwater penetrates, infiltration pathways can form and pore pressure can move underground, causing earthquakes.
Before the study, “to our knowledge, there were no direct observational links between climate change-induced melting and increased seismic risk,” Simon said. While there was a previously known relationship between water and earthquakes, Simon’s team was the first to specifically connect climate change-related meltwater to earthquakes. Scientists sought to determine whether glacial meltwater driven by global warming could also contribute to increased seismic activity. “Our study provides the first direct observational link between climate change-induced snow and glacial melting and a measurable increase in near-term seismic hazard.”
In the Mont Blanc region that the team focused on, seasonal earthquakes caused by annual snowmelt have already been observed. The area experiences greater shaking in late summer, when meltwater peaks, and fewer shaking during the winter months. Using seismometers, the researchers compiled a catalog of 12,303 earthquakes between 2006 and 2022. “The earthquakes are clustered along a known shear zone crossing the Mont Blanc tunnel, where water temperature, conductivity and isotopic data indicate a dominant input of young meltwater at the surface,” Simon explained. This area, with a predominance of meltwater, has more earthquakes than the rest of the region.
In 2015, a severe heat wave in the area caused a sharp rise in glacial meltwater and coincided with an increase in tremors. The earthquake catalog shows a clear jump in seismic activity in the following years, both in frequency and magnitude.
Next, Simon and his team turned to modeling to confirm the role of heat wave-induced meltwater in the increase in seismic activity.
“The model shows a clear increase in earthquakes starting in 2015 at higher altitudes in the Mont Blanc massif and the neighboring Swiss Alps. This indicates stronger melting at previously frozen elevations, opening up new infiltration pathways,” Simon explained. Additionally, the models demonstrated a time lag. Earthquakes are only triggered when meltwater has time to seep through the rock. “The shallow earthquakes aligned with runoff from the previous year and the deeper events aligned with runoff from two years earlier.”
The results indicate the possibility of a new, previously unknown relationship between climate change and earthquakes, and suggest the need for further research. Mutter expressed skepticism about the likelihood that meltwater is actually responsible for the earthquakes, saying, “The meltwater is on the surface. It’s not clear to me how the water is brought to the fault.”
However, if research continues to strengthen this link, there may be concern for communities affected by earthquakes around the world. Rising temperatures and heat waves caused by climate change will increase the melting of glaciers and could cause more earthquakes around the world.
Mutter suggested recording seismic activity more closely so humans can be prepared for impacts: “What you can do is monitor the induced seismicity very carefully. You can map the distribution of these small earthquakes and that could indicate which faults are activating.”
As climate change continues to melt the world’s remaining glaciers, Simon warned that the resulting meltwater will likely affect plate tectonic pressures and increase seismic risk. He said that “in the future, this may raise the risk for alpine communities, and other glaciated regions could face similar climate-modulated seismic hazards.”
The research by Simon and his team opens the door to the possibility of better earthquake preparedness for mountain communities near glaciers around the world.
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