Earthquake activity will increase due to glacial retreat

A recent study from Colorado State University (CSU) provides compelling evidence that climate change can influence the frequency of earthquakes. The research adds to a growing body of work suggesting that shifts in climate can directly impact the seismic cycle.

The study focused on the Sangre de Cristo Mountains in southern Colorado, where an active fault runs along the western edge of the range. Researchers discovered that during the last ice age, the weight of glaciers suppressed fault activity. 

However, as the ice melted, the fault experienced increased slip, indicating that earthquake activity along such faults could rise in response to glacial retreat.

“Climate change is happening at a rate that is orders of magnitude faster than we see in the geologic record,” said first author Cece Hurtado, who conducted the study as part of her master’s thesis at Colorado State University. 

“We see this in the rapid mountain glacial retreats in Alaska, the Himalayas and the Alps. In many of these regions, there are also active tectonics, and this work demonstrates that as climate change alters ice and water loads, tectonically active areas might see more frequent fault movements and earthquakes due to rapidly changing stress conditions.”

Linking climate and earthquake activity

While it’s well established that tectonic changes influence climate – for example, through mountain uplift altering atmospheric circulation and rainfall – research linking climate shifts to tectonic activity is still rare. 

The CSU study is among the few that show how climate change can directly impact seismic processes.

“We’ve been able to model these processes for a while, but it’s hard to find examples in nature,” said Sean Gallen, an associate professor of geosciences at CSU and the senior author of the study. “This is compelling evidence. It suggests that the atmosphere and the solid Earth have tight connections that we can measure in the field.”

A closer look at the Sangre de Cristo fault

The Sangre de Cristo Mountains, once blanketed by glaciers during the last ice age, provided an ideal setting for studying the relationship between glacial retreat and fault activity. 

Using remote sensing and field data, researchers reconstructed the extent of ancient glaciers and calculated the weight these ice masses exerted on the fault. They then measured how much the fault had displaced over time.

The analysis revealed that fault slip rates have been five times faster since the glaciers melted compared to the period when the region was glaciated. This acceleration suggests that as the glaciers melted, the fault experienced a “rebound,” catching up to the background tectonic rate of movement.

“It’s basically like a small lever that’s tweaking the rate at which the fault moves, but that long-term rate is set by the background rate of the tectonic processes,” Gallen explained.

Implications for seismic hazard assessment

The findings have significant implications for understanding what drives earthquake activity and for assessing seismic risks in areas experiencing rapid glacial retreat or significant water loss.

“This work implies that the repeat time isn’t necessarily going to be periodic,” Gallen said. “You can have periods of time where you have a bunch of earthquakes in quick succession and a lot of time where you don’t have any earthquakes.”

The study’s results may help refine models used to reconstruct prehistoric seismic records and estimate the recurrence intervals of active faults. By factoring in hydrologic processes, such as glacial retreat, over geologic time, seismologists can improve hazard assessments for tectonically active regions.

Glacial retreat and earthquake activity

The research was grounded in a public database of high-resolution elevation data, which served as the foundation for understanding the fault’s displacement. 

Hurtado and Gallen also conducted field surveys using high-precision GPS instruments to supplement the elevation data and measure fault displacement. The timing of fault movement was determined based on the age of sediment deposits near the fault.

The researchers noted that the Sangre de Cristo Mountains offered a unique opportunity to study the interplay between glacial retreat and tectonics. The range is part of the Rio Grande rift, which has a known background slip rate, providing a baseline for comparison.

Earth’s climate and tectonic systems

As glaciers continue to retreat rapidly in regions such as Alaska, the Himalayas, and the Alps, the CSU team’s findings serve as a preview of how other glacier-adjacent faults might respond to a warming climate. 

The study highlights the interconnectedness of the Earth’s climate and tectonic systems, highlighting the potential for climate-driven changes to increase seismic activity in tectonically active areas.

By shedding light on this relationship, the researchers hope to deepen understanding of seismic hazards and encourage further study of how climate change shapes the Earth’s dynamic systems. “This is a crucial step in understanding how climate and tectonics interact,” Hurtado concluded.

The study is published in the journal Geology.

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