According to a new study published in the Journal Chaos, the same solar heat that warms your skin on a summer day can subtly affect when and where an earthquake occurs.
Japanese and international researchers have discovered evidence that heat from the sun could contribute to seismic activity on Earth, paving new pathways for improving earthquake prediction models.
The study is based on previous studies establishing a causal relationship between solar activity and earthquakes, but scientists are currently identifying a specific mechanism, heat transfer from the sun to the Earth’s surface.
“Solar heat can promote changes in atmospheric temperature, which can affect rock properties and groundwater movements,” said Matheus Henrique Junqueira Saldanha, one of the study’s authors. “Such variations can make rocks more brittle and more prone to breaking, for example. And changes in rainfall and snowmelt can change the pressure on the boundaries of the tectonic plate.”
While traditional seismology focuses primarily on the movement of tectonic plates and the accumulation of strain energy, this study suggests that environmental factors affected by the sun can play a supportive role in determining when that energy is released.
The researchers looked into multiple pieces of evidence, including seasonal variation in seismic patterns on the Earth and the relationship between surface temperature and earthquake occurrence. By analyzing a broad dataset of seismic records along with solar activity and surface temperature measurements, they identified meaningful correlations.
This approach differs from previous theory that suggests that electromagnetic effects or tidal forces can link solar activity to earthquakes. Instead, the heat transfer hypothesis provides a more direct and measurable connection between the sun and the earthquake events.
Perhaps most convincing was the discovery that earthquake prediction models are more accurate when they incorporate Earth’s surface temperature data. This improvement was particularly pronounced in shallow earthquakes.
“That makes sense because heat and water mostly affect the upper layers of the Earth’s crust,” says Junqueira Saldanha.
Timing factors have become particularly clear. Researchers observed that earthquake predictability differs when working with the expected time frame of heat to pass through the Earth’s system, taking into account delays in Sunspot activity.
This study is upon a time when earthquake prediction is one of the biggest challenges in seismology. Despite great advances in understanding how earthquakes occur, predicting them with sufficient accuracy and lead times to save lives remains elusive.
The 2011 Japan earthquake caused a devastating tsunami, contributing to Fukushima’s nuclear disaster, killing more than 18,000 people. It serves as a clear reminder of the importance of improving earthquake prediction capabilities.
Current prediction models rely heavily on historical seismic patterns, fault line characteristics, and strain measurements. However, these approaches have major limitations in providing practical warnings.
By examining seasonal variation in seismic patterns, the researchers found that seismic activity did not remain constant throughout the year. This seasonal variation supports the hypothesis that environmental factors affected by solar heat, such as groundwater movement, rainfall patterns, and rock thermal expansion, play a trigger for earthquakes.
Researchers adopted sophisticated mathematical and computational methods to analyze the relationships between these variables. Their analysis reveals what they call “shared dynamic information” between solar activity and earthquakes, suggesting interconnected systems rather than isolated phenomena.
The study also documented “large-scale nondeterminism” in the relationship between solar activity and earthquakes. This shows that while solar heat contributes to seismic activity, it serves as one factor among many people rather than a major cause.
Another author of the study, Dr. Yoshito Hirata, worked with Junqueira Saldanha in a 2022 study, which first established the causal relationship between solar activity and earthquakes. Their ongoing research now points to practical applications for this knowledge.
The research team includes scientists from Tsukuba University in Japan and the National Institute of Advanced Industrial Science and Technology, and gathered expertise in complex systems, geophysics and statistical analysis.
“These factors may not be the main factors in earthquakes, but they may still play a useful role in predicting seismic activity,” explained Junqueira Saldanha.
Looking ahead, researchers suggest that by incorporating predictions of solar activity into detailed earth temperature models, earthquake prediction systems can be enhanced. This integration explains the multiple pathways where solar heat ultimately affects seismic activity.
In areas that are prone to catastrophic earthquakes, even a modest improvement in forecasting capabilities can prove to be invaluable for emergency preparation and response.
“It’s an exciting direction and I hope our research will shed some light on the larger picture of what causes earthquakes,” concluded Junqueira Saldanha.
The findings are published in the March 4th issue of Chaos, published by the American Institute of Physics.
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