Caltech Study Identifies Link Between Groundwater Levels and Seismic Activity

While tectonic plate shifts are the primary cause of earthquakes, other natural forces, such as hydrological dynamics, exert pressure on faults.

A new study from Caltech has identified a connection between changes in groundwater levels and increased seismic activity. This research suggests that natural forces, specifically hydrological dynamics, play a role in exerting pressure on faults, thereby influencing earthquake occurrences.

The Research

The study, conducted in Jean-Philippe Avouac's laboratory and led by former graduate student Krittanon Sirorattanakul, was published in the journal Science Advances on March 25.

The team analyzed seismic activity across various regions of California over a 16-year period, from 2006 to 2022.

Key Findings

Researchers observed that areas experiencing more significant fluctuations in groundwater levels exhibited a greater seasonal variation in seismic activity. In Northern California, these groundwater changes correlated with an increase in seismic activity by up to 10 percent.

Notably, these hydrological changes did not result in immediate seismic events. The peak increase in seismic activity occurred approximately half a month after the peak groundwater changes. This work provides insights into factors that contribute to earthquake nucleation.

Implications and Further Considerations

The study also suggests that human activities, such as groundwater extraction for consumption or oil pumping, could modulate seismic activity levels.

Researchers note that understanding these factors can improve earthquake forecasting models, which track seismic trends and averages over time.

The study also examined the Earth's tides as a potential influence but found that tidal forcing, despite similar stress magnitudes to hydrological forces, did not significantly increase earthquake activity. The team posits that the difference in timescale is crucial, with tidal cycles being much shorter (12 hours) compared to annual groundwater accumulation and dissipation.