Researchers develop new algorithms to enhance earthquake forecasting

New research published in Seismological Research Letters offers new information on the precursory scale increase (PSI), a phenomenon characterized by a sudden increase in the rate and size of earthquakes in a localized area before a larger seismic event. 

“Our research is essential for advancing our understanding of how seismic activity escalates in the lead-up to a major earthquake,” said lead author Dr. Annemarie Christophersen, Hazard and Risk Scientist at GNS Science.

The study proposes two novel techniques for automatically detecting PSI in earthquake catalogs. By studying both real and simulated data, the researchers discovered that big earthquakes can have several PSI identifications. 

They discovered a link between the size of the precursory area and the time leading up to a major earthquake, smaller areas correspond to longer precursor times, and vice versa.

This is a significant step forward in understanding how seismic activity builds up before major earthquakes, with immediate implications for improving medium-term earthquake forecasting. 

Such projections are important for the public since they allow for improved preparedness and more effective risk management techniques.

The study was mostly done in Aotearoa New Zealand, a country recognized for high seismic activity because of its location on the Pacific Ring of Fire, where tectonic plates frequently collide. 

This geographical backdrop stresses the importance of the findings, as New Zealand has undergone multiple severe earthquakes in the past, including the terrible Christchurch earthquake of 2011 which was a 6.3 magnitude earthquake that caused widespread infrastructural damage in the region. 

By improving understanding of PSI, the research hopes to strengthen New Zealand’s National Seismic Hazard Model, which is crucial in estimating seismic risk across the country.

The findings were published on October 11, 2024, and were part of ongoing earthquake prediction research, expanding on prior work that tried to examine and comprehend earthquake sequences leading up to significant seismic occurrences. 

Historically, PSI detection was based on manual and time-consuming approaches, which limited the analysis of these occurrences. 

The researchers aimed to better understand how the size of precursory earthquake areas and the time leading up to a major earthquake are related. 

Dr. Christophersen and her team created two algorithms to automatically detect PSI in earthquake catalogs, which represents a considerable departure from earlier manual identification methods. 

These methods were used on both real earthquake data and simulated datasets based on the known physics of earthquake events. 

Their findings indicated that most big earthquakes had numerous PSI realizations, each with a different antecedent time, area, and magnitude. 

The algorithms showed a balanced relationship between the time leading up to an earthquake and the area where precursory earthquakes occur. This means that as the time gets closer to a major earthquake, smaller areas experience more seismic activity. 

This finding supports the original principles of the EEPAS (Every Earthquake a Precursor According to Scale) model, which predicts how smaller earthquakes can signal the likelihood of a larger one.

“Our next step is to include our findings in the EEPAS model to improve medium-term earthquake forecasting, which is a direct input into public earthquake forecasting and the National Seismic Hazard Model,” said Christophersen.

“These resources help us to make better decisions on where to build and to prioritize the strengthening of existing infrastructure to make New Zealand more resilient to large earthquakes.”

References:

¹ Algorithmic Identification of the Precursory Scale Increase Phenomenon in Earthquake Catalogs – Annemarie Christophersen, David A. Rhoades, Sebastian Hainzl – Seismological Research Letters 2024 – October 8, 2024 – https://doi.org/10.1785/0220240233

² New research advances understanding of increased seismicity before large earthquakes – GNS Science – October 11, 2024

³ Christchurch, New Zealand – Britannica – Accessed October 13, 2024

Harsha Borah

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