A new study published in Seismological Research Letters provides new information about precursor scale increase (PSI). PSI is a phenomenon characterized by a sudden increase in the incidence and magnitude of earthquakes in a local area, preceding a larger seismic event.
“Our study is essential to advancing our understanding of how seismic activity increases in the lead up to large earthquakes,” said Annemarie, lead author and hazard and risk scientist at GNS Science.・Dr. Christophersen says:
This study proposes two new techniques to automatically detect PSI in earthquake catalogs. By studying both real and simulated data, the researchers found that large earthquakes can have multiple PSI identifications.
They found that there was a relationship between the size of the precursor region and the time leading up to a major earthquake, such that the smaller the region, the longer the precursor time and vice versa.
This is an important step forward in understanding how seismic activity accumulates before large earthquakes, and has immediate implications for improving medium-term earthquake predictions.
Such forecasts are important to the public because they improve preparedness and enable more effective risk management techniques.
This study was primarily conducted in Aotearoa New Zealand. The country is located on the Pacific Ring of Fire and is known for high seismic activity due to frequent plate collisions.
The study’s findings come as New Zealand has been hit by several severe earthquakes in the past, including the horrific 2011 Christchurch earthquake, a magnitude 6.3 quake that caused widespread infrastructure damage in the region. emphasizes the importance of
By increasing our understanding of PSI, this research hopes to strengthen the New Zealand National Seismic Hazard Model, which is important in estimating seismic risk across New Zealand.
The study results, published on October 11, 2024, are part of an ongoing earthquake prediction study and expand on previous work that investigated and sought to understand the seismic sequences that lead to significant earthquake occurrences. Ta.
Until now, PSI detection has been based on manual and time-consuming approaches, which has limited analysis of these occurrences.
The researchers aimed to better understand how the size of the precursor earthquake region 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. This is very different from previous manual identification methods.
These techniques were used on both real seismic data and simulated datasets based on the known physics of seismic events.
Their findings showed that most large earthquakes have multiple PSI realizations, each with different antecedent times, areas, and magnitudes.
The algorithm showed that there is a balanced relationship between the time leading up to an earthquake and the region where precursor earthquakes occur. This means that as a major earthquake approaches, more seismic activity occurs in smaller areas.
This finding supports the original principles of the EEPAS (Earnings of All Earthquakes According to Magnitude) model, which predicts how smaller earthquakes can signal the potential for larger earthquakes.
“Our next step is to incorporate our findings into the EEPAS model to improve medium-term earthquake predictions, which will be a direct input into official earthquake forecasts and the National Seismic Hazard Model,” Christophersen said. he said.
“These resources will help us make better decisions about where to build and prioritize strengthening existing infrastructure to make New Zealand more resilient to major earthquakes.”
References:
1 Algorithmic Identification of Precursor Scale Increase Phenomena 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 study advances understanding of increased seismic activity before major earthquakes – GNS Science – October 11, 2024
3 Christchurch, New Zealand – Britannica – Accessed 13 October 2024
