http://www.digitaljournal.com/tech-and-science/science/data-mining-reveals-clues-behind-california-earthquakes/article/548003

Data mining reveals clues behind California earthquakes

Posted Apr 20, 2019 by Tim Sandle
By applying advanced data mining techniques, researchers have been able to assess earthquake data and this analysis has revealed hidden clues about major California earthquake triggers. The new information may assist with prevention.
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USGS
Research undertaken at the U.S. Department of the Environment's Los Alamos National Laboratory using a powerful new computational method has revealed new clues about earthquakes. The researchers applied the analysis to archived records pertaining to southern California's seismic history. The detailed analysis has revealed new information about a plethora of previously undetected small earthquakes. This information is of great value for future earthquake predictions are well as providing a rich stream of information about the stress in the earth's crust.
California is a region of the world where earthquakes are common. The earliest known earthquake was documented in 1769 by the Spanish explorers and Catholic missionaries, and the most recent major earthquake was in South Napa in 2014 where 200 people were injured. The level of damage from the South Napa Bay quake was over £360 million.
While the major earthquakes are well-douched, scientists have long suspected that there have been other plate movements that have triggered minor disruptions to the surface. These are difficult to discern from the data collected by seismologists over the years, drawn from various readings and instruments. To assess this the research team undertook a massive data mining operation, assessing the Southern California Seismic Network for real quakes buried in the noise, plus other vibration data caused by non-quake vibrations such as road traffic.
Data from 400 seismic sensors in California was assessed using the data mining process, with the data drawn over the course of a ten-year period. From this analysis the scientists identified over 180,000 earthquakes in the region, almost all would have been unnoticed by the inhabitants of California.
The researchers have used the data mining and advanced computational techniques to develop a system for tracking subtle changes to the mantel, what they are calling 'quake fingerprints'.
Commenting on the study, lead researcher Professor Daniel Trugman states: "It's very difficult to unpack what triggers larger earthquakes because they are infrequent, but with this new information about a huge number of small earthquakes, we can see how stress evolves in fault systems."
He adds: "This new information about triggering mechanisms and hidden foreshocks gives us a much better platform for explaining how big quakes get started." It is hoped the detailed findings will help to address questions around how, where and why earthquakes happen.
The outcome of the study is published in the journal Science. The research paper is titled "Searching for Hidden Earthquakes in Southern California."