Hidden faults found at US quake hotspot- experts warn of catastrophe

"Now, researchers have discovered that the junction actually contains at least five tectonic plates or fragments deep below the surface, making the region far more complex than previously thought. That means there may be an unaccounted earthquake hazard in the area, and current models could be underestimating the true risk. Because the junction lies off the coast and influences both the San Andreas and Cascadia systems, revisions to the model could affect risk calculations for millions of people along the West Coast."

"For decades, the Mendocino triple junction was believed to be where three tectonic plates meet: the San Andreas Fault ending in the north, the Cascadia Subduction Zone in the south, and the Mendocino Fault in the east. Because three major fault systems converge there, the area is one of the most active earthquake zones in the US and could produce a magnitude 8.0 quake."

"If the models don't include these hidden faults, they may underestimate how much stress is building up underground. That means a larger earthquake could happen unexpectedly, because the hidden faults could suddenly release energy in ways the old models didn't predict. The team suspected something more complex was happening at the Mendocino Triple Junction, as a large magnitude 7.2 earthquake in 1992 occurred at a much shallower depth than expected."

The Mendocino triple junction contains at least five tectonic plates or fragments deep below the surface, creating a more complex tectonic structure than the traditional three-plate model. The added plates and hidden faults introduce unaccounted earthquake hazards and could mean current seismic models underestimate stress accumulation. Because the junction lies offshore and interacts with both the San Andreas and Cascadia systems, revised fault models could change risk estimates for millions of people along the West Coast. Past anomalies, such as a 1992 magnitude 7.2 quake at unusually shallow depth, support suspicion of deeper complexity and the need for improved mapping.

Read at Mail Online