Three tectonic plates come together at the Mendocino triple junction off northern California. Recent research shows this area has more complex geology than we thought.
Scientists studied small earthquakes recorded by seismometers in the Pacific Northwest. They found hidden faults and discovered that the junction consists of five moving parts instead of just three.
“This means we may need to update our earthquake prediction models,” says David Shelly, a seismologist from the United States Geological Survey. He compares it to an iceberg—what’s visible on the surface is just a small part of a larger structure beneath.
To confirm their findings, the researchers also checked their data with tidal sensitivity models. The daily pull of tides creates tiny stresses in the rocks, allowing scientists to test their interpretations of these small earthquakes.
The study revealed a chunk of the North American plate has broken off and is being pulled down by the Gorda plate. They also confirmed the existence of the Pioneer fragment, an older section of rock being dragged underneath.
The three plates involved—North American, Gorda, and Pacific—interact in ways that could lead to significant earthquakes. The new findings also suggest that the subduction surface is shallower than previously thought.
This research shifts our understanding of the plate boundary’s location. For example, a 7.2-magnitude earthquake in California in 1992 occurred at a much shallower depth than earlier models predicted.
“This changes our assumptions about where faults are located,” notes Kathryn Materna, a tectonic geodesist at the University of Colorado Boulder.
Understanding these movements is crucial. The San Andreas Fault and the Cascadia subduction zone are capable of causing devastating earthquakes. Studying the underlying tectonic processes helps scientists better predict seismic risks.
As more data emerges, researchers are piecing together a clearer picture of California’s fault lines. With this knowledge, we can aim for better preparedness for potential earthquakes.
The study is published in Science, providing new insights into one of the most seismically active regions in the United States. For more details, check the published research here.
Source link
MSFT Content
