Precursor
In a new study published recently in Geophysical Research Letters, scientists warn that a major earthquake fault, dormant for 12,000 years, is awakening.
This fault, called the Tintina Fault, stretches like a massive scar, diagonally across the Yukon Territory in northwestern Canada and into Alaska, USA, for approximately 1,000 kilometers.
It was previously widely believed that the Tintina Fault, while once highly active, was no longer a threat. Monitoring data from recent decades seems to confirm this: aside from occasional minor earthquakes of magnitude 3 or 4, the Tintina Fault has been remarkably quiet.
However, past earthquake studies in the region have largely relied on historical records and modern instrumental monitoring, which together cover only a few hundred years. For an earthquake fault with activity cycles of tens of thousands or even millions of years, this is like trying to judge a person's lifetime based on a single second of observation—clearly insufficient. To truly understand the nature of the Tintina Fault, scientists need to search for traces of earthquakes from its distant past.
A roughly 130-kilometer-long section of the Tintina Fault, which escaped complete glaciation during the ancient ice ages, preserves some of the oldest landforms. This presents an excellent opportunity for scientists, much like archaeologists, to search for seismic traces of past fault activity.
In this study, scientists utilized a variety of technologies, including satellites, aircraft, and drones, to create high-resolution topographic data of the region with unprecedented precision.
A careful analysis of the data revealed two crucial reference points on either side of the fault: an ancient landform dating back approximately 2.6 million years, and a terrace carved by glacial meltwater approximately 132,000 years ago. By measuring the horizontal displacement of these features on either side of the fault, scientists discovered that the 2.6 million-year-old feature was offset by approximately 500 to 1,500 meters, while the 132,000-year-old terrace was offset by 65 to 85 meters.
This clearly indicates that the Tintina Fault is not as quiet as previously thought. Based on the measurements, scientists calculated that the average slip rate of the Tintina Fault over the long past has been approximately 0.2 to 0.8 millimeters per year.
The most crucial discovery: scientists noticed that features formed 12,000 years ago (at the end of the last ice age) show almost no signs of deformation.
This finding is significant because it indicates that the Tintina Fault's last violent eruption occurred at least 12,000 years ago, and that it has been unusually quiet since then.
You might think that if it's been fine for 12,000 years, doesn't that mean it's completely quiet? Actually, this isn't the case. In fact, this is precisely why scientists are warning about this. For an active, seismic fault, a long period of dormancy could be accumulating energy for the next powerful eruption.
It's like two wooden boards glued together with strong glue. You pull them in opposite directions. Initially, the boards remain stationary, but the force you apply accumulates. When the accumulated energy exceeds the adhesive strength of the glue, the boards snap apart with a loud "pop."
It's important to note that movement on both sides of the Tintina Fault hasn't stopped. Although its speed appears slow (0.2 to 0.8 mm per year), on average, it has accumulated a "slip deficit" of approximately 6 meters during this 12,000-year "dormant" period.
According to theoretical models, this "slip deficit" is very close to the critical value, meaning that this seismic fault, dormant for 12,000 years, is awakening. If all its stored energy were released in a single earthquake, the magnitude would exceed 7.5 on the Richter scale. Scientists said that this study revealed previously unrecognized earthquake risks and issued an evidence-based warning based on this. For people in surrounding areas, monitoring facilities should be deployed or strengthened as soon as possible to improve the earthquake resistance of infrastructure and thus be better prepared for an uncertain future.
Μου αρέσει