By Stacy Liberatore for Dailymail.com
20:04 28 September 2023, updated 20:26 28 September 2023
- A 7.8 magnitude earthquake shook the Seattle area 1,100 years ago
- Experts found that the explosion came from two fault lines that ruptured simultaneously
- Read more: Seattle could be hit by a tsunami with waves up to 42 feet high
A 7.8-magnitude “mega-earthquake” rocked the Seattle area 1,100 years ago, when two fault lines ruptured simultaneously, and experts fear it could happen again.
The faults are located in Puget Sound, which includes Seattle, Tacoma and Olympia, and have ruptured in the past, but the ancient quake was 30 times stronger than current fault zone warning signs indicate.
A team of scientists led by the University of Arizona uncovered the natural disaster and determined that it caused landslides and a local tsunami that would be catastrophic if it struck the region, which is inhabited by more than four million people today.
The 2005 scenario found that even a magnitude 6.7 earthquake would kill more than 1,600 people, destroy nearly 10,000 buildings and cause total economic losses of $50 billion.
The fault lines in question are the Seattle Fault Zone (SFZ), located beneath and around the city, and another from the Saddle Mountain Fault Zone (SMFZ) in southwest Washington.
Researchers pulled fossilized Douglas fir trees from six Puget Sound sites associated with the Seattle and Saddle Mountain fault zones, which were believed to have been destroyed by seismic activity.
The team then measured radiocarbon concentrations in the wood, allowing them to determine the year each tree fell from its roots.
All the trees were killed within six months, between 923 and 924.
These results explain two scenarios that could have occurred.
Read more: Experts on red alert for huge earthquake off US coast – after a crack was discovered in a 600-mile-long fault line at the bottom of the Pacific Ocean
The hole, which is spewing hot fluid, is located 50 miles offshore Oregon, bordering a dipping fault known as the Cascadia Subduction Zone, which runs from northern California to Canada.
In these first cases, the two fault zones were ruptured as two earthquakes hours to months apart — the Seattle Fault Zone was hit by a 7.5-magnitude earthquake, and the Saddle Mountain Fault Zone was hit by a 7.3-magnitude quake.
“The second possibility is a single, larger, multi-fault earthquake rupturing both the Seattle and Saddle Mountain fault zones with an estimated average magnitude of 7.8.” Advancement of science is reading.
In the study, the team noted that simultaneous ruptures have occurred elsewhere in the modern world, including a 7.9-magnitude earthquake in 2001 in southern Alaska, a 7.3-magnitude earthquake in southern California in 1992, and a 7.8-magnitude earthquake that struck New Zealand in 2016 – but This event included more than 20 distinct errors.
In the case of Puget Sound, scientists believe the two faults may be kinematically related.
A 2022 study by researchers from the Washington State Department of Natural Resources also looked at a massive earthquake that struck Seattle, but that quake had a magnitude of only 7.5.
The model showed that 42-foot waves would submerge the city within three minutes.
The 42-foot waves will circle the Seattle Great Whale landmark, reaching inland as far as Lumen Field, home of the Seattle Seahawks, and T-Mobile Park, where baseball’s Seattle Mariners play.
Thirty miles south of downtown, the Port of Tacoma can see waves up to three miles inland.
“Amateur organizer. Wannabe beer evangelist. General web fan. Certified internet ninja. Avid reader.”