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The looming threat of a catastrophic West Coast earthquake, often referred to as ‘The Big One’, has long been a source of apprehension for Americans. Recent devastating seismic events in regions like Thailand and Myanmar serve as a stark reminder of the destructive power of major seismic activity.
Images emerging from Southeast Asia in the wake of a recent magnitude 7.7 earthquake vividly illustrate the horrifying consequences of such powerful tremors. Reports indicate thousands are feared dead, numerous structures have been leveled, and the potential for severe flooding due to dam failure adds to the catastrophe.
Within the United States, anxieties regarding a major natural disaster are expanding beyond California. As earthquakes occur across various states, a growing number of citizens are expressing fear that they too might be vulnerable to a seismic event.
Rising Earthquake Concerns Across the US
Geologist Robert Yeats, author of ‘Earthquake Time Bombs,’ emphasizes the considerable risks associated with the location of several large American cities within the Pacific Northwest’s Cascadia subduction zone.
‘Expert groups have conducted resilience assessments in Washington and Oregon to evaluate the repercussions of inadequate preparedness for a major earthquake,’ Yeats stated.
Even regions of New England and Texas, areas not traditionally associated with high seismic activity, have experienced record-setting earthquakes in recent years, following a period of relative calm.
Nevertheless, the West Coast remains the primary focus of geological monitoring, with experts suggesting a major seismic event could occur in the near future.
Projections estimate that a 7.8-magnitude earthquake could result in 1,800 fatalities and $200 billion in damages. This AI-generated image offers a visualization of a potential earthquake scenario in San Francisco.
The US Geological Survey (USGS) has reported multiple ‘significant’ earthquakes in California already this year. Data indicates that 2024 witnessed a higher frequency of earthquakes in the state compared to any period in the last three decades.
Furthermore, experts caution that certain regions are alarmingly unprepared for these potentially devastating earthquakes, which they warn could lead to thousands of deaths and trillions of dollars in damages.
While pinpointing the precise timing of an earthquake remains impossible, scientists employ historical data and patterns of seismic activity to better understand earthquake trends and risks.
Steven Sobieszczyk, a USGS spokesperson, clarified that scientists utilize historical records combined with current seismic readings to identify areas facing the highest earthquake risks today.
Understanding the Cascadia Subduction Zone
A section of the Pacific Northwest is situated on a subduction zone, where the Juan de Fuca tectonic plate is sliding beneath the North American plate.
Subduction zones are responsible for generating the planet’s most powerful earthquakes.
These major seismic events originate when friction between the plates causes them to lock together, leading to a gradual accumulation of stress along their boundary, known as a fault line.
Eventually, when the built-up stress surpasses the fault’s strength, a rupture occurs. This release of stored energy generates a shockwave that propagates towards the Earth’s surface, manifesting as an earthquake.
The Cascadia subduction zone extends from Northern California to British Columbia, Canada. It underlies Oregon and Washington and stretches offshore into the Pacific Ocean.
Experts note an unusually low frequency of earthquakes in this region recently, which paradoxically could indicate increasing stress accumulation.
Researchers estimate that approximately eight major earthquakes have struck this zone in the past 3,500 years, suggesting another significant event could be imminent.
‘This tectonic boundary experienced a massive earthquake [magnitude 9.0] in the year 1700,’ Sobieszczyk stated.
‘Civilizations in the region documented intense ground shaking during the 1700 event, which also triggered substantial tsunami waves that traveled across the Pacific Ocean,’ the USGS expert added.
Predictions regarding the potential consequences of a similar earthquake striking the Cascadia subduction zone today suggest it could become the most devastating natural disaster in North American history.
Experts caution that the Cascadia subduction zone could unleash ‘The Big One’ – a potentially catastrophic earthquake capable of devastating the West Coast.
The US West Coast is a prime earthquake zone, with USGS projections highlighting the entire coastal region from California to Washington as high-risk. The red area near Memphis indicates the New Madrid seismic zone, another area of significant seismic activity.
Projections indicate the potential for thousands of landslides and the collapse of an estimated 7,000 road bridges.
FEMA estimates that a staggering 85 percent of ports and drinking water treatment plants would suffer severe damage or destruction, along with 77 percent of the region’s airports, railways, schools, and hospitals.
Evidence from the previous Cascadia earthquake offers further insights into the potential devastation the subduction zone could unleash again.
Radiocarbon dating reveals that coastal forests were submerged in seawater as the landmass abruptly subsided approximately 300 years ago during the last major quake.
Analyzing the speed of trans-Pacific tsunami waves, researchers have determined that the 1700 earthquake likely occurred around 9 pm PT on January 26, 1700.
Yeats noted that the ‘repeat time’ – the interval between major earthquakes – varies from 1,200 years in the northern Cascadia zone to just 250 years in the southern section, closer to California.
This variability is a key factor leading many experts to consider Cascadia as overdue for a major seismic catastrophe.
‘This implies that scientists can confidently predict future great earthquakes in Cascadia, but predicting the precise timing remains elusive – it could be tomorrow or a century from now,’ Yeats clarified.
Could a massive earthquake trigger a devastating tsunami along the US coastline? Earthquakes can generate tsunamis by causing vertical displacement of the ocean floor, displacing massive volumes of water and creating powerful waves.
The Cascadia subduction zone, underlying Washington, Oregon, and Northern California, is considered ‘overdue’ for another major earthquake event.
If ‘The Big One’ strikes imminently, Yeats anticipates gas leaks from ruptured underground pipelines igniting widespread fires.
Furthermore, the earthquake would likely be followed by a tsunami similar to the 2011 Tohoku-oki tsunami which resulted in over 18,000 fatalities in Japan.
In Oregon alone, estimated property losses could reach $32 billion. Coastal towns including Tillamook, Astoria, Seaside, Cannon Beach, Coos Bay, and Newport face the risk of inundation, with the coastline potentially subsiding by up to 10 feet permanently.
Seismic Risks in San Francisco and Northern California
USGS estimations indicate a nearly 75 percent probability of a significant earthquake impacting the San Francisco Bay Area in the foreseeable future.
Across the broader Northern California region, this probability increases to a staggering 95 percent.
Sobieszczyk pointed out that the Bay Area has a history of experiencing numerous significant and destructive earthquakes, notably the 1906 San Francisco earthquake, which registered at least 7.7 on the Richter scale.
This earthquake struck the California coast on April 18, 1906, igniting fires that raged for days. Ultimately, 80 percent of the city was destroyed, and over 3,000 lives were lost.
Over 300,000 residents were rendered homeless as approximately 30 fires consumed 25,000 structures across 490 city blocks. Rebuilding San Francisco cost $350 million, equivalent to $8 billion in today’s value.
The three primary fault lines in the Bay Area posing the greatest threat of triggering a major earthquake are the Hayward fault, the Calaveras fault, and the notorious San Andreas fault – which extends along much of the California coastline.
Survivors survey the ruins of the Grand and Palace Hotel following the 1906 San Francisco earthquake in California.
Cracks visible on East Street in the aftermath of the earthquake, which was estimated to measure between 7.7 and 8.3 on the Richter scale.
Could an earthquake threaten Los Angeles? This major US metropolis is among several California cities situated along the San Andreas fault line.
Earthquake Vulnerability in Los Angeles
Experts at Caltech indicate that Southern California faces a particularly elevated risk of a major earthquake.
Currently, Southern California experiences an average of one earthquake approximately every three minutes.
A study revealed that between 2008 and 2017, Southern California was subjected to 1.81 million earthquakes, the majority of which were too minor to be perceptible to humans.
In 2024, Los Angeles recorded 2,420 earthquakes with magnitudes reaching up to 4.6.
Los Angeles has experienced some of California’s most powerful earthquakes, including the 1994 Northridge earthquake, one of the most destructive and deadly in the state’s recorded history.
This magnitude 6.7 seismic event caused widespread building collapses across Los Angeles, Ventura, Orange, and San Bernardino counties. The Northridge earthquake tragically resulted in 60 fatalities, over 7,000 injuries, and left thousands homeless.
According to Sobieszczyk, Southern California’s susceptibility to major earthquakes stems from a tectonic plate boundary that runs parallel to the state’s coastline.
This boundary, known as the San Andreas Fault, marks the zone where the Pacific plate slides past the North American plate, generating significant seismic waves.
The southern segment of the San Andreas Fault passes within 35 miles of Los Angeles, making the city particularly vulnerable to earthquakes originating from this fault. A major earthquake in this region could potentially cause up to 1,800 deaths and inflict damages estimated at $213 billion.