Megatsunami warning: Three US States could face direct impact within 50 years

Time of India

20-05-2025

A groundbreaking study from Virginia Tech, published in the
, has issued an urgent warning: within the next 50 years, three U.S. states—Alaska, Hawaii, and Washington—are at significant risk of experiencing catastrophic megatsunamis.
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These colossal waves, potentially reaching up to 1,000 feet, could result from massive earthquakes and geological events, threatening millions of lives and causing unprecedented damage.
What is a megatsunami ?
A megatsunami is a very large wave created by a large, sudden displacement of material into a body of water. Unlike an ordinary tsunami, a megatsunami is characterized by extremely large wave heights, often hundreds of meters, and is typically caused by massive underwater displacements like large landslides or volcanic eruptions.
Megatsunamis can reach wave heights of hundreds of meters and are often triggered by massive underwater events like large landslides, glacier collapses, or meteorite impacts. Megatsunamis can inundate coastal areas much further inland and with greater force than regular tsunamis.
In October 1936, a megatsunami occurred in Lituya Bay in Alaska with a maximum run-up height of 150 metres (490 ft) in Crillon Inlet at the head of the bay.
The four eyewitnesses to the wave in Lituya Bay itself all survived and described it as between 30 and 76 metres (100 and 250 ft) high.
Cascadia Subduction Zone : A ticking time bomb
Stretching from Northern California to Vancouver Island, the Cascadia Subduction Zone is a major fault line where the Juan de Fuca Plate is slowly sinking beneath the North American Plate. This tectonic boundary has the potential to produce a magnitude 8.0 or greater earthquake, with scientists estimating a 15% chance of such an event occurring within the next 50 years.
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The last significant rupture along this fault occurred in 1700, but the risk remains high.
A major earthquake in this region could cause coastal land to sink by up to 6.5 feet, dramatically expanding floodplains and increasing flood risks. The resulting tsunami could send waves up to 40 feet high, devastating communities along the Pacific Northwest coast, including northern California, northern Oregon, and southern Washington.
Experts warn that public awareness remains low, and evacuation times could be as short as 10 minutes, leaving little room for escape.
Alaska: A double threat from earthquakes and landslides
Alaska faces a dual threat from both seismic activity and climate change-induced landslides. The Aleutian Islands, part of the Pacific Ring of Fire, are prone to powerful earthquakes. A study from the University of Hawaiʻi at Mānoa estimates a 9% chance of a magnitude 9.0 or greater earthquake in the Aleutians within the next 50 years.
Such an event could generate a mega-tsunami with waves reaching up to 75 feet, impacting coastal communities along the Alaska Peninsula and potentially affecting areas as far away as Hawaii.
Additionally, melting glaciers in Alaska are destabilizing slopes, increasing the risk of massive landslides into the ocean. These landslides can displace large volumes of water, generating tsunamis that could inundate nearby coastal areas.
The combination of seismic and climatic factors makes Alaska particularly vulnerable to devastating tsunami events.
Hawaii: Volcanic collapses pose tsunami risk
Hawaii's unique geological features also place it at risk. The Big Island's active volcanoes, such as Kīlauea, are susceptible to flank collapses—massive landslides where large sections of the volcano's flank slide into the ocean. These collapses can displace enormous amounts of water, generating tsunamis that can affect coastal areas of Hawaii.
While the probability of such events is lower compared to other regions, the potential impact on Hawaii's densely populated coastal areas makes it a significant concern.
Urgent call for preparedness:
The study underscores the need for immediate action to prepare for potential mega-tsunamis. Experts advocate for enhanced
, improved infrastructure, and public education campaigns to ensure communities are ready to respond effectively. In the Pacific Northwest, for instance, FEMA estimates that a magnitude 9 earthquake along the Cascadia Subduction Zone could result in over 13,000 fatalities and displace more than a million people.
Coastal regions must invest in resilient infrastructure, including elevated buildings and tsunami-resistant designs, to withstand the impacts of such disasters. Additionally, updating evacuation plans and conducting regular drills can save lives by ensuring that residents know how to respond quickly and safely.
Global implications and climate change considerations:
While the immediate focus is on the United States, the global implications of mega-tsunamis are profound.
Rising sea levels due to climate change exacerbate the risks associated with these events, as higher ocean levels can increase the extent of flooding and damage. International collaboration in monitoring seismic activity and sharing early warning information is crucial to mitigate the effects of such disasters worldwide.
Conclusion:
The recent study serves as a stark reminder of the vulnerabilities faced by coastal regions in Alaska, Hawaii, and the Pacific Northwest.
With the potential for mega-tsunamis within the next 50 years, these communities must take proactive measures to prepare for such catastrophic events. Through enhanced preparedness, resilient infrastructure, and public awareness, the impact of these disasters can be mitigated, saving lives and protecting livelihoods.
As scientists continue to monitor seismic activity and climate change effects, the need for comprehensive disaster planning and international cooperation becomes ever more critical. By learning from past events and investing in future resilience, we can better safeguard our coastal communities against the looming threat of mega-tsunamis.
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