Deadly Megaquake and Tsunami Could Leave Japan, Indonesia, China, Australia, Hawaii, and the west coast of North and South America?
A megaquake and resulting tsunami could impact Japan, Indonesia, China, Australia, Hawaii and the west coasts of North and South America. A massive earthquake with a magnitude of 9.0 or higher—along with a resulting tsunami, could potentially affect these regions, depending on its location and characteristics. Megaquakes typically occur along subduction zones, where tectonic plates converge, and they can displace enormous volumes of water, generating tsunamis that travel across oceans.
Let’s break this down by region based on known geological risks:
Japan: Japan sits on the Pacific Ring of Fire and has a history of megaquakes, like the 9.1 magnitude Tohoku earthquake in 2011, which triggered a devastating tsunami. A future megaquake along the Nankai Trough or Japan Trench could again cause widespread destruction and a deadly tsunami.
Indonesia: Also on the Ring of Fire, Indonesia is prone to megaquakes due to the subduction of the Indian Plate beneath the Sunda Plate. The 9.1–9.3 magnitude Sumatra-Andaman earthquake in 2004 generated a tsunami that killed over 227,000 people across multiple countries, showing the region’s vulnerability.
China: While China itself isn’t directly on a major subduction zone, its southeastern coast could be affected by tsunamis from megaquakes in nearby regions, such as the Philippine Sea Plate or South China Sea. The impact would depend on proximity and wave direction.
Australia: Australia’s northern and western coasts face some tsunami risk from earthquakes in Indonesia or the Pacific. The 2004 Indian Ocean tsunami caused minor surges along Western Australia’s coast, but a closer megaquake could have a larger effect, though the continent’s stable interior shields it from direct quakes of this scale.
Hawaii: Located in the central Pacific, Hawaii is highly vulnerable to tsunamis from megaquakes around the Pacific Rim. The 1946 Aleutian Islands earthquake (8.6 magnitude) and the 1960 Chile earthquake (9.5 magnitude) both sent destructive tsunamis to Hawaii, killing dozens.
West Coast of North America: The Cascadia Subduction Zone, stretching from Northern California to British Columbia, is capable of producing a magnitude 9+ earthquake. Such an event could generate a massive local tsunami, inundating coastal areas within minutes, while also sending waves across the Pacific. The 2011 Japan tsunami caused significant damage in California and Oregon, demonstrating this risk.
West Coast of South America: Chile and Peru lie along the Nazca Plate’s subduction zone, one of the most active seismic regions globally. The 1960 Valdivia earthquake (9.5 magnitude), the largest ever recorded, triggered a tsunami that devastated Chile and reached Hawaii, Japan, and beyond. A similar event could again threaten this coast and radiate outward.
Could One Event Affect All These Places?
A single megaquake and tsunami impacting all these regions simultaneously would require an extraordinarily powerful event in a specific location, likely in the Pacific Ocean, given its vast reach. The Pacific Ring of Fire hosts most of the world’s subduction zones, making it the prime candidate. For example:
A megaquake in the Cascadia Subduction Zone could devastate the U.S. and Canadian west coasts and send waves toward Hawaii, Japan, and possibly Australia.
A repeat of the 2004 Sumatra event could hit Indonesia, Australia, and parts of China’s coast, with smaller waves reaching the Americas via the Indian and Pacific Oceans.
A Chilean megaquake could strike South America, Hawaii, Japan, and the U.S. West Coast, as seen in 1960.
However, the energy of a tsunami dissipates as it travels, so while distant regions might experience waves, the deadliest impacts are usually closer to the epicenter. A truly global catastrophe affecting all these areas at full force is less likely from one event, but a series of megaquakes in a short period (triggered by stress transfer along fault lines) could compound the danger.
Areas at Risk
Japan Japan’s economy could lose $1.81 trillion if a megaquake were to occur off its Pacific coast, potentially triggering tsunamis and building collapses that could kill around 300,000 people. There is an 80% chance of a magnitude 8 to 9 earthquake along the Nankai Trough, which runs 900 km off Japan’s southwest Pacific coast, where the Philippine Sea Plate is subducting under the Eurasian Plate. A magnitude 9 quake in 2011 killed more than 15,000 people and triggered a tsunami and reactor meltdowns at a nuclear power plant.
Indonesia A magnitude 9.2 earthquake struck off the coast of Northern Sumatra, Indonesia, in 2004, causing a tsunami that led to over 227,000 fatalities and displaced 1.7 million people across 14 countries. Some houses along the coast in Jayapura, Indonesia were destroyed during the 2011 Tōhoku earthquake and tsunami.
China Following an 8.2-magnitude earthquake in Myanmar on March 28, 2025, China issued a tsunami warning, raising concerns about potential localized waves.
Australia The 2004 tsunami caused by the earthquake in Indonesia also affected Australia.
Hawaii During the 2011 Tōhoku earthquake and tsunami, Hawaii estimated damage to public infrastructure alone at $3 million, with damage to private properties, including resort hotels, estimated at tens of millions of dollars.
West Coast of North and South America Tsunami surges were reported along the Pacific Coast of Mexico and South America after the 2011 earthquake in Japan, but caused little damage in most places. In Peru, a 1.5 m wave damaged more than 300 homes, while in Chile, a surge damaged more than 200 houses, with waves reaching up to 3 m. In the Galápagos Islands, a 3 m surge injured one man and damaged buildings
Current Risks: As of today, March 31, 2025, no specific megaquake is predicted, but these regions remain at risk due to their tectonic settings. Early warning systems, like the Pacific Tsunami Warning Center, help mitigate loss of life, though infrastructure damage remains a major concern. Scientists continue to monitor subduction zones for signs of strain buildup, but predicting exact timing remains impossible.
