Unimaginable economic losses amounting to $1.81 trillion, countless deaths potentially reaching up to 330,000, and catastrophic damages could result from a mega-earthquake striking Japan, according to a report published on Monday (31.03.2025). The report warns that such an earthquake would trigger devastating tsunamis and the collapse of hundreds of buildings. Issued as Japan anticipates a major earthquake along its Pacific coast, the report estimates damage totaling 270.3 trillion yen, nearly half of the country’s GDP, significantly higher than the previous estimate of 214.2 trillion yen. In the updated assessment, the report incorporates inflationary pressures and current data collected on-site, with an increased area expected to flood, as noted in the presidency’s report. Japan is one of the most earthquake-prone countries, and the government estimates an 80% probability for an earthquake between magnitudes 8 and 9 along the Nankai Trough. In the worst-case scenario, based on a magnitude 9 earthquake in the region, Japan might need to evacuate 1.23 million residents, approximately 10% of its total population. Up to 298,000 people could lose their lives due to tsunamis and building collapses if the earthquake occurs late at night during winter. The trench spans about 900 kilometers off the southwestern coast of Japan in the Pacific, where the Philippine Sea Plate subducts beneath the Eurasian Plate. The accumulated tectonic stress could result in a mega-earthquake roughly every 100 to 150 years. Last year, Japan issued its first warning for a ‘relatively higher probability’ of a magnitude 9 earthquake in the trench following a 7.1-magnitude quake at the trench’s edge. In 2011, a magnitude 9 earthquake caused a deadly tsunami and the subsequent nuclear disaster at the Fukushima Daiichi plant, claiming over 15,000 lives.