On December 19, 2025, a series of new government reports and expert analyses cast a sobering light on Tokyo’s ever-present earthquake risk, revealing that a major seismic event could still spell disaster for Japan’s capital and its surrounding prefectures—despite years of dedicated mitigation efforts. The latest projections, released by a government panel and widely reported by outlets including Kyodo News Agency and BERNAMA, estimate that a powerful earthquake beneath Tokyo could result in as many as 18,000 fatalities, a figure that, while lower than previous estimates, still exceeds the government’s own reduction targets.
The scenario assumes a magnitude 7.3 quake striking the metropolitan area, with the epicenter in the southern central part of Tokyo. According to the panel, two-thirds of the projected deaths—about 12,000—would be the result of fires ignited in the aftermath, a chilling reminder of the city’s vulnerability to both natural and secondary disasters. The remaining fatalities are expected to stem from building collapses, with an estimated 5,300 people losing their lives as structures crumble under the intense shaking. The panel’s calculations also account for deaths linked to indirect consequences, such as prolonged stays in disaster shelters, with this number estimated to fall between 16,000 and 41,000 depending on the severity of infrastructure outages.
This new estimate marks a reduction of 5,000 deaths compared to the government’s 2013 forecast, a change attributed to improved seismic retrofitting, the widespread installation of seismic breakers, and enhanced fire prevention measures in Tokyo’s densely packed wooden neighborhoods. As reported by BERNAMA-Kyodo, “the latest estimate, made on the basis of a magnitude 7.3 quake hitting the metropolitan area, is 5,000 lower than the previous calculation in 2013, reflecting an increase in seismic-prepared buildings and fire prevention measures in densely packed districts with many wooden houses.”
Still, the projected toll remains higher than the government’s stated goal of halving fatalities from the 2013 estimate. The government’s ambition to reduce deaths is underscored by the stark comparison to the 2011 disaster in northeastern Japan, when a magnitude 9.0 earthquake and tsunami claimed 15,900 lives. The Tokyo scenario, though involving a lower-magnitude quake, would strike the heart of the nation’s political and economic center, potentially crippling core functions and infrastructure.
Economic losses from such a disaster would be staggering. The government’s worst-case scenario projects damages totaling 82.6 trillion yen (about US$530 billion), a figure that includes both direct destruction—such as the collapse and burning of up to 402,000 buildings—and indirect losses from reduced business activity over the following year. This estimate, while down by around 13 trillion yen from the previous projection, still represents a massive blow to Japan’s economy. The breakdown includes approximately 45 trillion yen in direct losses from building collapses and fires, and an additional 38 trillion yen in lost productivity as businesses struggle to recover.
Timing and weather conditions could dramatically worsen the situation. The worst-case scenario envisions the quake striking at 6:00 pm on a winter evening, with winds blowing at 8 meters per second (about 28.8 kilometers per hour). Such conditions would fan the flames of post-quake fires and increase the risk of casualties. In this scenario, 110,000 buildings could collapse and 270,000 could be consumed by fire, according to government figures reported by Tuoi Tre News.
The human impact would not be limited to those killed or injured in the initial disaster. The government estimates that up to 4.8 million people could be forced to evacuate their homes within two weeks if power and water outages persist. Even more striking, about 8.4 million people across Tokyo and the neighboring prefectures of Chiba, Kanagawa, Saitama, and Ibaraki could be stranded and unable to return home, especially if the quake occurs during a weekday at noon. This figure includes up to 880,000 visitors—foreign tourists and business travelers—who could find themselves trapped far from shelter or support.
In a separate estimate, the panel considered the possibility of a magnitude 8 earthquake along the Sagami Trough, south of the capital. Although the likelihood of such an event occurring in the near future is considered low, the potential consequences are even more dire: up to 23,000 deaths, primarily due to the risk of a devastating tsunami and the need for rescue operations across a much broader area. This figure is a significant reduction from earlier estimates of 70,000 deaths, reflecting improvements in disaster preparedness and modeling.
Tokyo’s vulnerability to mass stranding is a particular concern for disaster planners. According to a Japanese government panel cited by NHK, if everyone tries to go home at once following a major quake, the resulting congestion could lead to falls, medical emergencies, and block emergency vehicles from reaching those in need. University of Tokyo Professor Hiroi Yu cautioned, “movement after massive disasters is harder than one would imagine,” and advised that “the basic rule is for people not to move once they are in a safe location, and not to try to go home immediately.” He further emphasized the importance of multiple methods for confirming the safety of loved ones, recommending the Disaster Emergency Message Dial system as a backup to phones, email, and social media.
Complicating matters further, the government has voiced concerns about the spread of artificial intelligence-generated fake images and misinformation on social media in the chaotic aftermath of a major quake. Such misinformation could spark panic, disrupt rescue efforts, and make it even harder for authorities to coordinate an effective response.
Recognizing these challenges, Japan’s disaster management minister Jiro Akama has pledged to use the new data to update preparedness and response measures. “We should maintain the capital’s core functions and reduce extreme damage,” Akama stated, signaling a renewed commitment to safeguarding Tokyo’s critical infrastructure and population. The government also plans to launch a new disaster management agency in fiscal 2026, aiming to strengthen efforts to reduce damage and ensure continuity of governance in the event of a major earthquake.
Despite the daunting figures, the reduction in projected deaths and property loss compared to previous estimates is a testament to the effectiveness of Japan’s ongoing investments in seismic safety and disaster readiness. The widespread retrofitting of buildings, advances in fire prevention, and the development of robust communication systems have all contributed to a more resilient metropolis. Yet, as the latest reports make clear, the risk remains very real—and the human, economic, and social consequences of a major quake would reverberate far beyond Tokyo’s city limits.
For now, the message from experts and officials is clear: continued vigilance, public education, and investment in preparedness are essential to reducing the toll when—not if—the next great earthquake strikes Tokyo.
