Latest news with #NaoshiHirata
Yomiuri Shimbun
10-07-2025
- Science
- Yomiuri Shimbun
Undersea Magma, Water May Be Inducing Quakes Around Tokara Islands; Lack of Instruments Nearby Limits Data
The detailed mechanism for the succession of earthquakes occurring off the Tokara Islands in Kagoshima Prefecture since June 21 remains unclear. Significant crustal movements have been confirmed in the surrounding area, and experts have said that these may be connected to the movements of undersea magma or water. According to the Japan Meteorological Agency, there have been 1,725 earthquakes measuring 1 or stronger on the Japanese seismic intensity scale of 7 around the islands which include Akusekijima Island, by 5 p.m. Wednesday. 'Very large crustal movements have been observed,' said Naoshi Hirata, chairperson of the government's Earthquake Research Committee and professor emeritus at the University of Tokyo, at a press conference Wednesday. Takarajima Island shifted 1.8 centimeters northeast between early June and July 2, according to analysis by the Geospatial Information Authority of Japan. Just before an earthquake that measured lower 6 on the intensity scale hit Akusekijima Island on July 3, Takarajima Island moved another 4.2 centimeters, this time to the south.'Knowing that the direction of crustal movements changed before the earthquake is very valuable information,' Hirata said. The oceanic Philippine Sea Plate subducts beneath the continental Eurasian Plate on the eastern side of the Tokara Islands. Superheated water can be released from parts of the subducting plate that are under extreme pressures. This superheated water melts surrounding rock layers, creating a 'magma reservoir.' It is hypothesized that an upflow of such magma is causing the earthquakes and crustal movements. There is also a hypothesis that water is the direct cause of the earthquakes. 'The possibility is high that water has flowed into the fault plane, making the geologic fault more prone to slip and causes earthquakes. The change in the direction of crustal movements can be explained by the flow of water into another fault,' said Junichi Nakajima, a professor of seismology at the Institute of Science Tokyo. Since there are no observation instruments on Akusekijima Island to determine the focus of the quakes, there is insufficient data for clarifying the mechanism. The Education, Culture, Sports, Science and Technology Ministry, which oversees the Earthquake Research Committee, is considering installing temporary observation instruments on the island to address this issue.
Asahi Shimbun
08-07-2025
- Science
- Asahi Shimbun
Expert: No link between Tokara quakes and Nankai Trough
The 'Tokara Theory' circulating online speculates that a series of recent earthquakes in Akusekijima and other Tokara islands will precede the long-anticipated Nankai Trough megaquake. (Provided by Kyushu Asahi Broadcasting Co.) The nation's top earthquake expert has dismissed claims circulating online that the recent chain of intense seismic activity off Kagoshima Prefecture's coast signals an impending Nankai Trough megaquake, saying there is no scientific evidence to support the connection. 'This is my personal view, but there is no study or data showing a causal link between earthquakes in the Tokara island chain and those in other regions,' said Naoshi Hirata, a seismologist and professor emeritus at the University of Tokyo, on July 7. Hirata made the comment following a regular meeting of the government expert panel he chairs, which assesses the risk of the long-expected Nankai Trough megaquake expected to occur within the next three decades. More than 1,600 tremors have been recorded in the Tokara region since June 21, ranging from barely perceptible ones to those strong enough to topple items off shelves and cause a fissure. This prompted social media speculation under the so-called 'Tokara Theory'—a hypothesis suggesting that the earthquakes in the Tokara area are a precursor to major seismic events in relatively distant parts of Japan. The largest tremor recorded in the recent Tokara swarm was below a magnitude 6. Hirata emphasized that earthquakes of this scale are not expected to affect areas as far as the main islands of Kyushu, Shikoku or Honshu—regions predicted to be impacted by a Nankai Trough earthquake. While downplaying the connection to a larger seismic event, Hirata reiterated the importance of general disaster preparedness. 'Japan is a country where earthquakes occur frequently,' he said. 'You should always be prepared to protect your life.'
Yomiuri Shimbun
29-06-2025
- Science
- Yomiuri Shimbun
Govt Panel Warns of Major Sea of Japan Quake;Probability Seen as 18% in Next 30 Years
The government's Earthquake Research Committee announced Friday that active submarine faults in the central to southern Sea of Japan off the coast from Hyogo to Toyama prefectures have a 16% to 18% probability of generating a magnitude-7 or larger earthquake within the next 30 years. Although the Noto Peninsula northern coast fault zone, which produced the magnitude-7.6 Noto Peninsula Earthquake in January 2024, was rated at almost 0% probability for another such event in that time frame, the committee urged caution because surrounding faults could still trigger major quakes. In response to the Noto Peninsula Earthquake, the committee released preliminary fault-location data last August. This time it assessed 23 offshore active faults capable of producing magnitude-7 or larger events that could bring shaking of lower-6 or stronger on Japan's seismic intensity scale and tsunami at least 1 meter high. Dividing the stretch of coast into eastern and western areas, the committee calculated that the eastern area, which has 14 faults including the Noto Peninsula northern coast fault zone that is capable of causing magnitude-7.8 to magnitude-8.1 events, has a 12% to 14% probability of a major quake. In the western area, which has nine faults with maximum potential quakes of around magnitude-7.7, the probability is 4% to 6%. In 1927, the western area experienced the magnitude-7.3 North Tango Earthquake, which claimed 2,912 lives. Committee chair Naoshi Hirata, a University of Tokyo professor emeritus, commented at a press conference: 'A probability exceeding 10% is extremely high. Please do not relax, thinking, 'An earthquake won't strike for a while.' Instead, prepare through disaster drills and other measures.'
&w=3840&q=100)
First Post
28-06-2025
- Science
- First Post
Govt panel says megaquake may hit Japan within next 30 years
Japan's Earthquake Research Committee warned the quake can occur in any of the 23 active faults and fault zones spanning at least 20 kilometres in the Sea of Japan read more Japan's Noto Peninsula was shaken by a massive 7.5 earthquake on January 1 last year A Japanese government panel has predicted that there is a 16 to 18 per cent likelihood of central Japan getting hit by a megaquake within the next 30 years. The Earthquake Research Committee announced Friday (June 27) that active faults off Kinki western region and Hokuriku central region were projected to trigger a quake of magnitude 7 or higher. The quake can occur in any of the 23 active faults and fault zones spanning at least 20 kilometres in the Sea of Japan, the panel said. STORY CONTINUES BELOW THIS AD The likelihood of a magnitude 7.0 or greater earthquake occurring along the western nine faults, primarily off the northern coast of the Kinki region, is estimated at 4 to 6 per cent. For the eastern 14 faults, including those off the Noto Peninsula, the probability is higher, ranging from 12 to 14 per cent. 'About 10% in the next 30 years is a high figure, signaling that (a large earthquake) could happen while we are alive,' University of Tokyo professor emeritus Naoshi Hirata, who heads the committee, was quoted as saying by Japan Times. 'We hope people will take measures such as making homes earthquake-resistant and securing furniture.' The fault zone north of the Noto Peninsula, the epicentre of the 2024 earthquake, has a near-zero percent chance of triggering a major quake in the next 30 years. Conversely, a fault and segments of a fault zone west of the peninsula are deemed the most likely among 23 sites to cause a significant quake, with probabilities of 1 to 2 per cent each. 'An earthquake like that of last year may not occur in a fault zone on the northern coast of the Noto Peninsula for a while, but it's quite possible that such a quake will occur in another area,' Hirata said. STORY CONTINUES BELOW THIS AD Notably, Japan's Noto Peninsula was shaken by a massive 7.5 earthquake on January 1 last year as the world celebrated the arrival of the New Year. Hirata urged the government to prepare for potential tremors and tsunamis at a scale on par with previous earthquakes. The panel also provided long-term evaluations and data on expected seismic intensity for quakes across the 23 faults. A quake in a fault off the coast of Fukui Prefecture is projected to reach a lower 6 on the Japanese seismic scale, the third-highest level, in parts of Fukui City.
Japan Times
28-06-2025
- Science
- Japan Times
Megaquake may hit central Japan within next 30 years, government panel says
Marine active faults off Japan's Kinki western region and Hokuriku central region are projected to trigger an earthquake with a magnitude of 7 or larger at a probability of 16% to 18% within the next 30 years, according to a government panel. The government's Earthquake Research Committee calculated the probability of such a temblor occurring in any of the 23 active faults and fault zones spanning at least 20 kilometers in the Sea of Japan, it announced Friday. Following the massive Noto Peninsula earthquake in central Japan in January 2024, the committee released information on the locations and lengths of the marine active faults, as well as the estimated magnitudes of possible quakes from them, in August 2024. The probability of a quake with a magnitude of 7.0 or higher occurring in the western nine faults, mainly off the northern coast of the Kinki region, stood at 4% to 6%, while that for the eastern 14 faults, including off the Noto Peninsula, came to 12% to 14%. "About 10% in the next 30 years is a high figure, signaling that (a large earthquake) could happen while we are alive," said University of Tokyo professor emeritus Naoshi Hirata, who heads the committee. "We hope people will take measures such as making homes earthquake-resistant and securing furniture." A fault zone to the north of the Noto Peninsula was projected to have nearly zero percent probability of causing a large quake in the next three decades, as it was the hypocenter of the 2024 earthquake. Meanwhile, a fault and parts of a fault zone to the west of the peninsula were assessed as being most likely to cause a large quake among the 23 sites, at 1% to 2% each. "An earthquake like that of last year may not occur in a fault zone on the northern coast of the Noto Peninsula for a while, but it's quite possible that such a quake will occur in another area," Hirata said. He stressed the need to prepare for possible tremors and tsunamis at a scale on par with last year's temblor. The committee newly recognized a fault off the coast of Toyama Prefecture, central Japan, as an active one, finding a 0.9% to 1% likelihood of causing an earthquake with a magnitude of 7.0. It will assess three faults off the coast of Niigata Prefecture, central Japan, next time, due to geological differences with other faults. Along with the long-term evaluations, the panel also released data on expected seismic intensity from quakes in the 23 faults. It said that a quake in a fault off the coast of Fukui Prefecture, central Japan, is seen registering lower 6, the third highest, on the Japanese seismic scale in some areas of Fukui's capital city of the same name. Meanwhile, a quake in a fault off Ishikawa Prefecture is projected to measure lower 6 in some areas of the prefectural capital of Kanazawa.
