三陸沖でスロースリップ加速　大地震発生につながる恐れは？真夏の地震対策も急務【サタデーステーション】(2026年5月30日)

Off the coast of Sanriku, a phenomenon called "slow slip," which is said to potentially trigger a massive earthquake, is accelerating. Furthermore, since April, earthquakes of magnitude 5 or higher have occurred in various locations. What is happening around Japan right now? (May 30th broadcast of "Saturday Station") ■ Slow Slip: Occurred before the Great East Japan Earthquake On the 15th of this month, an earthquake with a maximum seismic intensity of 5- occurred in Miyagi Prefecture. The Tohoku Shinkansen temporarily suspended operations, and a wide area was affected. Also, on April 20th, a magnitude 7.7 earthquake occurred off the coast of Sanriku. A 79 cm tsunami was observed at Kuji Port in Iwate Prefecture, and a warning for a subsequent earthquake off the coast of Hokkaido and Sanriku was issued. In addition, earthquakes with a maximum seismic intensity of 5-+ have occurred in northern Nagano Prefecture and the Amami region of Kagoshima Prefecture. Since April, a total of seven earthquakes with a seismic intensity of 5- or higher have been observed throughout Japan. Among the areas experiencing increased seismic activity, the Sanriku coast is currently the most active. The government's Earthquake Research Committee announced that since the April 20th Sanriku offshore earthquake, an acceleration of slow slip (non-seismic slip) without accompanying shaking has been confirmed around the epicenter. They are warning of the potential for a major earthquake. In fact, this type of slow slip occurred before the Great East Japan Earthquake, and it has been suggested that it may have triggered a massive earthquake. Is there a possibility of another major earthquake occurring off the Sanriku coast? Yutaro Okada, Assistant Professor, International Research Institute of Disaster Science, Tohoku University: "The amount of strain distributed by slow slip is very small. However, it could potentially be the final push that triggers an earthquake." Slow slip is a phenomenon where strain is released over time as a fault slowly shifts. At the same time, strain is transferred to another location, and if this strain is added to an area where strain has already accumulated, it could potentially accelerate the occurrence of an earthquake. However, slow slips have been observed in the Nankai Trough and off the coast of Chiba Prefecture, and they do not necessarily lead to major earthquakes. Yutaro Okada, Assistant Professor, International Research Institute of Disaster Science, Tohoku University: "The difference between slow slips that lead to major earthquakes and ordinary slow slips that do nothing will be an important topic for future research." Meanwhile, Professor Emeritus Junzo Kasahara of the University of Tokyo points out the possibility that seismic activity off the coast of Sanriku could lead to major earthquakes in other areas. Junzo Kasahara, Professor Emeritus, University of Tokyo: "In the past, seismic activity off the coast of Sanriku has been associated with earthquakes off the coast of Kushiro, Nemuro, and Shikotan. Therefore, since an earthquake of about magnitude 8 occurred in Shikotan after this (Sanriku earthquake), and especially after the Tokachi-oki earthquake, these areas (off the coast of Nemuro and Kushiro) also have a high probability of being linked." He also says he is paying attention to the earthquake that occurred in northern Nagano Prefecture last month. Professor Emeritus Junzo Kasahara, University of Tokyo: "There were about two earthquakes of around magnitude 5 in quick succession along the Itoigawa-Shizuoka Tectonic Line fault zone. Since this fault zone is connected to the Nankai Trough, overall, there's a possibility that activity related to the Nankai Trough is quite active." ■ Evacuation in the midst of extreme heat: A major challenge A massive earthquake could strike at any time. One thing we must be careful about is the intense summer heat. Last July, the Kamchatka Peninsula earthquake occurred. Tsunami warnings were issued for a wide area on the Pacific coast. Many people were forced to evacuate for extended periods in the intense heat, and some were hospitalized due to heatstroke. Professor Yamori of the Disaster Prevention Research Institute, Kyoto University, points out that measures to cope with the heat after evacuation were insufficient. Professor Katsuya Yamori, Disaster Prevention Research Institute, Kyoto University: "We've received reports of people fleeing outdoors but finding it too hot, or even indoors, finding it unheated due to a lack of air conditioning. In the worst-case scenario, we're concerned that there could be casualties, such as disaster-related deaths." Local governments are being forced to take action. Tomoaki Miyagawa, Head of the Information and Disaster Prevention Division, Kuroshio Town: "Those are the solar panels that were installed last year." Kuroshio Town, located on the Pacific coast of Kochi Prefecture, is projected to expe...