講演情報
[S25-06]SWOT衛星を用いた2025年カムチャツカ半島地震津波インバージョン解析
*石島 清宏1,2、綿田 辰吾3 (1. 東京大学大学院理学系研究科 地球惑星科学専攻、2. エム・アール・アイリサーチアソシエイツ株式会社、3. 東京大学地震研究所)
2025年7月29日23:25(UTC)頃にカムチャツカ半島付近で発生したM8.8の地震により津波が発生した．日本では久慈港で最大1.3mの津波が観測された他，アメリカ・ハワイ州やカリフォルニア州などでも1mを超える津波が観測された．NASAは陸域および海域の水面変動観測を目的とした干渉SAR，SWOT（Surface Water and Ocean Topography）を用いて本津波を観測したと発表した（NASA 2025）．NASA SWOTはカムチャツカ半島沖北緯45°東経165°の上空約900km付近を，地震発生70分後に通過し，水面変動を観測した．本研究では，NASA SWOTの観測データのうち潮位変動の補正を行った海面高データを用いて，震源域から遠ざかる方向に伝播している水面変動を確認するとともに，SWOT衛星観測データを用いた津波インバージョン解析の試みについて報告する．
On July 29, 2025, at about 23:25 UTC, an M8.8 earthquake occurred near the Kamchatka Peninsula, and the tsunami was observed in Japan, with a maximum height of 1.3 meters recorded at Kuji port. Additionally, tsunamis with heights exceeding 1 meter were observed in Hawaii and California, USA. NASA announced that interferometric SAR satellite SWOT (Surface Water and Ocean Topography), an interferometric SAR satellite operated by NASA to observe the water level change on land and sea, passed over the area approximately 900 km above 45°north latitude and 165°east longitude off the coast of the Kamchatka Peninsula 70 minutes after the earthquake and observed the sea surface height anomaly (NASA 2025). In this study, we used the sea level data from the NASA SWOT observations, corrected for tidal variations, to confirm the propagation of the sea surface variations in the directions away from the epicenter. We report tsunami source inversion analysis using the SWOT observation data.
On July 29, 2025, at about 23:25 UTC, an M8.8 earthquake occurred near the Kamchatka Peninsula, and the tsunami was observed in Japan, with a maximum height of 1.3 meters recorded at Kuji port. Additionally, tsunamis with heights exceeding 1 meter were observed in Hawaii and California, USA. NASA announced that interferometric SAR satellite SWOT (Surface Water and Ocean Topography), an interferometric SAR satellite operated by NASA to observe the water level change on land and sea, passed over the area approximately 900 km above 45°north latitude and 165°east longitude off the coast of the Kamchatka Peninsula 70 minutes after the earthquake and observed the sea surface height anomaly (NASA 2025). In this study, we used the sea level data from the NASA SWOT observations, corrected for tidal variations, to confirm the propagation of the sea surface variations in the directions away from the epicenter. We report tsunami source inversion analysis using the SWOT observation data.