マサヤ火山の地下に2つの活動中マグマ溜まりを確認（Double trouble: Two active magma reservoirs indicated at Masaya volcano）

2026-10-01 ペンシルベニア州立大学(Penn State)

＜関連情報＞

• https://www.psu.edu/news/earth-and-mineral-sciences/story/double-trouble-two-active-magma-reservoirs-indicated-masaya
• https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2026GL123214

二重の脅威：衛星測地学を用いてニカラグアのマサヤ火山で2つの活発なマグマ溜まりが特定される Double Trouble: Two Active Magma Reservoirs Identified at Masaya Volcano, Nicaragua, Using Satellite Geodesy

E. Johnson, Y. C. Kim, C. Wauthier
Geophysical Research Letters  Published: 23 July 2026
DOI:https://doi.org/10.1029/2026GL123214

Abstract

We analyze and model ground deformation at Masaya volcano, Nicaragua, using Sentinel-1 Interferometric Synthetic Aperture Radar (InSAR) time series spanning January 2018–February 2024. Time series show the Masaya Central Reservoir (MCR) experienced ∼3 cm of line of sight (LOS) displacement away from the satellite north of the Santiago crater from 2018 to mid-2022 (Period 1), followed by movement toward the satellite from mid-2022 to 2024 (Period 2), interpreted as inflation of the MCR due to new magma supply from depth. Using a point-source (“Mogi” model), our geodetic inversions identify a preferred source location of the approximate center of the Masaya caldera, a depth of ∼3,200 m, and a volume change of ∼−1.3 × 10⁶ m³ in Period 1 and ∼4.5 × 10⁵ m³ in Period 2. Throughout 2018–2024, the area around the active Santiago crater consistently showed motion away from the satellite, attributed to a second deflating shallower reservoir located at ∼200 m depth.