Regime-dependent vertical land motion controls on Icelandic coastal sea-level trends: A multi-source geodetic assessment
Marine Geology, cilt.503, sa.January 2027, ss.1, 2027 (Hakemli Dergi)
- Yayın Türü: Makale / Tam Makale
- Cilt numarası: 503 Sayı: January 2027
- Basım Tarihi: 2027
- Doi Numarası: 10.1016/j.margeo.2026.107927
- Dergi Adı: Marine Geology
- Sayfa Sayıları: ss.1
- Yıldız Teknik Üniversitesi Adresli: Evet
Özet
Iceland is one of the most geodynamically complex coastal settings on Earth: glacial isostatic adjustment, present-day glacial unloading, volcanic deformation, and mid-ocean-ridge spreading all act at once, so tide gauges there record a mix of land motion and ocean change rather than ocean change alone. The land-motion component is isolated by comparing tide-gauge sea-level trends with satellite altimetry trends at five Icelandic stations spanning contrasting geodynamic settings over 1997–2023, using the DUACS L4 reprocessed altimetry product. Tide-gauge trends range from −3.71 ± 1.02 mm/yr at glacially-rebounding Hofn–Hvanney up to +10.10 ± 1.12 mm/yr (Olafsvik) and + 9.10 ± 0.60 mm/yr at volcanically-subsiding Sandgerdi, while altimetry trends are far more uniform, from +2.43 to +3.59 mm/yr. The resulting land-motion estimates are evaluated against independent GNSS velocities and three glacial-isostatic-adjustment models. At Hofn–Hvanney the land is rising by +6.72 mm/yr by this estimate; the nearest GNSS velocity exceeds the glacial-isostatic-adjustment prediction by +10.32 mm/yr, consistent with a substantial elastic response to present-day Vatnajokull ice loss, a process the standard models do not capture. At Sandgerdi the land is subsiding by −6.41 mm/yr, consistent with independent radar-interferometry velocities of −5.26 mm/yr and with the volcanic unrest that began on the Reykjanes Peninsula in 2020. The spread across the three glacial-isostatic-adjustment models themselves ranges from 0.39 mm/yr at Olafsvik to 2.65 mm/yr at Hofn–Hvanney. These results show that reliable coastal sea-level monitoring in geodynamically active regions requires decomposing the land-motion budget separately for each geodynamic setting, rather than applying a single regional correction.
Iceland is one of the most geodynamically complex coastal settings on Earth: glacial isostatic adjustment, present-day glacial unloading, volcanic deformation, and mid-ocean-ridge spreading all act at once, so tide gauges there record a mix of land motion and ocean change rather than ocean change alone. The land-motion component is isolated by comparing tide-gauge sea-level trends with satellite altimetry trends at five Icelandic stations spanning contrasting geodynamic settings over 1997–2023, using the DUACS L4 reprocessed altimetry product. Tide-gauge trends range from −3.71 ± 1.02 mm/yr at glacially-rebounding Hofn–Hvanney up to +10.10 ± 1.12 mm/yr (Olafsvik) and + 9.10 ± 0.60 mm/yr at volcanically-subsiding Sandgerdi, while altimetry trends are far more uniform, from +2.43 to +3.59 mm/yr. The resulting land-motion estimates are evaluated against independent GNSS velocities and three glacial-isostatic-adjustment models. At Hofn–Hvanney the land is rising by +6.72 mm/yr by this estimate; the nearest GNSS velocity exceeds the glacial-isostatic-adjustment prediction by +10.32 mm/yr, consistent with a substantial elastic response to present-day Vatnajokull ice loss, a process the standard models do not capture. At Sandgerdi the land is subsiding by −6.41 mm/yr, consistent with independent radar-interferometry velocities of −5.26 mm/yr and with the volcanic unrest that began on the Reykjanes Peninsula in 2020. The spread across the three glacial-isostatic-adjustment models themselves ranges from 0.39 mm/yr at Olafsvik to 2.65 mm/yr at Hofn–Hvanney. These results show that reliable coastal sea-level monitoring in geodynamically active regions requires decomposing the land-motion budget separately for each geodynamic setting, rather than applying a single regional correction.