On the Move: 2023 Observations on Real Time Graben Formation, Grindavík, Iceland

• Published in: Geophysical Research Letters
• Main Authors: Gregory P. DePascale, Tomáš J. Fischer, William Michael Moreland, Halldór Geirsson, Pavla Hrubcová, Vincent Drouin, Danielle Forester, Méline Payet‐‐Clerc, Diana Brum daSilveira, Josef Vlček, Benedikt G. Ófeigsson, Ármann Höskuldsson, Helga Kristín Torfadóttir, Iðunn Kara Valdimarsdóttir, Birta Dís Jónsdóttir Blöndal, Ingibjörg Jónsdóttir, Sigurjón Jónsson, Thor Thordarson
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2024
• Subjects: Iceland; graben formation; plate boundary; tectonics; reykjanes peninsula; earthquakes; Geophysics. Cosmic physics; QC801-809; Grindavík
• Online Access: https://doi.org/10.1029/2024GL110150; https://doaj.org/article/5cda169356be4b4bb8975b3c34e32db2

Abstract Grabens, or valleys formed during extensional tectonic events, are common but rarely observed during formation. In November 2023, inelastic surface deformation formed abruptly along Iceland's plate boundary in Grindavík. We documented graben formation in real‐time through satellite mapping (InSAR), seismicity, GNSS data, repeated lidar surveys, and field mapping. Five normal faults and ∼12 fissures ruptured the surface delineating two grabens separated by a horst, a context not present in other contemporary case studies. The graben normal faults slipped rapidly (over hours) and maximum surface motions coincided with the occurrence of turbulent seismic swarms in both space and time. Although 3 eruptions took place ∼15 km northeast of Grindavík from 2021 to 2023, attributed to magma intrusions (i.e., dikes), none of these also formed grabens. Thus, the Grindavík grabens shows evidence for tectonic origins. Real‐time monitoring of these phenomena provide insight into graben formation on Earth and potentially on other planets.