The mid-crustal low-velocity zones in Iceland revealed by multimodal surface wave

The evolution of the Icelandic crust has been significantly influenced by magmatism associated with the Icelandic hotspot and the Mid-Atlantic Ridge. The spreading mid-ocean ridge and fissure swarms create favorable conditions for magma migration, feeding active volcanic activities on the surface. Previous receiver function studies have reported the mid-crustal low-velocity zone (MCLVZ) as a crucial characteristic. However, it is absent in the previous model representing the overall features of Iceland. Recently, the frequency-Bessel transform method (F-J method) has been proposed, enabling the effective extraction of multi-mode dispersion curves from ambient noise data. We collect continuous seismic data from the HOTSPOT network in Iceland for 2 years, as well as other supplementary data, covering the main regions of Iceland. Using the F-J method, we extract multi-mode dispersion curves of 0.02-0.4 Hz. Subsequently, we obtain an Icelandic average Vs model, including an MCLVZ with an amplitude of 3%. Moreover, through the analysis of local region data, we identify MCLVZs in the western fjords and the central volcanic zone of Iceland. Our results supplement the previously lacking MCLVZ feature in the Icelandic average structure, suggesting the presence of MCLVZs in both volcanic and non-volcanic regions of Iceland. The elevated temperature and partial melting associated with the volcanic activity may be not the sole reasons for MCLVZs. Further research on the distribution of MCLVZs in Iceland is needed in the future.