Spatial and temporal volcanotectonic evolution of Santorini volcano, Greece

Abstract

Volcanic and tectonic activities in the Aegean region have controlled the evolution of Santorini volcano, including changes in the shape and size of the island through time. Previous studies associate much of the island’s volcanic activity with the presence of regional faults, but a comprehensive volcanotectonic study that clarifies the relationship between dyking and faulting in the island has not been made. Here we present a detailed structural analysis focused on the northern caldera wall of Santorini, where numerous dykes and faults outcrop and can be studied in the mesoscale. To augment our discussion of dyke and fault interactions, we combine previous volcanological and geophysical observations with our structural analysis to report the volcanotectonic evolution of the northern part of the island and design a conceptual spatial-temporal model. We mapped 91 dyke segments and 15 faults and classified the latter, where possible, with respect to their observed or recorded kinematics, their size, and the active stress field under which they were formed based on prior geophysical data. We relate our observations to a mechanical unconformity within the northern caldera wall. Our field observations, coupled with previous numerical, geophysical, and volcanological studies, offer insights on the interaction between dykes and faults and indicate the conditions under which the faults facilitated magma emplacement, or not, during the volcano’s activity. Our analysis attempts to answer an essential question: under what conditions do crustal faults facilitate or inhibit magma propagation to the surface, with application to the island of Santorini.

Volcano‐Tectonic Evolution of the Christiana‐Santorini‐Kolumbo Rift Zone

“…Instead, they are influenced by more complex faults such as the Kolumbo Fault or the Christiana Fault (Figure 5f) (Preine, Karstens, Hübscher, Crutchley, et al., 2022), which have much lower throws (<100 m). Also, faults observed within the Thera Pyroclastic Formation in the caldera of Santorini have only minor throws (<100 m) (Drymoni et al., 2022).…”

“…in Iceland (Acocella & Trippanera, 2016), the northern Ethiopian rift (Keir et al, 2006), and the Costa Rica rift (Wilson et al, 2019), where a competition between magmatic and tectonic strain accommodation has been identified (Corti et al, 2003). Numerous dikes have been identified at the cliffs of Santorini (Drymoni et al, 2020(Drymoni et al, , 2022 and also inside the crater of Kolumbo (Nomikou et al, 2012), which are roughly NE-SW aligned (Heath et al, 2019). In addition, the presence of the low-velocity body underneath the northern caldera basin and Kolumbo in 3-5 km depth implies that the shallow crust is strongly overprinted by magmatism (Heath et al, 2019;Hooft et al, 2019;McVey et al, 2020;Schmid et al, 2022).…”

Extensional Faulting Around Kolumbo Volcano, Aegean Sea—Relationships Between Local Stress Fields, Fault Relay Ramps, and Volcanism

“…(1999) (Figure 1b). These lineaments broadly correlate with seismic velocity anomalies in the upper 3 km of the crust (Heath et al., 2019; McVey et al., 2020), as well as the orientations of exposed dyke intrusions onshore (Drymoni et al., 2021, 2022). The Columbus Line (more recently referred to as the “Kolumbo Line,” e.g., Heath et al., 2019) can be projected northeastward as a seafloor ridge structure to the Kolumbo edifice, and then further to the northeast as the Kolumbo Volcanic Chain in the Anhydros Basin (Figure 1b).…”

The Taverna San Felice Dike (NE of Roccamonfina Volcano): Unraveling Magmatic Intrusion Processes and Volcano‐Tectonics in the Tyrrhenian Margin of the Southern Apennines

“…The reconstruction of the dike geometry based on structural and field data indicates an average thickness of 5 m in the lower part and >25 m in some segments of the middle part, with an average thickness of ∼20 m (Figures 6m and 6n). Compared to other examples of magmatic dikes worldwide, from the Italian volcanoes of Etna (1.9 m, Scudero et al., 2019) and Somma‐Vesuvius (1.2 m, Porreca et al., 2006), the Mijakejima island (Japan, 1.3 m, Geshi & Oikawa, 2014), the Icelandic East Rift zone (4 m, Gudmundsson, 1983) and Askja volcano (0.8 m, Trippanera et al., 2018), the Oslo Rift (Norway, <2 m, Poppe et al., 2020), the Timna Igneous Complex (Israel, 1.5–32 m, Baer et al., 1994), and the Santorini island (Greece, 2–10 m, Drymoni et al., 2022), the thickness of TSF dike is well above the average. The only comparable cases are those from the East Rift and Timna Igneous Complex, which however exceed 3 and 1 km in length, respectively, whereas the exposed TSF dike is less than 1 km.…”