## 5 Discussion
### Extensional Collapse in the Central Betic Cordillera
Interaction between southward-directed extension over the Mecina detachment and indentation tectonics in the Alboran Sea produce folding and strike-slip faulting in the Alboran Sea coast. Moho depth was taken from [PERSON] et al. [163] and [PERSON] et al. [156]. The geometry of the Mecina detachment was taken from [PERSON] et al. [152] and [PERSON] et al. [24]. The latest paleostresses determined in the W and SW of the Granada Basin suggest local E-W and NE-SW compression and align with the shortening observed by GNSS data. Reverse faulting is parallel to the Miocene thrusting in Sierra Gorda and perpendicular to the active shortening in the southern Sierra Gorda and the Sierra Tejeda [37]. This compressional front does not represent a fixed boundary of the collapse and only dumps locally the extensional collapse, as the GNNS MALA station continues to record an S-SW motion relative to a stable NEVA one (Figure 6a). The crustal heterogeneities [165] could be responsible for the development of this compressional front. Meanwhile, active indentation tectonics have affected the Alboran Sea [36; 166; 167], reaching the Iberian coast [101]. The compressions due to the active indentor form a fixed boundary and stop the southward directed collapse, producing well-developed E-W to ENE-WSW folds onshore and offshore in the Campo de Dalias (Figure 6b) [24]. Finally, the northern border of the Sierra Nevada appears to be inactive [157], and GNSS data indicate that it may be affected by shortening (Figure 5). Actually, the shallow extension is not as important to the north, in the South Iberian domain. Although it has been an area affected by arc-parallel extension [72; 73; 74; 145; 168], recent tectonic data do not suggest that this region is affected by stretching [30]. Moreover, seismicity is only found locally at the basement of the mountain front and the Guadalquivir Basin foreland [100; 169; 170] and in the southernmost part, in the Granada Basin [30; 135]. On the other hand, the collapse from the Sierra Nevada onto the South Iberian domain is probably not as important as that in the south because the crust is already thickened towards the north [57; 153]. In short, our data support a terminal subduction model of Iberian lithosphere beneath the Alboran Domain [79; 80; 82; 84; 85], producing rollback and subsidence in the Western Alboran Basin and uplift in the central Betic Cordillera. The latter is also affected by a NW-SE compression due to the Eurasia-Nubia convergence [28; 171]. This framework leads to the extensional collapse from the Sierra Nevada towards the western Alboran Sea. In the Betic Cordillera and likely further Mediterranean arcs, such as the Calabrian and the Hellenic Arcs, extensional collapse processes are ongoing, as recorded in relation to different orogenies throughout geological history. Examples include the Appalachian [172] and Western Gneiss Region, Norway [173] during the Paleozoic, and the Basin and Range Province (western United States and northwestern Mexico) during the Cretaceous [3; 10; 11]. The Mediterranean arcuate orogens are characterized by simultaneous thickening and thinning processes occurring in close proximity, leading to a synovogenic extensional collapse unlike the most prominent example of active postorogenic gravitational collapse occurring in the Tibetan Plateau [6; 7; 9]. All of these orogens have experienced similar Neogene-Quaternay evolution comprising the following tectonic processes [162]. On one hand, the crustal thickening, through either fold and thrust formation related to the Eurasia-Nubia convergence and/or slab tearing of previously subducting slabs [57; 62; 81; 174], generate thicker crust. On the other hand, recent and active subduction with rollback [34; 175; 176; 177; 178] are derived in the formation of back-arc basins in the inner part of the arcs [12; 180], resulting in a thinner crust.