The Mid-Atlantic ridge on Reykjanes

Reykjanes volcanic system with its well-defined fissure swarms is an actively rifting volcanic area, around 45 kilometers in length, 30 of which are on land; the rest is submarine and connects with the Reykjanes Ridge. The center of the volcanic system is within a 5 kilometer-wide rift zone, consisting of normal and transform faults running NE-SW creating a rough graben-like structure. The bedrock of the site consists of subglacially erupted basalt ridges (tindar) of Pleistocene age, a >14,000-year-old picrite shield lava of Háleyjabunga, and a 14,000-year-old olivine tholeiite shield lava of Sandfellshæð in the north. Postglacial lavas younger than 8,500 years cover much of the southern part of the area. The youngest lava erupted from the Stampar cone row in 1210-1211 CE. It began with an offshore eruption creating the tuff cones of Vatnsfell and Karl before extending northwards inland.
Faults with over 20 meters of throw occur throughout the older lavas and tindar. The rate of subsidence is around 6.5 mm/year, the rate of extension is around 8-9 mm/year (Sæmundsson et al., 2020). The core of volcanic system has a productive geothermal system of 1.5 km2, with a reservoir temperature up to 320°C at 3 kilometers depth (Khodayar et al., 2018).