Larderello is a frazione of the comune of Pomarance, in Tuscany in central Italy, renowned for its geothermal productivity. The region of Larderello has experienced occasional phreatic eruptions, caused by explosive outbursts of steam trapped below the surface. The water is contained in metamorphic rocks where it is turned to steam which is then trapped …Larderello is a frazione of the comune of Pomarance, in Tuscany in central Italy, renowned for its geothermal productivity. The region of Larderello has experienced occasional phreatic eruptions, caused by explosive outbursts of steam trapped below the surface. The water is contained in metamorphic rocks where it is turned to steam which is then trapped beneath a dome of impermeable shales and clay. The steam escapes through faults in the dome and forces its way out in the hot springs. It possesses a dozen explosion craters 30–250 m in diameter. The largest is the Lago Vecchienna crater which last erupted around 1282, now filled by the Boracifero Lake.