One of these, the 30km-long row of craters, Lakag gar, with about 100 separate craters, erupted in 1783. The gases and ashes from this eruption poisoned the grasslands, causing tremendous damage in the countryside. This brought widespread famine and resulted in the deaths of tens of thousands of people through starvation. The lava flow from this eruption is the largest known in the world, covering 565 square km. Shield volcanoes of the Hawaiian type, like Skjaldbrei ur near Thingvellir, are also numerous, but the only one active in historical times is the new Surtsey volcano.
Craters created by volcanic explosions are also quite common.
The most famous Icelandic volcano is Hekla, which was renowned throughout the Catholic world during the Middle Ages for being the abode of the damned. Since its first recorded eruption in 1104, which destroyed vast areas, including the j rs rdalur settlement, Hekla has erupted 17 times in historic time continually bringing damage to the surrounding countryside. At the beginning of its eruption in March 1947, a column of smoke and ash rose to 100,000 feet. The eruption lasted 13 months. In May 1970, a number of small craters in Hekla erupted and the lava flow lasted for some two months.