Gunung Batur or Mount Batur is an active volcano located at the center of two concentric calderas north west of Mount Agung, Bali, Indonesia. The south east side of the larger 10×13 km caldera contains a caldera lake. The inner 7.5-kilometer-wide caldera, which was formed during emplacement of the Bali (or Ubud) ignimbrite, has been dated at about 23,670 and 28,500 years ago
Mt. Batur was initially formed in the shape of a sharply pointed cone over 3,500 meters above sea level. A terrific explosion blew the point off the cone, atomized a large portion of the volcano and collapsed the bulk of the mountain into the magma chamber, which was emptied by the initial cataclysm.
Before the present caldera was born, Penelokan and Kintamani lay on the western slope of the ‘first’ Gunung Batur. Now Penelokan and Kintamani are spread out along the top of the caldera’s outer crater rim. The present younger, smaller volcano-of the effusive rather than explosive type-gradually grew out of the crater floor over a period of hundreds of thousands of years.