The northern landscape of Lombok is dominated by its magnificent volcano, Mt Rinjani, which towers 3726m above sea level and is the second highest volcano in Indonesia.
Local communities in the foothills surrounding the mountain range were startled on Monday, 27 April 2009, when Rinjani suddenly sprang into life, spewing out red hot lava and throwing ash down onto their homes. Since then the volcano has remained active, with eruptions escalating on 2 May with a series of large explosions within 15 minutes.
While it would be worrying if Mt Rinjani itself suddenly came to life, the truth is that the “mother volcano of Lombok” has been dormant for centuries and it is the smaller volcanic cone, Mt Baru Jari – formed when Rinjani blew its top – that is now making its presence known.
Gunung Baru Jari (from the local Sasak language meaning “newly formed mountain”), was formed a couple of hundred years ago and juts from the crater in the interior of Mt Rinjani. It’s been estimated that the force needed to create the new cone and the crater would have been equal to around 300 Hiroshima-type atomic bombs.
Baru Jari is surrounded by a beautiful turquoise lake, Danau Segara Anak, which was formed when Rinjani exploded and the resulting crater filled with water. Today the lake flows in a crescent shape, 4km wide and around 230m deep, with plentiful fish, birds and other wildlife. The lake is a major tourism attraction and a popular destination for those climbing the volcano, with beautiful views, waterfalls and the Aik Kalak hot springs located on the northeast of the crater.
Fortunately, it is this lake which softens any major calamity from Baru Jari’s eruptions, with most of the minor lava flows being cooled when they hit the water. Of course, the view must be spectacular, with molten lava suddenly hitting water and solidifying, hissing steam and throwing hardened lava into the air.
I was fortunate enough to observe something similar on the big island of Hawaii many years ago when I watched red hot lava flow across the lava crust before tumbling down a cliff into the ocean below. The sudden transition from molten lava to solidified rock, hitting the cold water of the ocean, sent geysers of water, steam and rocks exploding in fury metres into the air. The scene was an awesome demonstration of the power of nature.
The current activity of Baru Jari has been classified at Level 2 Alert which advises no human activity within 4km of the eruption point, and has meant the temporary closure of trekking to the lake and summit of Mt Rinjani. However, trekkers are still being permitted to hike to the shoulder of the mountain to observe the eruptions. The normal route will be reopened as soon as the National Volcanology and Disaster Mitigation agency declares the area safe again. The Head of Mining and Energy Services for Nusa Tenggara Barat, Heryadi Rachmat, and a team of government geologists and volcanologists are on the mountain at the moment monitoring the crater, and seismographic equipment has now been moved in closer proximity to the volcano in order to better monitor future developments.
Heryadi confirmed that the eruptions on 2 May took place at 3:50 pm local time, with second and third explosions coming at intervals of five minutes. He said his agency recorded four tectonic quakes in the area on the following morning, lasting between 70 seconds and 120 seconds each.
Observers at the scene report that a small crater has emerged on the eastern face of the mountain. Volcanic ash clouds have been measured at an altitude of 8,000 meters and a thin layer of volcanic ash has blanketed Senaru village located on the foothills of the volcano.
Experts report that the current state of the volcano poses no imminent threat to local populations. Baru Jari volcano last erupted in 2004, when it spewed lava and volcanic dust, but did not cause injury or loss of life. Previously Baru Jari also spread thick ash in 1944, 1966 and 1994. The frequent eruptions are believed to be the result of gas accumulation and will not lead to bigger explosions.
Head of the Mt Rinjani National Park, Arief Toengkagie, said his officers have been deployed along hiking routes to prevent hikers from entering the volcano area. Adventurous people who wish to hike to the shoulder of the mountain to observe the activity are being permitted entry. Face masks, goggles or glasses to protect against ash, and the assistance of qualified guides and porters are essential for this trek. There are a number of licensed guides operating in Senggigi and the Gilis, and at Senaru and Sembalun in north Lombok. Rinjani Trek is the specialist for this area.
Every year an average of 9,000 people hike the mountain, 4,000 of them foreign tourists, mostly from Australia, Europe and Asia. The mountain is being considered for Geopark and World Natural Heritage status by the United Nations Educational, Scientific and Cultural Organization (UNESCO).
