Mt. Bromo's eruptive activity in Java's Ring of Fire
Java counts 18 active volcanoes of which Mt. Bromo is the most famous one in East Java. The island Java is indeed a Ring of Fire if you know that the 6 volcanoes described erupted 227 times since 1799. That is more than 1 eruptions a year (table 1, just below).
At Mt. Bromo as part of the Ring of Fire you are actually standing in an ancient moonlike landscaped caldera with Mt. Bromo as the current centre of activity. You might already be wondering what a caldera is?
Mt. Bromo occupies the central part of the Tengger caldera. A caldera is a volcanic feature usually formed by the collapse of land, following a volcanic eruption. The caldera rim culminates at more than 2600 m above sea level, and the inner caldera floor is around 2,100 m a.s.l.
More than 60 explosive eruptions - mainly with VEI = 2 - have been reported to have occurred on Bromo over the past four centuries. VEI stands for Volcanic Explosivity Index. Volume of products, eruption cloud height, and qualitative observations are used to determine the explosivity value. The scale is open-ended with the largest volcanoes in history given magnitude 8 (wikipedia.org, 2015).
Until now, only two casualties were reported at Mt. Bromo. Two tourists were killed during the 2004 eruption after venturing too close to the volcano. The present-day active crater, through which magmatic degassing occurs, is Bromo’s smallest (500 m in diameter) and northernmost crater (Bani, P. et al., 2013).
Table 1. General information about a few active volcanoes in East Java
| Volcano | Altitude (m) | First recorded activity | Eruptions since 1800 | Highest VEI | Last eruption (VEI) |
|---|---|---|---|---|---|
| Kelud | 1731 | 1000 | 16 | 5 | 1990 (4) |
| Semeru | 3676 | 1818 | 58 | 3 | Ongoing (2) |
| Bromo | 2329 | 1767 | 56 | 3 | 2010 (1) |
| Lamongan | 1651 | 1799 | 41 | 3 | 1898 (2) |
| Raung | 3332 | 1586 | 50 | 5 | 1993 (1) |
| Kawah Ijen | 2386 | 1796 | 6 | 2 | 1993 (1) |
Tenggerese are the locals living in the vicinity of Mt. Bromo
The Tenggerese or Tengger people are an ethnic minority and living around this futuristic moonlike landscape. You will find about 100,000 Tengger people in more than 40 villages within the Bromo-Tengger-Semeru National Park. This Hindu minority is lead by Pak Tomo, the spiritual leader. Helios Transport interviewed Pak Tomo in February 2015 in Cemara Lawang, the leader of 48 shamans. The leader of the shaman coordinates the Kasada ceremony, is responsible for spiritual matters as well as for daily dilemmas.
Lusi Mudflow south of Surabaya and near Mt. Bromo
Many people think that there is a relatio between the mudflow Lusi and the volcano Mt. Bromo. This phenomenon deserves a visit; surreal landscape with an amazing story. Adriano Mazzini who is working at the University of Oslo, has been working on Lusi for several years. We used his suggestions for articles to compile an interesting and research based story.
Literature
Bani, P., Surono, M. Hendrasto, H. Gunawan, and S. Primulyana. Sulfur dioxide emissions from Papandayan and Bromo, two Indonesian volcanoes. Natural Hazards Earth System Sciences, 13:2399-2407, 2013.
www.wikipedia.com. Volcanic Explosivity Index. https://en.wikipedia.org/wiki/Volcanic_explosivity_index, 2015.
www.wikipedia.com. Caldera. https://en.wikipedia.org/wiki/Caldera, 2015.