Indonesia - Mt Merapi Flashcards
1
Q
Indonesia’s tectonic setting
A
- Widespread subduction along the entire 3000km length of the Indonesian archipelago
- Much of Indonesia is an island arc formed by subduction of the Indo-Australian plate beneath the Eurasian plate
- To the east of the chain of islands, the continental shelf of northern Australia is in collision with the Eurasian plate
- These plate movements produce very high levels of seismicity ad volcanicity
2
Q
Features of Mt Merapi
A
- Strato-volcano which reaches nearly 3000m
- Highly active, with eruption events in 1994, 1997, 2001 and 2006
- On each occasion, a dome developed in the crater, which eventually collapsed, producing pyroclastic flows
3
Q
Mt Merapi eruption
A
- October-November 2010
- VEI 4
- Pyroclastic flows extended 4km north, 11.5km west, 7km east, 15km south
- Lava bombs were thrown 4km from the summit in all directions, eruption happened at the start of the rainy season, triggering lamar’s fed by ash from the eruption and from earlier eruptions
- Ash falls forced the closure of Yogyakarta airport for over a fortnight and emissions of sulphur dioxide caused acid rain to fall over a large part of the region
- Overall, 357 people were killed by the Merapi eruption, 277 were injured, while approximately 410,000 in the vicinity of the volcano became refugees
- Large numbers of livestock were killed and ash fall and pyroclastic flows amounting to 130 millionm^3 of material destroyed crops and infrastructure such as buildings, power lines and bridges
- Total economic impact from the eruption of Mount Merapi in 2010 was estimated at £450 billion.
4
Q
Modifying vulnerability
A
- Indonesia’s Centre for Volcanology and Geological Hazard Mitigation (CVGHM) was established 1920
- Key division is Volcano Observation Section, has constructed permanent observatories on several active volcanoes
- First seismograph was set up on Mount Merapi in 1924, but the capacity of the technology was limited
- Funding for the program was restricted due to Indonesia’s weak economy
- Was a Dutch colony until the end of WW2, its emergence into independence was accompanied by political tension and violence amongst competing groups, managing volcanoes was therefore given low priority
- Gradually CVGHM was been able to upgrade monitoring instruments and widen geographical coverage, today more than 60 volcanoes monitored
- Indonesia has also established a National Agency for Disaster Management, this agency has helped to install lahar sensors and closed circuit television to monitor locations at greatest risk
- CVGHM works closely with local governments, advising them on mitigation strategies such as community preparedness
- Permanent settlement is forbidden on highest slopes around crater, villagers on the southern slopes (at greatest risk) have been encouraged to relocate to safe zones, in some cases receiving financial assistance and a small plot of land as incentives to move
5
Q
Modifying loss
A
- Resources Indonesia can deploy once an eruption is underway are limited
- Many of the farming communities affected also have limited resources
- Indonesia has some well-trained and well-equipped emergency services, including military who are experienced in search rescue
- Temporary shelters in safe zones are available in case of evacuation and sometimes these are upgraded into permanent residential areas
- Authorities have also cleared river channels of volcanic material and other debris in order to reduce the risk of flooding and to contain lahars
- Some of his material has a commercial value (eg. road building), and people living along the river valleys have used it for rebuilding houses and community facilities
