Bronggang – Impact of 2010 Mt. Merapi Eruption

Learning and Reflections from Bronggang: Preparedness is Key
Bronggang is a village approximately 15km from Mt. Merapi, and offers a lesson on the importance of preparedness and vigilance in the shadow of an active volcano. The learning that can be gleaned from this site is invaluable, as the eerie alien landscape of a devastated village buried in pyroclastic material stands silently as a memorial of the limits of human preparedness.

1. There were many casualties in the village of Bronggang as the order to evacuate was not given until it was too late (45 killed). According to eye witnesses, the village headman was still at a meeting, discussing if the order of evacuation was to be given.

2. Many people felt that Bronggang would not be affected by the eruption, as there was no historical record of pyroclastic material hitting the locality. The government had also built an evacuation center near the village, leading to many thinking that Bronggang would be a safe place to flee to in the event of an eruption. The psychological impact of perceived safety may have lulled the villagers into complacency.

Currently, there are no plans to restore Bronggang; it is a silent reminder of the limitations of human preparedness. Living in the shadow of Mt. Merapi is indeed a dance with death. However, the deluge of pyroclastic material and subsequent lahar flows has provided ample valuable natural resources for the adjacent village. Fertile soils still provide farming opportunities, and the volcanic sand is plumbed by sand miners.

Ever opportunistic, people who live in the shadow of Mt. Merapi have learnt to find boon in adversity.

 The evacuation sign...that did not lead to safety

Sand miners taking a break

 House destroyed by pyroclastic fallout

 Investigation into nature of deposits: pyroclastic or lahar material

(notice cloud of loose material blown away by the wind: the deposits are still loose, 2 years on)

 House partially buried in pyroclast and ash fallout

 Interior of a house destroyed by ash fallout

 Destroyed house, with partial revegetation visible in middle ground

 Extent of damage to houses caused by pyroclastic fallout

 Padi fields nourished by volcanic ash deposits

 EOS and NIE staff exploring Bronggang

Remains of a tree blasted apart by the extreme heat of the pyroclastic flow

 Poignant reminder of the frailty of life

School visit and BPPTK (Merapi Observatory) Mitigation efforts, what can be done to reduce risk

Learning and Reflections from School Visit (SMP Negiri 1)
& BPPTK (Merapi Observatory)


The visit to SMP Negiri 1 provided some rich learning for us to understand how the locals, living in the shadow of Mt. Merapi, coped with the most recent eruption in 2010. Here are some snapshots of the mitigation taken by the locals and how the community supported the rebuilding of lives, 2 years down:

1. The school was closed and evacuation was done from the area as SMP Negiri was within the evacuation zone announced by the local authorities. This prompt and quick response to the instructions given by the authorities allowed the school to be used as a emergency point for disaster relief.

2. During the 2010 eruption from Mt. Merapi, ash falls covered the school and this was evidenced by the thick layers of ash by the sides of the roads leading up to the school. 2 years down, the ash has not quite been removed from the vicinity of the school...BUT the school itself was operational and all volcanic deposits within the school have been removed, thanks to the collaborative effort of students and the local community.

3. The last eruption in 2010 from Mt. Merapi left many people homeless and they had to shift into temporary shelters. At the time of the school visit, many of the students were still staying in temporary shelters. However, many of them do not show signs of emotional trauma and instead display a resilience and a cheerful disposition. This resilience in the face of challenges is most heartening!

Hearing from the Principal's perspective, it is amazing how swiftly the local government acts on to, and with expert logistical help, evacuate the locales that are within the danger zone. The deployment of the army and police, ever-ready for disaster relief and evacuation, is something that helps to reduce the unnecessary loss of human lives.

 SMP, NIE and EOS staff at dialogue hosted by the school 

Incredible hospitality provided by the hosts (including locally grown snakeskin fruit!)

At the BPPTK (Merapi Observatory), we were treated to sights of a different nature:

The Merapi Observatory is a scientific laboratory and monitoring station all rolled into one. Primarily, it houses equipment to monitor critical locations on and around Mt. Merapi; BPPTK serves as an advanced warning post to broadcast information to the local authorities, so that evacuation can be done to minimise loss of lives in the event of an eruption from Merapi.

1. BPPTK staff are extremely fit...because they are on rotation to climb Mt. Merapi and maintain critical monitoring equipment: these equipment relay visual and non-visual information (such as temperature, chemical and seismic activity) to the main office of BPPTK. Even during lull periods, the staff keep themselves entertained by playing badminton!

2. BPPTK makes use of advanced technology such as high-definition CCTVs and computerised seismographs in its efforts to monitor seismic and volcanic activity near Mt. Merapi. They even have backup power generators to ensure that the equipment remain operational in the event of electrical power loss from the main power stations. However, they still rely on tried and tested "ancient" technology, such as the kinemetric seismograph. There is never too much effort and preparation to ensure that the proper monitoring of Mt. Merapi is carried out.
(on a lighter note...the staff claim that the ancient devices remain because they prefer the old stuff is less complicated to read. I guess...use whatever is useful, there is never too much redundancy in monitoring Mt. Merapi and in providing sound advice to help mitigate the dangers of an explosive and active volcano).

Dr. Purbo explaining the various equipment in the observatory 

CCTV constantly monitoring real time changes on and around Mt. Merapi 

A chemist's haven: endless bottles of chemicals to analyse soil and rock composition

Machines to slice rock into thin fragments for visual and chemical analysis 

Labeled and archived samples of pyroclast and other minerals from different eruptions 

Pyroclastic material inside a soft drink bottle, recovered from a prior eruption

Mitigation Effort

Responding to volcanic hazards

Emergency shelters

Emergency Shelters are located outside a 10-kilometre exclusion zone around the volcano. Local residents can flee to these shelters in times of eruption.

Relocation Program

The government wanted the survivors of the 2010 eruption to move to safer locations. However, many of them objected to the relocation plan and wanted to build their houses near their previous neighbourhood. Those families relocated were also given cattle, seeds and saplings to resume their livelihood.

http://www.irinnews.org/printreport.aspx?reportid=92624

Temporary shelters

Temporary shelters were constructed in Yogyakarta and Central Java provinces to house displaced residents. A daily food allowance of 5,000 rupiah would be given to people living in temporary shelters for three to six months.

http://www.irinnews.org/printreport.aspx?reportid=92624

Hazard Mapping

Maps are produced to map out pyroclastic flows and surges and mudflows (lahar) using Geographical Information Systems. This will allow scientists to forecast areas of impacts and pinpoint regions at a high risk of lethal hazards. This information will help hazard managers to decide if a particular population needs to be evacuated.

Sabo Dams

Sabo dams can protect the area from mudflow (lahar flow) and debris flow and also reduce the velocity of flow. These structures come in a  pair. The main dam helps to trap sediments while the secondary dam protects the main dam from scour. Small lahar also be diverted away from properties by artificial channels. However, the presence of these structures may lead to an explosion in a pyroclastic surge, resulting in greater damage.

Sabo dam

Mitigation- Class Activity

Background

During the 2010 eruption, some people living in Kinahrejo, the area in the highest hazard zone at the southern flanks of Mt Merapi were not willing to evacuate. The Javanese believe that Mt Merapi is the home to many spiritual creatures and these spiritual creatures have the power over volcanic eruptions. Kinahrejo is also the home of Mbah Marijian, the gatekeeper of Mt Merapi.

Instruction

The class is divided into three teams: residents, scientists and the local government. The local residents and scientists will take turns to justify their stand based on the given information. The local government will then decide whether to evacuate the residents based what the teams have presented and decide on the alert level (Level 1-4). Questions can be raised by the opposing party and the local government after each team has stated their stand. The residents and scientists can also raise questions to the local government after a decision is made. The teacher then concludes the session by summing up the main points.

Role: Local Residents

Why should we not evacuate?

• Some of the residents also believe that those who perished in the previous eruptions are punished by the spiritual creatures and hence, try to appease the spiritual creatures by presenting their offerings and wait
•  Locals rely heavily on their livestock for their livelihood and they are reluctant to abandon their animals. People evacuated will return to their homes daily to take care of their livestock. These people believe that they would have time to flee before the volcano erupts and they are afraid that their livestock will be stolen
•  Residents are not directly affected in the previous eruptions so they are more reluctant to evacuate

Web Resource: http://www.ox.ac.uk/media/science_blog/101110.html

                             http://mountmerapi.net/living-with-volcanoes/

Role: Scientists
Why evacuate?  

• Real-time seismic monitoring shows an increase seismic activity (volcanic-tectonic    earthquakes). When magma moves towards the surface, earthquake will be triggered  as  the magma breaks rocks that is in its way.
• There is a bulge in the summit, observed through visual monitoring
•  White plume of smoke rose above the crater

Web Resource: http://volcano.oregonstate.edu/what-are-signs-volcano-about-erupt

Role: Local Government

Should we evacuate? When?

• Most volcanoes show sign of eruption months and weeks before the eruption occur. It is important for evacuation to take place at the right time.
• Evacuated residents have to be provided with the practical items and food at the temporary shelters
• People evacuated to the temporary shelters will be concerned of their livelihood. They might be faced with financial problems, as they could not earn their living through the sale of milk or labour in the sand mining industry. The situation will be worse for those who make daily trips home to take care for their lifestock, for money will have to be spent on petrol as they commute to and fro.

Warning system

There are four levels in the warning system and this level is determined by visual and instrumental data:

Level 1 alert is where Mt Merapi is at its normal level of activity

Level 2 alert is where Mt Merapi is having a more than its normal level of activity and there will be intensive coordination with the local government

Level 3 alert will be sounded when Mt Merapi shows an increase in activity

Level 4 alert will be raised when Mt Merapi is likely to erupt and evacuation will occur.

The warning is disseminated through the radio. 

Visual Monitoring

Seismograph

Outcome

The eruption in 2010 killed the renowned mystical guardian of Merapi volcano, Mbah Marijan and 34 others who had refused to evacuate the village of Kinahrejo.

Web Resource http://www.msnbc.msn.com/id/39846256/ns/world_news-asia_pacific/t/least-killed-indonesia-volcano-erupts/

School visit and BPPTK (Merapi Observatory) Mitigation efforts, what can be done to reduce risk

Bronggang – Impact of 2010 MT Merapi eruption on the affected village

Kaliadem - Geog investigation, identifying deposits and analyze impacts.

kaliadem is located at the base of Mt Merapi, 4km away from the peak. 
At the site, we had the opportunity to study the different types of intrusive and extrusive igneous rocks.

we were excited to be able to catch a superb view of Mt Merapi in the morning.

Amphibole (Black crystal with a 120 degree cleavage) indicate the presence of  water (Hydra minerals).  This tells us that there is a high possibility that a violent eruption happened in the area. Moisture in the minerals created more gas and bubbles, resulting in explosive eruption

Presence of lithic fragments in intrusive volcanic rock. 

Brown/orange stains on the rocks around the degassing hole, with steam still emitting from the hole.

The situation above suggested that a lot of heat is still being trapped by the rocks. The gas emitted from the hole is steam, and it contains a lot of moisture as oxidation is happening around the area, causing a brownish tint on the rocks. This shows that the eruption happened recently, and was likely a violent eruption due to the presence of large amount of moisture within the rocks.

Degassing happens after the eruption and not before, suggesting that previously gas was not able to escape due to the high viscosity of the magma, resulting in explosive eruption.

Possible investigation/inquiry questions
- Is it a recent or ancient eruption?
- Was the eruption violent or gentle?

Old vs New deposits. At the bottom we can see presence of new deposits, loose, homogenous materials with no vegetation. On the other side (top part), presence of old deposits with vegetation.

Pyroclastic deposits spread over a large, up to 15km away from the crater!! Can see the lahar flow at the left side of the middle part of the photo.

Coarse/Bigger materials such as boulders, rocks area deposited closer to the volcano. But lahar can follow the topography of the area and wash hugh boulders downstream, over long distances.

Hyperconcentrated lahar flow quickly increase their volume as they incorporate sediments of different sizes and weight along their travel paths. Highly erosive and destructive, strong enough to break and shift bridges as seen above.

Prambanan Temple – Effect of 2006 Earthquake

Prambanan temple – Unesco world cultural heritage

Background – With over 240 Hindu temples located near Piyungan, Prambanan is a Unesco World Cultural Heritage site and is more than 1100 years old. Earthquake resulted in extensive damage to this beautiful place.

Wreckage in Prambanan, after the 2006 earthquake devastated the area.

Yogyakarata Prambanan – Geological settings

Geology – Situated at the flat land between two hilly areas (West Progo Mountain and Southern Mountain), Prambanan is located at the foot of Mt Merapi and at the end of Opak River Fault, a 40 km secondary fault perpendicular to the main fault at the subduction zone where the Indo-australian plate descend beneath the Eurasian place. The left and right side of the fault moved at different speeds.

2006 Earthquake – Mag 6.3

More than 5000 dead, 83000 homes damaged and 1.5 million homeless in the densely populated Yogyakarta. Prambanan temple was also in a wreckage, with most of the shrines and temples being destroyed.

There used to be more than 240 temples and shrines. But only a few remained after the 2006 earthquake.

Why is the 2006 Earth so devastating, especially the area near Prambanan?

1.     The Earthquake in 2006 produced tremors along the Secondary fault (Opak river fault). Tremors along secondary fault lines are often shallow, less than 10km away from the surface. The impact of shallow earthquake can be quite severe despite the lower magnitude because the energy from the quake would have less time to dissipate, resulting in great damage to the area.

2.      Prambanan is located at the end of the secondary fault as seen in the figure. As such, Prambanan received the greatest impact as the seismic energy is concentrated at the end of the secondary fault.

3.      Prambanan is on the soft volcanic rocks of the deposits from Mt Merapi, which amplify and prolong shaking when there is earthquake. Half of the Prambana temple built on swamp filled with reclaimed soft soil, the other half on solid ground. As such, the earth resulted in a long crack in the middle, causing much devastation to the temple.   
4.   Wrong restoration of the Siva Temple before 2006 resulted in more harm – Before the 2006 earthquake, clay and cement were used to join the stone blocks, which is different from the ancient way of construction using interlock system. This proved to be a mistake as  the cement and clay are too rigid and does not allow flexibility in the structure, as such many temples crumbled and collapsed during the 2006 earthquake.

Interlock system used in the past, which proved to be more earthquake resistant since it allow the stones more flexibility and movement to counter the tremors from the earthquake.

Secondary impact on tourism.

Tourism is a key economic sector for Yogyakarta, providing employment and income directly and indirectly to thousands of people. Hundreds of craft villages that make souvenirs, arts and crafts were greatly affected. (Bali tourism board)

Locals walking around to pick up metal cans and
sell them to make a living.