- Sieh, K., and D. Natawidjaja, 2000, Neotectonics of the Sumatran fault, Indonesia: Journal of Geophysical Research 105, 28,295-28,326.
- Konca, A.O., Avouac, J-P., Sladen, A., Meltzner, A., Sieh, K., Fang, P., Li, Z.,Galetzka, J., Genrich, J., Chlieh, M., Natawidjaja, D., Bock, Y., F, Partial rupture of a locked patch of the Sumatra megathrust during the 2007 earthquake sequence, Nature, vol 456 pp 631-635, Dec 4, 2008
- Briggs, R., Sieh, K., Amidon, W., Galetzka, J., Prayudi, D., Suprihanto, I., Sastra, N., Farr, T. Persistent elastic behavior above a megathrust rupture patch: Nias Island, West Sumatra, J. Geophys. Res., VOL. 113, B12406, doi:10.1029/2008JB005684, 2008.
- Shyu, J.B.H., Chung, L.-H., Chen, Y.-G., Lee, J.-C. and Sieh, K. (2007), Re-evaluation of the surface ruptures of the November 1951 earthquake series in eastern Taiwan, and its neotectonic implications. J. Asian Earth Sci., 31, 317-331.
- McClosky, J., Antonioli, A., Piatanesi, A., Sieh, K., Steacy, S., Nalbant, S., Cocco, M., Giunchi, C., Huang, J.D., Dunlop, P., Near-field propagation of tsunamis from megathrust earthquakes, Geophysical Research Letters, VOL 34, I4316, doi:10.1029/2007GL030494, 2007.
- Chlieh, M., Avouac, J-P., Hjorleifsdottir, V., Song, T-R. A., Chan, J., Sieh, K., Sladen, A., Herbert, H., Prawirodirdjo, L., Bock, Y., Galetzka, J., Coseismic Slip and Afterslip of the Great (Mw9.15) Sumatra-Andaman Earthquake of 2004. Bull. Seism. Soc. Am., Vol. 97, No 1A, pp.S152-S173, January 2007, doi: 10.1785/0120050631.
- A. O. Konca, V. Hjorleifsdottir, D. V. Helmberger, K. Sieh, J-P. Avouac, R. Briggs, A. Meltzner, J. Galetzka, D. H. Natawidjaja, B. Suwargadi, Rupture kinematics and strong ground motion estimates of the 2005, Mw 8.6 , Nias Earthquake from the joint inversion of seismic and geodetic data. Bull. Seism. Soc. Am., Vol. 97, No. 1A, pp. S307-S322, January 2007, doi: 10.1785/0120050632.
- Borrero, J., Sieh, K., Chlieh, M., Synolakis, C., Tsunami forecasts for Western Sumatra. PNAS 2006 Vol 103, no. 52, Pgs. 19673-19677; doi:10.1073/pnas.0604069103.
Monday, April 13, 2009
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Monday, April 6, 2009
Indonesian Scientists Develop a Community-based Landslide Early Warning System
Landslides form some of the worst disasters in Indonesia. Over the past seven years, more than 36 landslides occurred resulting in the deaths or disappearance of 1226 people and millions of US dollars in losses.
Most areas susceptible to landslides are densely populated, due to the presence of fertile soil and good water resources which often contribute to slope instability. Despite efforts to establish slope protection zones by restricting development and settlement, efforts to carry out a relocation program have been difficult due to socio-economic constraints. Thus, a landslide early warning system is urgently needed to guarantee the safety of communities in such areas.
Dr. Dwikorita Karnawati from the Geological Engineering Department of the Gadjah Mada University-Indonesia (GED-GMU) led the team seeking to install early warning systems in several pilot areas, including Banjarnegara Regency and Karanganyar Regency in Central Java, as well as Situbondo Regency East Java. The teams were multi-disciplinary, with experts such as geologists from GED-GMU (Mr. Ign. Sudarno and Mr. Fajar Tri Prasetya), a civil engineer from GMU (Dr. Teuku Faisal Fathani), A GMU sociologist (Mr. Suharto), accompanied by Dr. Paul Burton from East Anglia University-UK and several local people.
To be effective, a landslide early warning system should be inexpensive, simple to operate and installed in the most appropriate sites. Therefore such systems must be based on the incorporation of sound technological and sociological approaches.
Most of the landslides occurring in the susceptible areas are debris slides which usually are initiated by extension cracks. Thus, the extensometer is considered the most appropriate monitoring and warning equipment, which should be placed by using extension wires across the extension cracks.
To guarantee such a comprehensive monitoring system, five sets of manual extensometers which cover the area of about 75 to 100 hectares were installed in the selected sites. Those extensometers were designed to stretch automatically across the cracks in response to the enlargement of the cracks caused by slope movement. The crack-extension is the indicator of the slope movement that proceeds a landslide. Accordingly, when the extensometer's string is stretched up to 4 cm in length (this length was defined based on previous empirical investigations at similar susceptible landslide areas), the connected alarm sounds an early warning to the community, allowing time for escape.
One extensometer was designed not only to monitor the lateral movement at the slope surface, but also the vertical deformation, as well as the rotational direction of the sliding. Thus, within one extensometer, three different directions of movement can be monitored by utilizing simple but low cost materials.
All of the monitoring system was connected with the siren alarm, which can be heard by the community up to a distance of 500 m. The first community group hearing the alarm then should hit the ‘thong-thong’ (local warning system made from wood or bamboo) to transfer the warning to the other community groups living in the distance beyond 500 m. This five extensometer installment needs to be incorporated with one rain gauge. The rain gauge was installed in the top of the slope to record the rainfall, because landslides in the area mostly occurr as the result of rain. The alarm was also set to start if the accumulative rain infiltration reaches 100 mm. This critical amount of rain infiltration was set based on previous research conducted by Karnawati (1996) and Su Su Ky (2007).
Because of the simplicity of its design, the equipment can be constructed in local home workshops. Thus, the three-directional extensometer will not only potentially reduce landslide risk to human life, but also stimulate the local economy.
Schematic performance of extensometer installed across the crack (Japan Landslide Society, 1996).
Rain gauge developed by T.F. Fathani & D.Karnawati,Gadjah Mada University, 2007 (Paten No. P00200800299). Extensometer developed by T.F. Fathani & D.Karnawati, Gadjah Mada University, 2007 (Paten No. P0020080030).
Evacuation drill at Kalitelaga Village, Banjarnegara District, Central Java Province, conducted on September 2007.
The Faculty of Engineering, Gadjah Mada University and the Indonesian Ministry of Development for Disadvantaged Regions reported that the early warning system equipment has worked properly in Kalitelaga District, at Banjarnegara Regency, Central Java. In November 2008, the extensometer alarm came on following the early warning issued by the rain gauge, giving the community enough time to move to safer ground. Several houses were damaged in the landslide and the access road to the village was buried. Fortunately, 35 families living were saved.
The challenge is to implement this early warning system (EWS) in areas where no landslide has yet occurred. Some resistance from the community, especially relating to setting aside land for the equipment, may be the most difficult problem to tackle. Encouraging the community to maintain the operation of the equipment is another challenge.
The government of Indonesia is considering other pilot EWS programs in Java and Sumatra.
Data courtesy of: Karnawati, et al, based on the Proceedings of the first World Landslide Forum, Tokyo , November 2008, pp. 305 - 308.
Most areas susceptible to landslides are densely populated, due to the presence of fertile soil and good water resources which often contribute to slope instability. Despite efforts to establish slope protection zones by restricting development and settlement, efforts to carry out a relocation program have been difficult due to socio-economic constraints. Thus, a landslide early warning system is urgently needed to guarantee the safety of communities in such areas.
Dr. Dwikorita Karnawati from the Geological Engineering Department of the Gadjah Mada University-Indonesia (GED-GMU) led the team seeking to install early warning systems in several pilot areas, including Banjarnegara Regency and Karanganyar Regency in Central Java, as well as Situbondo Regency East Java. The teams were multi-disciplinary, with experts such as geologists from GED-GMU (Mr. Ign. Sudarno and Mr. Fajar Tri Prasetya), a civil engineer from GMU (Dr. Teuku Faisal Fathani), A GMU sociologist (Mr. Suharto), accompanied by Dr. Paul Burton from East Anglia University-UK and several local people.
To be effective, a landslide early warning system should be inexpensive, simple to operate and installed in the most appropriate sites. Therefore such systems must be based on the incorporation of sound technological and sociological approaches.
Most of the landslides occurring in the susceptible areas are debris slides which usually are initiated by extension cracks. Thus, the extensometer is considered the most appropriate monitoring and warning equipment, which should be placed by using extension wires across the extension cracks.
To guarantee such a comprehensive monitoring system, five sets of manual extensometers which cover the area of about 75 to 100 hectares were installed in the selected sites. Those extensometers were designed to stretch automatically across the cracks in response to the enlargement of the cracks caused by slope movement. The crack-extension is the indicator of the slope movement that proceeds a landslide. Accordingly, when the extensometer's string is stretched up to 4 cm in length (this length was defined based on previous empirical investigations at similar susceptible landslide areas), the connected alarm sounds an early warning to the community, allowing time for escape.
One extensometer was designed not only to monitor the lateral movement at the slope surface, but also the vertical deformation, as well as the rotational direction of the sliding. Thus, within one extensometer, three different directions of movement can be monitored by utilizing simple but low cost materials.
All of the monitoring system was connected with the siren alarm, which can be heard by the community up to a distance of 500 m. The first community group hearing the alarm then should hit the ‘thong-thong’ (local warning system made from wood or bamboo) to transfer the warning to the other community groups living in the distance beyond 500 m. This five extensometer installment needs to be incorporated with one rain gauge. The rain gauge was installed in the top of the slope to record the rainfall, because landslides in the area mostly occurr as the result of rain. The alarm was also set to start if the accumulative rain infiltration reaches 100 mm. This critical amount of rain infiltration was set based on previous research conducted by Karnawati (1996) and Su Su Ky (2007).
Because of the simplicity of its design, the equipment can be constructed in local home workshops. Thus, the three-directional extensometer will not only potentially reduce landslide risk to human life, but also stimulate the local economy.
Schematic performance of extensometer installed across the crack (Japan Landslide Society, 1996).
Rain gauge developed by T.F. Fathani & D.Karnawati,Gadjah Mada University, 2007 (Paten No. P00200800299). Extensometer developed by T.F. Fathani & D.Karnawati, Gadjah Mada University, 2007 (Paten No. P0020080030).
Evacuation drill at Kalitelaga Village, Banjarnegara District, Central Java Province, conducted on September 2007.The Faculty of Engineering, Gadjah Mada University and the Indonesian Ministry of Development for Disadvantaged Regions reported that the early warning system equipment has worked properly in Kalitelaga District, at Banjarnegara Regency, Central Java. In November 2008, the extensometer alarm came on following the early warning issued by the rain gauge, giving the community enough time to move to safer ground. Several houses were damaged in the landslide and the access road to the village was buried. Fortunately, 35 families living were saved.
The challenge is to implement this early warning system (EWS) in areas where no landslide has yet occurred. Some resistance from the community, especially relating to setting aside land for the equipment, may be the most difficult problem to tackle. Encouraging the community to maintain the operation of the equipment is another challenge.
The government of Indonesia is considering other pilot EWS programs in Java and Sumatra.
Data courtesy of: Karnawati, et al, based on the Proceedings of the first World Landslide Forum, Tokyo , November 2008, pp. 305 - 308.
Friday, March 27, 2009
Situ Gintung Dam Collapses in Tangerang, Banten
The 10-meter high Situ Gintung river dam collapsed on Friday, March 27, 2009 morning around 2 am and has inundated around 400 homes of which 250 were damaged or destroyed in Tangerang, Banten, near Jakarta. The police announced that a total of 100 people had been confirmed dead in the incident and 14 citizens of the district were reported missing (updated April 1, 2009).
Torrential rains Thursday raised the level of a reservoir behind the dam to almost 55 yards above capacity, apparently because the gate leading to the spillway was too small. The dam was overtopped, eroding the dam surface and resulting in a breach 70 metres (230 ft) wide at around 2 am on 27 March local time. Cracks were reportedly visible in the face of the dam embankment from around midnight. The dam operators apparently sounded a warning siren shortly before the dam failed. A surge of water and debris several meters high was sent into the town of Cirendeu, washing away cars, houses and a brick-built bridge.The flood hit while most of the population was asleep and left standing water up to 2.5 meters (8.2 ft) deep. Many people remain trapped in the town with around half of the townspeople taking to their rooftops to avoid the floodwater. The flood also submerged five power terminals cutting drinking water supplies to the nearby suburb of Lebak Bulus.
Emergency repairs to the dam structure are already underway and the government has begun inspections of similar dam structures.
Image sources : BBC news
Torrential rains Thursday raised the level of a reservoir behind the dam to almost 55 yards above capacity, apparently because the gate leading to the spillway was too small. The dam was overtopped, eroding the dam surface and resulting in a breach 70 metres (230 ft) wide at around 2 am on 27 March local time. Cracks were reportedly visible in the face of the dam embankment from around midnight. The dam operators apparently sounded a warning siren shortly before the dam failed. A surge of water and debris several meters high was sent into the town of Cirendeu, washing away cars, houses and a brick-built bridge.The flood hit while most of the population was asleep and left standing water up to 2.5 meters (8.2 ft) deep. Many people remain trapped in the town with around half of the townspeople taking to their rooftops to avoid the floodwater. The flood also submerged five power terminals cutting drinking water supplies to the nearby suburb of Lebak Bulus.
Emergency repairs to the dam structure are already underway and the government has begun inspections of similar dam structures.
Image sources : BBC news
Tuesday, March 10, 2009
Indonesian government raises alert on Semeru volcano in East Java
The Indonesian Volcanology Center has raised a maximum alert on the Mount Semeru volcano in East Java, warning of potentially dangerous lava flows.The 3,676-metre (12,060-ft) Semeru is one of the most active volcanoes on Java Island. Geographically, it’s located at the position of 8° 06’ 30’’ Latitude and 112° 55’ Longitude. Its highest point is called Mahameru (+ 3676 meter) which is the highest peak on Java. Seven people were killed by the mountain's heat clouds in 1994.
The alert status was raised on the afternoon of Friday, March 6, 2009, following a number of volcanic quakes indicating that there might be a larger eruption. The authority said that at the moment it was not necessary to evacuate residents around the mountain, but warned those carrying out activities such as sand mining to avoid rivers because of lava flows and forbade climbers to access the area within 4 km of the peak. Indonesians often live and work on the slopes of volcanoes because of the rich volcanic soil and supplies of minerals.
Based on satellite images, volcanic activity so far would not disturb air traffic. The nearest major city to Semeru is Surabaya. The area is also popular with hikers and nearby Mount Bromo is a well known tourist site.
Saturday, March 7, 2009
Review of "The Yogyakarta Earthquake of May 27, 2006” Book
• Hardcover: 288 pages• Publisher: Star Pub Co; 1st edition (January 31, 2008)
• Language: English
• ISBN-10: 0898633044
• ISBN-13: 978-0898633047
The book is comprised of twenty-five international scientific papers about the Yogyakarta earthquake. It includes information on the geologic and seismological structure of the Yogyakarta Special Province and the Central Java Province and the effects of the 2006 earthquake on the local communities.
The Mw 6.3 earthquake of May 27, 2006, which occurred near the City of Yogyakarta, Indonesia, was the largest in the region over the last 60 years. Although this was a moderate earthquake, it resulted in severe consequences: 5,700 fatalities, 37,000 injuries, the destruction or heavy damage to over 300,000 buildings and economic losses of approximately 28 trillion rupiahs (approximately 3.1 billion US dollars). The purpose of this volume is to memorialize conditions in Yogyakarta, especially the Bantul area, at the time of the earthquake, the effects and consequences of the earthquake, as well as to present some of the lessons learned in order to enhance hazard preparedness, mitigation and response. Work on the volume began three months after the earthquake and was completed within one year.
The volume consists of three parts which focus on issues related to the geology and seismology of Yogyakarta in Central Java; the impact of the earthquake on buildings, schools, and temples and suggestions for earthquake-resistant construction. Social issues, health care, and policies for the enhancement of disaster management are also treated.
The contributing authors are world experts in geology, seismology, hazard mitigation, emergency response and related topics. Construction policies and standards, social policies, governmental emergency procedures and management issues, dealing with local customs are among the issues and topics discussed and explained by experts from Indonesia, Japan, Russia, Germany, England and the USA.
You can obtain the book here.
Tuesday, March 3, 2009
Landslide Prone areas, March 2009
Landslide prone areas in March 2009, in all provinces of Indonesia. Presented both as maps and tables by the Indonesian Government. You can find it here.
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