Learning Lessons from Natural Disasters in Asia: A Photo Archive

Editors: Andres W.C. Oreta (DLSU-Manila)

Hideki Ohta (TokyoTech) Mark Zarco (University of the Philippines-Diliman) Jiro Kuwano (Saitama University) Contributors: Kazuhiko Kawashima, Pennung Warnitchai, Rolando Orense, Sandra Catane Jonathan Dungca

Natural hazards like earthquakes, landslides, floods, typhoons and tsunamis can lead to natural disasters which spoil both the built and natural environment. The society’s vulnerability to natural hazards has lead to catastrophic natural disasters which lead to numerous deaths and injuries, the destruction of important infrastructures such as buildings, bridges and roads and devastation of nature. The photo archive reminds us that natural hazards are part of our existence. To live sustainably with natural hazards. we have to manage our natural and built environment so that natural disasters can be mitigated or prevented. It is hoped that through this photo archive, lessons can be learned and proper action will be pursued. (Cover: Text by A.W.C. Oreta / Photo by P. Warnitchai)

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Ground Shaking Effects On Bridge Structures

The Collapse of the Hanshin Metropolitan Expressway. The 18 span-bridge of Route 3, Kobe Line collapsed due to strong excitation (1995 Hyogo-Ken Nambu earthquake). Due to the insufficient shear strength of the columns, brittle shear failure occurred. Premature shear failure of columns occurred at the termination of main reinforcements due to insufficient development length.

Lessons Learned Seismic safety policy for bridges should be adopted so that important bridge structures maintain their function after an earthquake. To enhance the seismic performance of the bridge columns for strong earthquakes, the inelastic deformation capacity of the columns should be improved. Ductility design should be emphasized in the current seismic codes.

Photos: K. Kawashima

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Buildings: Shake, Rattle and Fall

Earthquake damage is sometimes concentrated at a particular story of a building due to vertical irregularities caused by discontinuities of strength and stiffness of the structural elements or concentration of masses at specific floors as observed in the 1995 Hyogo-ken Nanbu Earthquake in Japan.

Lessons Learned: Soft story failures can be prevented by the proper planning of the architectural and structural form of the building and by emphasizing ductility design of the columns, walls and beams. Photos: K. Kawashima

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Foundation on Liquefied Ground

Lessons Learned: Regional planners should consider liquefaction hazards in the planning, design and construction of transportation networks.

Nihonkai-chubu earthquake (1983, M7.7) hit the northwest of Japan. The approach to the Gomyoko bridge in Wakami town in Akita prefecture was destroyed, but no severe structural damage to the bridge was found. It appears that the damage was not caused by the direct impact of seismic inertia force, but by the loss of shear strength of the foundation ground due to liquefaction. A lot of sand volcanoes were found in the adjacent paddy field. Liquefied ground could not maintain even a gentle slope, nor support the embankment on it.

Photos: J. Kuwano

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Liquefaction Hazards onInfrastructures

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The 1995 Hyogo-Ken Nambu earthquake (M7.6) and the 1990 Luzon earthquake (M7.7) caused widespread damage to buildings and other structures. The port of Kobe which rests on reclaimed land suffered severely due to lateral spreading of the liquefied ground. Many buildings in Dagupan City in the Philippines, although located about 100 km from the epicenter, sank or tilted due to the liquefaction of loose saturated sand deposits.

LessonsLearned:

When constructingcritical

infrastructures on sites prone to liquefaction,

countermeasuresmust be

implementedto mitigate or

reducepossible damage.

Photo: J. Kuwano

Photo: R. Orense

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Landslide Hazards On July 12, 1993 an earthquake of M7.8, which generated a tsunami, hit Southwestern Hokkaido, resulting in extensive damage to life and property. The ground shaking which caused landslides destroyed several roads and highways affecting major transportation networks.

Lessons Learned: Mountainous areas are susceptible to landslides and rockfalls during strong ground shaking and rainfall. Disaster mitigation technology like slope protection and soil stability should be implemented on sites highly vulnerable to landslides to reduce their impact.

Photos: R. Orense

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Super Typhoons and Deadly Billboards

Lessons Learned Strict enforcement of regulations in the design, construction and

maintenance of outdoor advertisements by local government units, advertisers and billboard fabricators should be done to reduce hazards of

billboards during typhoons and earthquakes.

Typhoon Xangsane ("Milenyo" in the Philippines) struck Metro Manila on September 28, 2006 with a wind speed of 120 kph and gust up to 150 kph. It was the strongest typhoon to hit Metro Manila in 11 years. Many huge steel billboards which have been erected along main thoroughfares were toppled by the strong winds causing a number of deaths and injuries to passersby and damaging vehicles and property.

Photos: W. Lopez (DPWH)

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Typhoon-Induced Lahar Flows Severe rainfall associated with the passage of super-typhoon “Reming” (International Name: Durian) on November 30, 2006 triggered lahars, landslides and flashfloods on the southeastern quadrant of Mayon Volcano, resulting in extensive damage to life and property. In the affected areas, numerous houses, roads and other infrastructures were either buried or swept away by the flowing lahar and rampaging flood waters.

Lessons Learned Land use on areas highly susceptible to lahar flows must be monitored or restricted. An improved weather forecasting technology and comprehensive risk maps will enhance the disaster preparedness plan of the community.

Photos: R. Orense

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Tsunami Disaster!

Lessons Learned There is a need to increase public awareness about the hazards due to tsunami. Tsunami disaster mitigation counter-measures at coastal areas should be developed to reduce their impacts. An international cooperation on tsunami early warning should be undertaken.

Photos: P. Warnitchai

Triggered by an earthquake (M=9.3) off the western coast of northern Sumatra on December 26, 2004, a series of destructive tsunami waves propagated throughout the Indian Ocean devastating communities along thousand of kilometers from the coastline. More than 280, 000 deaths and missing were reported in Indonesia, Thailand, Sri Lanka, Malaysia, India, Myanmar, Maldives, Bangladesh, Somalia, Tanzania and Kenya.

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Rock-Slide Debris Avalanche

On 17 February 2006, a large-scale landslide buried the entire Guinsaugon village in St. Bernard town, Southern Leyte, Philippines, after days of heavy rainfall. The landslide destroyed around 500 houses and a primary school building, resulting in 1,119 deaths. The intensity of the rainfall prior to the disaster, coupled with the existence of weak and fragmented rocks due to faults, and the steep slopes, were all ingredients to failure.

Photo: R. Orense

Photo: Dana Batnag

Lessons Learned A comprehensive landslide susceptibility map, in-placed warning system and evacuation plan should be developed to enhance disaster preparedness. A comprehensive landslide susceptibility map for the Philippines should be developed to enhance disaster preparedness.

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Disasters and Development On August 3, 1999 after several days of continuous heavy rainfall, a

disastrous landslide occurred in Antipolo City, Philippines.

The landslide destroyed several houses

in Cherry Hills Subdivision, resulting in at least 58 people dead.

When the subdivision was developed, large amounts of materials

were removed from the mountain slope without corresponding slope protection works.

Heavy rainfall triggered the slide.

Lessons Learned Engineering geology and geotechnical hazard assessment should be required in any development project especially in landslide-prone areas. Landslide risk management strategies must be adopted to avoid risk, reduce likelihood or reduce consequences.

Photo: R. Punongbayan

Photo: R. Orense

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What a Waste! Severe natural disasters like the Hyogo-ken Nanbu earthquake or the Indian Ocean Tsunami generate a large amount of waste and debris that can overwhelm existing solid waste management facilities or force communities to use disposal options that otherwise would not be environmental friendly.

Tsunami Disaster!

Photo: P. Warnitchai

Photo: K. Kawashima

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Tsunami Disaster Mitigation

level to minimize damage due to future lahars.

Photos: H. Ohta

People in a village called Hiro, Wakayama in Japan have constructed at their own expense a protective embankment along the shoreline after a tsunami in 1854. The construction took 4 years. The embankment was 3.5m high and 2m wide at the top and 600m long. The embankment have been looked after by the village people from generation to generation and eventually saved many lives of the village people in 1946 when they had another big tsunami.

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Seismic Strengthening & Retrofitting To mitigate the damage on existing structures due to future earthquakes, seismic strengthening and retrofitting must be carried out.

Steel jackets can be used as a standard retrofit method for single RC piers that were designed according to the pre-Hyogo-1980 Design Specifications of Highway Bridges in Japan. X-bracings can be installed in buildings to increase their lateral load carrying capacity.

Photo: K. Kawashima

Photo: A. Oreta

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Acknowledgement

The photo archive “Learning Lessons from Natural Disasters in Asia” was a product of the editorial board meeting held last March 21, 2007 at the College of Engineering, University of the Philippines, Diliman. The members present in the editorial meeting were Hideki Ohta (Tokyo Tech), Andres Oreta (DLSU), Mark Zarco (UPD), Jiro Kuwano (Saitama University), Sandra Catane (UPD), Thirapong Pipatpongsa (Tokyo Tech) and Jonathan Dungca (DLSU). The photo archive was presented at the the 7th workshop of Group 3 last December 4, 2007 at UP Diliman. The photo archive would not have been completed without the photos contributed by the members of Research Group 3 and other researchers indicated in the respective photos.