Tsunami

COPRI commissioned post-tsunami assessment trips to India, Sri Lanka and Thailand. Unlike our Technical Council on Lifeline and Earthquake Engineering (TCLEE) partners in this effort, this is the first post-disaster effort undertaken by COPRI. Our mission: to learn what we could from the devastating tsunami impacts for the sake of those who must make informed decisions when planning to avoid future tsunami damages and loss of life. Our limited work is no substitute for that of local experts in each country who will plan and execute reconstruction, develop corrective actions, and consider planning/zoning issues. Still, we must learn what we can for the sake of tsunami prone areas in the U.S. and elsewhere in the world where COPRI members practice.

The Sri Lanka team spoke to a tsunami survivor in Hambantota (southeast coast) where the tsunami runup height was 11 meters. We explained that we were engineers here to understand the impacts so that similar disasters could be avoided. The man’s immediate family survived the event, but his parents and most of his sister’s family were killed. It was a heart-wrenching story; he thanked us for helping his village and asked us to pray for him. Suddenly, our mission seemed insignificant and shallow compared to his suffering. Upon reflection, however, it seems that in our role as civil engineers we must learn from this tragic experience in order to help in any, albeit small, way.

The Indian team covered the east coast region of India from Pondicherry in the north to Nagapattnam in the south. The Sri Lankan team traveled from Colombo on the west coast to Trincomalee on the north-east coast. The Thai team traveled on the west coast from Ban Nam Kem to the southern tip of Phuket Island. Overall, tsunami runup elevations in impacted areas ranged from several to more than 11 meters and inundation penetrated inland as much as several kilometers.

Ports and Harbors: Port impacts were relatively small and associated with vessel movements, breakwater armor damage, building flooding, wharf damage, and sedimentation. The Indian team visited the Port of Chennai and a modern oil terminal in Nagore on the Bay of Bengal. Damage at the former was limited to that associated with ship movements, sediment transport and minor breakwater armor movement. There was no visible damage at the latter. The Indian team also visited S. Andaman Island, about 800 miles off the coast from Chennai. The port complex for the Andaman islands is adjacent to the city of Port Blair, and suffered major damage from vessel impact, the earthquake and a tectonic variation in the water depth. The port now has 1 meter more of water depth. Drydocks and port buildings were flooded, but there was no loss of life within the port. The Sri Lankan team visited the Ports of Colombo, numerous fishing ports (Panadura, Beruwala, Hikkaduwa, Hambantota, and others), Port of Galle, and Port of Trincomalee. Colombo experienced minor flooding; a container ship lost control and ran aground. Impacts at most of the fishing ports included the scattering/damage of the fishing fleet, backside breakwater damage and flood related building damage. A dredge was deposited on top of a wharf at the Port of Galle which also experienced 2 meters of sedimentation and significant building damage. Damage was insignificant at the Port of Trincomalee. Tsunami impact at an estuarine fishing harbor at Ban Nam Kem included grounding/damage to vessels and destruction of a concrete wharf.

Bridge Damage, Karaikal, India

Roads and Bridges: A relatively large number of bridges were damaged by the tsunami. In many cases, damage resulted from scour of bridge abutments, piers or causeways leading to the bridge. In Karaikal India (approximately 30 km north of Nagapattnam) a pedestal supporting the primary bridge in town collapsed. A Bailey bridge had been installed to span the collapsed pedestal until permanent repairs could be made. Many bridges and causeways were damaged in Sri Lanka particularly in the eastern provinces including the largest bridge in the country at Arugam Bay. Interestingly, it seems that coastal roadways suffered only minor damage.

Beaches, Inlets and Coastal Structures: Beaches impacts were site-specific. In many cases, the beaches showed little impact from the tsunami. Coastal inlets were dramatically scoured in Sri Lanka especially in the east. Coastal structures throughout Sri Lanka held up reasonably well and, in many cases, protected hinterland areas. Characteristic seawall damage was the loss of armor rock on the landward side or crest of the structure. The beach area in the Khao Lak and Cape Pakarang in Thailand, where tsunami runup was 8 to 10 meters, was severely eroded over a large extent. Sand dunes at Karon Beach in Thailand were observed to provide a level of protection to shoreline areas. Many Thai seawalls were overtopped but remained intact and served to protect hinterland areas.

was extensive and sobering. The visage of damaged homes went on for miles and miles in each country. Thousands of deaths occurred in many of the densely populated villages. The team observed that debris carried by the tsunami wave was a major contributor to injuries, death and coastal building damage. Debris in rural areas was characterized by mats or rafts of wood pieces; more developed areas, building remnants and cars. Damage in less developed areas was most extensive owing to inferior building practices. The outer few rows of homes were often thoroughly destroyed and served to (partially) protect rows further inland. Extensive building damage was observed, however, two and three story buildings of good construction facilitated vertical evacuation from the tsunami in some cases.

In Summary, the COPRI team witnessed the aftermath, and continuation of, immense human suffering. The team extended its understanding of the devastating impacts of tsunami waves. Additionally, the team gained new knowledge while having had our basic knowledge reinforced. We have learned that flooding and loss of life follows directly from land elevation; that basic education of tsunami wave and flood phenomena will save lives; that flood zone mapping and the development of vertical or horizontal evacuation will save lives, that a tsunami warning system is imperative; and that buildings, homes, and bridges need to be built properly. Additionally, we have observed that wave heights change dramatically from place to place, that the lee side of an island nation can be significantly impacted by a tsunami, that tsunamis can penetrate well inland, and that beaches, palm trees, and seawalls can survive.

It has been an honor for the COPRI team to participate in this emprise. More information regarding this work can be found at www.coprinstitute.org. Team members will prepare a published report and will make presentations at two upcoming COPRI conferences: Solutions to Coastal Disasters in Charleston, South Carolina, May 8-11, 2005, and Waves 2005 in Madrid, Spain, July 3-7, 2005.

Thailand: Dr. David Kriebel- Professor of Ocean Engineering, United States Naval Academy

Dr. Robert (Tony) Dalrymple- Professor of Civil Engineering, Johns Hopkins University

India: Martin Eskijian- Engineering Supervisor/Marine Facilities Division, California State Lands Commission