Wat r the safer construction practices against tsunami
Mitigation measures for risks associated with geohazards can broadly
be classified in six categories: (1) land use plans, (2) enforcement of
building codes and good construction practice, (3) early warning
systems, (4) construction of physical protection barriers, (5) network
of escape routes and "safe" places and (6) community preparedness and
awareness building.
Early warning systems and construction of physical protection
barriers have been singled out as specific tasks in the proposed ICG
research. Together with the other four categories, they form the
backdrop for a mitigation strategy.
The results of hazard and risk mapping and analyses will be used to
formulate mitigation strategies to assist decision-making on the need
and cost-benefit of hazard mitigation works. Based on such a strategy,
protection measures can be developed and their cost-effectiveness and
environmental soundness compared.
A mitigation strategy would involve: (1) identification of possible
disaster triggering scenarios, and the associated hazard level; (2)
analysis of possible consequences for the different scenarios; (3)
assessment of possible measures to reduce and/or eliminate the potential
consequences of the danger; (4) recommendation of specific remedial
measure and if relevant reconstruction and rehabilitation plans; and (5)
transfer of knowledge and communication with authorities and society.
The strategy developed by ICG and NGI for the tsunami-affected areas of
Thailand after the 26th December 2004 Indian Ocean tsunami provides a
good example of what can be done.
Any mitigation strategy needs to be adapted for different natural
hazards and different parts of the world. Especially for developing
countries, it is vital to establish and promote proper land-use planning
and construction practices to regulate human activities that increase
risk to earthquakes, landslides or tsunamis and to prevent settlement of
communities in high-risk areas.
Physical protection measures include, but are not limited to,
integrated land use planning, drainage, erosion protection, vegetation
and ground improvement techniques, barriers (earth ramparts, artificial
elevated land, anchoring systems, retaining structures), and offshore or
onshore walls to reduce the energy or the loads induced by geohazards
(e.g. landslide, rock slide, tsunami, floods).
Buildings need to be designed (and placed in locations) to withstand
the impact forces of geohazards and to provide safe dwellings for
people. Land can also be elevated to ensure that buildings are above a
critical height, for example to protect against tsunami danger.
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