General Tsunami Resources
Tsunami Mitigation Strategies
While tsunamis can not be prevented, or their destructive effects entirely avoided, actions can be taken to mitigate the risks of this hazard, thereby reducing the impacts on life, physical structures and livelihoods. The first step in mitigating the tsunami hazard and reducing vulnerability is to gain an understanding of the threat and potential effects should a tsunami occur. Some of the more direct physical effects of tsunami include: • Loss of life; • Damage to, or destruction of buildings, boats, critical facilities and coastal infrastructure; • Loss of coastline; and • Excessive scattered debris. Less direct effects, and those with sometimes long-term consequences, can include: • Contamination of coastal soils; • Diminished domestic water supply due to contamination of shallow wells and aquifers (with salt water and other toxic substances); • Disease outbreaks; • Interruption of business and economic processes; and Disruption of education and social services. • It can take many years for communities to recover from the effects of tsunamis, rebuild homes and physical infrastructure, and regain economic stability. Oftentimes disasters and subsequent recovery processes reveal complex inter-relationships and dependencies. For example, seawater over inland areas due to a tsunami increases salinity of soils and can render land unsuitable for cultivation. If arable land is reduced, food supply is diminished and farmers must seek other employment, which dramatically affects their livelihoods. Tsunami risks can be mitigated through many of the same actions that minimize the effects of other coastal hazards such as flooding, storm surge and high surf. By no means an exhaustive list of all possible mitigation strategies, those outlined here serve as a starting point for consideration. Additionally, because the Tsunami Awareness Kit was developed specifically for the Pacific Islands, this document presents a number of strategies unique to the island environments.
Prepared by the
Pacific Disaster Center. 2005.
Tsunami Awareness Kit
General Tsunami Resources • • • • • Land use management to minimize development in areas of potential tsunami inundation. Preservation of natural barriers or dunes along coastlines. Establishment of design standards, building codes, or guidelines for construction of buildings within coastal areas. Increased public awareness and education about tsunami risks, warning signs and preparedness actions. Development of a warning system to alert people to evacuate to higher ground or to upper stories of sturdily built structures.
Strategy 1: Land Use Management
Building Placement The late seismologist, Ian Everingham conducted extensive research and wrote numerous publications concerning earthquake and tsunami phenomena and their effects in the Pacific Islands. Concerning building placement, he suggests: • A simple precaution against damage from most tsunamis is for all buildings to be placed 2-3 metres above the high tide level (Everingham, 1976). Special precautions should be made for buildings supplying essential services, however, as is seen by the $300,000 damage caused to a government communications station at Torokima, on the west coast of Bougainville by a 2 metre tsunami following a magnitude 7.7 earthquake in the east Solomon Sea on 20 July, 1975 (Everingham, et al, 1977).
The International Tsunami Survey Team (ITST) deployed after the 1998 Aitape, Papua New Guinea tsunami recommended the following land use considerations: • • Residents should not be relocated in locales fronted by water and backed by rivers or lagoons; and Schools, churches, and other critical facilities should never be located closer than 400m from the coastline, and preferably 800m in at-risk areas.
Strategy 2: Planting and Environmental Preservation
Preserve Dunes And Other Natural Barriers Professor Hugh...