protect the coastal mega-infrastructure as well as the natural marine environment. This paper will not address global hazards such as global warming and acid rain, but briefly address some of the major regional or local hazards and their impact and mitigation.
o Earthquakes
Japan is subject to hundreds of earthquakes each year because of its geographic location, and geological characteristics along the Pacific Rim, affected by 4 major subduction zones.The Kansai Region is at the juncture of these zones in a region relatively more difficult to forecast. The Hyogo-ken Nanbu earthquake was a tragic. devastating impact on the community and coastal region centered on Kobe. Many lessons have been learned regarding the foundations and construction of coastal structures. In principle, future designs must improve means to decouple the vertical and lateral forces of the quake. Since many of the structures are offshore. some isolation is possible by soft landing using buoyancy to decouple some of the seismic forces. The natural environment is also impacted by the seismic forces directly and indirectly by the damage caused by ruptures to offshore pipelines, storage tanks, and sewer lines, dumping hazardous material into the marine environment. Improved structural design and perhaps early warning can provide some mitigation. Presently, the Kyoshin Earthquake network consists of about 1000 land based stations with surprisingly only a few stations offshore, where over 80 % of the earthquakes occur. There is a plan to extend this network at several latitudes projecting 150 km offshore. The offshore stations should become part of a numerical model that can measure a greater dynamic range of seismic measurements to better understand the process before and after a serious quake. Even a 10 second warning can help to automatically disconnect gas and electric lines. Any improvement in forecasting can improve risk assessment.
o Tsunamis
Tsunamis are manifested by severe seismic events or avalanches especially in coastal waters Protection against tsunami damage also depends on improved structural design and early warning Tsunami warning networks are operating in the Pacific and can provide sufficient warning time to take some mitigation measures, unless, of course, it occurs near the source of the tsunami itself. Tsunami damage has been severe to coastal communities and the marine environment as well.
o Typhoons
Japan is in the path of the most frequent route of typhoons in the west Pacific area. The torrential rains cause erosion and flooding and the sustained high velocity winds can cause damage to superstructures as well as natural vegetation and can develop large storm surges that can do even greater damage to coastal structures, and coastal and offshore terrain of the natural marine environment. Mitigation through improved structural design and early warning offer the best solutions. Early warning is possible by making computer models of every coastal basin to calculate the storm surge levels based on the geological aspects of the basin i.e., coastal seafloor, surf zone and inland terrain and the direction, size and wind velocity levels of the typhoon. Such modeling techniques are being used in the U.S. for hurricanes.
o Marine Pollution
Man made intrusions in the coastal environment are the reclamation, dredging, and construction activities in coastal areas that cause loss of wetlands and habitat and marine vegetation that have a degenerative effect on marine life. This, coupled with point and non point source pollution amplify the damage to the marine environment. River outflows, sewer outfalls and ocean dumping are major sources for water quality degradation. Enforcement of existing regulations governing industrial, agricultural and residential pollution and wise administration of land use can result in enormous improvements in water quality.
4. Protecting the Natural Environment
There are many ways to protect the marine environment, especially through monitoring and enforcement of regulations. However, it is first necessary to develop an environmental baseline. using available data and information, to make a comprehensive atlas of Osaka Bay and be able to determine status and assess any changes. Once a baseline is established, monitoring on a long term basis is needed to determine and understand the meaning of changes and the action required.
In the U S., a wide variety of marine instrumentation systems are used to sample, measure, and analyze water quality, sediments, and marine life for
