Initiation process of earthquakes and its implications for seismic hazard reduction strategy.

For the average citizen and the public, "earthquake prediction" means "short-term prediction," a prediction of a specific earthquake on a relatively short time scale. Such prediction must specify the time, place, and magnitude of the earthquake in question with sufficiently high reliability. For this type of prediction, one must rely on some short-term precursors. Examinations of strain changes just before large earthquakes suggest that consistent detection of such precursory strain changes cannot be expected. Other precursory phenomena such as foreshocks and nonseismological anomalies do not occur consistently either. Thus, reliable short-term prediction would be very difficult. Although short-term predictions with large uncertainties could be useful for some areas if their social and economic environments can tolerate false alarms, such predictions would be impractical for most modern industrialized cities. A strategy for effective seismic hazard reduction is to take full advantage of the recent technical advancements in seismology, computers, and communication. In highly industrialized communities, rapid earthquake information is critically important for emergency services agencies, utilities, communications, financial companies, and media to make quick reports and damage estimates and to determine where emergency response is most needed. Long-term forecast, or prognosis, of earthquakes is important for development of realistic building codes, retrofitting existing structures, and land-use planning, but the distinction between short-term and long-term predictions needs to be clearly communicated to the public to avoid misunderstanding.

Environmental services of biodiversity.

Humans derive many utilitarian benefits from the environmental services of biotas and ecosystems. This is often advanced as a prime argument to support conservation of biodiversity. There is much to be said for this viewpoint, as is documented in this paper through a summary assessment of several categories of environmental services, including regulation of climate and biogeochemical cycles, hydrological functions, soil protection, crop pollination, pest control, recreation and ecotourism, and a number of miscellaneous services. It is shown that the services are indeed significant, whether in ecological or economic senses. Particularly important is the factor of ecosystem resilience, which appears to underpin many of the services. It should not be supposed, however, that environmental services stem necessarily and exclusively from biodiversity. While biodiversity often plays a key role, the services can also derive from biomass and other attributes of biotas. The paper concludes with a brief overview assessment of economic values at issue and an appraisal of the implications for conservation planning.