7.4 Methods of hazard assessment h The essential problem of volcanic prediction is not the identification of the onset of an eruption, but the assessment of the level to which the activity will ultimately escalate and the rate of escalation. There are no specific precursors to eruptive climaxes such as the emission of glowing avalanches, and it is therefore necessary to assess the situation on a probabilistic basis, utilizing : 0) (ii) (iii) 04 Global statistics for the onset of glowing avalanche emission as a function of time elapsed after the beginning of the eruption. Regional statistics on the ratio of eruptions, which have included glowing avalanche emis- sion, to those which had no associated avalanches. Historical data on, or geological reconstructions of, the particular eruptive characteristics of the volcano in question. A weighting factor to take into account the trend of activity, i.e. whether increasing or de creasing, at the eruption in question. From recent studies made on the first two of the above items, probability statistics can be given for example for the time interval between the onset of eruption and the emission of the first glowing avalanche. From these the probability can be given whether’s glowing avalanche is yet to occur, as a function of time elapsed since the eruption onset. Similar probability assess- ments based on global or regional experience could be made for other types of volcanic activity, e.g. tephra falls, mudflows and lava flows. The problem of quantifying the hazard is one of the least well defined but one of the most critical issues in volcanic risk management. 24 VIII. RISK ANALYSIS - A METHODOLOGY 8.1 Factors affecting impact Much work has been done in the earth sciences to define the physical characteristics of 
**Analysis**
The text appears to be discussing the methods and challenges of predicting and assessing the risks associated with volcanic eruptions. The focus is on the scientific and probabilistic aspects of hazard assessment, including the use of statistics and historical data to predict the likelihood and timing of various types of volcanic activity. This suggests that the text is related to the field of natural sciences, specifically volcanology, and is likely to be of interest to researchers and professionals in this field.

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Natural resources and environment, Science and technology