USING GIS IN THE PROBABILISTIC ASSESSMENT OF EARTHQUAKE TRIGGERED LANDSLIDE HAZARDS

Summit Ridge, located in the North Santa Cruz Mountains, California, was heavily affected by landsliding during the 1989 Loma Prieta earthquake (M_w=7.0). Widespread shallow failures, along with 17 deep-seated landslides, caused extensive damage. In order to study possible methods of assessing landslide hazard a geographical information system (GIS) was utilised. Geological, geotechnical, geomorphological and seismological data were used in a deterministic analysis using two standard earthquake slope stability models (pseudo-static and Newmark displacement). The models were used to assess the landslide potential that existed during the Loma Prieta event. It was found that, of these two models, the Newmark displacement model proved most successful at predicting the location of shallow unstable slopes. However, because both models are deterministic in nature they did not take into account any of the error and uncertainty in the input parameters. Therefore, a probabilistic Newmark displacement method of analysis was developed. This was achieved by incorporating the principles behind a recently developed probabilistic technique which utilises the pseudo-static slope stability model. The method calculates the probability that a slope will exceed a certain critical value of Newmark displacement and thus fail. The use of such an analysis resulted in a more realistic distribution of hazard when compared with the distribution of actual landslides triggered by the 1989 earthquake. Subsequent to this, the probabilistic method was used to undertake a landslide hazard assessment for Summit Ridge given a postulated earthquake located on the Northern East Bay segment of the Hayward fault.     

Correlating Some Physical and Chemical Factors with Concentrations of Heavy Metals in a River Bed

The data collected from South Creek, NSW, make it possible to seek some common underlying factors which contribute to the various differences in concentration, distance of transport, etc. Basic equations and the corresponding correlation values are given. Some correlations are so close that, subject to well planned pilot sampling, they could be used to reduce the number of samples needed for other surveys.     

The Architects of the "Large Policy" Plus Two

Warren Zimmermann , First Great Triumph: How Five Americans Made Their Country a World Power . New York : Farrar, Straus and Giroux , 2002 . xii + 562 pp. Illus., notes, index.     

Religious transnationalism among Ghanaian immigrants in Toronto: a binary logistic regression analysis

Thanks to pioneering work within anthropology, students of international migration acknowledge that most immigrants do not sever their ties with the homeland, but rather maintain them through a variety of cross‐border relationships. While scholarly work has proliferated, since the early 1990s, over the transnational economic and political activities of immigrants, to date, only few analysts have examined the religious practices with which immigrants sustain memberships in multiple locations. In addition, most available studies on transnational migration has dwelled on qualitative methods, such as participant observation, focus groups discussions and in‐depth interviews with a handful of informants, with little or no inclination towards the quantitative measurement of key variables implicated in the process. The prevalence of ethnographic methods in this area of research has, quite understandably, engendered charges of exaggeration, given the tendency of such techniques ‘to sample on the dependent variable’, to borrow the phrase of Alejandro Portes. Using data collected from a survey among Ghanaian immigrant congregations in Toronto, this study seeks to statistically predict the propensity to engage in transnational religious practices by way of a binary logistic regression analysis. In addition, the study examines how the transnational religious activities of the sampled immigrants relate to, overlap with, and differ from other kinds of transnational practices they pursue.     

THE PRICE OF METAPHOR

In his critical response to our skeptical inquiry, “Does Culture Evolve?” (History and Theory, Theme Issue 38 [December 1999], 52–78), W. G. Runciman affirms that “Culture Does Evolve.” However, we find nothing in his essay that convinces us to alter our initial position. And we must confess that in composing an answer to Runciman, our first temptation was simply to urge those interested to read our original article–both as a basis for evaluating Runciman's attempted refutation of it and as a framework for reading this essay, which addresses in greater detail issues we have already raised. Runciman views the “selectionist paradigm” as a “scientific”“puzzle‐solving device” now validated by an “expanding literature” that has successfully modeled social and cultural change as “evolutionary.” All paradigms, however, including scientific ones, give rise to self‐validating “normal science.” The real issue, accordingly, is not whether explanations can be successfully manufactured on the basis of paradigmatic assumptions, but whether the paradigmatic assumptions are appropriate to the object of analysis. The selectionist paradigm requires the reduction of society and culture to inheritance systems that consist of randomly varying, individual units, some of which are selected, and some not; and with society and culture thus reduced to inheritance systems, history can be reduced to “evolution.” But these reductions, which are required by the selectionist paradigm, exclude much that is essential to a satisfactory historical explanation–particularly the systemic properties of society and culture and the combination of systemic logic and contingency. Now as before, therefore, we conclude that while historical phenomena can always be modeled selectionistically, selectionist explanations do no work, nor do they contribute anything new except a misleading vocabulary that anesthetizes history.