Transportable Seismic Discriminants: The Use of Cross-Spectral Measurements to Reduce Parameter Scatter and Identification Error,
Abstract : Much progress has been made in regional seismic discrimination over the past ten years. Aided by the availability of high-quality waveforms and ground-truth databases, researchers discovered the discrimination capabilities of Lg/P and S/P spectral ratios, especially at high frequencies. However, when spectral ratios or signal parameters which perform well in one geographic area are applied to events in another, the results are typically uncertain or erroneous. This was illustrated during the identification analysis of the Dec. 31, 1992 Novaya Zemlya event: the same data were analyzed by a number of researchers who came to uncertain or conflicting conclusions. For regional discrimination to work in a CTBT context, this problem must be overcome. The most obvious factors contributing to transportability failure include geographic variability of source and path effects. However, noise and the inherent instability of spectral ratio calculations at low SNR's and restricted bandwidths are also likely factors. Regional seismic spectra rarely follow the model of a flat low-frequency spectrum with smooth high-frequency rolloff. This is especially true for quarry explosions, where long time-delay ripple firing can add harmonic distortion. Good signal processing practice dictates that measurements be made only at frequencies where there is sufficient SNR, which often means the use of cross spectral and system identification methods. This project will extend the discrimination research conducted to date to include these methods.
Extracting and Processing Signal Parameters for Regional Seismic Event Identification
This paper provides an overview of the processes of parameter extraction, parameter evaluation, and parameter processing leading to regional seismic event identification. The concepts are illustrated using two examples which utilize data from the NORESS array. Sources of error leading to mis-identifications are also given, as well as a discussion of future challenges as they relate to the procedures outlined.
Exploring the Textual Alchemy of Legal Gender: Experimental Statutes and the Message in the Medium
This article draws on original empirical research to explore the politics of experimental feminist statutes. It has two main aims. First, it traces how conventional legislative drafting techniques have participated in the wider social creation and continuance of sex/gender norms. It shows how dominant statutory expressions of sex and gender that might otherwise appear timeless have shifted with social change and legal innovation. The article contributes to debates in feminist legal studies, legal anthropology, and legislative drafting by making visible, and analysing the particular power of legislative text, its ‘alchemy’, in expressing and re-creating sex/gender as a social, cultural and political artefact. Second, drawing on this research, the article explores what the Future of Legal Gender project might consider and do when drafting an experimental statute to decertify legal gender. Addressing questions of positionality, believability, legal form and the use of potentially innovative or contested drafting techniques (the singular “they”, the second person), the article explores tensions between legislative drafting and feminist legal method, as well as the benefits for bringing feminist analysis and perspectives to this important aspect of legal practice. Given that legislative drafting does not merely inscribe pre-agreed policy ideas into legal text but helps to shape emerging ontologies of gender, then drafting an experimental statute invites feminists to pay attention to interlinked questions of substance and form in the exploration of prefigurative legal futures.