Exploring the potential linkages between oil‐field brine reinjection,crystalline basement permeability,and triggered seismicity for the Dagger Draw Oil field,southeastern New Mexico,USA, using hydrologic modeling

We used hydrologic models to explore the potential linkages between oil‐field brine reinjection and increases in earthquake frequency (up to M_d 3.26) in southeastern New Mexico and to assess different injection management scenarios aimed at reducing the risk of triggered seismicity. Our analysis focuses on saline water reinjection into the basal Ellenburger Group beneath the Dagger Draw Oil field, Permian Basin. Increased seismic frequency (>M_d 2) began in 2001, 5 years after peak injection, at an average depth of 11 km within the basement 15 km to the west of the reinjection wells. We considered several scenarios including assigning an effective or bulk permeability value to the crystalline basement, including a conductive fault zone surrounded by tighter crystalline basement rocks, and allowing permeability to decay with depth. We initially adopted a 7 m (0.07 MPa) head increase as the threshold for triggered seismicity. Only two scenarios produced excess heads of 7m five years after peak injection. In the first, a hydraulic diffusivity of 0.1 m² s^?1 was assigned to the crystalline basement. In the second, a hydraulic diffusivity of 0.3 m² s^?1 was assigned to a conductive fault zone. If we had considered a wider range of threshold excess heads to be between 1 and 60 m, then the range of acceptable hydraulic diffusivities would have increased (between 0.1–0.01 m² s^?1 and 1–0.1 m² s^?1 for the bulk and fault zone scenarios, respectively). A permeability–depth decay model would have also satisfied the 5‐year time lag criterion. We also tested several injection management scenarios including redistributing injection volumes between various wells and lowering the total volume of injected fluids. Scenarios that reduced computed excess heads by over 50% within the crystalline basement resulted from reducing the total volume of reinjected fluids by a factor of 2 or more.     

Pinochet: The Politics

Against the background of the Pinochet affair, the author considers that a new era of international politics is in the process of being created. The House of Lords' ruling which has allowed extradition procedures against the former Chilean dictator, is understood as a formidable and groundbreaking decision in international law based on the defence of human rights against crimes committed by authoritarian and unlawful rulers. The decision taken under the European Convention on extradition and the setting up of a Permanent International Criminal Court in the summer of 1998 are, according to the author, signs that international law and international politics are moving in the direction of a universal acceptance that violators of human rights must bepunished.
However, the author is also cautious about the tension between the new path opened to international politics and the old power politics based on the absolute and indivisible sovereignty of the state. Double standards will certainly prevail and powerful states, in particular the United States, are reluctant to accept that international law and international politics are in the process of change.     

FINGERPRINTING OF ROMAN MINTS USING LASER‐ABLATION MC–ICP–MS LEAD ISOTOPE ANALYSIS*

In this paper we present data to demonstrate the applicability of laser‐ablation MC–ICP–MS isotope analysis to archaeological artefacts, in this case Roman silver coins. The technique requires no chemical preparation, does minimal damage to the sample and yields external reproducibility that is better than conventional TIMS analysis; ²⁰⁷Pb/²⁰⁶Pb =±0.015% 2σ in comparison with ²⁰⁷Pb/²⁰⁶Pb =±0.04% 2σ, respectively. We show that Pb isotope compositions give isotope fingerprints to mints despite the likely reworking of the metal during coin production.     

Lyndon Johnson's War? Part 1: Escalation

At the beginning of 1964 there were around 20,000 US military ‘advisers’ in South Vietnam, working alongside the South Vietnamese army in the latter's campaign against the communist guerrillas, led and supplied by the government of North Vietnam. By the summer of 1965 there were 125,000 American troops in the country, with more pledged for future deployment. Most of these were not ‘advisers’, but combat forces openly engaged in fighting the communists. In addition, since March 1965, a sustained American bombing campaign had been waged against targets in North Vietnam. This transformation in the nature of the American commitment to South Vietnam had been brought about by two factors: the continued weakness of South Vietnamese governments as military and civilians struggled for control; and the growing strength and success of the communist guerrillas. South Vietnam was regarded as a vital American interest for two reasons: it was perceived as a test of US resolution throughout the rest of the world; and, following the famous ‘domino theory’, it was believed that the loss of South Vietnam to communism would precipitate the weakening and eventual collapse of other non‐communist states in the region. Although there was opposition to the escalation of the war, both in Congress and the administration, there were also voices notably in the military, who wished to press on further and faster. The administration adopted a middle course, gradually increasing its commitment and continually planning for the next step. Although political motives undoubtedly played a part in this more measured approach—there was a presidential election in November 1964—it is clear that President Johnson was not at all convinced that any policy he chose would save South Vietnam. At the same time, he feared the consequences of withdrawal, both at home and abroad. A deeply insecure man, he allowed himself to be persuaded by his principal advisers, to whom he felt indebted for personal as well as political reasons.