Cascadia Subduction Tremor muted by crustal faults

Deep, episodic slow slip on the Cascadia subduction megathrust of western North America is accompanied by low-frequency tremor in a zone of high fluid pressure between 30 and 40 km depth. Tremor density (tremor epicenters per square kilometer) varies along strike, and lower tremor density statistically correlates with upper plate faults that accommodate northward motion and rotation of forearc blocks. Upper plate earthquakes occur to 35 km depth beneath the faults. We suggest that the faults extend to the overpressured megathrust, where they provide fracture pathways for fluid escape into the upper plate. This locally reduces megathrust fluid pressure and tremor occurrence beneath the faults. Damping of tremor and related slow slip caused by fluid escape could affect fault properties of the megathrust, possibly influencing the behavior of great earthquakes

The relationship between the perception of distributed leadership in secondary schools and teachers' and teacher leaders' job satisfaction and organizational commitment

This study investigates the relation between distributed leadership, the cohesion of the leadership team, participative decision-making, context variables, and the organizational commitment and job satisfaction of teachers and teacher leaders. A questionnaire was administered to teachers and teacher leaders (n=1770) from 46 large secondary schools. Multiple regression analyses and path analyses revealed that the study variables explained significant variance in organizational commitment. The degree of explained variance for job satisfaction was considerably lower compared to organizational commitment. Most striking was that the cohesion of the leadership team and the amount of leadership support was strongly related to organizational commitment, and indirectly to job satisfaction. Decentralization of leadership functions was weakly related to organizational commitment and job satisfaction

A Naturally Occurring Polymorphism at Drosophila melanogaster Lim3 Locus, a Homolog of Human LHX3/4, Affects Lim3 Transcription and Fly Lifespan

Lim3 encodes an RNA polymerase II transcription factor with a key role in neuron specification. It was also identified as a candidate gene that affects lifespan. These pleiotropic effects indicate the fundamental significance of the potential interplay between neural development and lifespan control. The goal of this study was to analyze the causal relationships between Lim3 structural variations, and gene expression and lifespan changes, and to provide insights into regulatory pathways controlling lifespan. Fifty substitution lines containing second chromosomes from a Drosophila natural population were used to analyze the association between lifespan and sequence variation in the 5′-regulatory region, and first exon and intron of Lim3A, in which we discovered multiple transcription start sites (TSS). The core and proximal promoter organization for Lim3A and a previously unknown mRNA named Lim3C were described. A haplotype of two markers in the Lim3A regulatory region was significantly associated with variation in lifespan. We propose that polymorphisms in the regulatory region affect gene transcription, and consequently lifespan. Indeed, five polymorphic markers located within 380 to 680 bp of the Lim3A major TSS, including two markers associated with lifespan variation, were significantly associated with the level of Lim3A transcript, as evaluated by real time RT-PCR in embryos, adult heads, and testes. A naturally occurring polymorphism caused a six-fold change in gene transcription and a 25% change in lifespan. Markers associated with long lifespan and intermediate Lim3A transcription were present in the population at high frequencies. We hypothesize that polymorphic markers associated with Lim3A expression are located within the binding sites for proteins that regulate gene function, and provide general rather than tissue-specific regulation of transcription, and that intermediate levels of Lim3A expression confer a selective advantage and longer lifespan

Deep crustal melt plumbing of Bárðarbunga volcano, Iceland

Understanding magmatic plumbing within the Earth’s crust is important for understanding volcanic systems and improving eruption forecasting. We discuss magma plumbing under Bárðarbunga volcano, Iceland, over a four-year period encompassing the largest Icelandic eruption in 230 years. Microseismicity extends through the usually ductile region of the Earth’s crust, from 7-22 km depth in a sub-vertical column. Moment tensor solutions for an example earthquake exhibits opening tensile crack behavior. This is consistent with the deep (> 7 km) seismicity being caused by the movement of melt in the normally aseismic crust. The seismically inferred melt path from the mantle source is offset laterally from the center of the Bárðarbunga caldera by ~12 km, rather than lying directly beneath it. It is likely that an aseismic melt feed also exists directly beneath the caldera and is aseismic due to elevated temperatures and pervasive partial melt under the caldera.Funding was by research grants from the NERC and the European Community’s Seventh Framework Program grant 308377 (Project FUTUREVOLC), and a number of graduate studentships from the NERC

Letter to the editor entitled “fairness and scientific correctness is needed in the debate on transgender athletes”

editorial reviewe

The mechanics of housing collectivism: How forms and functions affect affordability

In countries worldwide, limited access to affordable housing is fuelling interest in collectivist solutions. Different organizational models are being developed to enable groups of people to own and control housing collectively. The benefits of such models have been widely promoted, not least in terms of delivering enhanced housing affordability for residents. However, evidence to support such claims is scarce and it remains unclear whether affordability is the product of collective forms and functions, or some other factor(s). To address this gap in knowledge, the paper presents findings from three case studies of English and Canadian housing collectives. Applying realist theories of causation, the processes affecting housing affordability are explained, conceptualizing two causal mechanisms which depict how organizational form, internal rules and regulatory activity, along with the unique role of the resident-owner, influence the setting of rents and prices. Further research is required to understand the prevalence of these mechanisms and their general application

Tidal Modulation of Nonvolcanic Tremor

Episodes of nonvolcanic tremor and accompanying slow slip recently have been observed in the subduction zones of Japan and Cascadia. In Cascadia, such episodes typically last a few weeks, and differ from “normal” earthquakes in their source location and momentduration scaling. The three most recent episodes in the Puget Sound/Southern Vancouver Island portion of the Cascadia subduction zone have been exceptionally well recorded. In each episode, we see clear pulsing of tremor activity with periods of 12.4 and 24-25 hours, the same as the principal lunar and lunisolar tides. This indicates that the small stresses associated with the solid-earth and ocean tides influence the genesis of tremor much more effectively than they do “normal” earthquakes. Because the lithostatic stresses are 105 times larger than those associated with the tides, we argue that tremor occurs on very weak faults.Published186 -1893.1. Fisica dei terremotiJCR Journalreserve