Faulting and hydration of the Juan de Fuca plate system

Author Posting. © Elsevier B.V., 2009. This is the author's version of the work. It is posted here by permission of Elsevier B.V. for personal use, not for redistribution. The definitive version was published in Earth and Planetary Science Letters 284 (2009): 94-102, doi:10.1016/j.epsl.2009.04.013.Multichannel seismic observations provide the first direct images of crustal scale normal faults within the Juan de Fuca plate system and indicate that brittle deformation extends up to ~200 km seaward of the Cascadia trench. Within the sedimentary layering steeply dipping faults are identified by stratigraphic offsets, with maximum throws of 110±10 m found near the trench. Fault throws diminish both upsection and seaward from the trench. Long-term throw rates are estimated to be 13±2 mm/kyr. Faulted offsets within the sedimentary layering are typically linked to larger offset scarps in the basement topography, suggesting reactivation of the normal fault systems formed at the spreading center. Imaged reflections within the gabbroic igneous crust indicate swallowing fault dips at depth. These reflections require local alteration to produce an impedance contrast, indicating that the imaged fault structures provide pathways for fluid transport and hydration. As the depth extent of imaged faulting within this young and sediment insulated oceanic plate is primarily limited to approximately Moho depths, fault- controlled hydration appears to be largely restricted to crustal levels. If dehydration embrittlement is an important mechanism for triggering intermediate-depth earthquakes within the subducting slab, then the limited occurrence rate and magnitude of intraslab seismicity at the Cascadia margin may in part be explained by the limited amount of water imbedded into the uppermost oceanic mantle prior to subduction. The distribution of submarine earthquakes within the Juan de Fuca plate system indicates that propagator wake areas are likely to be more faulted and therefore more hydrated than other parts of his plate system. However, being largely restricted to crustal levels, this localized increase in hydration generally does not appear to have a measurable effect on the intraslab seismicity along most of the subducted propagator wakes at the Cascadia margin.Supported by the Doherty Foundation and the National Science 449 Foundation under grants OCE002488 and OCE0648303 to SMC and MR

The effects of writing on learning in science, social studies, and mathematics : A meta-analysis

This meta-analysis examined if students writing about content material in science, social studies, and mathematics facilitated learning (k = 56 experiments). Studies in this review were true or quasi-experiments (with pretests), written in English, and conducted with students in Grades 1 to 12 in which the writing-to-learn activity was part of instruction. Studies were not included if the control condition used writing to support learning (except when treatment students spent more time engaging in writing-to-learn activities), study attrition exceeded 20%, instructional time and content coverage differed between treatment and control conditions, pretest scores approached ceiling levels, letter grades were the learning outcome, and students attended a special school for students with disabilities. As predicted, writing about content reliably enhanced learning (effect size = 0.30). It was equally effective at improving learning in science, social studies, and mathematics as well as the learning of elementary, middle, and high school students. Writing-to-learn effects were not moderated by the features of writing activities, instruction, or assessment. Furthermore, variability in obtained effects were not related to features of study quality. Directions for future research and implications for practice are provided

Tobacco control policies, social inequality and mental health populations: time for a comprehensive treatment response

Author version made available in accordance with the publisher's policyA recent report conducted by Access Economics for SANE Australia has comprehensively reviewed the economic costs of smoking for Australian smokers with mental illness and found that the financial cost to these smokers is $33 billion (AUST) per year [1]. Internationally, research has estimated the economic costs of smoking to reach$500 billion (US) by 2010 [2]. This prompts a long-standing debate about tobacco control initiatives and their effectiveness and consequences for vulnerable populations. Chapman [3] has argued for increased tobacco control, stating that those who see tobacco as a legitimate product and tobacco control as jeopardising the financial benefits gained through tobacco excise are ill-informed regarding its social costs and the ethics of continuing to support its revenue-raising role. However, the price and demand relationship of some commodities may be very elastic for some groups within the population, that is, raising taxes on them will not necessarily lead to reduced demand for those commodities. It is time to unpack the debate and advocate for more to be done for smokers with mental illness, beyond mere broad population-based tobacco control strategies and policies and piecemeal support to quit