The Past,Present, and Future of Geodemographic Research in the United States and United Kingdom

This article presents an extensive comparative review of the emergence and application of geodemographics in both the United States and United Kingdom, situating them as an extension of earlier empirically driven models of urban socio-spatial structure. The empirical and theoretical basis for this generalization technique is also considered. Findings demonstrate critical differences in both the application and development of geodemographics between the United States and United Kingdom resulting from their diverging histories, variable data economies, and availability of academic or free classifications. Finally, current methodological research is reviewed, linking this discussion prospectively to the changing spatial data economy in both the United States and United Kingdom.     

Membrane Interface Probe Protocol for Contaminants in Low‐Permeability Zones

Accurate characterization of contaminant mass in zones of low hydraulic conductivity (low k) is essential for site management because this difficult‐to‐treat mass can be a long‐term secondary source. This study developed a protocol for the membrane interface probe (MIP) as a low‐cost, rapid data‐acquisition tool for qualitatively evaluating the location and relative distribution of mass in low‐k zones. MIP operating parameters were varied systematically at high and low concentration locations at a contaminated site to evaluate the impact of the parameters on data quality relative to a detailed adjacent profile of soil concentrations. Evaluation of the relative location of maximum concentrations and the shape of the MIP vs. soil profiles led to a standard operating procedure (SOP) for the MIP to delineate contamination in low‐k zones. This includes recommendations for: (1) preferred detector (ECD for low concentration zones, PID or ECD for higher concentration zones); (2) combining downlogged and uplogged data to reduce carryover; and (3) higher carrier gas flow rate in high concentration zones. Linear regression indicated scatter in all MIP‐to‐soil comparisons, including R² values using the SOP of 0.32 in the low concentration boring and 0.49 in the high concentration boring. In contrast, a control dataset with soil‐to‐soil correlations from borings 1‐m apart exhibited an R² of ≥0.88, highlighting the uncertainty in predicting soil concentrations using MIP data. This study demonstrates that the MIP provides lower‐precision contaminant distribution and heterogeneity data compared to more intensive high‐resolution characterization methods. This is consistent with its use as a complementary screening tool.     

Long aftershock sequences in North China and Central US: implications for hazard assessment in mid-continents

Because seismic activity within mid-continents is usually much lower than that along plate boundary zones, even small earthquakes can cause widespread concerns, especially when these events occur in the source regions of previous large earthquakes. However, these small earthquakes may be just aftershocks that continue for decades or even longer. The recent seismicity in the Tangshan region in North China is likely aftershocks of the 1976 Great Tangshan earthquake. The current earthquake sequence in the New Madrid seismic zone in central United States, which includes a cluster of M ~ 7.0 events in 1811–1812 and a number of similar events in the past millennium, is believed to result from recent fault reactivation that releases pre-stored strain energy in the crust. If so, this earthquake sequence is similar to aftershocks in that the rates of energy release should decay with time and the sequence of earthquakes will eventually end. We use simple physical analysis and numerical simulations to show that the current sequence of large earthquakes in the New Madrid fault zone is likely ending or has ended. Recognizing that mid-continental earthquakes have long aftershock sequences and complex spatiotemporal occurrences are critical to improve hazard assessments.     

Quantification of the Attenuation of Storm Surge Components by a Coastal Wetland of the US Mid Atlantic

Coastal wetlands are receiving increased consideration as natural defenses for coastal communities from storm surge. However, there are gaps in storm surge measurements collected in marsh areas during extreme events as well as understanding of storm surge processes. The present study evaluates the importance and variation of different processes (i.e., wave, current, and water level dynamics with respect of the marsh topography and vegetation characteristics) involved in a storm surge over a marsh, assesses how these processes contribute to storm surge attenuation, and quantifies the storm surge attenuation in field conditions. During the Fall of 2015, morphology and vegetation surveys were conducted along a marsh transect in a coastal marsh located at the mouth of the Chesapeake Bay, mainly composed of Spartina alterniflora and Spartina patens. Hydrodynamic surveys were conducted during two storm events. Collected data included wave characteristics, current velocity and direction, and water levels. Data analysis focused on the understanding of the cross-shore evolution of waves, currents and water level, and their influence on the overall storm surge attenuation. Results indicate that the marsh area, despite its short length, attenuates waves and reduces current velocity and water level. Tides have a dominant influence on current direction and velocity, but the presence of vegetation and the marsh morphology contribute to a strong reduction of current velocity over the marsh platform relative to the currents at the marsh front. Wave attenuation varies across the tide cycle which implies a link between wave attenuation and water level and, consequently, storm surge height. Storm surge reduction, here assessed through high water level (HWL) attenuation, is linked to wave attenuation across the front edge of the marsh; this positive trend highlights the reduction of water level height induced by wave setup reduction during wave propagation across the marsh front edge. Water level attenuation rates observed here have a greater range than the rates observed or modeled by other authors, and our results suggest that this is linked to the strong influence of waves in storm surge attenuation over coastal areas.     

Chromophoric Dissolved Organic Matter (CDOM) In Rainwater,Southeastern North Carolina,USA

The abundance and optical characteristics of dissolved organic matter (DOM) were determined in 120 rain samples collected in Wilmington, North Carolina, USA, between February 21, 2002 and August 11, 2003. All rainwater samples contained chromophoric dissolved organic matter (CDOM) as well as fluorescent compounds. The absorbance spectra of CDOM in the samples decreased exponentially with wavelength with little or no measurable absorbance past 550 nm. Fluorescence excitation emission spectra (EEMS) of the precipitation revealed the presence of four major peaks indicating both terrestrial and marine influences. There was a strong positive correlation between total integrated fluorescence and the absorbance coefficient at 300 nm in rainwater samples, suggesting that these optical properties are directly interrelated and that the compounds responsible for absorbance may be the same as those responsible for fluorescence. Air-mass back-trajectory analysis indicated elevated CDOM levels in continentally influenced rainwater relative to marine dominated events implying that anthropogenic and/or terrestrial sources are important contributors to CDOM levels in precipitation. The presence of highly absorbing and fluorescing CDOM in rainwater has significant ramifications in atmospheric chemistry and may play a previously unrecognized role in the wavelength dependent spectral attenuation of solar radiation by atmospheric waters.     

Gray swans: comparison of natural and financial hazard assessment and mitigation

Even advanced technological societies are vulnerable to natural disasters, such as the 2011 Tohoku earthquake and tsunami, and financial disasters, such as the 2008 collapse of the US housing and financial markets. Both resulted from unrecognized or underappreciated weaknesses in hazard assessment and mitigation policies. These policies relied on models that proved inadequate for reasons including inaccurate conceptualization of the problem, use of a too-short historic record, and neglect of interconnections. Japanese hazard models did not consider the possibility of multiple fault segments failing together, causing a much larger earthquake than anticipated, and neglected historical data for much larger tsunamis than planned for. Mitigation planning underestimated the vulnerability of nuclear power plants, due to a belief in nuclear safety. The US economic models did not consider the hazard that would result if many homeowners could not pay their mortgages, and assumed, based on a short history, that housing prices would keep rising faster than interest rates. They did not anticipate the vulnerability of the financial system to a drop in housing prices, due to belief that markets functioned best without government regulation. Preventing both types of disasters from recurring involves balancing the costs and benefits of mitigation policies. A crucial aspect of this balancing is that the benefits must be estimated using models with significant uncertainties to infer the probabilities of the future events, as we illustrate using a simple model for tsunami mitigation. Improving hazard models is important because overestimating or underestimating the hazard leads to too much or too little mitigation. Thus, although one type of disaster has natural causes and the other has economic causes, comparison provides insights for improving hazard assessment and mitigation policies. Instead of viewing such disasters as unpredictable and unavoidable “black swan” events, they are better viewed as “gray swans” that—although novel and outside recent experience—can be better foreseen and mitigated.     

西藏班公湖-怒江缝合带--深部地球物理结构给出的启示

通过跨越缝合带的综合地球物理和地质调查研究，查明了地质上推测的“班公湖一怒江缝合带”的深部结构和构造，提出了下述观点：现有资料尚不足以证明，“班公湖一怒江缝合带”是严格意义上的缝合带，而趋向表明是一个老的弧后拉张区，在后来的印度大陆与拉萨地块碰撞挤压过程中，先是沉积了巨厚的第三纪地层，仅在20Ma(?)以来才转变成挤压体制，形成多条逆冲断裂；纳木错一申扎逆冲的蛇绿岩片带代表着侏罗纪洋的主要缝合带位置，在其闭合过程中洋壳与陆壳一起向北发生俯冲，并形成班戈岩带所代表的岩浆弧，在岩浆弧后出现了拉张区；下地壳向北挤压增厚，物理性质不同的上、下地壳之间相互运动而形成了一条缓倾的剪切片理化带，南北长达300km，命名为主羌塘逆冲断裂带(MQT)；并使班戈岩片整体向南逆推上去，致使地壳分层增厚；在拉张期伦坡拉小地块向下运动，20Ma以后转变成压缩体制后又开始向上逆推，再加上后期的剥蚀，致使班戈深成岩体出露于地表；唐古拉山、各拉丹冬等年轻的火山岩浆带与地表显示的构造活动无直接关系，推测应是地壳深层作用引起的构造岩浆活动的显示。     

Subduction cycling of volatiles and trace elements through the Central American volcanic arc: evidence from melt inclusions

Compositions of melt inclusions in olivine (Fo_90-64) from 11 localities in Guatemala, Nicaragua and Cost Rica along the Central American Volcanic Arc are used to constrain combined systematics of major and trace elements and volatile components (H₂O, S, Cl, F) in parental melts and to estimate volcanic fluxes of volatile elements. The melt inclusions cover the entire range of compositions reported for whole rocks from Central America. They point to large heterogeneity of magma sources on local and regional scales, related to variable contributions of diverse crustal (from the subducting and overriding plates) and mantle (from the wedge and incoming plate) components involved in magma genesis. Water in parental melts correlates inversely with Ti, Y and Na and positively with Ba/La and B/La (with the exception of Irazú Volcano), which indicates mantle melting fluxed by Ba-, B- and H₂O-rich, possibly, serpentinite-derived fluid beneath most parts of the arc. Different components with melt-like characteristics (high LREE, La/Nb and probably also Cl, S and F and low Ba/La) control the geochemical peculiarities of Guatemalan and Costa Rican magmas. The composition of parental magmas together with published data on volcanic volumes and total SO₂ flux from satellite measurements are used to constrain fluxes of volatile components and to estimate total magmatic flux in Central America. We found that volcanic flux accounts for only 13% of total magmatic and volatile fluxes. The remaining 87% of magmas remained in the lithosphere to form cumulates (∼39%) and intrusives (∼48%). The intrusive fraction of magmatic flux may be significantly larger beneath Nicaragua compared to Costa Rica. Interestingly, total fluxes of magmas and volatiles in Central America are quite similar to the global average estimates. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Facilitating linkage of climate policies through the Paris outcome

The Durban Platform for Enhanced Action negotiations are likely to lead to a Paris outcome that embodies a hybrid climate policy architecture, combining top-down elements, such as for monitoring, reporting, and verification, with bottom-up elements, including ‘Intended Nationally Determined Contributions’ from participating countries, detailing plans to reduce emissions, based on national circumstances. For such a system to be cost-effective – and thus more likely to embody greater ambition – a key feature will be linkages among regional, national, and sub-national climate policies. By linkage, we mean formal recognition by a mitigation programme in one jurisdiction of emission reductions undertaken in another jurisdiction for the purposes of complying with the first jurisdiction's requirements. The Paris outcome could play at least four different roles with respect to linkage of heterogeneous policy instruments. First, it could discourage linkage, either by not allowing countries to count international transfers toward their mitigation contributions, or by limiting the number or types of transferred units that can be counted for compliance purposes. Second, it could be silent on the topic of linkage, creating legal and regulatory uncertainty about whether international transfers are allowed. Third, it could expressly authorize linkage but not provide any further details about how linkage should occur, leaving it to future United Nations Framework Convention on Climate Change negotiating sessions to work out the details or to national governments to develop bilateral or multilateral linkage arrangements. Finally, the Paris outcome could establish institutional arrangements and rules that facilitate and promote linkage. We examine how a future international policy architecture could help facilitate the growth and operation of a robust system of international linkages. Several design elements merit serious consideration for inclusion in the Paris outcome, either in the core agreement or by establishing a process for subsequent international elaboration. At the same time, including detailed linkage rules in the core agreement is not desirable because this could make it difficult for rules to evolve in light of experience.

Policy relevance

These findings have implications for the efficient and effective design of an international climate policy architecture by detailing the role that linkage can play in supporting heterogeneous climate policies at the regional, national, and sub-national levels.