Articles in 2011

The mechanisms that govern the growth of debris flows are largely unclear, hampering efforts to assess natural hazards in landslide-prone areas. Experiments suggest that high bed-water content increases flow velocity and mass entrainment in landslides.

The origin of water in the Earth–Moon system is an open question. Geochemical analysis of the rocks retrieved by the Apollo missions show that lunar and terrestrial water are isotopically distinct, suggesting acquisition after the Moon's formation.

The contribution of glaciers and ice caps to global sea-level rise is uncertain: they are incompletely counted and the calculation is challenging. A new estimate from the best available data suggests a contribution of about 12 cm by 2100.

Continental lithosphere can undergo pervasive internal deformation, but patterns of flow within the lithosphere are difficult to observe. Determination of seismic Rayleigh-wave anisotropy in the crust and mantle of the Aegean region reveal matching orientations of regional-scale anisotropic fabric and the directions of extension during the last significant episodes of deformation.

The M_w 8.8 Chile earthquake on 27 February 2010 occurred in a broad region where tectonic loading has been accumulating since the great 1835 earthquake. A joint inversion of tsunami and geodetic data suggests that the 2010 earthquake rupture only partly overlapped with the zone of preseismic locking.

The origins of the non-mass-dependent oxygen isotope anomaly in planetary materials remain controversial. An analysis of the carbon and oxygen isotopes of organic matter from a carbonaceous chondrite suggests that the signature was acquired in the envelope of the protosolar nebula, triggered by the photodissociation of carbon monoxide.

Continental crust is less dense than that of the oceans, and less likely to sink into the mantle. Nevertheless, an analysis of a high-pressure rock from the Swiss Alps suggests that more than one cycle of crustal sinking and return is possible.

How the giant sediment-hosted gold deposits of Nevada were formed is disputed. A model linking regional tectonics with magma emplacement and fluid generation at depth suggests that these deposits result from an optimal coincidence of processes.

The eruption of the Siberian Trap flood basalts resulted in the heating and combustion of coals and organic-rich sediments at the time of the Permian mass extinction. The presence of char in distant lake sediments linked to the eruption suggests that fly ash could have been generated by the coal combustion, and then dispersed globally, creating toxic marine conditions.

The Adula nappe, Central Alps, was thought to be a mélange of rock fragments, some of which were subducted and then exhumed from the mantle. Lu–Hf dating of two populations of garnets in one rock sample instead indicates that the nappe twice experienced subduction and exhumation as one coherent unit.

During the Eocene, profuse magmatism and hydrothermal activity in the Great Basin of western North America produced Earth’s second largest concentration of gold in Nevada. An integration of mineral analyses, experimental data and age and isotope data suggests a magmatic source for these deposits.

The present state and future evolution of Himalayan glaciers has been controversial. An analysis of remotely sensed frontal changes and surface velocities from glaciers in the greater Himalaya between 2000 and 2008 shows large regional variability in the responses of Himalayan glaciers to climate change.

The impact of external influences on European temperatures before 1900 has been thought to be negligible. An analysis of reconstructions of seasonal European land temperatures and simulations from three global climate models instead suggests that external forcing is responsible for a best guess of 75% of the observed winter warming since the late seventeenth century.

The extent of snow cover and sea ice in the Northern Hemisphere has declined since 1979, suggesting a positive feedback of surface reflectivity on climate. A synthesis of a variety of remote sensing and field measurements suggests that this albedo feedback from the Northern Hemisphere cryosphere falls between 0.3 and 1.1 W m⁻² K⁻¹.

Atmospheric deposition of mercury to remote areas has increased threefold since pre-industrial times. Reductions in sea-ice cover accelerate the photodegradation of biologically accessible mercury in Arctic waters, according to an analysis of the isotopic composition of bird eggs in northern latitudes.

The East Antarctic ice sheet retreated at the end of the last glacial period. Terrestrial and marine data suggest that the retreat began 14,000 years ago, indicating that the East Antarctic ice sheet probably did not contribute to meltwater pulse 1a 14,700 years ago.

Following a hypothesized complete cessation of carbon dioxide emissions, global climate models simulate approximately constant global mean temperatures for centuries. Long-term simulations with the Canadian Earth System Model suggest that, on these timescales, regional changes in temperature and precipitation are nevertheless significant, and that Southern Ocean warming at intermediate depths could affect the stability of Antarctic ice.

Manganese oxide minerals control numerous environmental processes, including the fate of contaminants. Laboratory experiments with a common species of marine bacteria reveal that bacterially generated superoxide can oxidize manganese ions, generating manganese oxides.

Water has been found in many lunar rock samples, but its sources are unknown. Isotopic analyses of Apollo samples of lunar mare basalts and highlands rocks suggest that a significant volume of water was delivered to the Moon by comets shortly after its formation by giant impact.