The Southern Region of Peru Earthquake of June 23rd, 2001

The western border of South America is one of the most important seismogenic regions in the world. In this region the most damaging earthquake ever recorded occurred. In June 23rd, 2001, another very strong earthquake (Mw = 8.1–8.2) occurred and produced death and damages in the whole southern region of Peru. This earthquake was originated by a friction process between Nazca and South American plates and affected an area of about 300 km × 120 km defined by the distribution of more than 220 aftershocks recorded by a local seismic network that operated 20 days. The epicenter of the main shock was localized in the northwestern extremity of the aftershock area, which suggests that the rupture propagated towards the SE direction. The modeling of P-wave for teleseismic distances permitted to define a focal mechanism of reverse type with NW-SE oriented nodal planes and a possible fault plane moving beneath almost horizontally in NE direction. The source time function (STF) suggests a complex process of rupture during 85 sec with 2 successive sources. The second one of greater size, and located approximately 100–120 km toward the SE direction was estimated to have a rupture velocity of about 2 km/sec on a 28°-dipping plane to the SE (N135°). A second event happened 45 sec after the first one with an epicenter 130km farther to the SE and a complex STF. This event and the second source of the main shock caused a Tsunami with waves from 7 to 8 meters that propagated almost orthogonally to the coast line, by affecting mainly the Camaná area.Three of all the aftershocks presented magnitudes greater or equal to Mw = 6.6, two of them occurred in front of the cities of Ilo and Mollendo (June 26th and July 7th) with focal mechanisms similar to the main seismic event. The aftershock of July 5th shows a normal mechanism at a depth of 75 km, and is therefore most likely located within the subducting Nazca plate and not in the coupling. The aftershocks of June 26th (Mw = 6.6) and July 5th (Mw = 6.6) show simple short duration STF. The aftershock of July 7th (Mw = 7.5) with 27-second duration suggests a complex process of energy release with the possible occurrence of a secondary shock with lower focal depth and focal mechanism of inverse type with a great lateral component. Simple and composed focal mechanisms were elaborated for the aftershocks and all have similar characteristics to the main earthquake.The earthquake of June 23rd caused major damages in the whole southern Peru. The damage in towns of Arequipa, Moquegua allow to consider maximum intensities from 6 to 7 (MSK79). In Alto de la Alianza and Ciudad Nueva zones from Tacna, the maximum intensity was of 7⁻ (MSK79).     

Irrigated afforestation of the Sahara and Australian Outback to end global warming

Each year, irrigated Saharan- and Australian-desert forests could sequester amounts of atmospheric CO₂ at least equal to that from burning fossil fuels. Without any rain, to capture CO₂ produced from gasoline requires adding about $1 to the per-gallon pump-price to cover irrigation costs, using reverse osmosis (RO), desalinated, sea water. Such mature technology is economically competitive with the currently favored, untested, power-plant Carbon Capture (and deep underground, or under-ocean) Sequestration (CCS). Afforestation sequesters CO₂, mostly as easily stored wood, both from distributed sources (automotive, aviation, etc., that CCS cannot address) and from power plants. Climatological feasibility and sustainability of such irrigated forests, and their potential global impacts are explored using a general circulation model (GCM). Biogeophysical feedback is shown to stimulate considerable rainfall over these forests, reducing desalination and irrigation costs; economic value of marketed, renewable, forest biomass, further reduces costs; and separately, energy conservation also reduces the size of the required forests and therefore their total capital and operating costs. The few negative climate impacts outside of the forests are discussed, with caveats. If confirmed with other GCMs, such irrigated, subtropical afforestation probably provides the best, near-term route to complete control of green-house-gas-induced, global warming.     

Rapid warming of Large Marine Ecosystems

The need to understand local effects of global climate change is most urgent in the Large Marine Ecosystems (LMEs) since marine ecosystem-based management requires information on the LME scale. Reported here is a study of sea surface temperature (SST) change in the World Ocean LMEs in 1957–2006 that revealed strong regional variations in the rate of SST change. The rapid warming in 1982–2006 was confined to the Subarctic Gyre, European Seas, and East Asian Seas. These LMEs warmed at rates 2–4 times the global mean rate. The most rapid warming was observed in the land-locked or semi-enclosed European and East Asian Seas (Baltic Sea, North Sea, Black Sea, Japan Sea/East Sea, and East China Sea) and also over the Newfoundland–Labrador Shelf. The Indian Ocean LMEs’ warming was slow, while two major upwelling areas – California and Humboldt Currents – experienced a slight cooling. The Subarctic Gyre warming was likely caused by natural variability related to the North Atlantic Oscillation. The extremely rapid surface warming in the enclosed and semi-enclosed European and East Asian Seas surrounded by major industrial/population agglomerations may have resulted from the observed terrestrial warming directly affecting the adjacent coastal seas. Regions of freshwater influence in the European and East Asian Seas seem to play a special role in modulating and exacerbating global warming effects on the regional scale.     

Cretaceous-Eocene compression in the central Southern Alps (N Italy) inferred from Ar/Ar dating of pseudotachylytes along regional thrust faults

The integration of structural analyses with ⁴⁰Ar/³⁹Ar dating of fault-related pseudotachylytes provides time constraints for the reconstruction of the Alpine evolution of the central portion of the South Alpine orogenic wedge. In the northern sector of the belt a Variscan basement is stacked southward on the Permian to Mesozoic cover along regional faults (Orobic and Porcile thrusts). Fault zones, slightly postdating a first folding event of Alpine age, experienced a complex evolution through the ductile and brittle deformation regime, showing greenschist facies mylonites overprinted by a penetrative cataclastic deformation. Generation of fault-related pseudotachylyte veins marks the onset of brittle conditions, lasting up to the youngest episodes of fault activity. ⁴⁰Ar/³⁹Ar dating of the pseudotachylyte matrix of 9 samples give two separated age clusters: Late Cretaceous (80–68 Ma) and latest Palaeocene to Middle Eocene (55–43 Ma). These new data provide evidence that the pre-Adamello evolution of the central Southern Alps was characterised by the superposition of different tectonic events accompanying the exhumation of the deepest part of the belt through the brittle–ductile transition. The oldest pseudotachylyte ages demonstrate that south-verging regional thrusting in the central Southern Alps was already active during the Late Cretaceous, concurrently with the development of a synorogenic foredeep basin where the Upper Cretaceous Lombardian Flysch was deposited.     

Deep seated magmas and their mantle roots: Introduction

<正>In the last decade there has been a considerable effort to better understand the joint evolution of mafic and ultramafic magmatic systems and their deep mantle roots,through integrated petrological and thermo-barometric studies.Magma generation is regarded as the result of complex processes including melting,creation of channels for melt transfer,and interaction with the wall-rocks.Complexities in magmatic systems involve metasomatism and the creation of metasomatic fronts,branching and splitting of magma volumes during their evolution,and vat-     

http://www.sciencedirect.com/science/article/pii/S1674987113000339

The Mottled Zone(MZ) or Hatrurim Formation,which occurs near the Levantine Transform in the South Levant,has been studied during the last 150 years but its origin remains debatable.Mottled Zone Complex/Complexes(MZC/MZCs) consist of brecciated carbonate and low-temperature calcium-hydro-silicate rocks,which include unusual high- and ultra-high-temperature low-pressure(HT-LP) meta-morphic mineral assemblages.The MZ has been regarded as a product of combustion of bituminous chalks of the Ghareb Fm.of Cretaceous(Maastrichtian) age.In this paper we present detailed geographic, geomorphologic,structural and geological data from the MZCs of the South Levant,which show that the MZCs cannot be stratigraphically correlated with the Ghareb Fm.,because MZC late Oligocene-late Pleistocene deposits occur within or unconformable i.e.,with stratigraphic hiatus,overlap both the late Cretaceous and,in places,Neogene stratigraphic units.We propose an alternative model for the formation of MZCs by tectonically induced mud volcanism during late Oligocene-late Pleistocene time. This model explains(i) the presence of dikes and tube-like bodies,which consist of brecciated exotic clastic material derived from stratigraphically and hypsometrically lower horizons;(ii) mineral assemblages of sanidinite facies metamorphism;(iii) multi-stage character of HT-LP pyrometamorphism;and (iv) multi-stage low-temperature hydrothermal alteration.High temperatures(up to 1500℃) mineral assemblages resulted from combustion of hydrocarbon gases of mud volcanoes.Mud volcanism was spatially and structurally related to neotectonic folds and deformation zones formed in response to opening of the Red Sea rift and propagation of the Levantine Transform Fault.Our model may significantly change the prospects for oil-and-gas deposits in the region.     

Current estimates of freshwater flux through Arctic and subarctic seas

As the world warms, the expectation is that the freshwater outflows from the Arctic Ocean to the North Atlantic will strengthen and may act to suppress the rate of the climatically-important Atlantic meridional overturning circulation. Hitherto, however, we have lacked the system of measurements required to estimate the totality of the freshwater flux through subarctic seas. Though observations remain patchy and rudimentary in places, we piece-together the results from recent large-scale observational programmes together with associated modelling, to establish preliminary maps of the rates and pathways of freshwater flux through subarctic seas. These fluxes are calculated according to two reference salinities, S = 34.8 to conform with the majority of estimates reported in the literature, and S = 35.2, the salinity of the inflowing Atlantic water, to calculate the freshwater balance of the ‘Arctic Mediterranean’. We find that 148 mSv of freshwater enters the Nordic Seas across its northern boundary. There it is supplemented by around 54 mSv of freshwater from Baltic runoff, Norwegian runoff, P − E and Greenland ice melt, so that the total freshwater contribution to the Nordic Seas from all sources is 202 mSv. Of this, around 51 mSv of freshwater is estimated to pass south to the deep Atlantic in the dense water overflows leaving an assumed balance of 151 mSv to leave the Nordic Seas in the upper water export through Denmark Strait. The corresponding estimate for the freshwater outflow west of Greenland is 103 mSv relative to 35.2 so that the total freshwater flux reaching the North Atlantic through subarctic seas is around 300 mSv.