Analyses of lake La Thuile sediment core

Lake La Thuile, in the Northern French Prealps (874 m a.s.l.), provides an 18 m long sedimentary sequence spanning the entire Lateglacial/Holocene period. The high resolution multi-proxy (sedimentological, palynological, geochemical) analysis of the uppermost 6.2 meters reveals the Holocene dynamics of erosion in the catchment in response to landscape modifications. The mountain belt is at relevant altitude to study past human activities and the watershed is sufficiently disconnected from large valleys to capture a local sedimentary signal. From 12,000 to 10,000 cal. BP (10 to 8 ka cal. BC), the onset of hardwood species triggered a drop in erosion following the Lateglacial/Holocene transition. From 10,000 to 4500 cal. BP (8 to 2.5 ka cal. BC), the forest became denser and favored slope stabilization while erosion processes were very weak. A first erosive phase was initiated at ca . 4500 cal. BP without evidence of human presence in the catchment. Then, the forest declined at approximately 3000 cal. BP, suggesting the first human influence on the landscape. Two other erosive phases are related to anthropic activities: approximately 2500 cal. BP (550 cal. BC) during the Roman period and after 1600 cal. BP (350 cal. AD) with a substantial accentuation in the Middle Ages. In contrast, the lower erosion produced during the Little Ice Age, when climate deteriorations are generally considered to result in an increased erosion signal in this region, suggests that anthropic activities dominated the erosive processes and completely masked the natural effects of climate on erosion in the late Holocene.

Raban Maur – Claude de Turin, Deux commentaires sur le libre de Ruth. Introduction, traduction, notes et index par P. Monat (Sources Chrétiennes 533), Les Éditions du Cerf, Paris, 2009; 190 pp. ISBN 978-2-204-09181-7.

Fil: Peretó Rivas, Rubén.

Palau, Gladys (et alli), Lógicas condicionales y razonamiento de sentido común. Barcelona, Gedisa, 2004, pp. 190

Fil: Corbalán, María Inés. Universidad Nacional de La Plata. Facultad de Humanidades y Ciencias de la Educación; Argentina.

Rosalía Baltar y Carlos Hudson (eds.) Figuraciones del siglo XIX. Libros, escenarios y miradas. Mar del Plata, Ediciones Finisterre y Universidad Nacional de Mar del Plata, 2007, 190 páginas

Fil: Pas, Hernán Francisco. Universidad Nacional de La Plata. Facultad de Humanidades y Ciencias de la Educación; Argentina.

Permeability, overburden stress and friction coefficients of ODP Hole 190-1173A and 190-1174B

Permeability measured on three samples in a triaxial cell under effective confining pressure from 0.2 to 2.5 MPa ranges from 10**-18 to 10**-19 m**2. Overall, results indicate that permeability decreases with effective confining pressure up to 1.5 MPa; however, measurements at low effective pressure are too dispersed to yield a precise general relationship between permeability and pressure. When the effective pressure is increased from 1.5 to 2.5 MPa, permeability is roughly constant (~1-4 x 10**-19 m**2). Samples deformed in the triaxial cell developed slickenlined fractures, and permeability measurements were performed before and after failure. A permeability increase is observed when the sample fails under low effective confining pressure (0.2 MPa), but not under effective pressure corresponding to the overburden stress. Under isotropic stress conditions, permeability decrease related to fracture closure occurs at a relatively high effective pressure of ~1.5 MPa. Coefficients of friction on the fractures formed in the triaxial cell are ~0.4.

Measurements of velocity-dependent and slip-dependent frictional strength in laboratory friction experiments on natural samples from IODP Expedition 316 and ODP Hole 190-1174B

Slowslip forms part of the spectrum of fault behaviour between stable creep and destructive earthquakes. Slow slip occurs near the boundaries of large earthquake rupture zones and may sometimes trigger fast earthquakes. It is thought to occur in faults comprised of rocks that strengthen under fast slip rates, preventing rupture as a normal earthquake, or on faults that have elevated pore-fluid pressures. However, the processes that control slow rupture and the relationship between slow and normal earthquakes are enigmatic. Here we use laboratory experiments to simulate faulting in natural rock samples taken from shallow parts of the Nankai subduction zone, Japan, where very low-frequency earthquakes - a form of slow slip - have been observed.We find that the fault rocks exhibit decreasing strength over millimetre-scale slip distances rather than weakening due to increasing velocity. However, the sizes of the slip nucleation patches in our laboratory simulations are similar to those expected for the very lowfrequency earthquakes observed in Nankai. We therefore suggest that this type of fault-weakening behaviour may generate slow earthquakes. Owing to the similarity between the expected behaviour of slow earthquakes based on our data, and that of normal earthquakes during nucleation, we suggest that some types of slow slip may represent prematurely arrested earthquakes.

Palau, Gladys (et alli), Lógicas condicionales y razonamiento de sentido común. Barcelona, Gedisa, 2004, pp. 190

Fil: Corbalán, María Inés. Universidad Nacional de La Plata. Facultad de Humanidades y Ciencias de la Educación; Argentina.

Rosalía Baltar y Carlos Hudson (eds.) Figuraciones del siglo XIX. Libros, escenarios y miradas. Mar del Plata, Ediciones Finisterre y Universidad Nacional de Mar del Plata, 2007, 190 páginas

Fil: Pas, Hernán Francisco. Universidad Nacional de La Plata. Facultad de Humanidades y Ciencias de la Educación; Argentina.