Oblique Convergence in the Himalayas of Western Nepal Deduced from Preliminary Results of GPS Measurements

A GPS network consisting of 29 sites was installed in central and western Nepal, with measurements taken in 1995 and partial remeasurements in 1997. Data suggest 15 +/−5 mm/yr of N180° convergence between the Higher Himalayas and India, a result that is consistent with N‐S shortening across the arcuate shape of the Nepalese Himalayas and an oblique underthrusting of the Indian crust below the High Himalayas of western Nepal. A 4 +/−3 mm/year E‐W extension and deviation of the principal shortening axes are inferred east of 83°E, where Quaternary faults (Darma‐Bari Gad fault system and Thakkhola graben) delineate a crustal wedge. This wedge is located on the SE projection of the Karakorum fault and may segment the Himalayan thrust belt. The convergence between the outer belt of western Nepal and India is less than 3 mm/yr, an attenuation consistent with creep on a dislocation locked beneath the Lesser Himalayas. A preliminary model suggests that this N 120°E striking dislocation is affected by a 19 mm/yr thrust component and a 7 mm/yr right lateral component

The tongue in speech and feeding: comparative articulatory modelling

Two major functions of the human vocal tract are feeding and speaking. As, ontogenetically and phylogenetically, feeding tasks precede speaking tasks, it has been hypothesised that the skilled movements of the orofacial articulators specific to speech may have evolved from feeding functions. Our study explores this hypothesis by proposing an original methodological approach. Vocal tract articulatory measurements on two male subjects have been recorded for speech and feeding by electromagnetic articulography. Two guided Principal Component Analysis (PCA) articulatory models of the jaw/tongue system have been built for speech and feeding tasks. The two articulatory models show similar reconstruction accuracy. The speech and feeding articulations have been reconstructed respectively from feeding and speech raw PCA models. Root mean square reconstruction errors show better capacity of the feeding model to be generalised to the other set of articulations than the speech model. Our study suggests therefore that the tested hypothesis cannot be excluded on articulatory grounds for our two cases and brings a new methodology into the discussion of the ontogenetic and phylogenetic origins of speech.--------------------------------------------------------------------------------<br/

The Mw=8.1 Antofagasta (North Chile) earthquake of july 30, 1995 : first results from teleseismic and geodetic data

A strong (Mw = 8.1) subduction earthquake occurred on July 30, 1995 in Antofagasta (northern Chile). This is one of the largest events during this century in the region. It ruptured the southernmost portion of a seismic gap between 18°S and 25°S. In 1992 we had used GPS to survey a network with about 50 benchmarks covering a region nearly 500 km long (N-S) and 200 km wide (E-W). Part of these marks were re-surveyed with GPS after the 1995 earthquake. Comparison towards the trench reaching 0.7 m. The inland subsided several decimeters. The Mejillones Peninsula was uplifted by more than 15 cm. Teleseismic body-wave modelling of VBB records gives a subduction focal mechanism and source time function with three distinct episodes of moment release and southward directivity. Modelling the displacement field using a dislocation with uniform slip in elastic half-space suggests a rupture zone with 19°-24° eastward dip extending to a depth no greater than 50 km with N-S length of 180 km and an average slip of about 5 m. The component of right-lateral slip inferred both from the teleseismic and geodetic data does not require slip partitioning at the plate boundary. That the well-constrained northern end of the 1995 rupture zone lies under the southern part of the Mejillones Peninsula increases the probability for a next rupture in the gap north of it. (Résumé d'auteur

Articulatory capacity of Neanderthals, a very recent and human-like fossil hominin

Scientists seek to use fossil and archaeological evidence to constrain models of the coevolution of human language and tool use. We focus on Neanderthals, for whom indirect evidence from tool use and ancient DNA appears consistent with an adaptation to complex vocal-auditory communication. We summarize existing arguments that the articulatory apparatus for speech had not yet come under intense positive selection pressure in Neanderthals, and we outline some recent evidence and analyses that challenge such arguments. We then provide new anatomical results from our own attempt to reconstruct vocal tract (VT) morphology in Neanderthals, and document our simulations of the acoustic and articulatory potential of this reconstructed Neanderthal VT. Our purpose in this paper is not to polarize debate about whether or not Neanderthals were human-like in all relevant respects, but to contribute to the development of methods that can be used to make further incremental advances in our understanding of the evolution of speech based on fossil and archaeological evidence<br/