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

Ground-based prediction of aircraft climb: point-mass model vs. regression methods

Predicting aircraft trajectories with great accuracy is central to most operational concepts ([1], [2]) and automated tools that are expected to improve the air traffic management (ATM) in the near future

: United States (2013)" Statistical prediction of aircraft trajectory: regression methods vs point-mass model

Abstract—Ground-based aircraft trajectory prediction is a critical issue for air traffic management. A safe and efficient prediction is a prerequisite for the implementation of automated tools that detect and solve conflicts between trajectories. Moreover, regarding the safety constraints, it could be more reasonable to predict intervals rather than precise aircraft positions. In this paper, a standard point-mass model and statistical regression method is used to predict the altitude of climbing aircraft. In addition to the standard linear regression model, two common non-linear regression methods, neural networks and Loess are used. A dataset is extracted from two months of radar and meteorological recordings, and several potential explanatory variables are computed for every sampled climb segment. A Principal Component Analysis allows us to reduce the dimensionality of the problems, using only a subset of principal components as input to the regression methods. The prediction models are scored by performing a 10-fold cross-validation. Statistical regression results method appears promising. The experiment part shows that the proposed regression models are much more efficient than the standard point-mass model. The prediction intervals obtained by our methods have the advantage of being more reliable and narrower than those found by point-mass model

Reasoning with Co-Variations

International audienceAdaptation is what allows a system to maintain consistent behavior across variations in operating environments. In some previous work, a symbolic representation of the variations between two or more elements of a set was proposed. This article goes one step further and defines co-variations as functional dependencies between variations. This gives us a natural deduction rule on variations, which we show can be easily extended to perform similarity-based reasoning. A method is also proposed to learn co-variations from the data. In this method, covariations correspond to object implication rules in a pattern structure

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