3D GPS velocity field and its implications on the present-day postorogenic deformation of the Western Alps and Pyrenees

We present a new 3D GPS velocity solution for 182 sites for the region encompassing the Western Alps, Pyrenees, and southern France. The velocity field is based on a Precise Point Positioning (PPP) solution, to which we apply a common-mode filter, defined by the 26 longest time series, in order to correct for network-wide biases (reference frame, unmodeled large scale processes, ¿). We show that processing parameters, such as troposphere delay modeling, can lead to systematic velocity variations of 0.1 - 0.5 mm/yr affecting both accuracy and precision, especially for short (< 5 yr) time series. A velocity convergence analysis shows that minimum time-series lengths of ~3 years and ~5.5 years are required to reach a velocity stability of 0.5 mm/yr in the horizontal and vertical components, respectively. On average, horizontal residual velocities show a stability of ~0.2 mm/yr in the Western Alps, Pyrenees, and southern France. The only significant horizontal strain rate signal is in the western Pyrenees with up to 4 x 10-9 yr-1 NNE-SSW extension, whereas no significant strain rates are detected in the Western Alps (< 1 x 10-9 yr-1). In contrast, we identify significant uplift rates up to 2 mm/yr in the Western Alps but not in the Pyrenees (0.1 ± 0.2 mm/yr). A correlation between site elevations and fast uplift rates in the northern part of the Western Alps, in the region of the Wurmian ice cap, suggests that part of this uplift is induced by postglacial rebound. The very slow uplift rates in the southern Western Alps and in the Pyrenees could be accounted for by erosion-induced rebound

GPS constraints on Indo-Asian convergence in the Bhutan Himalaya: Segmentation and potential for a 8.2-8.8 Mw earthquake

The seismogenic setting of Bhutan is unusual due to its lower-than-average 20th century seismic moment release (Drukpa et al. 2006), its absence of a reliable historical record, and its unusual location near the Shillong plateau where a great earthquake in 1897 resulted in ≈10 m of N/S shortening of the Indian plate to its south (Gahalaut et al. 2011). Despite these indicators that lower than normal convergence velocities should currently prevail, the GPS velocity between Shillong and Lhasa suggests that convergence in Sikkim and Bhutan occurs at velocities exceeding 20 mm/yr. GPS points between the Greater Himalaya and the Shillong Plateau measured in 2003, 2006 and 2012 permit us to quantify Bhutan\u27s seismogenic potential

Nietzsche and Amor Fati

This paper identifies two central paradoxes threatening the notion of amor fati [love of fate]: it requires us to love a potentially repellent object (as fate entails significant negativity for us) and this, in the knowledge that our love will not modify our fate. Thus such love may seem impossible or pointless. I analyse the distinction between two different sorts of love (eros and agape) and the type of valuation they involve (in the first case, the object is loved because we value it; in the second, we value the object because we love it). I use this as a lens to interpret Nietzsche?s cryptic pronouncements on amor fati and show that while an erotic reading is, up to a point, plausible, an agapic interpretation is preferable both for its own sake and because it allows for a resolution of the paradoxes initially identified. In doing so, I clarify the relation of amor fati to the eternal return on the one hand, and to Nietzsche?s autobiographical remarks about suffering on the other. Finally, I examine a set of objections pertaining both to the sustainability and limits of amor fati, and to its status as an ideal

Global Positioning System measurements of strain accumulation and slip transfer through the restraining bend along the Dead Sea fault system in Lebanon

An edited version of this paper was published in Geophysical Journal International by Blackwell Publishing. Blackwell Publishing retains the copyright to this paper (Copyright 2007). See also: http://www.blackwell-synergy.com/doi/abs/10.1111/j.1365-246X.2006.03328.x; http://atlas.geo.cornell.edu/deadsea/publications/Gomez2007_GJI.htmApproximately 4 yr of campaign and continuous Global Positioning System (GPS) measurements across the Dead Sea fault system (DSFS) in Lebanon provide direct measurements of interseismic strain accumulation along a 200-km-long restraining bend in this continental transform fault. Late Cenozoic transpression within this restraining bend has maintained more than 3000 m of topography in the Mount Lebanon and Anti-Lebanon ranges. The GPS velocity field indicates 4-5 mm yr-1 of relative plate motion is transferred through the restraining bend to the northern continuation of the DSFS in northwestern Syria. Near-field GPS velocities are generally parallel to the major, left-lateral strike-slip faults, suggesting that much of the expected convergence across the restraining bend is likely accommodated by different structures beyond the aperture of the GPS network (e.g. offshore Lebanon and, possibly, the Palmyride fold belt in SW Syria). Hence, these geodetic results suggest a partitioning of crustal deformation involving strike-slip displacements in the interior of the restraining bend, and crustal shortening in the outer part of the restraining bend. Within the uncertainties, the GPS-based rates of fault slip compare well with Holocene-averaged estimates of slip along the two principal strike-slip faults: the Yammouneh and Serghaya faults. Of these two faults, more slip occurs on the Yammouneh fault, which constitutes the primary plate boundary structure between the Arabia and Sinai plates. Hence, the Yammouneh fault is the structural linkage that transfers slip to the northern part of the transform in northwestern Syria. From the perspective of the regional earthquake hazard, the Yammouneh fault is presently locked and accumulating interseismic strain

Present-day deformation of the Pyrenees revealed by GPS surveying and earthquake focal mechanisms until 2011

The Pyrenean mountain range is a slowly deforming belt with continuous and moderate seismic activity. To quantify its deformation field, we present the velocity field estimated from a GPS survey of the Pyrenees spanning 18 yr. The PotSis and ResPyr networks, including a total of 85 GPS sites, were installed and first measured in 1992 and 1995 1997, respectively, and remeasured in 2008 and 2010. We obtain a deformation field with velocities less than 1 mm yr−1 across the range. The estimated velocities for individual stations do not differ significantly from zero with 95 per cent confidence. Even so, we estimate a maximum extensional horizontal strain rate of 2.0 ± 1.7 nanostrain per year in a N S direction in the western part of the range. We do not interpret the vertical displacements due to their large uncertainties. In order to compare the horizontal strain rates with the seismic activity, we analyse a set of 194 focal mechanisms using three methods: (i) the 'r' factor relating their P and T axes, (ii) the stress tensors obtained by fault slip inversion and (iii) the strain-rate tensors. Stress and strain-rate tensors are estimated for: (i) the whole data set, (ii) the eastern and western parts of the range separately, and (iii) eight zones, which are defined based on the seismicity and the tectonic patterns of the Pyrenees. Each of these analyses reveals a lateral variation of the deformation style from compression and extension in the east to extension and strike-slip in the west of the range. Although the horizontal components of the strain-rate tensors estimated from the seismic data are slightly smaller in magnitude than those computed from the GPS velocity field, they are consistent within the 2σ uncertainties. Furthermore, the orientations of their principal axes agree with the mapped active faults

Present-day uplift of the western Alps

International audienceCollisional mountain belts grow as a consequence of continental plate convergence and eventuallydisappear under the combined effects of gravitational collapse and erosion. Using a decade ofGPS data, we show that the western Alps are currently characterized by zero horizontal velocityboundary conditions, offering the opportunity to investigate orogen evolution at the time ofcessation of plate convergence. We find no significant horizontal motion within the belt, but GPS andlevelling measurements independently show a regional pattern of uplift reaching ~2.5 mm/yr in thenorthwestern Alps. Unless a low viscosity crustal root under the northwestern Alps locally enhancesthe vertical response to surface unloading, the summed effects of isostatic responses to erosion andglaciation explain at most 60% of the observed uplift rates. Rock-uplift rates corrected from transientglacial isostatic adjustment contributions likely exceed erosion rates in the northwestern Alps. In theabsence of active convergence, the observed surface uplift must result from deep-seated processes