Geodetically derived velocities from Central Asia show that Northern Afghanistan, the Tajik Pamir, and northwestern Pakistan all move northward with comparable large velocities toward Eurasia. Steep velocity gradients, hence high strain rates, occur only across the Main Pamir Fault zone and with lesser magnitude between the northernmost Hindu Kush and the south and southeast margins of the Tajik Depression. Localized shortening is not apparent on any active India‐Hindu Kush crustal boundary; hence, crustal convergence between India and Eurasia in Central Asia is absorbed primarily on the northern and western margins of the Pamir. This concentrated strain on the Pamir margins is consistent with one, geometrically complex, interface between subducting Asian lithosphere and the Pamir. That interface might curve westward such that the Hindu Kush seismic zone is a continuation of the Pamir seismic zone, or alternatively, Hindu Kush earthquakes might occur in convectively unstable mantle lithosphere mechanically detached from surface faults.

Recordings in western Tibet of Rayleigh and Love waves at periods less than 70 s from aftershocks of the 2008 Sichuan earthquake cannot be matched by an isotropic velocity model beneath Tibet. These intermediate‐period Rayleigh and Love waves require marked radial anisotropy in the middle crust of Tibet, with the vertically polarized S‐waves propagating more slowly than S‐waves with horizontal polarization. The magnitude of anisotropy inferred using paths entirely within Tibet is slightly greater than that obtained previously from a tomographic inversion of a dataset covering a larger region. Anisotropy in the middle crust likely reflects deformation of the middle crust, and is consistent with the notion of mid‐crustal flow and thinning of the crust.

We use ten years of GPS data from nine continuous and six semi‐continuous GPS stations in a transect across the Southern Alps to measure rates of relative vertical movement with typical 1 σ uncertainties of 0.3–0.5 mm/yr. The estimated vertical rates define a fairly smooth profile across the range, with the highest rates of ∼5 mm/yr found near the crest of the mountains and ∼20–30 km southeast of the Alpine Fault. The distribution of vertical rates supports models based on horizontal velocities from GPS surveys in which interseismic coupling on the Alpine Fault decreases from 100% near the surface to zero by 13–18 km depth.

Convergence of 29 ± 1 mm/yr between the NW corner of the Indian plate and Asia is accommodated by a combination of thrust and strike‐slip faulting on prominent faults and apparent distributed deformation within the Hindu Kush, Pamir, South Tien Shan and Kohistan Ranges. An upper bound to the slip rate of known faults is obtained by ignoring distributed strain and rotation: convergence occurs on thrust faults north of the Peshawar Basin (13 ± 1 mm/yr) and in the Alai‐South Tien Shan (12 ± 2 mm/yr), and shear on the northeast‐trending northern Chaman‐Gardiz‐Konar system (18 ± 1mm/yr) and the Darvaz‐Karakul fault zone (11 ± 2 mm/yr). Slip rates on the Herat and Talas‐Ferghana faults are small (<2 mm/yr). Shortening not attributable to known active faults occurs within the Hindu Kush and central Pamir (16 ± 2 mm/yr) with concomitant east‐west extension in the latter of 9 ± 2 mm/yr. This diversity of strain styles confirms the importance of mechanical heterogeneity to continental tectonics and shows that the Pamir, although less than half the size, behaves more like Tibet than like a linear belt of localized deformation.

Since early 2000 we have installed and operated four continuous GPS (CGPS) stations and seven semi-continuous stations in a broad transect across the Southern Alps. We occupied the semi- continuous stations for several months at a time, with gaps between occupations. We have analysed the data from these and other regional CGPS stations to create vertical position time series, from which we determine rates of relative vertical movement across the mountain range. An error model that accounts for both white noise and power law components yields standard errors of 1 mm/yr or smaller. After regional filtering to reduce common-mode effects, the noise structure in the GPS time series is significantly less correlated than flicker noise. The estimated vertical rates define a reasonably smooth profile across the range, though there are apparently anomalous signals within a few km of the Alpine fault. The highest vertical rates of ~6-7 mm/yr relative to stations on the Pacific plate well to the east are found 6-12 km north-west of the main divide of the mountains and ~15 km south- east of the Alpine fault. The rates derived using three independent processing strategies are in broad agreement, with just one site showing a discrepancy at the 5% significance level. The observed rates are generally in line with those expected, given that the Alpine fault is currently locked to a depth of ~8 km. A simple dislocation model of deformation that fits horizontal GPS campaign data collected between 1994 and 2002 predicts certain features of the observed vertical deformation signal, but also contains clear discrepancies.

Observations of relative motion in a geodetic network in Ladakh, India, and across southern Tibet indicate slow shear on the Karakorum fault, rapid east-west extension across the whole of southern Tibet, and constant are-normal convergence between India and southern Tibet along the Himalayan are. Measurements of ten campaign-style and six permanent sites with global positioning system (GPS) precise geodesy provide these bounds on the style and rates of the large-scale deformation in the Tibet-Himalaya region. Divergence between sites at Leh, Ladakh, India, and Shiquanhe, western Tibet, as well as slow relative motion among sites within the Ladakh network, limit right-lateral slip parallel to the Karakorum fault to only 3.4 +/- 5 mm/yr. This low rate concurs with a recent estimate of 3-4 mm/yr for Late Holocene time, but disagrees with the much higher rate of 30-35 mm/yr that has been used to argue for plate-like behavior of the Tibetan Plateau. Convergence between Ladakh and the Indian subcontinent at 18.8 +/- 3 mm/yr at 224degrees +/- 17degrees (1sigma) differs little from estimates of convergence across the central segment of the Himalaya. Finally, lengthening of the baseline between Leh, Ladakh, and Lhasa (in southeastern Tibet) at 17.8 +/- 1 mm/yr or between Leh and Bayi (farther to the southeast) at 18 +/- 3 mm/yr, is consistent with an extrapolation of rates of east-west extension of the Tibetan Plateau based both on shorter GPS baselines (e.g., Lhasa-Simikot) and on diverging slip vectors of earthquakes in the Himalaya. We interpret these results to indicate that Tibet behaves more like a fluid than like a plate.

Cosmic ray exposure ages for formation of perched alluvial terraces and for abandonment of an alluvial/debris-flow fan on opposite sides of the Tangtse Valley (the outflow at the northwest end of Lake Panggong, which is in the Karakorum Range of Western Tibet) provide evidence of a humid period at ∼11.5 to ∼7 ka. This is consistent with other regional records and supports a controversial chronology for the sedimentary record from Lake Panggong. Fan abandonment appears to have occurred at ∼11.5 ka as the climate presumably became more humid in response to initiation of enhanced monsoonal circulation, consistent with previously reported onset of humid conditions in a sedimentary record from the easternmost basin of the lake. In contrast, the terraces did not form until about 7 ka with downcutting of the transverse valley by overflow from Lake Panggong. This lag can be explained in light of the bathymetry of Lake Panggong; the modern lake consists of five basins separated by shallow sills, and outflow through the Tangtse Valley could not occur until the water level was substantially above its present level. The easternmost basin receives the inflow of the major rivers feeding the lake, making its chemistry highly sensitive to changes in precipitation. However, sustained wet conditions are required to fill the basins to the west to the sill depth necessary for overflow through the Tangtse Valley and resultant downcutting and terrace formation.

We measure an average slip rate of 4 ± 1 mm yr−1 along the Karakorum fault, heretofore considered one of Earth's greatest strike‐slip faults and thought by many to play a key role in Asian deformation kinematics. Levees of a debris flow, and contours of the fan on which it was deposited, have been displaced 40 ± 5 m. Concentrations of 10Be in boulders from the debris flow yield ages of 11–14 ka, implying a slip rate of 4 ± 1 mm yr−1 during that period. A fresher debris flow has been offset 2–2.5 m since 1–2 ka, implying the occurrence of an earthquake with M ∼ 7 since that time. Concentrations of 10Be in boulders on the crest of the most extensive moraine near Leh imply that the most recent major glacial advance occurred at 90 ± 15 ka. This is consistent with the inference of others that alpine glaciers in this region have not necessarily expanded in concert with Northern Hemisphere continental ice sheets. If features, including lateral moraines, that Liu inferred to have been offset 300–350 m by the Karakorum fault date from the same period, they too imply a slip rate of 3–4 mm yr−1. This slip rate is comparable to rates of extension across grabens within Tibet. With recent evidence that slip along the Altyn Tagh fault occurs at ∼10 mm yr−1, our rate suggests that slip along the boundaries of Tibet is not significantly more rapid than extension within the plateau. Hence, plate tectonics, in the strictest sense, ought not be applied to Tibet, because Tibet does not behave as a rigid plate.

New heat flow measurements and relocated hypocenters that constrain the subduction geometry of the Pacific plate at the Kermadec trench yield an estimate of shear stress on the thrust fault. With the exception of a few relatively high values (>60 mW m−2) on the upper forearc region near the active volcanic ridge, most of the 64 heat flow values along two profiles across the forearc range from 20 to 40 mW m−2. Corrections for bottom water temperature variations that caused nonuniform temperature gradients were required for most measurements. The means of the most reliable values for the northern and southern profiles are 28.9±5.8 mW m−2 (n = 33) and 28.9±7.2 mW m−2 (n = 19), respectively, and the measurements show no apparent systematic variation along the profiles over the range ∼50 to 150 km distance from the trench. The means of the 10 values at each of two sites on the Pacific plate seaward of the profiles are 57.2±6.3 and 60.2±6.6 mW m−2. Redeterminations of focal depths and fault plane solutions of earthquakes in the vicinity of the heat flow profiles indicate thrust faulting on a plane dipping 17°±2°. Calculated values of heat flow for a two‐dimensional analytical approximation to conduction through the upper plate, diffusion into the downgoing slab, and advection by that slab are consistent with either a uniform stress of ∼40±17 MPa along the thrust fault or stress increasing linearly at ∼0.5±0.2 MPa km−1 with distance from the trench axis. The comparable scatter in the heat flow measurements about those calculated from these simple stress distributions does not show one to be a better approximation than the other.

Although regional climates throughout much of the world appear to have become more arid in late Cenozoic time, sedimentation rates, and therefore presumably erosion rates, have increased. For sustained erosion of elevated terrain, at least where glaciers are not the major erosive agent, rivers must incise. Therefore bed-load transport by rivers should be a rate-limiting process in erosion. Theories of bed-load transport call for a threshold in either stream power per unit area or shear stress before the bed load can be moved, and most transport should be accomplished during high discharge. The frequency- magnitude distribution of floods shows that the ratio of magnitudes of, for example, 100 yr floods and annual floods is greater in arid than in humid environments. Thus, a shift toward more arid conditions may have increased relative magnitudes of rare floods or, conversely, increased the frequency of large floods. Such a shift, despite a decrease in precipitation and discharge, could have doubled incision rates, particularly in regions already quite arid.

Extensive lithospheric deformation on the eastern margin of the India/Eurasia collision has brought three major rivers into exceptionally close proximity. For over 300 km the Salween, Mekong, and Yangtze Rivers are only tens of kilometers apart, ∼10 times closer than rivers of comparable length elsewhere in the world. We view deeply incised river valleys as displacement markers that move with the underlying crust over time scales of at least tens of millions of years. Accordingly, the close spacing of these major rivers and their nearly parallel trends reflect the large crustal strains near the eastern Himalayan syntaxis. These river characteristics are consistent with two primary phases of deformation in this tectonic setting: NE‐SW shortening of ∼0.5 oriented radially from the eastern syntaxis, followed by dextral shear strain of 6±1 along a north trending zone. Pervasive shearing of this magnitude throughout the ∼150‐km‐wide region of anomalous drainage would account for ∼1000 km of northward motion of India relative to southern China. Directly east of this region, another ∼1000 km of northward motion is likely to have been accommodated by pervasive shearing through a zone hundreds of kilometers wide. Finally, we draw attention to the remarkable accord between the arcuate paths of each of the three great rivers in the broader southeastern Tibet region and small circles that curve around the eastern Himalayan syntaxis.

Cold mantle lithosphere is gravitationally unstable with respect to the hotter buoyant asthenosphere beneath it, leading to the possibility that the lower part of the mantle lithosphere could sink into the mantle in convective downwelling. Such instabilities are driven by the negative thermal buoyancy of the cold lithosphere and retarded largely by viscous stress in the lithosphere. Because of the temperature dependence of viscosity, the coldest, and therefore densest, parts of the lithosphere are unavailable for driving the instability because of their strength. By comparing theory and the results of a finite element representation of a cooling lithosphere, we show that for a Newtonian fluid, the rate of exponential growth of an instability should be approximately proportional to the integral over the depth of the lithosphere of the ratio of thermal buoyancy to viscosity, both of which are functions of temperature, and thus depth. We term this quantity 'available buoyancy' because it quantifies the buoyancy of material sufficiently weak to flow, and therefore available for driving convective downwelling. For non-Newtonian viscosity with power law exponent n and temperature-dependent pre-exponential factor B, the instabilities grow superexponentially, as described by Houseman & Molnar (1997), and the appropriate timescale is given by the integral of the nth power of the ratio of the thermal buoyancy to B. The scaling by the 'available buoyancy' thus offers a method of determining the timescale for the growth of perturbations to an arbitrary temperature profile, and a given dependence of viscosity on both temperature and strain rate. This timescale can be compared to the one relevant for the smoothing of temperature perturbations by the diffusion of heat, allowing us to define a parameter, similar to a Rayleigh number, that describes a given temperature profile's tendency toward convective instability. Like the Rayleigh number, this parameter depends on the cube of the thickness of a potentially unstable layer; therefore, mechanical thickening of a layer should substantially increase its degree of convective instability, and could cause stable lithosphere to become convectively unstable on short timescales. We estimate that convective erosion will, in 10 Myr, reduce a layer thickened by a factor of two to a thickness only 20 to 50 per cent greater than its pre-thickened value. Thickening followed by convective instability may lead to a net thinning of a layer if thickening also enhances the amplitude of perturbations to the layer's lateral temperature structure. For the mantle lithosphere, the resulting influx of hot asthenosphere could result in rapid surface uplift and volcanism.

The geological features now exposed at Mormon Point, Death Valley, reveal processes of extension that continue to be active, but are concealed beneath the east side of Death Valley. Late Cenozoic sedimentary rocks at Mormon Point crop out in the hangingwall of the Mormon Point low-angle normal fault zone, a fault zone that formed within a releasing bend of the oblique-slip (right-normal slip) fault zone along the east side of Death Valley. The late Cenozoic sedimentary rocks were part of the valley when the low-angle fault zone was active, but during late Quaternary time they became part of the Black Mountains block and were uplifted. Rocks and structures exposed at Mormon Point are an example of the types of features developed in a releasing bend along the margins of a major pull-apart structure, and in this example they are very similar to features associated with regional detachment faults.The oldest sedimentary rocks in the hangingwall of the Mormon Point low-angle fault zone dip steeply to moderately east or north-east and were faulted and rotated in an extensional kinematic environment different from that recorded by rocks and structures associated with younger rocks in the hangingwall. Some of the younger parts of the late Cenozoic sedimentary rocks were deposited, faulted and rotated during movement on the Mormon Point low-angle normal fault. Progressively, strata are less faulted and less rotated. The Mormon Point low-angle normal fault has an irregular fault surface whose segments define intersections that plunge 18 degrees-30 degrees, N10 degrees-40 degrees W, with a maximum of 22 degrees, N22 degrees W that we interpret to be the general direction of slip. Thus, even though Death Valley trends north, movement on the faults responsible for its formation was at least locally north-northwest. Gouge and disrupted conglomerates along the faults are interpreted to have formed either as adjustments to accommodate space problems at the corners of blocks or along faults that bounded blocks during their displacement and rotation.The younger units of the late Cenozoic sedimentary rock sequence and the geomorphic surfaces developed on them are rarely faulted, not rotated, and overlap the Mormon Point low-angle faults. Active faults cut Holocene alluvium north of the late Cenozoic rocks and form the present boundary between Mormon Point and the Black Mountains. The distribution of active faults defines a releasing bend that mimics the older releasing bend formed by the Mormon Point low-angle fault zone. Rocks and structures similar to those exposed above the Mormon Point low-angle fault zone are probably forming today beneath the east side of Death Valley north-west of Mormon Point.

A microearthquake survey was conducted in the central Andes of Peru, east of the city of Lima, to study the seismicity and style of tectonic deformation of the Peruvian Andes. Although most of the stations forming the temporary seismographic network were located on the high Andes, the vast majority of the microearthquakes recorded occurred to the east of the mountain belt: on the Huaytapallana fault in the Eastern Cordillera and beneath the western margin of the sub-Andes. Thus the sub-Andes appear to be the physiographic province subject to the most intense seismic deformation. Focal depths of the crustal events in this region range generally from 15 to 35 km and some events beneath the sub-Andes appear to be as deep as 40–50 km. The fault-plane solutions of events in the sub-Andean margin show thrust faulting on steep planes oriented roughly north-south, similar to that observed in teleseismic earthquakes studied using body wave modelling. The Huaytapallana fault in the Cordillera Oriental also shows relatively high seismicity along a NE-SW trend that agrees with the fault scarp and the east-dipping nodal plane of two large earthquakes that occurred on this fault on 1969 July 24 and October 1. Microearthquakes of intermediate depth recorded during the experiment show a flat seismic zone about 25 km thick at a depth of about 100 km. This agrees with recent observations showing that beneath Peru the slab first dips at an angle of about 30° to a depth of 100 km and then flattens following a quasi-horizontal trajectory. Fault-plane solutions of intermediate-depth microearthquakes have horizontal T axes oriented east-west suggesting slab pull is the dominant force in the downgoing slab.

Active and recent faulting along the main north—south road in Tibet is dominated by normal faulting occurring on northerly-trending planes and by strike-slip faulting, both of which reflect an east-west extension of the plateau. Normal faulting is prevalent in the southern half of the plateau, but we saw no evidence for any major graben in the northern half. Strike-slip faulting on roughly easterly-trending structures is m ore prevalent in the northern half, but conjugate faulting, with right-lateral slip on northwesterly-trending planes and left-lateral slip on northeasterly-trending planes, is common in the southern half. In two areas, we also observed components of thrust faulting, apparently in association with young strikeslip faulting. Our most important results are bounds on the rates of slip on the two main strands of the Kunlun strike-slip fault system, which trends east-w est through the Kunlun range. Ground moraine containing boulders of pyroxenite is separated by 30 km from the nearest outcrop of such rock, implying that amount of displacement in the last 1.5 to 3 M a. Therefore the average rate of slip during the Quaternary period has been between 10 and 20 mm/a , with a likely value of 13 mm/a . Abundant fresh tension cracks and mole tracks imply continued slip on the main strand, the Xidatan -Tuosuohu-Maqu fault, and the likely occurrence of a major earthquake in the last few hundred years. Consistent offsets of gullies and dry stream channels of about 10 m may reflect slip of that amount during such an earthquake, and possible multiple offsets at one site suggest that slip may occur by large displacements of 10 m during infrequent great earthquakes. Along the other strand, the Kunlun Pass fault, offsets of roughly 50 to 150 m of, apparently, post-glacial valleys and of one glacier and its terminal moraine suggest a Holocene rate of slip between 5 and 20 mm/a , and most likely about 10 mm/a , on this fault. These rapid rates of displacement imply that Tibet is being extruded rapidly eastward, at a rate com parable to the rate at which India is penetrating into Eurasia, and therefore that, at present, a substantial fraction of this penetration is being absorbed by the eastward extrusion of Tibet.