Bryan L. Isacks

• PhD
• Cornell University

Earthquake hypocenters recorded in the Andean Southern Puna seismic array (25-28°S; 70-65°W) provide new constraints on the shape of the subducting Nazca plate beneath the Puna plateau, the transition into the Chilean-Pampean flatslab and the thermal state of the mantle and crust. Some 270 new mantle hypocenters suggest that the subducting slab und...

We investigate the depths of crustal earthquakes (<80 km depth) of the central Andes (5°S to 35°S) to constrain the relationship between earthquake locations and inferred faults. We assemble parameters from 138 moderate-sized (7.0 > Mw ≳ 5.5) earthquakes from the Global CMT catalog and previous work spanning 1944-2007. For 38 well-recorded events,...

Jack Oliver, a pioneering researcher, instigator of major national and international observational programs, and an inspiring mentor for numerous graduate students and young researchers, died peacefully in his Ithaca, N. Y., home on 5 January 2011. He was 87 years old. Jack's early work on surface waves, his monumental contributions to plate tecton...

A detailed study of seismic wave propagation in the Fiji-Tonga region shows that there exists in the upper mantle an anomalous zone whose thickness is about 100 km and whose upper surface is approximately defined by the zone of seismic foci extending to depths of about 700 km. Attenuation of seismic waves within the zone is anomalously low and velo...

- Seismic activity associated with the collision of the continental part of the Australian plate with the oceanic Melanesian arcs along Papua New Guinea and the Banda arc provides an unusual opportunity to study the relative excitation of the seismic shear waves Sn and Lg. These waves are produced by earthquakes located along the arcs in the upper...

Large and impulsive second P arrivals (4–12 s after the initial P arrivals) from intermediate depth earthquakes located in the New Hebrides island arc are observed at distances of 7–14° on the records produced by short-period seismographs in Fiji. These second P arrivals are caused by refraction from a zone of rapidly increasing P velocity at about...

Preliminary locations for earthquakes recorded by the Central Andean southern PUNA seismic array, which operated between December 2007 and November 2009, show widespread low magnitude seismicity in the region of the well known teleseismic gap between 25°S and 28°S, which is here referred to as the Antofalla teleseismic gap. The southern PUNA experi...

The northeastern edge of the Bolivian Eastern Cordillera is an example of a tectonically active plateau margin where orographically enhanced precipitation facilitates very high rates of erosion. The topography of the steepest part of the margin exhibits the classic signature of high erosion rates consisting of high-relief V-shaped valleys where lan...

The distribution of earthquake depths within the continental crust defines the seismogenic thickness (TS), over which at least some part of crustal deformation is accommodated by rapid release of stored elastic strains. Intraplate continental seismicity is often thought to be restricted to the upper crust where TS is within the range of 15 to 20 km...

The western Andean mountain front forms the western edge of the central Andean Plateau. Between 18.5° and 22°S latitude, the mountain front has ~3000 m of relief over ~50 km horizontal distance that has developed in the absence of major local Neogene deformation. Models of the evolution of the plateau, as well as paleoaltimetry estimates, all call...

Very prominent high frequency seismic waves arriving after the S phase from deep earthquakes (550–600 km) are interpreted as shear waves guided by the part of the suboceanic lithosphere, the Nazca plate, that has descended into the mantle beneath western South America. The large amplitudes and character of the phase suggest that the lithosphere des...

High-frequency shear waves (0.5–2 Hz) recorded at regional distances at WWSSN stations in western South America are classified according to their apparent velocity and frequency/amplitude character. For propagation paths crossing any given region, the observations are abundant and consistent. Sn is not observed at distances beyond about 15.5° along...

Analysis of seismograms from 70 deep-focus earthquakes recorded at nearby stations in the Fiji Islands has yielded estimates of the waveforms of P waves radiated from deep sources and of the seismic moments of the events. The earthquake sample consists of all well-recorded events in 1965–66 located in a limited hypocentral region within 4° of the s...

This study investigates crustal deformation of the central Andes using accurate focal parameters of intraplate earthquakes to understand how the seismically active Andean crust relates to our global understanding of continental crustal deformation. Intraplate focal parameters are determined through long-period P and SH waveform inversion and short-...

Despite convergence across the strongly coupled seismogenic interface between the South American and Nazca plates, the dominant neotectonic signature in the forearc of northern Chile is arc-normal extension. We have used 1 m resolution IKONOS satellite imagery to map nearly 37,000 cracks over an area of 500 km2 near the Salar Grande (21°S). These f...

In the Central Andes, the frictional coupling between South America and the subducting Nazca Plate occurs beneath the Coastal Cordillera of northern Chile. One of the most distinctive characteristics of the Coastal Cordillera is a suite of EW topographic scarps located between 19° and 21.6°S latitude. These scarps are associated with predominantly...

Northernmost Chile is home to a well-preserved disequilibrium landscape of great antiquity. Contrasting drainage patterns are developed on the western slope of the Altiplano plateau. The oldest of these patterns is a now-relict parallel-patterned drainage network. In places a younger pattern, comprising a series of deeply incised canyons, or quebra...

The Coastal Cordillera of northern Chile is located in the hyperarid Atacama Desert and is situated over the interplate seismic zone of the Nazca-South America convergent plate boundary. The Coastal Cordillera is bounded to the west by a 1000 m high escarpment that plunges directly to the sea north of Iquique but to the south has a 1-5 km wide Plei...

120 shallow focal mechanisms in the crust above the subducted Nazca plate were assembled from the Harvard CMT catalog and published studies covering over 40 years of seismicity. The study area included the Andes crust above three major segments of the subducted plate, the Peruvian and Argentinean flat-slab segments and the intervening segment where...

We describe the along-strike changes in geomorphology on the western Andean mountain front of Peru and northern Chile, using the newly released SRTM 90 m digital topography. Strong contrasts in drainage systems and slope distributions occur along the mountain front between Lima, Peru and Santiago, Chile in concert with major latitudinal changes in...

▪ Abstract The enigma of continental plateaus formed in the absence of continental collision is embodied by the Altiplano-Puna, which stretches for 1800 km along the Central Andes and attains a width of 350–400 km. The plateau correlates spatially and temporally with Andean arc magmatism, but it was uplifted primarily because of crustal thickening...

Twice-daily satellite observations from the Special Sensor Microwave Imager (SSM/I) indicate melt onset and refreeze on southeast-Alaskan icefields. Melt and refreeze are based on 37 GHz vertically polarized brightness temperatures (Tb) and diurnal-amplitude variations (DAV). Two types of melt regime have different summer characteristics. Onset is...

Timing of snowmelt and freeze-up was estimated for glaciers in the Coast and St Elias Ranges of Alaska, U.S.A., and British Columbia, Canada, using twice-daily brightness temperatures (Tb) from the U.S. Defense Meteorological Satellite Program's Special Sensor Microwave/Imager (SSM/I). Melt and freeze-up were determined for a 37 GHz vertically pola...

We examine the western slope of the central Andes Mountains between 17S and 30S in an effort to elucidate the effects of along strike climate variability on landscape process and form. This region is most opportune for study because the mountain front is, to a first order, a relatively simple monoclinal structure and several lines of evidence point...

A new digital elevation model (DEM) with 20 m resolution of the forearc region of northern Chile highlights the remarkable system of fault scarps disrupting the low relief Paleogene surface of the Coastal Cordillera. The scarps range in height from tens to hundreds of meters (up to 300 m) and appear sharp and youthful. However, the hyper-arid clima...

Satellite observations from high resolution visible images, synthetic aperture radar (SAR) and passive microwave instruments such as the Special Sensor Microwave/Imager (SSM/I) make it possible to assess glacier melting at a range of spatial and temporal scales. The mass balance of mid-latitude mountain glaciers integrates the effects of numerous c...

[1] Abstract: We interpret the interseismic crustal velocity field of the central Andes using a simple three-plate model in which the Andean mountain belt is treated as a rigid microplate located between the Nazca and South American (SoAm) plates. We assume that the Euler vectors associated with these plates are strictly coaxial and that the surfac...

The ability of synthetic-aperture radar (SAR) to record change in glaciers and icefields on seasonal to interannual time-scales is useful in maritime mountain regions where visible data are often obscured by clouds. A time series of RADARSAT and second European Remote-sensing Satellite (ERS-2) SAR images shows dramatic changes related to the onset...

The tropical glaciers in the central Andes are sensitive indicators of climatic variability. They are an important water resource, but are presently in a state of rapid retreat. Spectral mixture analysis using Landsat Thematic Mapper (TM) images was used to identify the ablation and accumulation zones and the transient snowline at two tropical site...

Late Pleistocene snowlines in the central Andes were 500–1200 m lower than at present. Radiocarbon dates imply that the late-Pleistocene glacial maximum in the region occurred prior to 20 14C ka, but lack of maximum limiting ages adds considerable uncertainty to the exact timing. Snowline modeling demonstrates that snowlines in the eastern and west...

Repeat-pass L-band interferometric synthetic aperture radar (InSAR) data for part of Hielo Patagónico Sur, Chile, were collected by the space-shuttle-based Spaceborne Imaging Radar C (SIR-C) over a 4 day span in October 1994. Three co-registered complex SAR images are used to generate phase-coherence maps, a digital elevation model (DEM) and an ice...

Repeat-pass L-band interferometric synthetic aperture radar (InSAR) data for part of Hielo Patagónico Sur, Chile, were collected by the space-shuttle-based Spaceborne Imaging Radar C (SIR-C) over a 4 day span in October 1994. Three co-registered complex SAR images are used to generate phase-coherence maps, a digital elevation model (DEM) and an ice...

Late Pleistocene and modern ice extents in central Nepal are compared to estimate equilibrium line altitude (ELA) depressions. New techniques are used for determining the former extent of glaciers based on quantitative, objective geomorphic analyses of a ∼90-m resolution digital elevation model (DEM). For every link of the drainage network, valley...

An exploration of the wavelet transform as applied to daily river discharge records demonstrates its strong potential for quantifying stream flow variability. Both periodic and non-periodic features are detected equally, and their locations in time preserved. Wavelet scalograms often reveal structures that are obscure in raw discharge data. Integra...

An exploration of the wavelet transform as applied to daily river discharge records demonstrates its strong potential for quantifying stream flow variability. Both periodic and non-periodic features are detected equally, and their locations in time preserved. Wavelet scalograms often reveal structures that are obscure in raw discharge data. Integra...

Worldwide, millions of dollars in property damage and loss of life are attributed to landslides annually. Landslides are frequent hazards in tectonically active mountain belts such as the Himalayas, Southern Alps of New Zealand, New Guinea, Japan, and the Andes, where uplift generates high topographic relief Steep slopes associated with regions of...

The evolution of four dynamic radar glacier zones at the surface of an alpine icefield in British Columbia is monitored using a time series of 33 First European Remote Sensing Satellite (ERS-1) synthetic aperture radar (SAR) images acquired from 1992 to 1994. These zones result from changing wetness and textural properties, and appear to represent:...

During the late Pleistocene, at least one episode of lake expansions occurred in the internally draining high plateau region of Bolivia. Some researchers have advocated that a wetter climate associated with a change in atmospheric circulation caused the development of the large paleo-lakes, while others have hypothesized that deglaciation contribut...

The enigma of continental plateaus formed in the absence of continental collision is embodied by the Altiplano-Puna, which stretches for 1800 km along the Central Andes and attains a width of 350–400 km. The plateau correlates spatially and temporally with Andean arc magmatism, but it was uplifted primarily because of crustal thickening produced by...

The evolution of four dynamic radar glacier zones at the surface of an alpine icefield in British Columbia is monitored using a time series of 35 First European Remote Sensing Satellite (ERS-1) synthetic aperture radar (SAR) images acquired from 1992 to 1994. These zones result from changing wetness and textural properties, and appear to represent:...

The space-shuttle-based SIR-C/X-SAR synthetic aperture radar (SAR) imaged part of Hielo Patagónico Sur (HPS; southern Patagonia ice field, South America) for five successive days during missions in April and October 1994. A significant meteorological event occurred during each mission, including a major storm in April and a sharp temperature decrea...

Shuttle imaging radar C/X band synthetic aperture radar (SIR-C/X-SAR) views of the South Patagonian Icefield in southern Chile and Argentina demonstrate the ability of spaceborne multiparameter radar to detect climatically driven, intra-annual changes in the snow and ice conditions on glaciers. The SIR-C/X-SAR system aboard space shuttle Endeavor a...

Analysis of 41 ERS 1 synthetic aperture radar images and simultaneous ground measurements of discharge for three large braided rivers indicates that the area of active flow on braided river floodplains is primarily a function of discharge. A power law correlation is found between satellite-derived effective width We and discharge Q, where We is the...

The Central Andean plateau is a 300-km-wide, nearly 4-km-high plateau which is situated above a 30°E-dipping segment of the subducted Nazca plate. Systematic changes in the topography, the upper mantle seismic attenuation (Q) structure, the lithospheric flexural rigidity and the distribution and chemistry of back-arc lavas indicate that the upper m...

The first topographic and ice-motion maps of the northwestern flank of Hielo Patagonico Norte (HPN, northern Patagonia Icefield), in Chile, were produced using satellite synthetic-aperture interferometric radar data acquired by NASA's Spaceborne Imaging Radar C instrument in October 1994. The topographic map has a IO m vertical precision with a 30...

Interferometric radar observations of Glaciar San Rafael, Chile, were collected in October 1994 by NASA's Spaceborne Imaging Radar C (SIR-C) at both L- (24cm) and C-band frequency (5.6cm), with vertical transmit and receive polarization. The C-band data did not yield good geophysical products, because the temporal coherence of the signal was signif...

The space-shuttle-based SIR-C/X-SAR synthetic aperture radar (SAR) imaged part of Hielo Patagónico Sur (HPS; southern Patagonia ice field, South America) for five successive days during missions in April and October 1994. A significant meteorological event occurred during each mission, including a major storm in April and a sharp temperature decrea...

With the anticipated completion of multilateral comprehensive nuclear test ban and nonproliferation treaties in the near future, it is essential for the monitoring efforts that multidisciplinary information on a given region is readily available and accessible in a digital, on-line format via electronic networks for use by concerned researchers and...

Interferometric radar observations of Glaciar San Rafael, Chile, were collected in October 1994 by NASA’s Spaceborne Imaging Radar C (SIR-C) at both L- (24 cm) and C-band frequency (5.6 cm), with vertical transmit and receive polarization. The C-band data did not yield good geophysical products, because the temporal coherence of the signal was sign...

The first topographic and ice-motion maps of the northwestern flank of Hielo Patagónico Norte (HPN, northern Patagonia Icefield), in Chile, were produced using satellite synthetic-aperture interferometric radar data acquired by NASA’s Spaceborne Imaging Radar C instrument in October 1994. The topographic map has a 10 m vertical precision with a 30...

As the target date (end of 1996) for the completion of multilateral comprehensive nuclear test ban treaty approaches, it is essential for the monitoring efforts that multidisciplinary information on any given region is readily available and accessible in a digital, on-line format via electronic networks for use by concerned researchers and decision...

Using multitemporal ERS 1 synthetic aperture radar (SAR) satellite imagery and simultaneous ground measurements of streamflow, a strong correlation (R2 = 0.89) was found between water surface area and discharge for a braided glacial river in British Columbia, Canada. Satellite-derived effective width (We) was found to vary with discharge (Q) as We...

THE Earth's most active zone of mantle seismicity arises from the subduction of the Pacific plate at the Tonga trench1. It is not known why this slab generates so many more earthquakes than other subducting slabs worldwide. Above the subduction zone the active Tofua (Tonga) volcanic arc is separated by the V-shaped Lau basin from a remnant arc, the...

Modern and last glacial maximum (LGM) snowlines in the central Andes (5°-23°S) have been mapped using remote sensing techniques and geographical information system technology. The general configuration of the snowline during the LGM was similar to present with the snowline rising from east to west in response to decreasing precipitation. LGM snowli...

We hypothesize that the steep frontal slope and high peaks of the Beni region and Himalayan front largely reflect the high orographic precipitation and high erosion rates occurring in these regions and that the more gentle topography of the semiarid Pilcomayo region reflects a tectonic landform only slightly modified by erosion. We propose that oro...

Analysis of high-resolution digital topography across 21 Plio-Pleistocene grabens in central and southern Tibet shows that high topography occurs along the graben margins. Profiles across these marginal highlands fit curves describing the flexure of an elastic plate under vertical loading. We interpret the features as flexural rift flank uplifts, r...

High resolution digital topography (three are-second grid) for most of Tibet provides new information to characterize the relief of the highest and largest plateau on Earth. The arid to semiarid central and northern part of the plateau interior has low relief (average slopes of similar to 5 degrees over 250 m windows) and a mean elevation of 5023 m...

Local network three-component digital data from the San Juan area, Argentina, provide the first seismological images of the deep crustal structure in the Andean foreland above a horizontal segment of the subducted Nazca plate. We have identified S-to-P seismic phases converted on the Moho by analysis of seismograms formed by taking the product of t...

This paper presents a new compilation of shallow seismicity and focal mechanism data that help constrain the model of extension in the North Fiji Basin. Earthquakes are broadly distributed throughout the basin, in marked contrast to the narrow earthquake zones observed near mid-ocean ridge spreading centers. Areas of relatively high activity includ...

Topography and heterogeneous crustal structure have major effects on the propagation of regional seismic phases. We are collecting topographical, geological, and geophysical datasets for Eurasia into an information system that can be accessed via Internet connections. Now available are digital topography, satellite imagery, and data on sedimentary...

We seek to determine the mantle lid thickness of the lithosphere and to constrain the mechanisms that are responsible for the Cenozoic uplift of the Tibetan plateau located behind the Himalaya collision zone and the western United States located behind the San Andreas transform/convergent plate boundary. Selected first P arrivals of International S...

Data from a digitally recording seismic network in San Juan, Argentina, provide the fnst images of crustal scale basement faults beneath the Precordillera. This seismicity is near the boundary between the Precordillera (a thin-skinned thrust belt) and the Sierras Pampeanas (a region of thick-skinned basement deformation), two seismically active tec...

Construction of a regional transect across the central Andes at 20[degrees]S sheds new light on the relationship between the Altiplano, Eastern Cordillera (EC), and Subandean zones and allows us to refine the two-stage model of Isacks (1988) for the growth of the Central Andes. This new model is based on examination of the regional geology and geop...

The central Andean plateau is one of the Earth's most remote and poorly mapped regions. The plateau has an average elevation of 3.7 km, and extends from central Peru to at least 30[degrees]S latitude. The plateau and flanking Subandean foldthrust belt (FTB) reach their greatest width near 20[degrees]S, and at this latitude both the FTB and the basi...

Newly dated Tertiary strata in the Bolivian central Andean plateau and synthesis of the Tertiary record in the adjacent Subandean fold-thrust belt constrain the age of deformation in both regions. Age of deformation within the plateau is determined by dated crosscutting relations associated with a regionally extensive high-level surface known as th...

An updated compilation of earthquake locations and focal mechanism solutions from the International Seismological Centre and Preliminary Determination of Earthquakes is the basis of a comprehensive study of the geometry of the Wadati-Benioff zone beneath western South America. The new data support previous mapping of a sharp flexure rather than a t...

The Portable Array for Numerical Digital Analysis (PANDA) network. a digitally recorded seismic array. operated for nine months in Jujuy province of northwestern Argentina. The network was deployed along the eastem edge of the Altiplano-Puna plateau in a major N-S thrust belt that is transitional in style between the thin-skinned deformation of the...

Several seismological observations suggest that there is a gap within the downgoing slab of Australian lithosphere plunging beneath the New Hebrides, and ages of elevated coral terraces on the New Hebrides Islands suggest that the islands are rising rapidly. We suggest that the creation of the gap in the slab, within the last 1 M.y., occurred by pa...

The topography and crustal structure variations along propagation paths and at the source and receiver sites are crucial information to understand the excitation and propagation of regional seismic phases and other aspects of the problems of nonproliferation, verification and yield estimation. Work in progress has realized useful datasets for Euras...

The valleys of the Mono Basin contain several sets of lateral and terminal moraines representing multiple stages of glaciation. The semi-arid climate with slow weathering rates preserved sequences of nested younger moraines within older ones. There is a well established relative chronology and recently exposure dating provided a new set of numerica...

A digitally recording seismic network was operated from September 1987 to May 1988 in the San Juan Province of northwestern Argentina. The data provide a detailed view of the crustal seismicity of Sierra Pie de Palo, one of the most seismically active mountain blocks of the Sierra Pampeanas and the site of the destructive Ms 7.3 Caucete earthquake...

A map of lateral variations in upper mantle P and S wave attenuations beneath the plateau was compiled using observations of seismic waveforms from shallow- and intermediate-depth earthquakes recorded by a portable seismic array deployed in Jujuy Province, Argentina. Large differences were found in the amplitudes and frequencies of P and S waves, r...

Arrival times of compressional (P) and shear (S) waves generated by earthquakes located in the New Hebrides subduction zone and recorded by local and regional arrays of seismographs are used to determine large-scale one- and three-dimensional elastic wave velocity structures of the subduction zone between 15-degrees and 20-degrees-S and from the su...

A regional study of the distribution and elevations of Pleistocene moraines in the Andes requires a method of determining relative age from space. One of our primary objectives is to establish the relative chronology of major climatic events responsible for glaciation in the Andes and other regions that are difficult to access on the ground and whe...

Computer graphics techniques are used to portray the shape of the subducted lithosphere as seen from different views. The configuration of the subducted lithosphere is represented by a surface that approximately fits the upper envelope of the slab-like spatial distribution of earthquake hypocentres in the Benioff-Wadati zone. Regions considered inc...

Geomorphic interpretation of geologic features using DEMs (Digital Elevation Models) and satellite imagery can yield useful information on long- term fault activity in the absence of detailed ground mapping. Mapping of probable active faults in Central Asia and estimation of the type of offset from DEMs is combined with digitizations of published f...

Lateral velocity variations in the Andean foreland near San Juan Province, Argentina, were detected by analyzing the station corrections computed as part of the joint location of local earthquake data. The events, recorded by a portable network (PANDA), have intermediate and shallow depths (about 100 km and less than 40 kin, respectively). The JHD...

Tilt and seismicity have been monitored in the central New Hebrides island arc since 1978. Releveling of the bench mark array on Efate island in late November 1986 revealed a 10μrad tilt up to the NNW since the previous leveling in April 1986. The tilt event was preceded by a magnitude 5.9 thrust event that occurred on October 25, 1986, at a depth...

Local network data from San Juan, Argentina, provides new information about crustal seismicity in the Andean foreland above a horizontal segment of the subducted Nazca Plate. Two areas of foreland seismicity are found, one associated with the Sierras Pampeanas basement uplifts, and the other beneath, but not within, the Precordillera foreland fold-...

Excellent surface exposures, known Benioff zone geometry, a dynamic morphology, and the availability of industry seismic reflection data all make the Andes at 30°S an excellent transect for investigating crustal-scale balanced sections. 150-170 km of horizontal shortening has occurred in three major belts located between the trench and the foreland...

Acquisition of nearly complete coverage of Thematic Mapper data for the central Andes between about 15°S to 34°S has stimulated a comprehensive and unprecedented study of the interaction of tectonics and climate in a young and actively developing major continental mountain belt. The paper briefly reviews the current state of our synoptic mapping of...

Data from a telemetered seismic network in Fiji provide new constraints on the crustal structure and active deformation within and around the Fiji Platform, an unusual fragmented arc complex situated within the Pacific/Indo-Australian plate boundary. Seismic refraction data indicate that crustal thickness in Fiji is typical of island arcs, averagin...

Topographic data are combined with data on structure magmatism, seismicity, and paleomagnetism to support a simple kinematical model for the late Cenozoic evolution of the central Andes. The model interrelates Andean uplift, a changing geometry of the subducted Nazca plate, and a changing outline of the leading edge of the South American plate. It...

Earthquake distribution and focal mechanisms from the Lau and North Fiji back-arc basins indicate a diffuse and shear-dominated system of deformation, at odds with traditional plate tectonic models of lithospheric accretion in back-arc basins. The entire back-arc region between the Tonga and New Hebrides arcs is more realistically modelled as a gia...

New observational data on the velocity structure, seismicity, and state of stress of the large submarine platform that includes the Fiji Islands demonstrate that the platform is an active participant in the pervasive regional deformation of the Pacific/Indian-Australian plate boundary. Refraction data collected within the Fiji platform demonstrate...

Seismic data, recorded by INPRES telemetered network located above one of the subhorizontal segments of the subducted Nazca plate Wadati-Benioff zone beneath western Argentina, were analyzed to determine the zone's fine structure. The depth of the center and the thickness of the subhorizontal Wadati-Benioff zone beneath the network were calculated...

The central New Hebrides island am is a morphologically complex area where the island blocks of Santo and Malekula replace the trench and override the D'Entrecasteaux Fracture Zone (DFZ), a major aseismic ridge, on the subducting plate. Earthquakes recorded by a local network have been located beneath the trench southwest of Malekula at depths of 6...

The topographic data combined with information on structure, magmatism, seismicity, and paleomagnetism support a simple kinematic model for the late Cenozoic evolution of the central Andes. The model does not require collisional effects or enormous volumes of intrusive additions to the crust but instead calls upon plausible amounts of crustal short...

This paper examines the spatial distribution deep earthquakes in the Tonga-Fiji-New Hebrides region of the southwest Pacific. Our interpretation emphasizes the complex Cenozoic tectonics of the Pacific/Indo-Australian plate boundary as a primary control on the distribution and deformation of subducted lithosphere. Most deep earthquakes in the inter...

Landsat Thematic Mapper (TM) images of portions of the Central Andean Puna-Altiplano volcanic belt have been tested for the feasibility of discriminating individual volcanic flows using supervised classifications. This technique distinguishes volcanic rock classes as well as individual phases (i.e., relative age groups) within each class. The spect...