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Orthogonal subduction of bathymetrically rough oceanic lithosphere along the northwestern flank of the Cocos Ridge imprints a distinctive style of deformation on the overriding Costa Rican forearc. We divide the Costa Rican forearc into three 100-160-km-long deformational domains based on the bathymetric roughness and thickness of the Cocos plate entering the Middle American Trench, the dip of the subducting plate, the variation in surface uplift rates of late Quaternary coastal deposits, and the orientations and types of faults deforming Paleogene and Neogene sedimentary rocks. In the ~100-km-long Nicoya domain, coastal deposits show localized surface uplift and arcward tilting above the downdip projections of the fossil trace of the Cocos-Nazca-Panama (CO-NZ-PA) triple junction and the Fisher seamount and ridge. In the ~120-km-long central Pacific forearc domain between the Nicoya Peninsula and Quepos, shallower (~60[degrees]) subduction of seamounts and plateaus is accompanied by trench-perpendicular late Quaternary normal faults. Steeply dipping, northeast-striking, margin-perpendicular faults accommodate differential uplift associated with seamount subduction. Uplift and faulting differ between the segments of the forearc facing subducting seamounts and ridges. Inner forearc uplift along the seamount-dominated segment is greatest inboard of the largest furrows across the lower slope. Localized uplift and arcward tilting of coastal deposits is present adjacent to subducting seamounts. In contrast, inboard of the underthrusting aseismic Cocos Ridge, along the ~160-km-long Fila Costefia domain between Quepos and the Burica Peninsula, mesoscale fault populations record active shortening related to the ~100-km-long Fila Costena fold-and-thrust belt. The observed patterns of faulting and permanent uplift are best explained by crustal thickening. The uplifted terraces provide a first-order estimate of permanent strain along the forearc in Costa Rica. The permanent strain recorded by uplift of these Quaternary surfaces exceeds the predicted rebound of stored elastic strain released during subduction-zone earthquakes.

The Chulitna terrane is an enigmatic, fault-bounded package of mid-Paleozoic to early Mesozoic sedimentary rocks and volcanics that are exotic to North America and show no clear affinity with any of the other allochthonous terranes in southern Alaska. Geologic mapping and geochemical analyses of Triassic strata from the Chulitna terrane indicate Triassic rifting of a Devonian volcanic arc and development of an asymmetric basin that was later deformed in the Cretaceous within the broadly defined suture between the Wrangellia composite terrane and the Mesozoic margin of North America. The structure of the region consists of an overturned synclinorium that verges southeast, Triassic strata in the core of the syncline, and basement rocks exposed in the hanging walls of a series of out-of-syncline thrusts on the southeastern, upright limb. The basement of the complex consists of serpentinite, vesicular flows of basaltic andesite with minor pillow lavas, and volcanic debris with blocks of andesite and minor Devonian red chert. From southeast to northwest, there are systematic changes in the facies associated with Triassic strata that overlie this basement. To the southeast, the basement is unconformably overlain by bedded sedimentary breccias that consist of subangular clasts of basement lithologies, including red chert, serpentinite, and andesite. Further to the northwest, in the hanging wall of a more rearward thrust, the red-bed strata consist of conglomerate intermixed with siltstone and cross-bedded sandstone. In the northwest on the overturned limb of the syncline, the red beds are composed of siltstone and sandstone interfingered with limestone. There is an overall increase in the thickness of the red-bed unit from southeast to northwest. On the northwestern limb of the syncline, the red beds overlie a 1500-m-thick basalt sequence with columnar jointed flows and pillow basalts interbedded with limestone. Geochemical analyses of clinopyroxene phenocrysts in the basalts show similarities with island-arc basalts, suggesting that volcanism was related to early rifting of an oceanic arc. A marine sandstone unit overlies the entire red-bed package along a flooding surface and thins to the southeast. These results are consistent with Triassic deposition within a rifted volcanic arc, an upland erosion surface to the southeast, and increasing thickness of the Triassic section toward a basin-bounding fault in the northwest. This basin was initially ~18 km wide prior to accretion along the Mesozoic margin of North America, which resulted in southeast-vergent folding and 30% shortening.

The current paper proposes a novel taxonomy of latent hazard anticipation by distinguishing modal, strategic, tactical, and operational hazard anticipation skills. Novice drivers face an increased risk of being involved in fatal motor vehicle crashes. Research involving both on-road and driving simulator studies suggests that novice drivers are especially poor at anticipating latent hazards. We reviewed and synthesized previous works on hazard anticipation in young drivers. Modal hazard anticipation skills are broader in nature and more applicable to the general traffic, roadway, and environmental conditions, while strategic, tactical, and operational hazard anticipation skills are more scenario-specific and necessary when navigating a potentially safety-critical situation. It is known that error-based feedback training programs can improve both tactical and strategic, but not yet operational and modal hazard anticipation abilities of novice drivers. Future research should explore individual differences in the effectiveness of training interventions for young novice drivers. [ABSTRACT FROM AUTHOR]

[1] The Fila Costena thrust belt in the forearc of Costa Rica is accommodating a significant portion of the convergence of the Cocos plate and Panama microplate. Geologic mapping of the thrust belt depicts a duplex with three horses that incorporate Eocene limestones and Oligocene to early Miocene clastics inboard of the subducting Cocos Ridge axis. By constructing a cross section at this location along a NE-SW trending transect perpendicular to the thrust belt, we constrain a shortening rate of approximately 40 mm/a and propose that as much as 50% of the total plate convergence rate is taken up in the inner forearc. The Eocene limestones at the base of the thrust sheets pinch out in both directions away from the onland projection of the Cocos Ridge axis owing to decrease in slip on faults and a lateral ramp in the basal decollement. The thrust belt terminates near the Panama border at the onland projection of the subducting Panama Fracture Zone. These observations suggest that shortening is propagating to the east with the migration of the Panama triple junction and the onset of shallow subduction of the thickened edge of the Cocos plate. The absence of similar features in the Nicaraguan forearc, where the subducting crust is older, subducts more steeply, and lacks incoming ridges and seamounts, indicates that deformation of the forearc basin in Costa Rica reflects greater coupling between the converging plates inboard of the Cocos Ridge. doi: 10.1029/2006TC001949.

A 220-km-long, single-channel seismic reflection profile crosses the northern Sumatra margin and presumed rupture zone of the December 2004 [M.sub.w]9.2 tsunamigenic earthquake and images active deformation across the forearc. At the largest wavelength (tens of kilometers), the forearc surface is defined by a steep, 55-km-wide outer slope, a 110-km-wide upper slope forming a broad depression between two forearc highs, and a 25-km-wide steep inner slope between the landward high and forearc basin. Superimposed on these prism-wide variations are anticlinal ridges spaced ~13 km apart; the inner and outer slopes are characterized by landward and seaward fold vergence, respectively. Between anticlines, growth strata deposited in slope basins are folded at -2-3 km wavelengths. These small folds deform the seafloor and increase in amplitude with depth, verging toward anticlinal hinges. We suggest that long-wavelength variations are consistent with variations in strength across the forearc. The ~13 km anticline spacing implies deformation of a slope apron that deforms independently of a stronger wedge interior. Growth strata geometries indicate ongoing deformation within individual basins. Our model for prism architecture suggests that the wedge interior advances during great earthquakes like the 2004 [M.sub.w]9.2 event, peeling up shallower and less competent trench fill, deforming the toe and the upper slope of the forearc, and producing seabottom uplift responsible for the tsunami. Keywords: forearc, Sumatra, growth sedimentation, wedge, tsunami.

Recent observations of cleavage patterns, strain histories, and kinematics across the Taiwan mountain belt depict systematic orogen-scale variations with respect to the synorogenic divide and suggest that the pattern of cleavage development is a predictable consequence of orogen stresses and kinematics. In Taiwan, continental crust within the collision is accreted in the prowedge facing Asia, but is advected eastward into the east-verging retrowedge, where the most deeply exhumed rocks are exposed. Wedge mechanics predict a reversal in the direction of plunge of the principal compressive stress at the topographic divide between the opposing wedges. The observation of a single cleavage in western Taiwan suggests that the cleavage in the prowedge remains stable with respect to the stress orientation. In contrast, the existence of a second crenulation cleavage in the retrowedge is evidence for an abrupt change in stress orientation and unstable buckling of preexisting prowedge fabrics. Advection of a fabric across a topographic divide in a doubly vergent wedge provides an explanation for the occurrence of cleavage fronts and fans in natural systems such as Taiwan. Keywords: cleavage fan, cleavage front, Taiwan, slaty cleavage, incremental strain.

[1] The Costa Rica portion of the Middle America Trench (MAT) is characterized by active tectonic erosion, a process that causes the removal of material from the base of the upper plate as the plate boundary migrates upward. Offshore studies demonstrate accelerated subduction erosion starting at the Miocene-Pliocene boundary, as the result of subduction of thickened Galapagos related crust, as presently represented by the Cocos Ridge. The subduction of the Cocos Ridge also caused uplift and exposure of the outer forearc on the Osa Peninsula, which offers a window to explore the tectonic evolution of the area. The rocks outcropping on Osa Peninsula are a middle Eocene-middle Miocene melange dominated by basalt, chert, and limestone resulting from accretion of seamounts. The accretion-dominated period of the MAT evolution ended at the Miocene-Pliocene boundary, when thickened crust, a paleo-Cocos Ridge, produced at the Galapagos hot spot arrived at the trench. The thick crust caused uplift and severe tectonic erosion of the accretionary edifice allowing exhumation of the Osa Melange. The change from accretion to erosion caused the outer forearc to be offset along subvertical faults that define small (kilometer to tens of kilometers size) blocks that are going through differential vertical movements in response to the morphology of the subducting ridge. Subduction accretion and erosion are two processes that can alternate in time and space or coexist along the same margin, so that mass removal can develop on a previously growing margin and completely remove an accretionary prism. Citation: Vannucchi, P., D. M. Fisher, S. Bier, and T. W. Gardner (2006), From seamount accretion to tectonic erosion: Formation of Osa Melange and the effects of Cocos Ridge subduction in southern Costa Rica, Tectonics, 25, TC2004, doi: 10.1029/2005TC001855.

Novice driver's [less than or equal to] 16-year-olds with [less than or equal to] 6 months' driving experience) have the highest crash involvement rates per 100 million vehicle miles (161 million vehicle kin). In the past, this was attributed to greater risk taking or poorly developed psychomotor skills. More recently, however; their high crash involvement rate has been hypothesized to be attributable largely to their relative inability to acquire and assess information in inherently risky situations. The current study seeks to evaluate this hypothesis by recording eye movements while 72 participants (24 novice drivers, 24 younger drivers, and 24 older drivers) drove through 16 risky scenarios in an advanced driving simulator There were significant age-related differences in driver scanning behavior, consistent with the hypothesis that novice drivers' scanning patterns reflect their failure to acquire information about potential risks and their consequent failure to deal with these risks. Actual or potential applications of this research include modification of these scenarios for display on a PC as a basis for a training module that would enable novice driver's to recognize risky scenarios before they encounter them on the road, in the hope of reducing their high fatality rate.

Structural and geomorphic analyses of the Fila Costena thrust belt in southwest Costa Rica indicate active thrusting within the inner forearc. The Fila Costena exposes three major thrust faults that imbricate the late Tertiary forearc basin sequence of the Terraba basin. The frontal thrust of the Fila Costena marks the boundary between an uplifting inner forearc and a subsiding outer forearc, with only local uplift astride the indenting Cocos Ridge. On the basis of surface constraints a cross section across the thrust belt suggests that all three thrusts flatten into parallelism with a low-angle decollement horizon near the contact between the basement and the cover sequence of the Terraba basin. This decollement lies at a depth of ~4 km. The minimum shortening recorded by restoration of fault-related folds is 17 km, or 45%. Observations of late Tertiary marine sediments, tilted and faulted late Quaternary fluvial terraces, and raised Holocene marine terraces indicate that Fila Costena uplift was likely initiated in the Quaternary and is ongoing. Given that the coastal mountains are separated from the Talamanca Range by a valley, the decollement that delaminates the forearc basin from the underthrusting forearc must continue as a flat beneath the valley but must link with the plate boundary along a crustal-scale ramp system, a structural geometry that has resulted in uplift of the Talamanca Range, the highest peaks in Central America. The dichotomy between uplift in the inner forearc and subsidence in the outer forearc is explained in terms of the response of an arcward thickening wedge to rough, subducting crust. INDEX TERMS: 8150 Tectonophysics: Plate boundary--general (3040); 8123 Tectonophysics: Dynamics, seismotectonics; 8010 Structural Geology: Fractures and faults; 8015 Structural Geology: Local crustal structure; 8005 Structural Geology: Folds and folding; KEYWORDS: forearc, thrust belt, Costa Rica.

[1] Subduction of seamounts and ridges along thinly sedimented convergent margins results in deformation of the overriding forearc. Exposures of newly recognized late Pleistocene, shallow water deposits (i.e., Marenco formation) record intervals of rapid subsidence and uplift across the Costa Rican forearc inboard of the subducting Cocos Ridge. In general, the Marenco formation is a fining upward, fossiliferious, late Pleistocene, marine sand disconformably overlying beveled surfaces cut across the competent Osa melange basement. The ~50 to 27 ka age of the Marenco formation is constrained by 12 accelerator mass spectrometry and two conventional (14)C dates obtained on marine macrofossils. The deposition of this sequence coincident with a general fall in sea level during oxygen isotope stage 3 requires >6 mm yr subsidence inboard of the northwest flank of the subducting Cocos Ridge. Presently, exposures of the Marenco formation are found at >75 m above sea level, requiring uplift rates in excess of 6 mm [yr.sup.-1]. We interpret the down and up history of vertical tectonism recorded by the Marenco formation as the response of the upper plate to variations in the elevation of the subducting Cocos Ridge. On the basis of a model where the upper plate deforms through bends because of roughness on a rigid downgoing plate, the rate, duration, and spatial distribution of vertical tectonism across the forearc are determined by the magnitude of the orthogonal component of the relative convergence vector and the bathymetry of the underthrusting plate. Application of this model to bathymetric data for the Cocos plate offshore yields a broad agreement between predicted future rates of subsidence and uplift and rates over the last 50 kyr recorded by the Marenco formation. Furthermore, analysis suggests that the arrival of the blunt-tipped leading edge of the Cocos Ridge (0.5-3 Ma) resulted in an initial period of very rapid (~30 mm [yr.sup.-1]) upliff. INDEX TERMS: 8105 Tectonophysics: Continental margins and sedimentary basins (1212); 3040 Marine Geology and Geophysics: Plate tectonics (8150, 8155, 8157, 8158); 8010 Structural Geology: Fractures and faults; KEYWORDS: Costa Rica, Marenco formation, forearc deformation. Citation: Sak, P. B., D. M. Fisher, and T. W. Gardner (2004), Effects of subducting seafloor roughness on upper plate vertical tectonism: Osa Peninsula, Costa Rica.

New apatite and zircon fission-track ages and previously published thermochronometric data are used to evaluate erosion rates and particle paths within the active Taiwan arc-continent collision. We present 20 new apatite fission-track ages and 6 new zircon fission-track ages. Apatite and zircon ages are all reset in the northern and eastern parts of Taiwan, although the region of reset apatite ages is larger. We interpret this pattern as resulting from crustal accretion at the western margin of the orogenic wedge combined with southward propagation of the collision zone. A one-dimensional thermal model including erosion provides prediction Of the fission-track ages. The distribution of reset ages is best explained with an erosion rate of 4-6 mm/yr. Given a propagation velocity of 60 mm/yr, this erosion rate implies that nearly 25 km of material has been eroded from northern Taiwan. The lack of reset [sup.40]Ar/[sup.39]Ar ages from muscovite and biotite suggests that rock-particle paths have a large horizontal component, a result consistent with an eroding orogenic-wedge model. Keywords: orogenesis, exhumation, fission-track dating, erosion, heat flow.

Subduction of hotspot-thickened seafloor profoundly affects convergent margin tectonics, strongly affecting upper plate structure, volcanism, and landscape evolution. In southern Central America, low-angle subduction of the Cocos Ridge and seamount domain largely controls landscape evolution in the volcanic arc. Field mapping, stratigraphic correlation, and [sup.40]Ar/[sup.39]Ar geochronology for late Cenozoic volcanic rocks of central Costa Rica provide new insights into the geomorphic response of volcanic arc landscapes to changes in subduction parameters (slab thickness, roughness, dip). Late Neogene volcanism was focused primarily along the now-extinct Cordillera de Aguacate. Quaternary migration of the magmatic front shifted volcanism northeastward to the Caribbean slope, creating a new topographic divide and forming the Valle Central basin. Stream capture across the paleo-Aguacate divide led to drainage reversal toward the Pacific slope and deep incision of reorganized fluvial networks. Pleistocene caldera activity generated silicic ash flows that buried the Valle Central and descended the Tarcoles gorge to the Orotina debris fan at the coast. Growth of the modern Cordillera Central accentuated relief along the new divide, establishing the Valle Central as a Pacific slope drainage basin. Arc migration, relocation of the Pacific-Caribbean drainage divide, and formation of the Valle Central basin resulted from slab shallowing as irregular, hotspot-thickened crust entered the subduction zone. The geomorphic evolution of volcanic arc landscapes is thus highly sensitive to changes in subducting plate character. Keywords: Costa Rica, volcanic arc, subduction, landscape evolution, geochronology.

We hypothesized that elevated partial pressures of [0.sub.2] would increase perivascular nitric oxide (.NO) synthesis. Rodents with [0.sub.2-] and NO-specific microelectrodes implanted adjacent to the abdominal aorta were exposed to [0.sub.2] at partial pressures from 0.2 to 2.8 atmospheres absolute (ATA). Exposures to 2.0 and 2.8 ATA [0.sub.2] stimulated neuronal (type I) NO synthase (nNOS) and significantly increased steady-state *NO concentration, but the mechanism for enzyme activation differed at each partial pressure. At both pressures, elevations in *NO concentration were inhibited by the nNOS inhibitor 7-nitroindazole and the calcium channel blocker nimodipine. Enzyme activation at 2.0 ATA 02 appeared to be due to an altered cellular redox state. Exposure to 2.8 ATA [0.sub.2], but not 2.0 ATA [0.sub.2], increased nNOS activity by enhancing nNOS association with calmodulin, and an inhibitory effect of geldanamycin indicated that the association was facilitated by heat shock protein 90. Infusion of superoxide dismutase inhibited .NO elevation at 2.8 but not 2.0 ATA [0.sub.2]. Hyperoxia increased the concentration of .NO associated with hemoglobin. These findings highlight the complexity of oxidative stress responses and may help explain some of the dose responses associated with therapeutic applications of hyperbaric oxygen. neuronal nitric oxide synthase; heat shock protein 90; calmodulin; hyperbaric oxygen

Tiger's-eye is an attractive and popular gemstone that is ubiquitous in stores that cater to rock and mineral collectors. For more than a century, textbooks and museum displays have identified the material as an archetype of pseudomorphism, i.e., the replacement of one mineral by another with the retention of the earlier mineral's shape. Our study has revealed that the textures responsible for the shimmer of tiger's-eye do not represent pseudomorphic substitution of quartz after preexisting crocidolite asbestos. Rather, we argue that tiger's-eye classically exemplifies synchronous mineral growth through a crack-seal vein-filling process. Keywords: tiger's-eye, crocidolite, quartz, pseudomorphism, crack-seal.

INTRODUCTION To understand the role of a human in a task, one frequently performs thorough task analyses. In contrast, mathematical and computer models are constructed infrequently and incompletely, perhaps because […], Typically, detailed quantitative and computer models of human operators performing real world tasks cannot easily be developed. We propose a technique that more easily allows for that development. We propose that when a cognitive task analysis has been carried out, a computer simulation model useful for approximations of task completion time is often within reach. The first step is to construct an activity network or order-of-processing diagram from the task analysis. Second, activity durations are found in the literature or approximated through multidimensional scaling. Finally, equations are written for calculating task completion time, or a program is written for simulations to estimate this time. Resulting models can be useful for optimizing system design. The approach is illustrated with an activity network by W. D. Gray, B. E. John, and M. E. Atwood (1993) for a telephone operator task. Simulations demonstrate the feasibility of using multidimensional scaling to obtain approximate activity durations. Th e approach is also illustrated with an order-of-processing diagram representing drivers reading roadside message displays. We point out that if a more detailed picture of unobservable mental processes in a task is needed, techniques have been developed for this through analysis of response times. Actual or potential applications of this research include system design, human-computer interaction, message comprehension, and simulation of information-processing tasks.

INTRODUCTION A significant amount of effort has been put into developing models of automobile drivers' route choice for both theoretical and practical purposes (for reviews, see Ben-Akiva & Lerman, 1997; […], Automobile drivers were recently found to be risk averse when choosing among routes that had an average travel time shorter than the certain travel time of a route considered as a reference. Conversely, drivers were found to be risk seeking when choosing among routes that had an average travel time longer than the certain travel time of the reference route. In a driving simulation study in which the reference route had a range of travel times, this pattern was replicated when the reference range was smaller than the ranges of the available routes. However, the pattern was reversed when the reference range was larger than the ranges of the available routes. We recently proposed a simple heuristic model that fit the relatively complex data quite well. Actual or potential applications of this research include the design of variable message signs and of route choice support systems.

INTRODUCTION Historically, 16-year-olds have been overinvolved in fatal crashes. Surprisingly, this overinvolvement has almost doubled in the last 20 years. For every 100 000 licensed 16-year-old drivers, there were 19 […], Driver education classes were once seen as a remedy for young drivers' overinvolvement in crashes, but research results from the early 1970s were disappointing. Few changes in the content or methods of instruction occurred until recently, but this could change rapidly. Personal computers (PCs) can now present videos or photorealistic simulations of risky, cognitively demanding traffic scenarios that require quick responses without putting the participant at risk. As such programs proliferate, evaluating their effectiveness poses a major challenge. We report the use of a fixed-base driving simulator to study the effects of both experience on the road and PC-based risk awareness training on younger drivers' part-task simulator driving performance in risky traffic scenarios. We ran three groups of drivers on the simulator: one group first trained on the PC (younger, inexperienced drivers) and two groups who received no PC training (younger, inexperienced and experienced drivers). Overall, the younger inexperienc ed drivers who were trained on a PC operated their vehicles in risky scenarios in ways that differed measurably from those of the untrained younger, inexperienced drivers and, more important, in ways that we believe would decrease their exposure to risk considering that, on average, their behavior was more similar to the behavior of the untrained, experienced drivers. More research is needed to demonstrate whet her these findings apply on the open road to the larger population of younger drivers. However, at least initially. the research suggests that PC-based risk awareness training programs have the potential to reduce the high crash rate among younger, inexperienced drivers.

Advanced Parking Management Systems use variable message signs to provide drivers with up-to-date information on the number of open spaces at selected parking lots throughout a city. Drivers passing a variable message sign must decide in which lot to park. Currently, it is not known what fraction will divert to each of the possible lots. This fraction is important to know, because it determines how large an affect an Advanced Parking Management System will have on traffic congestion. In this article, we report two experiments designed to test alternative models of drivers' parking decisions. Both experiments use an advanced driving simulator. This simulator makes it possible to approximate the load that drivers actually experience on the roadway so as get to a more realistic assessment of the strategies employed. Previous research had indicated that drivers use some variation of expected utility theory to select among lots. We find instead that most drivers use a lexicographic decision strategy. Such a strategy greatly reduces the cognitive load on the driver. CE Database keywords: Parking; Decision making; Driver behavior.