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We examined a dual pathway, longitudinal mediational model in which child sexual abuse (CSA) influences adulthood-interpersonal functioning and sexual risk through its impact on resiliency resources and psychological distress. Women were recruited from two obstetrics and gynecological clinics serving primarily low-income, inner-city women (N = 693) and interviewed at pretest (Time 1) and 6-month follow-up (Time 2). The proposed mediators were resiliency resources (i.e., self-esteem and self-efficacy) and psychological distress (i.e., depressive and posttraumatic stress symptoms). The interpersonal outcomes were general interpersonal problems (measured via recent loss of interpersonal resources, lack of perceived current social support, and recent social conflict) and HIV/sexual risk (measured via lack of confidence asserting safe-sex practices, intimate-partner risk, and perceived barriers to safe sex). A respecified, partial structural equation model implying full mediation supported our hypotheses. Model fit was assessed using the chi-square goodness-of-fit statistic, comparative-fit index (CFI), root mean square error of approximation (RMSEA), and standardized root mean square residual (SRMR; CFI = .96, RMSEA = .05, SRMR = .04). The impact of CSA on interpersonal problems was mediated through its effect on psychological distress, whereas the impact of CSA on HIV/sexual risk was mediated through its effect on resiliency resources. Implications for intervention are discussed. (PsycINFO Database Record

Major depressive disorder (MDD) is a serious and prevalent mental health issue. As the majority of MDD cases are identified and treated by one's primary care physician, it is imperative that care providers utilize accurate and efficient methods for diagnosing MDD in primary care settings. The present study is the first to investigate the accuracy of the Quick Inventory of Depressive Symptomatology-Self Report (QIDS-SR(16)) as a screen for MDD. A heterogeneous sample of 155 primary care patients completed the QIDS-SR(16) prior to attending a primary care appointment. Participants were then assessed for psychopathology using the Structured Clinical Interview for DSM-IV-TR Axis I Disorders (SCID) by clinicians who were blind to QIDS-SR(16) scores. Scores on the QIDS-SR(16) were compared to clinician-assessed current and lifetime diagnoses derived from the SCID, which represented the gold-standard criterion measure. Receiver operator characteristic analysis was utilized to determine the optimal QIDS-SR(16) cut score to correctly classify participants based on their MDD status as assessed by the SCID. The test revealed a robust area under the curve (.82, p

The ascent of magma to the Earth's surface is commonly modeled by assuming a fixed dike or flow geometry from a deep subsurface reservoir to the surface. In practice, however, this flow geometry is produced by deformation of the crust by ascending overpressured magma. Here, we explore how this elastic deformation is coupled to magma ascent using a model of a planar dike whose width is allowed to evolve with depth in the crust. The model predicts that, for points well below the surface, the dike gradually narrows with height above the source reservoir as the overpressure of the magma relative to the minimum horizontal stress in the crust decreases. For a bubbly compressible magma, the flow accelerates to the surface and reaches the speed of sound at the vent, as for rigid conduit flow. However, it is now able to decompress to atmospheric pressure at the vent by contraction of the conduit. Our calculations predict eruption rates on the order of 0.1–10 $m^2/s$ per unit length of a dike, for magma supplied from a reservoir with overpressure in the range − 10 MPa to + 20 MPa.

A low-energy (Volcanic Explosivity Index [VEI] 1), small-volume (0.001 km3 Dense Rock Equivalent [DRE]) eruption of highly crystalline basalt occurred at Cerro Negro volcano, Nicaragua, August 5–7, 1999. This eruption followed three earthquakes (each ∼Mw 5.2) with strike-slip and oblique-slip focal mechanisms, the first of which occurred approximately 11 h before eruptive activity and within 1 km of Cerro Negro. Surface ruptures formed during these events extend up to 4 km from Cerro Negro, but concentrate ∼1 km south of Cerro Negro. Surface ruptures did not occur within 300 m of the cone, however, three new vents formed on the south flank and base of Cerro Negro and on trend with the Cerro La Mula–Cerro Negro volcanic alignment. Earthquake swarms were located northwest and southeast of Cerro Negro and seismicity was elevated for up to 11 days after the initial event. The temporal and spatial patterns of earthquake swarms, surface ruptures, and the eruption location can be explained using the Hill [J. Geophys. Res. 82 (1977) 1347] model for earthquake swarms in volcanic regions, where an eruption is triggered by tectonically induced changes in the regional stress field. In this model, tectonic strain, rather than magmatic overpressure causes dilation of the conduit for magma ascent. Numerical simulations for the 1999 eruption illustrate that the observed velocities (up to 75 m s−1) and fountain heights (50–300 m) can be achieved by eruption of magma with little excess magmatic pressure, in response to changes in Coulomb stress along the Cerro La Mula–Cerro Negro alignment. These observations and models show that 1999 Cerro Negro activity was a tectonically induced small-volume eruption in an arc setting, with the accommodation of extensional strain by dike injection.

The goal of probabilistic volcanic hazard assessment is to translate complex volcanological data and numerical models into practical hazard estimates for communities potentially affected by volcanic eruptions. Probabilistic volcanic hazard assessment quantifies volcanic hazards and illustrates uncertainties about the magnitude and consequences of volcanic activity. Planning based on probabilistic volcanic hazard assessment has the potential of mitigating the effects of volcanic eruptions when they occur. This paper presents an approach developed to estimate volcanic hazards related to tephra fallout and illustrates this approach with a tephra fallout hazard assessment for the city of Leon, Nicaragua, and the surrounding area. Tephra fallout from eruptions of Cerro Negro volcano has caused damage to property and adverse health effects and has disrupted life in this area. By summarizing the geologic and historical records of past eruptions of Cerro Negro on a probability tree, it is shown that the inhabitan...

Xenoliths in pyroclastic fall deposits from the 1975 Tolbachik eruption constrain the timing and development of subsurface conduits associated with basaltic cinder cone eruptions. The two largest Tolbachik vents contain xenoliths derived from magmatic and hydromagmatic processes, which can be correlated with observed styles of eruption activity. Although many basaltic eruptions progress from early hydromagmatic activity to late magmatic activity, transient hydromagmatic events occurred relatively late in the 1975 eruption sequence. Magmatic fall deposits contain 0.01–0.3 vol.% xenoliths from 500 m depth into the dry-out zone around the conduit, disrupting and ejecting 10 5 –10 6 m 3 of wall-rock through hydromagmatic processes with conduits widening to 8–48 m. Hydromagmatic falls contain 60–75 vol.% of highly fragmented xenoliths, with juvenile clasts displaying obvious magma-water interaction features. During the largest hydromagmatic event, unusual breccia-bombs formed containing a wide range of fresh and pyrometamorphic xenoliths suspended in a quenched basaltic matrix. Hydromagmatic activity during the 1975 Tolbachik eruption occurred below likely fragmentation depths for a basalt containing 2.2 wt.% magmatic water. This activity is more likely related to conduit-wall collapse rather than variations in conduit-flow pressure. In contrast, larger volume silicic eruptions may have transient hydromagmatic events in response to conduit flow dynamics above the magma fragmentation depth. The 1975 Tolbachik volcanoes are reasonably analogous to Quaternary basaltic volcanoes in the Yucca Mountain region and can guide interpretations of their poorly preserved deposits. The youngest basaltic volcanoes near Yucca Mountain have cone deposits characterized by elevated xenolith abundances and distinctive xenolith breccia-bombs, remarkably similar to 1975 Tolbachik deposits. Extrapolation of 1975 Tolbachik data suggests conduits for some Yucca Mountain basaltic volcanoes may have widened locally on the order of 50 m in response to late-stage hydromagmatic events.

Cerro Negro volcano, Nicaragua, continued a 147-yr-long duration of cinder-cone activity with a major eruption in 1995. Small, phreatically driven eruptions began in May 1995 and continued for 79 days. Following a 95 day repose, the main eruption produced 8 × 106 m3 of basalt from Cerro Negro over 13 days of activity and deposited 5 mm of ash in the city of Leon. Although the damage from the 1995 eruptions was fortunately minor, previous tephra falls from Cerro Negro have produced significant crop damage and multiple deaths through building collapse. In spite of its apparent longevity for a historically active cinder cone, Cerro Negro has mass-flow rates typical of arc-related basaltic cinder cone volcanoes. Volcanic hazards beyond 3 km from Cerro Negro consist of tephra falls. Few models are available to calculate tephra-fall risks from basaltic volcanoes such as Cerro Negro, and none have been applied to dispersive cinder cone eruptions. A convective-dispersive model of Suzuki is modified and evaluated using detailed data from the 1995 Cerro Negro eruption and is found to reasonably calculate tephra-fall thickness between 8 and 30 km from the vent. This model is used with detailed data from previous Cerro Negro eruptions in a tephra-fall hazard assessment. Cerro Negro also appears to have had a steady-state eruption rate since about A.D. 1900, which is used to estimate the timing of the next eruption as before A.D. 2006. The potential tephra fall from Cerro Negro in Leon, Nicaragua, is calculated as 2.2 mm/yr until 2006, with 95% confidence that deposits will be

The June–August 1995 eruption of Cerro Negro, a small-volume basaltic cinder cone in Nicaragua, provided a unique opportunity to quantify 222Rn degassing from soils in response to explosive volcanic activity. 222Rn was monitored at 29 stations using electrostatically charged teflon 222Rn detectors distributed north and southeast of the volcano. A pulse of elevated 222Rn degassing occurred early in the eruption along a > 1 km long zone, extending at least 750 m beyond the base of the cinder cone. Observation of this 222Rn pulse shows that large changes in soil 222Rn concentration can occur simultaneously at widely separated stations in response to even comparatively small-volume intrusions and volcanic eruptions. Frequent 222Rn sampling at multiple stations provides a sense of the magnitude, time scales and area affected by convective gas transport during volcanic eruptions.

The distribution and timing of areal basaltic volcanism are modeled using three nonhomogeneous methods: spatio-temporal nearest neighbor, kernel, and nearest-neighbor kernel. These models give nonparametric estimates of spatial or spatio-temporal recurrence rate based on the positions and ages of cinder cones and related vent structures and can account for migration and shifts in locus, volcano clustering, and development of regional vent alignments. The three methods are advantageous because (1) recurrence rate and probability maps can be made, facilitating comparison with other geological information; (2) the need to define areas or zones of volcanic activity, required in homogeneous approaches, is eliminated; and (3) the impact of uncertainty in the timing and distribution of individual events is particularly easy to assess. The models are applied to the Yucca Mountain region (YMR), Nevada, the site of a proposed high-level radioactive waste repository. Application of the Hopkins F test, Clark-Evans test, and K function indicates volcanoes cluster in the YMR at the >95% confidence level. Weighted-centroid cluster analysis indicates that Plio-Quaternary volcanoes are distributed in four clusters: three of these clusters include cinder cones formed