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The findings reported here describe the effects from a cohort-controlled trial of Making Choices (MC), a universal social-emotional skills training program. From teacher ratings, 688 third-grade students were classified into 4 risk profiles using measures of aggression, social competence, classroom concentration, and peer relations. High-risk students were more aggressive and less socially competent, on-task, and liked by peers; low-risk students were less aggressive and more socially competent, on-task, and liked by peers. Program effects were estimated as changes in profile membership between pretest and posttest assessments. Relative to high-risk students in comparison cohorts, a greater proportion of high-risk students in MC cohorts had moved to low-risk groups at posttest. Low-risk students in MC cohorts tended to remain at lower risk while a larger proportion of low-risk students in the comparison cohorts joined higher-risk groups. Social-emotional skills training appears to confer benefits ...

In elastic media, finite-difference (FD) implementations of free-surface (FS) boundary conditions on partly staggered grid (PSG) use the highly dispersive vacuum formulation (VPSG). The FS boundary is embedded into a “vacuum” grid layer (null Lame’s constants and negligible density values) where the discretized equations of motion allow computing surface displacements. We place a new set of compound (stress-displacement) nodes along a planar FS and use unilateral mimetic FD discretization of the zero-traction conditions for displacement computation (MPSG). At interior nodes, MPSG reduces to standard VPSG methods and applies fourth-order centered FD along cell diagonals for staggered differentiation combined with nodal second-order FD in time. We perform a dispersion analysis of these methods on a Lamb’s problem and estimate dispersion curves from the phase difference of windowed numerical Rayleigh pulses at two FS receivers. For a given grid sampling criterion (e.g., six or ten nodes per reference S wavelength λS), MPSG dispersion errors are only a quarter of the VPSG method. We also quantify root-mean-square (RMS) misfits of numerical time series relative to analytical waveforms. MPSG RMS misfits barely exceed 10 % when nine nodes sample the minimum S wavelength \(\lambda _{\text {MIN}}^{\mathrm {S}}\) in transit (along distances \(\sim \)145\(\lambda _{\text {MIN}}^{\mathrm {S}}\)). In same tests, VPSG RMS misfits exceed 70 %. We additionally compare MPSG to a consistently fourth-order mimetic method designed on a standard staggered grid. The latter equates the former’s dispersion errors on grids twice denser and shows higher RMS precision only on grids with six or less nodes per \(\lambda _{\text {MIN}}^{\mathrm {S}}\).

Military personnel and families experience significant challenges and need skills that will prepare them for extended periods of separation and other military demands. Relationship and marriage education programs are often helpful. However, there is a need for life skills programs that also teach military members to manage finances and legal matters, garner social support, and access community resources that are not often accessible to personnel and families in the National Guard and Military Reserves. Essential Life Skills for Military Families was developed to integrate relationship and life skills into a short-term course that has been offered to National Guard and Military Reserve members and families. This article describes the theoretical basis for the program, the program evaluation, and qualitative findings from participants, and identifies strategies for overcoming challenges to offering this kind of relationship skills program.

[1] We perform three-dimensional (3-D) numerical calculations of dynamic rupture along non-planar faults to study the effects of fault roughness on rupture propagation and resultant ground motion. The fault roughness model follows a self-similar fractal distribution over length scales spanning three orders of magnitude, from ~102 to ~105 m. The fault is governed by a strongly rate-weakening friction, and the bulk material is subject to Drucker-Prager viscoplasticity. Fault roughness promotes the development of self-healing rupture pulses and a heterogeneous distribution of fault slip at the free surface and at depth. The inelastic deformation, generated by the large dynamic stress near rupture fronts, occurs in a narrow volume around the fault with heterogeneous thickness correlated to local roughness slopes. Inelastic deformation near the free surface, however, is induced by the stress waves originated from dynamic rupture at depth and spreads to large distances (>10 km) away from the fault. The present simulations model seismic wave excitation up to ~10 Hz with rupture lengths of ~100 km, permitting comparisons with empirical studies of ground-motion intensity measures of engineering interest. Characteristics of site-averaged synthetic response spectra, including the distance and period dependence of the median values, absolute level, and intra-event standard deviation, are comparable to appropriate empirical estimates throughout the period range 0.1–3.0 s. This class of model may provide a viable representation of the ground-motion excitation process over a wide frequency range in a large spatial domain, with potential applications to the numerical prediction of source- and path-specific effects on earthquake ground motion.

Objectives To compare the mortality experience of 112 justices of the US Supreme Court with that expected in the general population. To identify variables associated with mortality within this cohort. Background Supreme Court justices are a select occupational cohort. High socio-economic status, advanced education, lifetime appointment, and the healthy worker effect suggest lower mortality. Sedentary work, stress, and a tendency to work beyond typical retirement age may attenuate this. Methods Standardized mortality ratios compare the observed mortality rates of justices with those expected in age- and sex-matched contemporary general populations. Poisson regression analyzes variables associated with mortality within the cohort. Results From 1789 to 2013, 112 justices (108 male) contributed 2,355 person-years of exposure. Mean age (standard deviation) at appointment was 53.1 years (6.7); at retirement 69.7 years (9.9); at death (n = 100) 74.4 years (10.3); and at end of the study for those alive (n = 12) 72.1 years (11.8). Standardized mortality ratios (95% ci) were: overall 0.87 (0.70-1.05); prior to 1950 0.92 (0.61-1.33); and from 1950 to 2013 0.66 (0.42-0.99). Variables in the final Poisson model and their associated mortality rate ratios (95% ci) were: age 1.06 (1.03-1.09); calendar year 0.99 (0.99-1.00); active status 0.41 (0.25-0.68); career length 1.04 (1.01-1.07); and chief justice 1.08 (0.59-1.84). Conclusions Supreme Court mortality was lower than that of the general population in the period from 1950 to the present, but was on par prior to 1950. Increasing age and career length were associated with greater mortality, while active status and later calendar year with lower. These results may add to a body of knowledge that may help to develop or refine models of mortality risk in increasingly aged working populations.

Treatment manuals are increasingly being used to guide interventions with individuals, families, groups, organizations, and communities. However, little is known about best practices in designing manuals. We describe a process that provides for the development of manuals and specifies the means by which manuals can be adapted for practice conditions and constraints. Manual development is conceptualized as comprising four systematic and recursive stages: (a) formulation, (b) revision, (c) differentiation, and (d) translation. We discuss issues and challenges in developing manuals that are responsive to a range of factors that influence social work practice, including advances in knowledge, the influence of evidence-based practice, the needs of individual clients, and contingencies linked to organizational policies, procedures, and leadership.

SUMMARY Simulations of earthquake rupture on the southern San Andreas Fault (SAF) reveal large amplifications in the San Gabriel and Los Angeles Basins (SGB and LAB) apparently associated with long-range path effects. Geometrically similar excitation patterns can be recognized repeatedly in different SAF simulations (e.g. Love wave-like energy with predominant period around 4 s, channelled southwestwardly from the SGB into LAB), yet the amplitudes with which these distinctive wavefield patterns are excited change, depending upon source details (slip distribution, direction and velocity of rupture). We describe a method for rapid calculation of the sensitivity of such predicted wavefield features to perturbations of the source kinematics, using a time-reversed (adjoint) wavefield simulation. The calculations are analogous to those done in adjoint tomography, and the same time-reversed calculation also yields path-sensitivity kernels that give further insight into the excitation mechanism. For rupture on the southernmost 300 km of SAF, LAB excitation is greatest for slip concentrated between the northern Coachella Valley and the transverse ranges, propagating to the NE and with rupture velocities between 3250 and 3500 m s–1 along that fault segment; that is, within or slightly above the velocity range (between Rayleigh and S velocities) that is energetically precluded in the limit of a sharp rupture front, highlighting the potential value of imposing physical constraints (such as from spontaneous rupture models) on source parametrizations. LAB excitation is weak for rupture to the SW and for ruptures in either direction located north of the transverse transverse ranges, whereas Ventura Basin (VTB) is preferentially excited by NE ruptures situated north of the transverse ranges. Path kernels show that LAB excitation is mediated by surface waves deflected by the velocity contrast along the southern margin of the transverse ranges, having most of their energy in basement rock until they impinge on the eastern edge of SGB, through which they are then funnelled into LAB. VTB amplification is enhanced by a similar waveguide effect.

Physical limits on ground-motion parameters can be estimated from spontaneous-rupture earthquake models but are subject to uncertainties in model parameters. We investigate physical limits at Yucca Mountain, Nevada, and assess sensitivities due to uncertainties in fault geometry, off-fault rock strength, the seismogenic depth, fault zone structure, and undrained poroelastic response of the fluid pressure. For the extreme scenario of nearly complete stress drop on the Solitario Canyon fault, peak ground velocity (PGV) at a site near the fault is sensitive to deep fault geometry and cohesive strength of shallow geologic units, while it is relatively insensitive to fault zone structure, the seismogenic depth, and pore-pressure response. Taking previous estimates of Andrews et al. (2007) as a benchmark, a 10° reduction in dip (from 60° to 50°) of the Solitario Canyon fault at depth, combined with doubled cohesion of shallow units, can increase both horizontal and vertical PGVs by over 1 m/s, to values exceeding 5 m/s. In a lower stress-drop scenario (constrained by regional extremes of coseismic slip inferred from the paleoseismic record), PGV is most sensitive to fault geometry at depth, is only modestly affected by fault zone structure, and is insensitive to cohesion of shallow units and pore-pressure response. Effects of rock strength on spectral acceleration are significant only at short periods (i.e., less than 3 s). The dipping normal-fault models predict asymmetric inelastic strain distributions with respect to the fault plane, with more intense inelastic deformation on the hanging wall, though that asymmetry may be moderated by poroelastic effects.

This study examined the social relations of bullies, victims, and bully-victims in second-grade classrooms. Bully-victims are identified as both bullies and victims. The sample consisted of 537 ethnically diverse second-grade students (247 boys, 290 girls) from 37 classrooms across 11 participating schools. Bullies, bully-victims, and victims tended to have somewhat distinct sociometric status and peer-assessed behavioral characteristics. Furthermore, bullies and bully-victims had distinct affiliation patterns. Bullies tended to be members of peer groups that contained few victims and most were in groups in which more than 50% of the members were not involved in bullying. In contrast, bully-victims tended to be members of groups that were composed primarily of bullies (i.e., bullies and bully-victims) and victims (i.e., victims and bully-victims). Implications for understanding the social dynamics of bullying in elementary school are discussed.

Dynamic rupture, and resultant ground motions up to 0.25 Hz, are simulated for an M w 7.6 earthquake on the southern San Andreas fault. Spontaneous rupture is modeled with slip-weakening friction, and 3D viscoelastic wave solutions are computed with a support-operator numerical method. The initial traction model is derived from inversions of the M w 7.3 1992 Landers strong ground-motion records, and borrows heavily from that used for the TeraShake2 simulations by Olsen et al. (2008). Heterogeneity in the traction model leads to focusing of the rupture front, and the focusing produces cases of supershear rupture velocity in asperities (areas of high initial traction), as well as cases of high peak slip rate and cohesive zone contraction in antiasperities. Separate solutions are computed for version 3.0 and 4.0, respectively, of the Southern California Earthquake Center Community Velocity Model (SCEC-CVM). We also compare the case of a flat ground surface (a common simplification made for finite-difference simulations) to the case of the ground surface conformed to regional topography. The overall distribution of simulated ground motion intensity is consistent with that derived from the empirical model of Campbell and Bozorgnia (2008), in the sense that the bulk of simulated pseudospectral velocity (PSV) values are within the 68% confidence intervals of the empirical model. Simulated PSVs corresponding to low probability in the empirical model are principally associated with basin wave-guide and directivity effects. An important example, first identified by the TeraShake1 simulations (Olsen et al. , 2006), is the stronger than expected ground motions at the site of Montebello due to a basin wave-guide effect. We find that this effect is lessened for version 4.0 of the SCEC-CVM, relative to version 3.0, due to a shallower model for the Chino basin.

SUMMARY This paper presents a verification of three simulations of the ShakeOut scenario, an Mw 7.8 earthquake on a portion of the San Andreas fault in southern California, conducted by three different groups at the Southern California Earthquake Center using the SCEC Community Velocity Model for this region. We conducted two simulations using the finite difference method, and one by the finite element method, and performed qualitative and quantitative comparisons between the corresponding results. The results are in good agreement with each other; only small differences occur both in amplitude and phase between the various synthetics at ten observation points located near and away from the fault—as far as 150 km away from the fault. Using an available goodness-of-fit criterion all the comparisons scored above 8, with most above 9.2. This score would be regarded as excellent if the measurements were between recorded and synthetic seismograms. We also report results of comparisons based on time–frequency misfit criteria. Results from these two criteria can be used for calibrating the two methods for comparing seismograms. In those cases in which noticeable discrepancies occurred between the seismograms generated by the three groups, we found that they were the product of inherent characteristics of the various numerical methods used and their implementations. In particular, we found that the major source of discrepancy lies in the difference between mesh and grid representations of the same material model. Overall, however, even the largest differences in the synthetic seismograms are small. Thus, given the complexity of the simulations used in this verification, it appears that the three schemes are consistent, reliable and sufficiently accurate and robust for use in future large-scale simulations.

SUMMARY We incorporate rate- and state-dependent friction in explicit finite difference (FD) simulations of mode II dynamic ruptures in elastic media, using the Mimetic Operators Split-Node (MOSN) method, with adjustable order of spatial accuracy (second-, fourth- or mixed-order accurate), including an option that is fourth-order accurate at the fault discontinuity as well as in the elastic volume. At fault points, the rate and state equations combined with the spatially discretized momentum conservation equations form a coupled system of ordinary differential equations (ODEs) for slip velocity and state variable. As a consequence of the rapid damping of velocity perturbations due to the direct effect, this system exhibits numerical stiffness that is inversely proportional to velocity squared. Approximate solutions to this velocity-state system are achieved by two different implicit schemes: (i) a fourth-order Rosenbrock integration of the full system using multiple substeps and (ii) low order integrations (backward Euler and trapezoidal) of the velocity equation, time-staggered with analytic integration of the state equation under the approximation of constant slip velocity over the time step. In assessing the numerical schemes, we use three test problems: ruptures with frictional resistance controlled by (i) a slip evolution law with strong velocity-weakening behaviour at high slip rates, representing thermal weakening due to flash heating of microscopic asperity contacts, (ii) the classic (low-velocity) slip evolution law and (iii) the classic aging evolution law. A convergence analysis is carried out using reference solutions from a spectral boundary integral equation method (BIEM) (a method restricted to homogeneous media, with nominal spectral accuracy in space and second-order accuracy in time for smooth solutions). Errors are measured by root-mean-square differences of fault-plane time histories (slip, slip rate, traction and state). MOSN shows essentially the same convergence rates as BIEM: second-order convergence for slip and state-variable misfits, with slower (but at least first-order) convergence for slip rates and tractions. For a given grid spacing, fourth-order MOSN is as accurate as BIEM for all variables except slip-rate. MOSN-Rosenbrock nominally has fourth-order temporal accuracy for the fault-plane velocity-state ODE integration (compared to lower-order accuracy for the other two MOSN schemes) and therefore provides an important theoretical benchmark. However, it is sensitive to details of the elastic calculation scheme and occasionally its adaptive substepping performs poorly, leading to large excursions from the reference solution. In contrast, MOSN-trapezoidal is robust and reliable, much easier to implement than MOSN-Rosenbrock, and in all cases achieves precision as good as the latter without recourse to substepping. MOSN-Euler has the same advantages as MOSN-trapezoidal, except that its nominal first-order temporal accuracy ultimately leads to larger errors in slip and state variable compared with the higher-order MOSN schemes at sufficiently small grid spacings and time steps.

Social relations of second grade students (247 boys, 290 girls) were examined in rural elementary classrooms. Cluster analysis of teacher ratings was used to identify interpersonal competence configurations including perceived unpopular-aggressive (i.e., Troubled ) and perceived popular-aggressive (i.e., Tough) subtypes for both boys and girls. Troubled children tended to have rejected status and were more likely to be either socially isolated or members of peer groups that did not contain popular classmates. Tough children were perceived by peers as being socially prominent (i.e., popular, cool, leaders) and they tended to associate with perceived popular peers. Tough boys had elevated levels of rejected or controversial sociometric status while Tough girls were distributed at expected levels across sociometric status classifications. The implications for intervention are discussed.

Aim To determine whether intrathecal baclofen (ITB) changes mortality risk in persons with cerebral palsy (CP). Method Records were reviewed for all persons with CP who were managed with ITB for hypertonicity at a specialty hospital in Minnesota between May 1993 and August 2007. A comparison cohort was randomly selected from clients of the California Department of Developmental Services who were initially evaluated between 1987 and 1990 and were matched to those with ITB for age, sex, Gross Motor Function Classification System (GMFCS) level, presence or absence of epilepsy, and feeding-tube use. Survival probabilities were estimated using the Kaplan–Meier method, and differences were tested via log-rank. Results Three hundred and fifty-nine persons with CP (202 males, 157 females) receiving ITB for hypertonicity (mean age 12y 8mo, SD 7y 9mo, range 3y 1mo to 39y 9mo) were matched to 349 persons without ITB pumps (195 males, 154 females; mean age 12y 7mo, SD 8y 4mo, range 2y 7mo to 40y). The proportion of patients at different GMFCS levels in the ITB and in the non-ITB cohorts, respectively, was as follows: level II 3% and 3%, level III 16% and 16%, level IV 38% and 37%, and level V 43% and 44%. Survival at 8 years of follow-up was 92% (SD 1.9%) in the ITB cohort and 82% (SD 2.4%) in the non-ITB cohort (p

Recent ground-motion observations suggest that surface-rupturing earth- quakes generate weaker near-fault ground motion than buried earthquakes. This dif- ference is significant in the period range of 0.3-3 sec. Contributing factors to this phenomenon may include the effect of fault zone weakness at shallow depth on rup- ture dynamics and rupture directivity during earthquakes. We present results from numerical experiments of spontaneous dynamic rupture and near-source ground-motion simulations of surface rupturing and buried earth- quakes and discuss mechanisms for the observed ground-motion differences. The surface-rupturing earthquake is modeled with a shallow zone of 5 km thickness con- taining areas of negative stress drop (within the framework of the slip-weakening fric- tion model) and lower rigidity. Surface-rupturing models with this weak zone generate lower amplitude ground velocity than do models without this modification. Observed ground-motion differences between surface and buried events are qual- itatively reproduced by imposing higher stress drop in the buried earthquakes than in the surface earthquakes, combined with introducing a deeper rupture initiation for buried rupture, enhancing upward rupture-directivity effects for the latter events. In the context of our simplified model parameterization, then, the observed differences in ground motion could arise from combined effects of relative weakness of the shal- low layer of faults, the relatively larger stress drops of buried ruptures, and a tendency of near-fault sites to record strong upward directivity from buried ruptures.

SUMMARY We present a numerical method to simulate spontaneous shear crack propagation within a heterogeneous, 3-D, viscoelastic medium. Wave motions are computed on a logically rectangular hexahedral mesh, using the generalized finite-difference method of Support Operators (SOM). This approach enables modelling of non-planar surfaces and non-planar fault ruptures. Our implementation, the Support Operator Rupture Dynamics (SORD) code, is highly scalable, enabling large-scale, multiprocessors calculations. The fault surface is modelled by coupled double nodes, where rupture occurs as dictated by the local stress conditions and a frictional failure law. The method successfully performs test problems developed for the Southern California Earthquake Center (SCEC)/U.S. Geological Survey (USGS) dynamic earthquake rupture code validation exercise, showing good agreement with semi-analytical boundary integral method results. We undertake further dynamic rupture tests to quantify numerical errors introduced by shear deformations to the hexahedral mesh. We generate a family of meshes distorted by simple shearing, in the along-strike direction, up to a maximum of 73 ◦ . For SCEC/USGS validation problem number 3, grid-induced errors increase with mesh shear angle, with the logarithm of error approximately proportional to angle over the range tested. At 73 ◦ , rms misfits are about 10 per cent for peak slip rate, and 0.5 per cent for both rupture time and total slip, indicating that the method (which, up to now, we have applied mainly to near-vertical strike-slip faulting) is also capable of handling geometries appropriate to low-angle surface-rupturing thrust earthquakes. Additionally, we demonstrate non-planar rupture effects, by modifying the test geometry to include, respectively, cylindrical curvature and sharp kinks.

Numerical simulations of earthquake rupture dynamics are now common, yet it has been difficult to test the validity of thesesimulations because there have been few field observations and no analytic solutions with which to compare the results. This paper describes the Southern California Earthquake Center/U.S. Geological Surve(SCEC/USGS) Dynamic Earthquake Rupture Code Verification Exercise, where codes that simulate spontaneous rupture dynamics in three dimensions are evaluated and the results produced by these codes are compared using Web-based tools. This is the first time that a broad and rigorous examination of numerous spontaneous rupture codes has been performed—a significant advance in this science. The automated process developed to attain this achievement provides for a future where testing of codes is easily accomplished. Scientists who use computer simulations to understand earthquakes utilize a range of techniques. Most of these assume that earthquakes are caused by slip at depth on faults in the Earth, but hereafter the strategies vary. Among the methods used in earthquake mechanics studies are kinematic approaches and dynamic approaches. The kinematic approach uses a computer code that prescribes the spatial and temporal evolution of slip on the causative fault (or faults). These types of simulations are very helpful, especially since they can be used in seismic data inversions to relate the ground motions recorded in the field to slip on the fault(s) at depth. However, these kinematic solutions generally provide no insight into the physics driving the fault slip or information about why the involved fault(s) slipped that much (or that little). In other words, these kinematic solutions may lack information about the physical dynamics of earthquake rupture that will be most helpful in forecasting future events. To help address this issue, some researchers use computer codes to numerically simulate earthquakes and construct dynamic, spontaneous rupture (hereafter called “spontaneous rupture”) solutions. For these types of numerical simulations, rather than prescribing the slip function at each location on the fault(s), just the friction constitutive properties and initial stress conditions are prescribed. The subsequent stresses and fault slip spontaneously evolve over time as part of the elasto-dynamic solution. Therefore, spontaneous rupture computer simulations of earthquakes allow us to include everything that we know, or think that we know, about earthquake dynamics and to test these ideas against earthquake observations.

Previous numerical simulations (TeraShake1) of large ( M w 7.7) southern San Andreas fault earthquakes predicted localized areas of strong amplification in the Los Angeles area associated with directivity and wave-guide effects from northwestward-propagating rupture scenarios. The TeraShake1 source was derived from inversions of the 2002 M w 7.9 Denali, Alaska, earthquake. That source was relatively smooth in its slip distribution and rupture characteristics, owing both to resolution limits of the inversions and simplifications imposed by the kinematic parameterization. New simulations (TeraShake2), with a more complex source derived from spontaneous rupture modeling with small-scale stress-drop heterogeneity, predict a similar spatial pattern of peak ground velocity (PGV), but with the PGV extremes decreased by factors of 2–3 relative to TeraShake1. The TeraShake2 source excites a less coherent wave field, with reduced along-strike directivity accompanied by streaks of elevated ground motion extending away from the fault trace. The source complexity entails abrupt changes in the direction and speed of rupture correlated to changes in slip-velocity amplitude and waveform, features that might prove challenging to capture in a purely kinematic parameterization. Despite the reduced PGV extremes, northwest-rupturing TeraShake2 simulations still predict entrainment by basin structure of a strong directivity pulse, with PGVs in Los Angeles and San Gabriel basins that are much higher than predicted by empirical methods. Significant areas of those basins have predicted PGV above the 2% probability of exceedance (POE) level relative to current attenuation relationships (even when the latter includes a site term to account for local sediment depth), and wave-guide focusing produces localized areas with PGV at roughly 0.1%–0.2% POE (about a factor of 4.5 above the median). In contrast, at rock sites in the 0–100-km distance range, the median TeraShake2 PGVs are in very close agreement with the median empirical prediction, and extremes nowhere reach the 2% POE level. The rock-site agreement lends credibility to some of our source-modeling assumptions, including overall stress-drop level and the manner in which we assigned dynamic parameters to represent the mechanical weakness of near-surface material. Future efforts should focus on validating and refining these findings, assessing their probabilities of occurrence relative to alternative rupture scenarios for the southern San Andreas fault, and incorporating them into seismic hazard estimation for southern California.

Foam rubber experiments simulating unilaterally propagating strike-slip earthquakes provide a means to explore the sensitivity of near-fault ground motions to rupture geometry. Subsurface accelerometers on the model fault plane show rupture propagation that approaches a limiting velocity close to the Rayleigh velocity. The slip-velocity waveform at depth is cracklike (slip duration of the order of narrower fault dimension W divided by S -wave speed β ). Surface accelerometers record near-fault ground motion enhanced along strike by rupture-induced directivity. Most experimental features (initiation time, shape, duration and absolute amplitude of acceleration pulses) are successfully reproduced by a 3D spontaneous-rupture numerical model of the experiments. Numerical- and experimental-model acceleration pulses show similar decay with distance away from the fault, and fault-normal components in both models show similar, large amplitude growth with distance along fault strike. This forward directivity effect is also evident in response spectra: the fault-normal spectral response peak (at period ∼ W /3 β ) increases approximately sixfold along strike, on average, in the experiments, with similar increase (about fivefold) in the corresponding numerical simulation. The experimental- and numerical-model response spectra agree with an empirical directivity model for natural earthquakes at long periods (near ∼ W / β ), and both overpredict shorter-period empirical directivity effects, with the amount of overprediction increasing systematically with diminishing period. We attribute this difference to rupture- and wavefront incoherence in natural earthquakes, due to fault-zone heterogeneities in stress, frictional resistance, and elastic properties present in the Earth but absent or minimal in the experimental and numerical models. Rupture-front incoherence is an important component of source models for ground-motion prediction, but finding an effective kinematic parameterization may be challenging.

In the context of the slip-weakening friction model and simplified asper- ity models for stress state, we calibrate dynamic rupture models for buried and surface-rupturing earthquakes constrained with statistical observations of past earth- quakes. These observations are the kinematic source models derived from source in- versions of ground-motion and empirical source models of seismic moment and rupture area. The calibrated parameters are the stress-drop distribution on the fault and average stress drop. We develop a set of dynamic rupture models that consist of asperities and surrounding background areas. The distribution of dynamic stress drop outside the asperity is characterized by a fraction of the stress drop on the as- perity. From this set of models, we identify dynamic fault models with defined stress- drop characteristics that satisfy the observations. The selected dynamic fault models show that surface-rupturing earthquakes are characterized by a large area of negative stress-drop surrounding the asperities, while buried earthquakes present positive or zero stress drop. In addition, the calibrated fault models that match the observations show that the average stress drop is independent of earthquake size for buried earth- quakes, but scale dependent for surface-rupturing earthquakes. This suggests that, in the context of our parameterization, buried earthquakes follow self-similarity scaling, and surface-rupturing earthquakes break this self-similarity. We apply the calibrated dynamic models to simulate near-source ground motion consistent with observations that suggest that buried earthquakes generate stronger ground motion than surface- rupturing earthquakes at high frequency. We propose possible mechanisms that satisfy this observation, as follows: buried rupture has a hypocenter location below the as- perity; this can produce strong directivity of the slip velocity function toward the free surface. That effect, in addition to a reduced fault area and low fracture energy during rupture, may be significant in enhancing high-frequency ground motion. On the other hand, surface-rupturing earthquakes have a shallow hypocenter, large fracture energy on the asperities, and enhanced energy absorption due to large areas of negative stress drop in the background area. These characteristics of large earthquakes inhibit severe directivity effects on the slip velocity function directly toward the free surface, redu- cing the high-frequency ground motion.

Earthquakes are among the most complex terrestrial phenomena, and modeling of earthquake dynamics is one of the most challenging computational problems in science. Computational capabilities have advanced to a state where we can perform wavefield simulations for realistic three-dimensional earth models, and gain more insights into the earthquakes that threaten California and many areas of the world. The Southern California Earthquake Center initiated a major earthquake research program called TeraShake to perform physics-based numerical simulations of earthquake processes for large geographical regions, at high resolution, and for high frequencies. For a large scale simulation such as TeraShake, optimization problems tend to emerge that are not significant in smaller scale simulations. This involves both large parallel computation and also massive data management and visualization coordination. In this paper, we describe how we performed single-processor optimization of the TeraShake AWM application, optimization of the I/O handling, and optimization of initialization. We also look at the challenges presented by run-time data archive management and visualization. The improvements made to the TeraShake AWM code enabled execution on the 40k IBM Blue Gene processors and have created a community code that can be used by seismologists to perform petascale earthquake simulations.

Structured needs assessment instruments aid in-service planning in the juvenile justice system. This article uses latent class analysis to classify juvenile offenders into categories or types based on need profiles using a sample of 542 youthful offenders. The study identified five profiles based on scores from a structured needs assessment instrument.

We propose a model for the effect of sedimentary basin depth on long-period response spectra. The model is based on the analysis of 3-D numerical simulations (finite element and finite difference) of long-period (2–10 s) ground motions for a suite of sixty scenario earthquakes (Mw 6.3 to Mw 7.1) within the Los Angeles basin region. We find depth to the 1.5 km/s S-wave velocity isosurface to be a suitable predictor variable, and also present alternative versions of the model based on depths to the 1.0 and 2.5 km/s isosurfaces. The resulting mean basin-depth effect is period dependent, and both smoother (as a function of period and depth) and higher in amplitude than predictions from local 1-D models. The main requirement for the use of the results in construction of attenuation relationships is determining the extent to which the basin effect, as defined and quantified in this study, is already accounted for implicitly in existing attenuation relationships, through (1) departures of the average “rock” site from our idealized reference model, and (2) correlation of basin depth with other predictor variables (such as Vs30).

SUMMARY We present a split-node finite difference (FD) method for modelling shear ruptures that is consistently fourth-order accurate in its spatial discretization, both in the interior of the model and at the fault. The method, called mimetic operator split node (MOSN), uses a staggered grid, and the fault plane is discretized using split nodes for both discontinuous displacement and discontinuous stress components. The method differs in several ways from previous FD methods for rupture modelling. (1) It uses one-sided differentiation (in the fault-normal direction) to retain high-order accuracy at the discontinuity. (2) The one-sided differentiation is implemented with mimetic FD operators that conserve the integration-by-parts formula (including boundary terms) in discrete form. (3) The mimetic operators lead naturally to the evaluation of conjugate tractions at the split-node displacement sites, as required to apply the frictionalsliding boundary conditions. In the interior of the grid, the mimetic operators reduce to the conventional fourth-order staggered-grid FD operators. We verify the accuracy of the MOSN method using two test problems: a fixed-speed rupture case (Kostrov’s problem), and the case of a spontaneous rupture with slip-dependent friction. In the former test, comparisons of slip and shear stress waveforms confirm the convergence of numerical results to the analytical solution as the grid is refined. In the latter test, assessment is based on both qualitative waveform characteristics and a quantitative convergence analysis that uses error metrics in rupture time, final slip and peak slip rate. Compared with a previously verified second-order scheme, the MOSN method shows significant reduction in artefacts attributable to numerical dispersion and also yields a considerable improvement in rupture arrival times. While from a practical standpoint the performance gains of MOSN over the second-order scheme are considerable, MOSN has comparatively poorer convergence rates, and loses its advantage in accuracy in the limit of very small spatial steps. We attribute the relatively low convergence rates to our use of a friction law that induces gradient discontinuities in the fault traction, violating the smoothness assumptions underlying the accuracy estimates, a limitation which may not apply to more complex, experimentally derived friction laws with smooth dependence on slip-rate and state variables. Our current implementation is 2-D and assumes a straight fault, but the method is extensible to more general 3-D geometries.

We apply the method of support operators (SOM) to solve the 3-D, viscoelastic equations of motion for use in earthquake simulations. SOM is a generalized finite-difference method that can utilize meshes of arbitrary structure and incorporate irregular geometry. Our implementation uses a 3-D, logically rectangular, hexahedral mesh. Calculations are second-order in space and time. A correction term is employed for suppression of spurious zero-energy modes (hourglass oscillations). We develop a free surface boundary condition, and an absorbing boundary condition using the method of perfectly matched layers (PML). Numerical tests using a layered material model in a highly deformed mesh show good agreement with the frequency-wavenumber method, for resolutions greater than 10 nodes per wavelength. We also test a vertically incident P wave on a semi-circular canyon, for which results match boundary integral solutions at resolutions greater that 20 nodes per wavelength. We also demonstrate excellent parallel scalability of our code.

This study focuses on the visualization of a series of large earthquake simulations collectively called TeraShake. The simulation series aims to assess the impact of San Andreas Fault earthquake scenarios in Southern California. We discuss the role of visualization in gaining scientific insight and aiding unexpected discoveries.

This study examined growth of children and adolescents with cerebral palsy (CP) who received services from the California Department of Developmental Services from 1987 to 2002. In all, 141 961 measurements of height and weight were taken from 24920 patients with CP (14103 males, 10817 females). Centiles of weight and height were determined by age, sex, and five levels of functional ability ranging from fully ambulatory to unable to walk, crawl, or feed self, and fed via gastrostomy tube. Resulting charts of height and weight centiles were compared with Centers for Disease Control and Prevention weight and height charts for the general population of the US. Centiles of height and weight of patients with CP were close to those of the general population for the highest functioning groups with CP, but lagged substantially for other groups. Presence of a feeding tube was associated with greater height and weight in the lowest functioning groups, with centiles for weight being 2 to 5 kg higher for those with gastrostomy tubes. The charts may assist in early identification of nutritional or metabolic difficulties beyond what might be expected for patients with similar functional disabilities.

Actuarial risk assessment instruments promise to increase decision-making accuracy and equity in settings such as the juvenile justice system, but both aims presume high levels of predictive validity. Prior research suggests that the predictive validity of some juvenile justice risk assessment instruments differs across gender and race/ethnicity. The Joint Risk Matrix (JRM) described herein is an instrument developed to increase the predictive validity of risk assessment for the diverse populations served by the nation’s juvenile courts. The predictive validity of the JRM was estimated on a sample of 536 court-involved juveniles. The instrument demonstrated acceptable levels of validity across all juveniles (AUC = .710). Gender-based differences were explained by gendered patterns of referral to out-of-home placements. Differences by race/ethnicity were reduced compared with previous reports. The findings suggest that risk assessment can be improved by including measures related to the behavior and demeanor of offenders and the cooperation of their parents or caretakers.

This study investigated the possibility of improved survival in cerebral palsy (CP) over a 20-year period. Participants were 47 259 persons with CP receiving services from the State of California between 1983 and 2002. The person-year approach was used. This asks whether the probability of dying in a given calendar year changes over the study period after age and severity of disability are taken into account. An appreciable improvement over time was found in children with severe disabilities and in adults who required gastrostomy feeding. In these groups, mortality rates fell by 3.4% per year. Therefore, life expectancies reported in earlier studies should be increased by approximately 5 years if adjustments to 2002 mortality rates are made. For other persons with CP there was, at most, a small improvement over the 20-year period. The results suggest there have been improvements in the treatment and care of the most medically fragile children. Gastrostomy feeding has become much more widespread over the past two decades, and the improved survival of persons with gastrostomies may reflect better understanding of their requirements.

Background. In the United States, people of color face disparities in access to health care, the quality of care received, and health outcomes. The attitudes and behaviors of health care providers have been identified as one of many factors that contribute to health disparities. Implicit attitudes are thoughts and feelings that often exist outside of conscious awareness, and thus are difficult to consciously acknowledge and control. These attitudes are often automatically activated and can influence human behavior without conscious volition. Objectives. We investigated the extent to which implicit racial/ethnic bias exists among health care professionals and examined the relationships between health care professionals’ implicit attitudes about racial/ethnic groups and health care outcomes. Search Methods. To identify relevant studies, we searched 10 computerized bibliographic databases and used a reference harvesting technique. Selection Criteria. We assessed eligibility using double independent screening based on a priori inclusion criteria. We included studies if they sampled existing health care providers or those in training to become health care providers, measured and reported results on implicit racial/ethnic bias, and were written in English. Data Collection and Analysis. We included a total of 15 studies for review and then subjected them to double independent data extraction. Information extracted included the citation, purpose of the study, use of theory, study design, study site and location, sampling strategy, response rate, sample size and characteristics, measurement of relevant variables, analyses performed, and results and findings. We summarized study design characteristics, and categorized and then synthesized substantive findings. Main Results. Almost all studies used cross-sectional designs, convenience sampling, US participants, and the Implicit Association Test to assess implicit bias. Low to moderate levels of implicit racial/ethnic bias were found among health care professionals in all but 1 study. These implicit bias scores are similar to those in the general population. Levels of implicit bias against Black, Hispanic/Latino/Latina, and dark-skinned people were relatively similar across these groups. Although some associations between implicit bias and health care outcomes were nonsignificant, results also showed that implicit bias was significantly related to patient–provider interactions, treatment decisions, treatment adherence, and patient health outcomes. Implicit attitudes were more often significantly related to patient–provider interactions and health outcomes than treatment processes. Conclusions. Most health care providers appear to have implicit bias in terms of positive attitudes toward Whites and negative attitudes toward people of color. Future studies need to employ more rigorous methods to examine the relationships between implicit bias and health care outcomes. Interventions targeting implicit attitudes among health care professionals are needed because implicit bias may contribute to health disparities for people of color.

This paper reviews aspects of fault geometry and geological structure that cause spatial variations in the level of ground motions expected from large-scenario earthquakes. These conditions include style of faulting, differences between surface faulting and buried faulting earthquakes, rupture directivity effects, basin effects and basin edge effects. These effects are illustrated in large-scale ground motion simulations of scenario earthquakes on the Puente Hills Blind Thrust and the Southern San Andreas fault. The impact of these effects on probabilistic seismic hazard is also explored by means of CyberShake calculations in which the ground motions at a given site from a very large number of earthquake scenarios are represented by simulated time histories in place of conventional ground motion attenuation equations used in probabilistic seismic hazard analysis. We find that the seismic hazard estimates are quite similar in some locations, such as downtown Los Angeles, but quite different at others, such as Whittier. These differences are attributable to the coupling of rupture directivity and basin effects that are present in the CyberShake and TeraShake calculations but not in the conventional attenuation relations. Copyright © 2006 John Wiley & Sons. Ltd.

Assessing accuracy of numerical methods for spontaneous rupture simulation is challenging because we lack analytical solutions for reference. Previous comparison of a boundary integral method (bi) and finite-difference method (called dfm) that explicitly incorporates the fault discontinuity at velocity nodes (traction- at-split-node scheme) shows that both converge to a common, grid-independent solution and exhibit nearly identical power-law convergence rates with respect to grid spacing Δ x . We use this solution as a reference for assessing two other proposed finite-difference methods, the thick fault (tf) and stress glut (sg) methods, both of which approximate the fault-jump conditions through inelastic increments to the stress components (inelastic-zone schemes). The tf solution fails to match the qualitative rupture behavior of the reference solution and has quantitative misfits in root- mean-square rupture time of ∼30% for the smallest computationally feasible Δ x (with ∼9 grid-point resolution of cohesive zone, denoted N c = 9). For sufficiently small values of Δ x , the sg method reproduces the qualitative features of the reference solution, but rupture velocity remains systematically low for sg relative to the reference solution, and sg lacks the well-defined power-law convergence seen for bi and dfm. The rupture-time error for sg, with N c ∼ 9, remains well above uncertainty in the reference solution, and the split-node method attains comparable accuracy with N c 1/4 as large (and computation timescales as ( N c ) 4 ). Thus, accuracy is highly sensitive to the formulation of the fault-jump conditions: The split-node method attains power-law convergence. The sg inelastic-zone method achieves solutions that are qualitatively meaningful and quantitatively reliable to within a few percent, but convergence is uncertain, and sg is computationally inefficient relative to the split-node approach. The tf inelastic-zone method does not achieve qualitatively meaningful solutions to the 3D test problem and is sufficiently computationally inefficient that it is not feasible to explore convergence quantitatively.

Structured risk assessment instruments are increasingly used in juvenile justice systems to support judicial decision making. They help juvenile justice authorities identify youths with a higher likelihood of repeat delinquency and reduce discretion associated with disposition decision making. To be effective, these instruments should be accurate across diverse populations. This study describes the predictive validity of the North Carolina Assessment of Risk (NCAR) in a sample of 9,534 adjudicated juveniles in North Carolina. Results show the predictive validity of the NCAR to differ by gender and race/ethnicity. Closer inspection reveals that risk factors for recidivism differed according to demographic group and that brief risk assessment instruments such as the NCAR leave other risk factors unmeasured. The results support the utility of risk assessment for juvenile justice decision making and suggest strategies to improve the validity of risk assessment for all offender groups.

Actuarial risk assessment instruments are used increasingly in juvenile justice to classify youths according to their risk of recidivism. The purpose of this article is to describe the results of two studies of one instrument: the North Carolina Assessment of Risk (NCAR). In the first study, the inter-rater reliability of the risk assessment instrument was estimated with a sample of 175 court counselors who rated videotaped vignettes of juvenile offenders. In the second study, predictive validity was assessed prospectively by following a statewide sample of 464 delinquent youths for 12 months. Findings indicate that the risk assessment instrument increases reliability as compared to clinical judgment. Moreover, risk scores are correlated significantly with rearrest. However, analyses also show that relationships between risk scores and recidivism vary for subgroups based on gender and race/ethnicity. Though challenges remain in improving the accuracy of risk assessment, the findings suggest that ...

Objectives. To determine independent predictors of ambulation among children with cerebral palsy and to develop a simple tool that estimates the probability that a child will walk. Methods. In a retrospective study of all children with cerebral palsy who were not yet walking at 2 to 3 \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \({1}/{2}\) \end{document} years of age, while receiving services from the California Department of Developmental Services during the years 1987–1999, we analyzed medical and functional data obtained annually by Department of Developmental Services physicians and social workers. Using logistic regression analyses, we determined independent predictors of a child's ability to walk well alone at least 20 feet, without assistive devices, by age 6. We then estimated the probabilities of walking at various levels of ability over time, using multistate survival analysis. Results. Of 5366 study subjects, 2295 (43%) were evaluated at age 6; 12.8% could walk independently and 18.4% walked with support. Independent predictors of successful ambulation included early motor milestones such as sitting (odds ratio: 12.5; 95% confidence interval: 5.8–27.2) and pulling to a stand (odds ratio: 28.5; 95% confidence interval: 13.4–60.4) when compared with lack of rolling at age 2, cerebral palsy type other than spastic quadriparesis (odds ratio: 2.2; 95% confidence interval: 1.5–3.1), and preserved visual function (odds ratio: 2.4; 95% confidence interval: 1.1–5.4). Our ambulation charts depict the probability of remaining nonambulatory, transitioning to 1 of 3 possible ambulatory states, or expiring at all subsequent ages through age 14. Conclusion. The ambulation charts provide a simple straightforward way to estimate the probability that a child with cerebral palsy who is nonambulatory at 2 to 3 \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \({1}/{2}\) \end{document} years of age will eventually walk with or without support.

The 1999 M 7.6 Chi-Chi (Taiwan) earthquake produced a data set of unparalleled size and quality, particularly in the near-source region where data have been previously quite scarce. The large amount of near-source data allows the verification of many predictions of thrust-fault behavior for faults that intersect the surface of the earth. Through rigorous three-dimensional dynamic models of the Chi-Chi earthquake, it can be shown that many aspects of the observed near-source ground motion in this event are direct effects of the asymmetrical dipping fault geometry. These effects include the hanging wall moving more than the footwall (with strongly peaked velocities right at the fault trace) and a transition from predominantly thrust motion in the south of the fault to largely left-lateral motion in the north. Building on the work of Oglesby and Day (2001), the current work helps to delineate the effects of fault geometry, nonuniform prestress, and dynamic waves on the physics of the Chi-Chi earthquake and dip-slip faults in general. In particular, we find that a completely homogeneous prestress pattern still fits the gross features of the near-source ground motion quite well. Additionally, the strike-slip component of motion near the fault trace is seen to be a combination of dynamic and static effects. Finally, dynamic overshoot is seen to be much larger for dip-slip faults than for otherwise identical vertical faults. The results emphasize the necessity of rigorous models that correctly account for both the effects of fault geometry and dynamic waves in the rupture and slip processes. Manuscript received 31 July 2000.

This paper reports findings from an evaluation of a school-based prevention program, called Making Choices, which was designed to decrease childhood aggression and peer rejection by teaching children social problem solving and relationship enhancement skills. Using a pre- to post-test control group design, 51 third graders received the intervention program and 50 received the no-intervention control condition. Controlling for pretest scores, children who received the Making Choices intervention had significantly higher scores on social contact, cognitive concentration, and displayed significantly lower overt aggression. Important moderation effects surfaced, indicating that the intervention differentially benefitted high-risk children.

The Campus Earthquake Program (CEP) of the University of California (UC) started in March 1996, and involved a partnership among seven campuses of the UC—Berkeley, Davis, Los Angeles, Riverside, San Diego, Santa Barbara, Santa Cruz—and the Lawrence Livermore National Laboratory (LLNL). The aim of the CEP was to provide University campuses with site-specific assessments of their earthquake strong motion exposure, to complement estimates they obtain from consultants according to the state-of-the-practice (SOP), i.e. Building Codes (UBC 97, IBC 2000), and Probabilistic Seismic Hazard Analysis (PSHA). The Building Codes are highly simplified tools, while the more sophisticated PSHA is still somewhat generic in its approach because it usually draws from many earthquakes not necessarily related to the faults threatening the site under study. Between 1996 and 2001, the site-specific studies focused on three campuses: Riverside, San Diego, and Santa Barbara. Each campus selected 1–3 sites to demonstrate the methods and procedures used by the CEP: Rivera Library and Parking Lots (PL) 13 and 16 at UCR, Thornton Hospital, the Cancer Center, and PL 601 at UCSD, and Engineering I building at UCSB. The project provided an estimate of strong ground motions at each selected site, for selected earthquake scenarios. These estimates were obtained by using an integrated geological, seismological, geophysical, and geotechnical approach, that brings together the capabilities of campus and laboratory personnel. Most of the site-specific results are also applicable to risk evaluation of other sites on the respective campuses. The CEP studies have provided a critical assessment of whether existing campus seismic design bases are appropriate. Generally speaking, the current assumptions are not acknowledging the severity of the majority of expected motions. Eventually, both the results from the SOP and from the CEP should be analyzed, to arrive at decisions concerning the design-basis for buildings on UC campuses. Published by Elsevier Ltd.

The 1999 M 7.1 Hector Mine earthquake ruptured a complex fault system with a branched structure in the north. This fault geometry and slip pattern presents a puzzle, because the northwest branch of this system should be in the stress shadow of the north branch, upon which nucleation likely took place. Through 3D dynamic models of this event, we show that the ability of rupture to propagate to the northwest branch most likely depends on the fact that rupture did not proceed to the surface on the north branch. This slip pattern leads to part of the northwest branch being brought above its failure stress and to subsequent rupture propagation and slip occurring on that branch. A similar effect can be seen in the case in which rupture is constrained not to propagate to the base of the north branch. Models with slip over the entire north branch do not produce rupture propagation and slip on the northwest branch. The results are robust with respect to details of the prestress pattern and hypocenter location. Large heterogeneity over small length scales in the final stress pattern is a natural product of the models, even when the initial stress field is quite homogeneous. We also find that the interaction between fault geometry and stress pattern helps to explain other observations in this event, including slow rupture propagation on the northwest branch. The results help to show that 3D dynamic effects may be crucial in determining rupture propagation and slip behavior on geometrically complex fault systems, although these effects may be hard to predict without detailed knowledge of the stress pattern and fault geometry prior to earthquakes. Manuscript received 31 January 2003.

We simulate 0- to 0.5-Hz 3D wave propagation through the Southern California Earthquake Center seismic velocity reference model, version 2, for the 1994 Northridge earthquake in order to examine the effects of anelastic attenuation and amplification within the near-surface sediments. We use a fourth-order finite-difference staggered-grid method with the coarse-grained frequency-independent anelastic scheme of Day and Bradley (2001) and a variable slip distribution from kinematic inversion for the Northridge earthquake. We find that the near-surface material with S -wave velocity ( V s) as low as 500 m/sec significantly affects the long-period peak ground velocities, compared with simulations in which the S -wave velocity is constrained to 1 km/sec and greater. Anelastic attenuation also has a strong effect on ground-motion amplitudes, reducing the predicted peak velocity by a factor of up to 2.5, relative to lossless simulations. Our preferred Q model is Q s/ V s = 0.02 ( V s in meters per second) for V s less than 1–2 km/sec, and much larger Q s/ V s (0.1, V s in meters per second) for layers with higher velocities. The simple model reduces the standard deviation of the residuals between synthetic and observed natural log of peak velocity from 1.13 to 0.26, relative to simulations for the lossless case. The anelastic losses have their largest effect on short-period surface waves propagating in the Los Angeles basin, which are principally sensitive to Q s in the low-velocity, near-surface sediments of the basin. The low-frequency ground motion simulated here is relatively insensitive to Q p, as well as to the values of Q s at depths greater than roughly that of the 2-km/sec S -wave velocity isosurface.

Objective: To investigate the excess mortality due to remote symptomatic epilepsy, taking account of frequency and type of seizures.Methods: The authors compared mortality in persons with (n = 8,156) and without (n = 72,526) history of epilepsy in a 1988 to 1999 California population of persons with mild developmental disabilities. Subjects had traumatic brain injury, cerebral palsy, Down syndrome, autism, or no identifiable condition. There were 506,204 person-years of data, with 1,523 deaths. Excess death rates and standardized mortality ratios were computed for the persons in the study with epilepsy, relative to those in the study without epilepsy. Controlled comparisons were made using logistic regression on person-years.Results: Compared to subjects with no epilepsy, the excess mortality was six (deaths per 1,000 persons per year) for persons with a recent (Conclusions: Persistent seizures are associated with increased mortality in remote symptomatic epilepsy. Mortality is highest among individuals with status epilepticus or generalized convulsions.

We analyze the stability and accuracy of the coarse-grain memory variable technique used for viscoelastic wave-field simulations. Our analysis shows that the general behavior of the coarse-grain system is well described by effective parameters ( M E and Q E ) that are derived from the harmonic average of the moduli over the volume of the coarse-grain cell. The use of these effective parameters proves essential for analyzing the performance and accuracy of the coarse-grain system for Q values less than about 20. A necessary stability condition for the coarse-grain system requires that the weighting coefficients be bounded between 0 and 1. Specifying the weights using the approach of Day and Bradley (2001) satisfies this condition for Q values of about 3 and larger; however, using unconstrained optimization techniques will often produce weights that violate this condition at much higher Q values. We also derive a variation of the original coarse-grain methodology called the element-specific modulus (ESM) formulation in which each element of the coarse-grain cell uses a different unrelaxed modulus. We demonstrate that the accuracy of the coarse-grain system for Q values lower than about 20 is significantly improved with the ESM formulation without increasing the computational cost. Finally, we present a technique for optimizing the accuracy of the coarse-grain system for very low Q based on the use of the effective quality factor ( Q E ). We demonstrate that using conventional optimization techniques that do not employ the effective parameter Q E will actually degrade the accuracy of the coarse-grain system. Manuscript received 21 March 2002.

Up to the present time, ground-motion calculations for future earthquakes have almost exclusively been made from kinematic models. However, dynamic faulting models offer many benefits over kinematic models, including the assurance the faulting models obey at least the general rules of elastodynamics and friction and contain a natural relationship between stress drop, slip, rise time, and rupture velocity. Dynamic models also offer insight into the physics of the rupture and slip processes and can show how these processes lead to patterns of ground motion. In the current work, we use the 3D finite-difference method and a suite of stochastic stress patterns, with variable assumptions on strength and stress inhomogeneity, to investigate two issues: (1) the effect of assumptions about stress pattern on the evolution of rupture and slip on the fault, and (2) the effect of these assumptions on the resultant ground motion. We find that stress drop has a complicated relationship with slip, rise time, and rupture velocity, especially in faults with strongly heterogeneous strength. We also find that these inhomogeneous-strength faults can produce highly inhomogeneous slip, even without any form of frictional restrengthening at healing time. Finally, we find that smoother strength models produce a better fit than the coarse models to the directivity pulse often observed on the surface. The results help to shed light on the transition of the faulting system between locally controlled and more globally controlled rupture and also show how dynamic models may be used to generate ground-motion estimates for seismic hazard calculations.

Scale-model earthquake experiments provide detailed, subsurface recordings of rupture propagation and fault motion that are unavailable for natural earthquakes and thereby offer an opportunity to test numerical earthquake simulation methods. Among the advantages realized from the use of experimental data are optimal sensor locations, precise knowledge of bulk and surface properties of the medium, detailed knowledge of the initial stress state, and experimental repeatability. We perform numerical simulations that closely reproduce the shape and duration of the acceleration pulses recorded adjacent to the fault surface in the foam rubber earthquake experiments of Brune and Anooshehpoor (1998). Outside of the event nucleation zone, experimental and simulated rupture velocities are nearly indistinguishable. With adjustment of the static friction coefficient within the constraints imposed by experimental measurements, the absolute amplitudes of the accelerations can be brought into close agreement, typically within a few tens of percent. Close agreement between simulation and experiment is also maintained when the frictional strength of the upper part of the fault plane is varied. The agreement of the numerical and experimental results verifies that the discrete numerical model accurately represents the continuum dynamics of the spontaneous rupture problem. The numerical simulations also facilitate further interpretation of the scale-model experiments. They support an interpretation in which fault displacement in the foam experiments occurs predominantly through a conventional frictional sliding mechanism rather than during fault opening episodes, resulting in a cracklike rather than pulselike mode of slip. The simulations further suggest a reinterpretation of the apparent rupture velocity measurements in the fault weak zone, with rupture slowing rather than accelerating. They also predict that the weak zone diminishes surface accelerations and velocities (relative to a uniform fault model) out to a distance that scales with weak-zone depth and may enhance amplitudes slightly at intermediate distances. Manuscript received 23 October 2001.

We recorded fault-zone trapped waves from aftershocks on portable seismometers in a tight linear array across the Lavic Lake fault, which was one of several faults that ruptured in the M 7.1 Hector Mine, California, earthquake on 16 October 1999. Trapped waves with large amplitudes and long duration at 4 to 7 Hz produced by aftershocks occurring within the rupture zone were recorded at stations close to the fault trace. However, the S waves registered at stations farther from the rupture zone for the same events were much briefer. Trapped waves recorded at the Hector Mine rupture zone are similar to those observed in the Landers rupture zone (Li et al., 1994a,b), but show higher frequencies. Simulations of these trapped waves indicate a 75 to 100-m-wide low-velocity and low-Q waveguide along the Hector Mine rupture zone in which the S velocity is reduced by about 40% to 50% from wall-rock velocities, and Q is 10 to 60 in the depth range from the surface to 10 km. We interpret this low-velocity waveguide as being a remnant of the process zone formed by inelastic deformation around the propagating crack tip during dynamic rupture in the 1999 Hector Mine earthquake. The reductions of velocities and Q within the Hector Mine rupture zone are similar to those within the Landers rupture zone, suggesting that the fault-zone rock was damaged to the same degree in the two earthquakes. The wave-guide width (75-100 m) on the Hector Mine rupture zone (40 km in the total length) is half that (150-250 m) of the Landers rupture zone (80 km in the total length), consistent with the scaling of process zone size to rupture length as predicted in some published dynamic rupture models. Locations of aftershocks for which we observed trapped waves show bifurcation of the northern Hector Mine rupture at depth, although only the west rupture branch broke to the surface.

Before the August 1999 Izmit (Kocaeli), Turkey, earthquake, theoretical studies of earthquake ruptures and geological observations had provided estimates of how far an earthquake might jump to get to a neighboring fault. Both numerical simulations and geological observations suggested that 5 km might be the upper limit if there were no transfer faults. The Izmit earthquake appears to have followed these expectations. It did not jump across any step-over wider than 5 km and was instead stopped by a narrower step-over at its eastern end and possibly by a stress shadow caused by a historic large earthquake at its western end. Our 3D spontaneous rupture simulations of the 1999 Izmit earthquake provide two new insights: (1) the west- to east-striking fault segments of this part of the North Anatolian fault are oriented so as to be low-stress faults and (2) the easternmost segment involved in the August 1999 rupture may be dipping. An interesting feature of the Izmit earthquake is that a 5-km-long gap in surface rupture and an adjacent 25° restraining bend in the fault zone did not stop the earthquake. The latter observation is a warning that significant fault bends in strike-slip faults may not arrest future earthquakes. Manuscript received 30 August 2000.

Portable and permanent broadband seismic stations in the neighborhood of the Gulf of California recorded a moment magnitude Mw 5.5 event on 26 Novem- ber 1997. This is the first time that a moderate event located in the Gulf of California extensional province was well recorded by local broadband seismic stations. The event was located at 29.754 N and 113.708 W and at a focal depth of 5.0 km in the southeastern end of the transform fault that connects the lower and upper Delfin basins. The hypocentral location and the results of the wave modeling indicate that this is a complex event that originated in the pull-apart Delfin basin. The focal mech- anism estimated from first motions ( 310, d 83, k 97) and body-wave modeling of P waves in the frequency band 0.05-0.5 Hz suggests that the rupture started with dip-slip (reverse faulting) motion and ended releasing the bulk of energy through strike-slip motion. Synthetics of surface waves in the frequency band 0.05- 0.1 Hz were also calculated using a triangular source-time function of 3 sec. The best match between the synthetics and observed surface waves recorded at 90 km from the epicenter was obtained using a fault geometry defined by a strike of 330 15, dip 85 5, and slip of 165 15. The spectral analysis of the Lg phase recorded at stations in the Peninsular Ranges gives a seismic moment of 1.28 10 17 N m (1.28 10 24 dyne cm), a source radius of 6.3 km and a stress drop of 0.22 MPa (2.2 bar). The source parameters inferred with S-wave spectra and the same model (Brune, 1970) give similar values.