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The Nine Mile Ranch (NMR) sequence began with three Mw 5.4–5.6 earthquakes within one hour of each other in December 2016 in the remote area of Fletcher Valley, Nevada; only 4 min separated the first and second events. We analyze this complex earthquake sequence in the Walker Lane to determine the geometry and driving mechanism(s), and to improve understanding of deformation and seismic hazard in this region. Field reconnaissance found that these earthquakes caused significant damage to the Nine Mile ranch house but no surface rupture. We precisely relocate 6000+ earthquakes to reveal activated planar structures, unmapped at the surface, including two large, orthogonal, conjugate faults. Moment tensor solutions, focal mechanisms, and relocations show the two conjugate faults to be a vertical, northeast-trending left-lateral strike-slip fault, and a northwest-trending right-lateral strike-slip fault that dips ∼60° to the northeast. The three main events lie at the intersection of both the faults, but the locations and orientations are most consistent with the first (Mw 5.6) and third (Mw 5.5) events rupturing the left-lateral northeast-trending fault plane; the second event (Mw 5.4) ruptured the right-lateral northwest-trending fault plane. Calculated static stress changes support this interpretation. Smaller events and structures show predominantly strike-slip and normal faulting. We calculate the local interseismic strain rate tensor and coseismic displacements using Global Positioning System data to determine whether nearby volcanic centers played a role in causing the fault geometry. Our results, combined with the spatiotemporal development of the sequence and the moment tensor solutions, indicate that regional scale tectonic forces are the dominant driving factors of this sequence. The NMR sequence adds to the documented variety of spatiotemporal patterns and driving mechanisms of earthquake sequences and swarms within the Walker Lane, providing further information and constraints on seismic hazard in this active region.

The Reno metropolitan area (located within the Truckee Meadows in northern Nevada) is subjected to significant seismic risk, primarily resulting from the region’s proximity to the Mount Rose fault system and the urban area’s presence within a large, thin (

On 15 May 2020 an Mww 6.5 earthquake occurred beneath the Monte Cristo Range in the Mina Deflection region of western Nevada. Rapid deployment of eight temporary seismic stations enabled detailed analysis of its productive and slowly decaying aftershock sequence (p=0.8), which included ∼18,000 autodetected events in 3.5 months. Double-difference, waveform-based relative relocation of 16,714 earthquakes reveals a complex network of faults, many of which cross the inferred 35-km-long east–northeast-striking, left-lateral mainshock rupture. Seismicity aligns with left-lateral, right-lateral, and normal mechanism moment tensors of 128 of the largest earthquakes. The mainshock occurred near the middle of the aftershock zone at the intersection of two distinct zones of seismicity. In the western section, numerous subparallel, shallow, north-northeast-striking faults form a broad flower-structure-like fault mesh that coalesces at depth into a near-vertical, left-lateral fault. We infer the near-vertical fault to be a region of significant slip in the mainshock and an eastward extension of the left-lateral Candelaria fault. Near the mainshock hypocenter, seismicity occurs on a northeast-striking, west-dipping structure that extends north from the eastern Columbus Salt Marsh normal fault. Together, these two intersecting structures bound the Columbus Salt Marsh tectonic basin. East of this intersection and the mainshock hypocenter, seismicity occurs in a narrow, near-vertical, east-northeast-striking fault zone through to its eastern terminus. At the eastern end, the aftershock zone broadens and extends northwest toward the southern extension of the northwest-striking, right-lateral Petrified Springs fault system. The eastern section hosts significantly fewer aftershocks than the western section, but has more moment release. We infer that shallow aftershocks throughout the system highlight fault-fracture meshes that connect mapped fault systems at depth. Comparing earthquake data with surface ruptures and a simple geodetic fault model sheds light on the complexity of this recent M 6.5 Walker Lane earthquake.

The Nevada Seismological Laboratory (NSL) at the University of Nevada, Reno, installed eight temporary seismic stations following the 15 May 2020 Mww 6.5 Monte Cristo Range earthquake. The mainshock and resulting aftershock sequence occurred in an unpopulated and sparsely instrumented region of the Mina deflection in the central Walker Lane, approximately 55 km west of Tonopah, Nevada. The temporary stations supplement NSL’s permanent seismic network, providing azimuthal coverage and near-field recording of the aftershock sequence beginning 1–3 days after the mainshock. We expect the deployment to remain in the field until May 2021. NSL initially attempted to acquire the Monte Cristo Range deployment data in real time via cellular telemetry; however, unreliable cellular coverage forced NSL to convert to microwave telemetry within the first week of the sequence to achieve continuous real-time acquisition. Through 31 August 2020, the temporary deployment has captured near-field records of three aftershocks ML≥5 and 25 ML 4–4.9 events. Here, we present details regarding the Monte Cristo Range deployment, instrumentation, and waveform availability. We combine this information with waveform availability and data access details from NSL’s permanent seismic network and partner regional seismic networks to create a comprehensive summary of Monte Cristo Range sequence data. NSL’s Monte Cristo Range temporary and permanent station waveform data are available in near-real time via the Incorporated Research Institutions for Seismology Data Management Center. Derived earthquake products, including NSL’s earthquake catalog and phase picks, are available via the Advanced National Seismic System Comprehensive Earthquake Catalog. The temporary deployment improved catalog completeness and location quality for the Monte Cristo Range sequence. We expect these data to be useful for continued study of the Monte Cristo Range sequence and constraining crustal and seismogenic properties of the Mina deflection and central Walker Lane.

Explosions are traditionally discriminated from earthquakes, using the relative amplitude of compressional and shear waves at regional and teleseismic distances known as the P/S discriminant. Pyle and Walter (2019) showed this technique to be less robust at shorter distances, in detecting small-magnitude earthquakes and low-yield explosions. The disparity is largely due to ground motion from small, shallow sources being significantly impacted by near-surface structural complexities. To understand the implications of wave propagation effects in generation of shear motion and P/S ratio during underground chemical explosions, we performed simulations of the Source Physics Experiment (SPE) chemical explosions using 1D and 3D velocity models of the Yucca Flat basin. All simulations used isotropic point sources in the frequency range 0–5 Hz. We isolate the effect of large-scale geological structure and small-scale variability at shallow depth (

The Pacific coast of the contiguous United States hosts the highest seismic risk in the country due to the intersection of high-seismic hazard and the high densities of population and infrastructure. The regional seismic networks in Washington, Oregon, Nevada, and California have operated for many years and have collected long catalogs and large amounts of seismic waveform data in a variety of formats, including digital records. These data are available for engineering purposes and research into earthquakes, other natural and man-made seismic sources, and the Earth’s structure. The West Coast networks are closely coordinating as they embark on the implementation of West Coast ShakeAlert, an earthquake early warning system.

The performance degradation of materials exposed to corrosive atmospheric environments is a serious problem. Corrosion maintenance strategies and cycles are informed largely by historical trends in corrosivity dependent on the location of interest. Assessments are often made with sparse experimental data and are generalized to certain materials and baseline conditions observed in the past. The development of a predictive model which can better inform maintenance strategies and cycles offers opportunities for time savings and cost avoidance. Such a model would need to predict corrosion damage accumulation as a function of material of interest, location of interest, and atmospheric conditions during the period of exposure of interest. Machine learning has recently gained attention as a way to model complex systems and processes. Atmospheric corrosion is certainly a complex process as there are many parameters that influence it which are uncontrolled and vary in difficult to predict ways. A machine learning algorithm would require data to learn from which might include environmental conditions such as temperature, relative humidity, UV light exposure, time of wetness, salt concentration, applied loads, and electrochemical data for substrates, inhibitors, and coatings. The ability of machine learning to determine models and relationships from large data sets is well demonstrated; however, a Bayesian model approach can be more suitable when data is limited, expensive or time consuming to obtain, and expert knowledge can be leveraged to construct the relationships. While certain meteorological variables are well categorized and easy to retrieve other variables like corrosion damage or salt deposition are sparsely reported if measured at all. For this reason, a Bayesian Network Model has been developed to better predict the corrosion damage accumulation of C1010 steel and three different aerospace coating systems applied over AA2024-T351. The network map was constructed from parameters (nodes) which are known to influence corrosion. Mathematical relationships were used to develop relationships between nodes or to calculate new nodes as available. Finite element analysis was used to refine the network map and provide supplemental inputs for features that are difficult to measure experimentally. The model was initially trained from historic corrosion data gathered from collaborators across the DoD. Contemporary experimental data was also gathered in a 19-site survey of field exposure sites across the world. This dataset provided further inputs for training and also data for validation and testing. The methodology behind model construction will be highlighted and model predictions will be compared against experimental results. To date, there has been good correlation between model predictions and experimental results for C1010 steel mass loss, which provides a basis to further extend the model to aerospace coating systems. Figure 1

Accelerated cabinet style corrosion tests are developed to determine the susceptibility of metals to specific types of corrosion such as pitting, intergranular corrosion (IGC), and exfoliation. How...

We estimate stress drops for 148 shallow (

After approximately two months of swarm-like earthquakes in the Mogul neighborhood of west Reno, NV, seismicity rates and event magnitudes increased over several days culminating in an Mw 4.9 dextral strike-slip earthquake on 26 April 2008. Although very shallow, the Mw 4.9 mainshock had a different sense of slip than locally mapped dip-slip surface faults. We relocate 7,549 earthquakes, calculate 1,082 focal mechanisms, and statistically cluster the relocated earthquake catalog to understand the character and interaction of active structures throughout the Mogul, NV earthquake sequence. Rapid temporary instrument deployment provides high-resolution coverage of microseismicity, enabling a detailed analysis of swarm behavior and faulting geometry. Relocations reveal an internally clustered sequence in which foreshocks evolved on multiple structures surrounding the eventual mainshock rupture. The relocated seismicity defines a fault-fracture mesh and detailed fault structure from approximately 2-6 km depth on the previously unknown Mogul fault that may be an evolving incipient strike-slip fault zone. The seismicity volume expands before the mainshock, consistent with pore-pressure diffusion, and the aftershock volume is much larger than is typical for an Mw 4.9 earthquake. We group events into clusters using space-time-magnitude nearest-neighbor distances between events and develop a cluster criterion through randomization of the relocated catalog. Identified clusters are largely mainshock-aftershock sequences, without evidence for migration, occurring within the diffuse background seismicity. The migration rate of the largest foreshock cluster and simultaneous background events is consistent with it having triggered, or having been triggered by, an aseismic slip event.

The mountain research community is still contending with the need to monitor ecosystems, both to improve local management practices and to address regional and global science questions related to the Future Earth themes of Dynamic Planet, Global Sustainable Development, and Transformations Towards Sustainability. How such efforts may be designed and coordinated remains an open question. Historical climate and ecological observatories and networks typically have not represented the scope or spatial and topographic distribution of near-surface processes in mountains, creating knowledge gaps. Grassroots, in situ investigations have revealed the existence of topoclimates that are not linearly related to general atmospheric conditions, and are also not adequately represented in gridded model products. In this paper, we describe how some of the disconnects between data, models, and applications in mountains can be addressed using a combination of gradient monitoring, uniform observational siting and standards, and modern technology (cyberinfrastructure). Existing observational studies need to expand their topographic niches, and future observatories should be planned to span entire gradients. Use of cyberinfrastructure tools such as digital telemetry and Internet Protocol networks can reduce costs and data gaps while improving data quality control processes and widening audience outreach. Embracing this approach and working toward common sets of comparable measurements should be goals of emerging mountain observatories worldwide.

Heart failure (HF) is one of the leading causes of hospitalization and readmissions. Our study aimed to examine racial disparities in heart failure patients including onset, mortality, length of stay (LOS), direct costs, and readmission rates. This is a secondary data analysis. We analyzed the risk-adjusted inpatient data of all patients admitted with HF to one health academic center. We compared five health outcomes among three racial groups (white, black, and Hispanic). There were 1006 adult patients making 1605 visits from 10/01/2011 to 09/30/2015. Most black patients were admitted in younger age than other racial groups which indicates the needs for more public health preventions. With risk adjustments, the racial differences in LOS and readmission rates remain. We stratified health outcomes by race/ethnic and type of HF. The findings suggest that further studies to uncover underlying causes of these disparities are necessary. Using risk-adjusted hospitalization data allows for comparisons of quality of care across three racial groups. The study suggests that more prevention and protection services are needed for African American patients with heart failure.

The goal of the eighth industrial fluid properties simulation challenge was to test the ability of molecular simulation methods to predict the adsorption of organic adsorbates in activated carbon materials. In particular, the eighth challenge focused on the adsorption of perfluorohexane in the activated carbon BAM-P109. Entrants were challenged to predict the adsorption in the carbon at 273 K and relative pressures of 0.1, 0.3, and 0.6. The predictions were judged by comparison with a benchmark set of experimentally determined values. Overall, good agreement and consistency were found between the predictions of most entrants.

A seismic compressed high-intensity radar pulse (CHIRP) survey of Pyramid Lake, Nevada, defines fault architecture and distribution within a key sector of the northern Walker Lane belt. More than 500 line-kilometers of high-resolution (decimeter) subsurface imagery, together with dated piston and gravity cores, were used to produce the first comprehensive fault map and attendant slip rates beneath the lake. A reversal of fault polarity is observed beneath Pyramid Lake, where down-to-the-east slip on the dextral Pyramid Lake fault to the south switches to down-to-the-west displacement on the Lake Range fault to the north. Extensional deformation within the northern two thirds of the basin is bounded by the Lake Range fault, which exhibits varying degrees of asymmetric tilting and stratal divergence due to along-strike segmentation. This structural configuration likely results from a combination of changes in slip rate along strike and the splaying of fault segments onshore. The potential splaying of fault segments onshore tends to shift the focus of extension away from the lake. The combination of normal- and oblique-slip faults in the northern basin gives Pyramid Lake its distinctive “fanning open to the north” geometry. The oblique-slip faults in the northwestern region of the lake are short and discontinuous in nature, possibly representing a nascent shear zone. In contrast, the Lake Range fault is long and well defined. Vertical slip rates measured across the Lake Range and other faults provide new estimates on extension across the Pyramid Lake basin. A minimum vertical slip rate of ∼1.0 mm/yr is estimated along the Lake Range fault. When combined with fault length, slip rates yield a potential earthquake magnitude range between M6.4 and M7.0. Little to no offset on the Lake Range fault is observed in the sediment rapidly emplaced at the end of Tioga glaciation (12.5–9.5 ka). In contrast, since 9.5 ka, CHIRP imagery provides evidence for three or four major earthquakes, assuming a characteristic offset of 2.5 m per event. Regionally, our CHIRP investigation helps to reveal how strain is partitioned along the boundary between the northeastern edge of the Walker Lane and the northwest Basin and Range Province proper.

The Source Physics Experiment (SPE) is a series of chemical explosions at the Nevada National Security Site (NNSS, formerly the Nevada Test Site) designed to improve our understanding of explosion physics. A future SPE will place an explosion at the hypocenter of a small, shallow earthquake, providing a direct earthquake‐to‐explosion experiment. Candidate earthquakes for this novel experiment come from a sequence of over 200 unusually shallow events that occurred in Rock Valley, Nevada, in the southeastern portion of the NNSS during 1993. We apply the Bayesloc multiple‐event location algorithm (Myers et al. , 2007, 2009) to determine the best possible locations and depths for these events. Past nuclear tests in the nearby Yucca Flat on the NNSS are relocated with the same method to provide insight into the accuracy and uncertainties associated with the Bayesloc location results for the Rock Valley earthquakes. This test suggests that we can accurately pinpoint the location of the Rock Valley events within approximately 1 km of their true locations using direct arrival times only. The incorporation of differential arrival times and a potential ground‐truth event can significantly decrease the already small uncertainties associated with the epicenter locations. Depth determinations have uncertainties of a few kilometers. Depth uncertainty may be reduced by developing an accurate 3D model of P ‐wave and S ‐wave velocity for Rock Valley.

The primary goal of the seventh industrial fluid properties simulation challenge was to test the ability of molecular simulation methods to predict the adsorption of organic adsorbates in zeolitic materials. The challenge focused, in particular, on the adsorption of perfluorohexane in the BCR-704 Faujasite zeolite. Entrants were challenged to predict the adsorption of perfluorohexane in the zeolite at 293 K and at relative pressures of 0.01, 0.05, 0.1, 0.2, 0.4, 0.6, and 0.8. The relative pressure (P/Po) is defined as that relative to the bulk saturation pressure predicted by the model at a given temperature (293 K in this case). The predictions were judged by comparison to a set of experimentally determined values which are published here for the first time and were not disclosed prior to the challenge to the entrants. Additional benchmark experimental studies, also described here-in, were carried out and provided to entrants in order to aid in the development of new force fields and simulation methods to be employed in the challenge. These studies included argon and nitrogen adsorption in the BCR-704 Faujasite zeolite. Elemental analysis of the BCR-704 Faujasite type zeolite was also available to entrants via the Institute of Reference Materials and Measurement (IRMM) report EUR 21065 [1] .

Over the last two years, the Nevada Seismological Laboratory has devel- oped and refined Nevada ShakeZoning (NSZ) procedures to characterize earthquake hazards in the Intermountain West. Simulating the ML 5.6-5.8 Little Skull Mountain (LSM) earthquake validates the results of the NSZ process and the ground shaking it predicts for Las Vegas Valley (LVV). The NSZ process employs a physics-based finite- difference code from Lawrence Livermore Laboratory to compute wave propagation through complex 3D earth models. Computing limitations restrict the results to low frequencies of shaking. For this LSM regional model the limitation is to frequencies of 0.12 Hz, and below. The Clark County Parcel Map, completed in 2011, is a critical and unique geotechnical data set included in NSZ predictions for LVV. Replacing default geotechnical velocities with the Parcel Map velocities in a sensitivity test produced peak ground velocity amplifications of 5%-11% in places, even at low frequencies of 0.1 Hz. A detailed model of LVV basin-floor depth and regional basin-thickness mod- els derived from gravity surveys by the U.S. Geological Survey are also important components of NSZ velocity-model building. In the NSZ-predicted seismograms at 0.1 Hz, Rayleigh-wave minus P-wave (R − P) differential arrival times and the pulse shapes of Rayleigh waves correlate well with the low-pass filtered LSM recordings. Importantly, peak ground velocities predicted by NSZ matched what was recorded, to be closer than a factor of two. Observed seismograms within LVV show longer du- rations of shaking than the synthetics, appearing as horizontally reverberating, 0.2 Hz longitudinal waves beyond 60 s after Rayleigh-wave arrival. Within the basins, the current velocity models are laterally homogeneous below 300 m depth, leading the 0.1 Hz NSZ synthetics to show insufficient shaking durations of only 30-40 s.

Well-designed electronic health records (EHRs) must integrate a variety of accurate information to support efforts to improve quality of care, particularly equity-in-care initiatives. This case study provides insight into the challenges those initiatives may face in collecting accurate race, ethnicity, and language (REAL) information in the EHR. We present the experience of an academic medical center strengthening its EHR for better collection of REAL data with funding from the EHR Incentive Programs for meaningful use of health information technology and the Texas Medicaid 1115 Waiver program. We also present a plan to address some of the challenges that arose during the course of the project. Our experience at an academic medical center can provide guidance about the likely challenges similar institutions may expect when they implement new initiatives to collect REAL data, particularly challenges regarding scope, personnel, and other resource needs.

Kinetics of polymer bond scission, the initial step in thermal decomposition of polyethylene and other vinyl polymers, was investigated as a function of the number of repeat units using an improved Reactive Molecular Dynamics (RMD) approach, which is introduced here. The rate of scission per bond is shown to depend on the degree of polymerization, an effect not captured by the conventional practice of modeling polymer decomposition with small-molecule Arrhenius parameters. In the new approach, implemented in an open-source C++ code RxnMD, well-behaved reactive force fields are generated using switching functions that activate and attenuate terms obtained from a conventional, non-reactive force field. In this way, predefined reaction types are modeled accurately by interpolating smoothly between non-reactive potential energy terms describing reactants, transition states, and products.

An unusually shallow swarm of earthquakes in Mogul, a suburb in west Reno, Nevada, started 28 February 2008 and continued for several months. Temporary instruments in the epicentral region constrained event depths and locations and provided onscale recordings of the strong ground motions and supplemented a network of over 21 permanent Advanced National Seismic System (ANSS) strong-motion stations deployed throughout the metropolitan Reno area. By the end of August, the swarm had produced over 200 earthquakes with magnitude ( M L ) greater than 2.0. The largest earthquake in the sequence occurred at 06:40 UTC on 26 April 2008 (11:40 p.m. on 25 April local time), with magnitude M L 4.7, M w 5.0, and a hypocentral depth of about 3.1 km. In the M w 5.0 mainshock, mean-horizontal peak ground acceleration exceeded 0.6 g at three stations. The strongest peak vector acceleration was 1164 cm/sec 2 , or about 1.19 g , at the station MOGL (∼0.4 km from the epicenter) at a frequency of about 3 Hz. The mean-horizontal peak velocity exceeded 12 cm/sec at the four nearest stations, and the peak vector velocity at the strongest was 54 cm/sec. The duration of the strongest shaking was about 2 sec at these stations. The observed peak accelerations and peak velocities decreased more rapidly with distance than predicted, to values below the median predictions at most stations in the Reno metropolitan area. The shallow source depth is, to some degree, a likely contributing factor to these unusual observations. The motions in the residential neighborhood near the epicenter are significantly greater than the seismic forces required by the 1985 Uniform Building Code Zone 3 that was in effect when the Mogul neighborhood was developed, but damage to the wood-frame structures in the neighborhood was minimal.

Poly dimethylsiloxanes with amino end groups were copolymerized with diesters of 4-methylcoumarins enzymatically using a lipase (Candida antarctica lipase) as a biocatalyst. In a separate synthesis, 4-methylcoumarin was also incorporated into the poly siloxanes-isophthalate copolymers by functionalization of hydroxyl groups in the isophthalate moiety. The synthesis and characterization of two sets of novel copolymers are presented. The thermal and flammability properties of these polymers have also been studied using TGA and microcalorimetry, respectively.

Composites of titanium dioxide (TiO2) nanoparticles and biocatalytically synthesized dimethylsiloxane copolyamides were prepared, and their thermal and flame-retardant properties were investigated. The flammability properties such as heat release capacity and total heat release were measured from microscale cumbustion calorimetry (MCC). The thermal degradation temperatures, char yields, and the heat-release capacities of these nanocomposites were significantly improved over the pure polymers. The heat-release capacities of the siloxane copolymer nanocomposites with 20wt% of TiO2 were found to be 167 and 129 J/g K, which is a 35% less than the pure polymers (260 and 194 J/g K, respectively). The SEM/EDAX surface-analysis studies on nanocomposite films and their char revealed that nanocrystalline-TiO2 plays an important role in forming carbonaceous silicate char on the surface as a protective layer.

Mobile, hand-held electronic devices such as Internet-enabled cell phones, personal digital assistants (PDAs), and similar tools are vastly expanding the potential to bring sophisticated Internet-based communications to a broader pool of users and workers than the traditional, wired Internet. In particular, such cellular devices are making possible a host of new mechanisms for remote interaction with seismic network hardware, seismic waveform data, and real-time seismic software systems in areas with reliable coverage. Many seismic network diagnostics and interactive processes can be extended to mobile devices, eliminating the need for personnel to be tethered to laptops and hard-wired Internet connections. With a properly written set of mobile-device applications, seismic networks can now provide their staffs with practical, 24–hour-a-day, seven-day-a-week access to network diagnostic tools and configuration tools and provide seismic-network information products to their staffs and constituents. To demonstrate the utility of mobile devices to seismic networks, we have written a suite of nine mobile-device applications, placed them in use for the Nevada Seismological Laboratory (NSL), and released their source code to the public. These applications assist in remote monitoring and reconfiguration of NSL real-time network operations; remote review and approval of information products for release; and widespread distribution of real-time results via Web-enabled mobile devices. We have used the server-side Web-scripting language PHP to construct these programs. Two of these programs facilitate interaction with the U.S. Geological Survey's ShakeMap program (Wald et al. 2005); three programs facilitate interaction with real-time systems and databases of the Antelope Environmental Monitoring System (BRTT 2008) via the Antelope interface to PHP (Lindquist et al. 2007); and the remaining four programs help manage Ref Tek RT130 data loggers (Ref Tek 2008), Motorola “Canopy” Internet-Protocol (IP) radios (Motorola 2008), seismic-station maintenance logs, and sensor calibration procedures. The NSL network staff routinely uses these mobile applications in …

The thermal degradation behavior of novel ultra-fire-resistant polymers and copolymers containing deoxybenzoin units in the backbone was studied by pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS). The polymers were synthesized by the polycondensation of 4,4′-bishydroxydeoxybenzoin (BHDB) with isophthaloyl chloride (to give polyarylates), phenylphosphonic dichloride (to give polyphosphonates), and their mixtures (to give poly(arylate- co -phosphonate) copolymers). The thermal decomposition, under nitrogen conditions, of BHDB-polyarylate was characterized by a simultaneous degradation of both the bisphenolic (deoxybenzoin) and isophthalate sub-units, whereas a three-step decomposition phenomenon was observed for the BHDB-polyphosphonate. BHDB-polymers containing phosphonate groups in the backbone did not show any phosphorus-based volatile decomposition products, whereas the corresponding bisphenol A-based polyphosphonates released volatile decomposition products comprised mainly of phosphorus-containing compounds.

In 2003, a magma intrusion event occurred at 25-30 km in the lower crust under the northwestern corner of Lake Tahoe, as evidenced by both an earth- quake swarm and a geodetic displacement. This study examines the seismicity as- sociated with that event and subsequent seismicity in the upper crust. HYPODD relocations showed that the deep swarm of approximately 1600 microearthquakes at the intrusion site was concentrated on a planar area with a strike of N42°W, dipping at 39° to the northeast. The largest microearthquake in this swarm was M 2.2, and an anomalously high b-value of 2.0 is seen in the recurrence-versus-magnitude plot. The swarm progressed over this plane in a somewhat irregular pattern for a period of roughly 5 months. Focal mechanisms of the deep-swarm events are highly variable and do not reflect the known regional stress field. Two months after the deep-swarm activity started, a shallow swarm of approximately 1100 microearthquakes began at 10-12-km depths in the shallow crust almost immediately above the deep swarm and continued through 2005. This swarm had a maximum M of 2.4 and a relatively high b-value of 1.5. Based on HYPODD relocations, hypocenters in this swarm are con- centrated in a narrow pipelike volume, and event depths progressed steadily upward over the more than 2 yr of observation. Focal mechanisms in this shallow swarm are more consistent with the regional stress field than those of the deep swarm. Within one focal depth horizontally of the deep swarm, postintrusion seismic activity increased significantly compared to prior years. Stress triggering from the deep magma intru- sion, although based on sub-bar stress changes in the shallow crust, is a feasible ex- planation of the observed increase.

The primary goal of the eighth industrial fluid properties simulation challenge was to test the ability of molecular simulation methods to predict the adsorption of organic adsorbates in activated carbon materials. The challenge focused on the adsorption of perfluorohexane in the activated carbon standard BAM-P109 (Panne and Thunemann 2010). Entrants were challenged to predict the adsorption of perfluorohexane in the activated carbon at a temperature of 273 K and at relative pressures of 0.1, 0.3, and 0.6. The relative pressure (P/Po) is defined as that relative to the bulk saturation pressure predicted by the fluid model at a given temperature (273 K in this case). The predictions were judged by comparison to a set of experimentally determined values, which are published here for the first time and were not disclosed to the entrants prior to the challenge. Benchmark experimental studies, described herein, were also carried out and provided to entrants in order to aid in the development of new force fields and simulation methods to be employed in the challenge. These studies included argon, carbon dioxide, and water adsorption in the BAM-P109 activated carbon as well as X-ray diffraction, X-ray microtomography, photoelectron spectroscopy, and atomic emission spectroscopy studies of BAM-P109. Several concurrent studies were carried out for the BAM-P108 activated carbon (Panne and Thunemann 2010). These are included in the current manuscript for comparison.

RMDff is a new forcefield that smoothly couples the reactive intersections of potential energy surfaces to model chemical reactions. The method uses switching functions to accomplish a smooth transition from reactant to product atom types. This paper demonstrates and tests RMDff for homolytic scissions. The reaction networks are described by localized events involving only a few atoms, so that the complex mechanisms employed in conventional kinetics modeling are not needed. Unlike quantum chemical calculations, which are feasible only for small molecules, this new valence-bond forcefield can be coupled with Reactive Molecular Dynamics to describe chemical reactions in large domains.

The 29 June 1992 Richter local magnitude (ML) 5.6 Little Skull Mountain earthquake, 20 km southeast of Yucca Mountain, caused rockfalls on steep slopes of Little Skull Mountain, while some semi-precarious rocks remained in place. The observation that ground motion was sufficient to cause rockfalls and yet leave semi-precarious rocks untoppled offers both upper- and lower-bound estimates of the history of ground motion at Little Skull Mountain. A ground-motion synthesis code, used in Yucca Mountain probabilistic seismic hazard analysis (PSHA), was applied to assess the spatial distribution of peak ground acceleration around Little Skull Mountain with respect to the surface attenuation and evidence for ground shaking during the earthquake. Instrumental records for the earthquake, rockfalls, remaining precarious rocks, intensity values estimated from damage to local facilities, and scaling of ground motions based on a recentML4.4 Little Skull Mountain aftershock were compared with model predictions. Predicted peak accelerations based on a kappa value of ∼20 ms (used in the Yucca Mountain PSHA) are too high to be consistent with this evidence of ground shaking. This suggests some ground-motion predictions conducted for the Yucca Mountain PSHA may need to be re-examined, and may be too conservative.

Dextral transtensional deformation is occurring along the Sierra Nevada–Great Basin boundary zone (SNGBBZ) at the eastern edge of the Sierra Nevada microplate. In the Lake Tahoe region of the SNGBBZ, transtension is partitioned spatially and temporally into domains of north–south striking normal faults and transitional domains with conjugate strike-slip faults. The normal fault domains, which have had large Holocene earthquakes but account only for background seismicity in the historic period, primarily accommodate east–west extension, while the transitional domains, which have had moderate Holocene and historic earthquakes and are currently seismically active, primarily record north–south shortening. Through partitioned slip, the upper crust in this region undergoes overall constrictional strain. Major fault zones within the Lake Tahoe basin include two normal fault zones: the northwest-trending Tahoe–Sierra frontal fault zone (TSFFZ) and the north-trending West Tahoe–Dollar Point fault zone. Most faults in these zones show eastside down displacements. Both of these fault zones show evidence of Holocene earthquakes but are relatively quiet seismically through the historic record. The northeast-trending North Tahoe–Incline Village fault zone is a major normal to sinistral-oblique fault zone. This fault zone shows evidence for large Holocene earthquakes and based on the historic record is seismically active at the microearthquake level. The zone forms the boundary between the Lake Tahoe normal fault domain to the south and the Truckee transition zone to the north. Several lines of evidence, including both geology and historic seismicity, indicate that the seismically active Truckee and Gardnerville transition zones, north and southeast of Lake Tahoe basin, respectively, are undergoing north–south shortening. In addition, the central Carson Range, a major north-trending range block between two large normal fault zones, shows internal fault patterns that suggest the range is undergoing north–south shortening in addition to east–west extension. A model capable of explaining the spatial and temporal partitioning of slip suggests that seismic behavior in the region alternates between two modes, one mode characterized by an east–west minimum principal stress and a north–south maximum principal stress as at present. In this mode, seismicity and small-scale faulting reflecting north–south shortening concentrate in mechanically weak transition zones with primarily strike-slip faulting in relatively small-magnitude events, and domains with major normal faults are relatively quiet. A second mode occurs after sufficient north–south shortening reduces the north–south Shmax in magnitude until it is less than Sv, at which point Sv becomes the maximum principal stress. This second mode is then characterized by large earthquakes on major normal faults in the large normal fault domains, which dominate the overall moment release in the region, producing significant east–west extension.

A deep earthquake swarm in late 2003 at Lake Tahoe, California (Richter magnitude < 2.2; depth of 29 to 33 kilometers), was coeval with a transient displacement of 6 millimeters horizontally outward from the swarm and 8 millimeters upward measured at global positioning system station Slide Mountain (SLID) 18 kilometers to the northeast. During the first 23 days of the swarm, hypocentral depths migrated at a rate of 2.4 millimeters per second up-dip along a 40-square-kilometer structure striking north 30° west and dipping 50° to the northeast. SLID's transient velocity of 20 millimeters per year implies a lower bound of 200 nanostrains per year (parts per billion per year) on local strain rates, an order of magnitude greater than the 1996 to 2003 regional rate. The geodetic displacement is too large to be explained by the elastic strain from the cumulative seismic moment of the sequence, suggesting an aseismic forcing mechanism. Aspects of the swarm and SLID displacements are consistent with lower-crustal magma injection under Lake Tahoe.

Lithospheric rifting most often initiates in continental extensional settings where “breaking of a plate” may or may not progress to sea floor spreading. Generally, the strength of the lithosphere is greater than the tectonic forces required for rupture (i.e., the “tectonic force paradox”), and it has been proposed that rifting requires basaltic magmatism (e.g., dike emplacement) to reduce the strength and cause failure, except for the case of a thin lithosphere (

Laboratory and theoretical studies suggest that there is a minimum patch size for rupture on faults, thus limiting observed earthquake sizes to above some moment or magnitude corresponding to this patch dimension. This limit, most likely being at a much lower magnitude than that which can be observed due to background noise of the Earth and to attenuation, is difficult to verify for real earthquakes. We have recorded earthquakes to as small as M -2 (Richter local magnitude) in the aftershock zone of the M 5.6 Little Skull Mountain earthquake of 29 June 1992. The network threshold for location is below M 0. However, by considering all the triggered earthquakes at station LSC, which is just above the aftershock zone, and combining these with the located events, the recurrence curve is extended well below the network threshold. We do this by forming a relation between the trace amplitudes of the LSC recordings and the network magnitudes for larger events and then assigning an estimated M to the smaller triggered events. The recurrence curve plotted for the combined data shows a constant b -value of 0.82 down to roughly M -1.2. We show that this magnitude is somewhat below the detection threshold of LSC. The smallest recorded events are similar in appearance to events larger by as much as 3 magnitude units in the aftershock zone, partly due to the band limitation of the 100-samples/sec data and local attenuation. S -to- P ratios much greater than 1 and broadband signals for these small events are indicative of normal tectonic earthquakes. The seismic moments of the very smallest events near M -2 are approximately 5 × 109 N m, larger than observations in deep mines by at least an order of magnitude. Because the source corner frequency is too high to be seen in the spectrum of the smallest earthquakes, we cannot estimate source radii. Manuscript received 19 February 2003.

We present a methodology for conducting a site-specific probabilistic analysis of fault displacement hazard. Two approaches are outlined. The first relates the occurrence of fault displacement at or near the ground surface to the occurrence of earthquakes in the same manner as is done in a standard probabilistic seismic hazard analysis (PSHA) for ground shaking. The methodology for this approach is taken directly from PSHA methodology with the ground-motion attenuation function replaced by a fault displacement attenuation function. In the second approach, the rate of displacement events and the distribution for fault displacement are derived directly from the characteristics of the faults or geologic features at the site of interest. The methodology for probabilistic fault displacement hazard analysis (PFDHA) was developed for a normal faulting environment and the probability distributions we present may have general application in similar tectonic regions. In addition, the general methodology is applicable to any region and we indicate the type of data needed to apply the methodology elsewhere.

The moment tensors and centroid depths are estimated for eastern California and western Nevada earthquakes from regionally recorded long-period seismograms using the moment-tensor inversion method. We compiled the moment tensor solutions into a catalog complete for earthquakes with M W > 4 since 1990. The earthquakes in this study are mostly located within the aftershock zones of Eureka Valley, Double Spring Flat, Coso, Ridgecrest, Fish Lake Valley, and Scotty's Junction, with the remaining earthquakes distributed across the region. We validated the moment tensor solutions by a comparison with Harvard centroid moment tensor (CMT) and P -wave first-motion focal mechanism solutions. The mean difference in strike, dip, and rake between our moment tensors and either Harvard CMT solutions or first-motion focal mechanisms were less than approximately 15° with a standard deviation less than 10°. We also examine the solution mean and variance by inverting resampled datasets using the delete- j Jackknife resampling method. Based on two well-recorded sample events, with more than 11 and 14 associated recording stations, the P - and T -axis trend and plunge can be determined to within ±10° when at least three or four well-distributed stations are used in the inversion. We separated the T -axis trends based on the approximate boundaries for three tectonic regions: Sierra Nevada, Walker Lane-eastern California shear zone, and Basin and Range. Relative to the mean T -axis trend for the Sierra Nevada, the mean T -axis trend for the Walker Lane region is rotated clockwise by 25° and the mean T -axis trend for the Basin and Range is rotated clockwise by 40°. We separated the earthquakes into strike-slip and normal-slip focal mechanisms based on a simple rake angle criterion. About 70% of modern earthquakes and 73% of the 11 large historical earthquakes since 1860 are in the strike-slip category. The fraction of seismic moment released as strike-slip earthquakes is approximately 50% for modern earthquakes and 75% for historical earthquakes. The difference is well within the variability expected from short catalogs. These results emphasize the importance of the component of right-lateral shear within the region and are qualitatively consistent with recent geodetic results. Manuscript received 11 January 2002.