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At least 1,297 records · Page 72Linked to original sources
USGS2012

Post-earthquake building safety assessments for the Canterbury Earthquakes

This paper explores the post-earthquake building assessment program that was utilized in Christchurch, New Zealand following the Canterbury Sequence of earthquakes beginning with the Magnitude (M w .) 7.1 Darfield event in September 2010. The aftershocks or triggered events, two of which exceeded M w 6.0, continued with events in February and June 2011 causing the greatest amount of damage. More than 70,000 building safety assessments were completed following the February event. The timeline and assessment procedures will be discussed including the use of rapid response teams, selection of indicator buildings to monitor damage following aftershocks, risk assessments for demolition of red-tagged buildings, the use of task forces to address management of the heavily damaged downtown area and the process of demolition. Through the post-event safety assessment program that occurred throughout the Canterbury Sequence of earthquakes, many important lessons can be learned that will benefit future response to natural hazards that have potential to damage structures.

Conference Paper↗
USGS2018

Development of a United States community shear wave velocity profile database

We present the details of a multi-institutional effort to develop an open-access shear-wave velocity ( V S ) profile database (PDB), which will include a public repository for V S profile data in the United States. V S profiles are an essential resource for ground motion modeling and other applications. The minimum requirements for a site to be included in the database are in situ geophysical V S measurements and location metadata (geodetic coordinates and elevation). Other information is included as available, including geotechnical logs, penetration resistance, laboratory test data, ground water elevation, and P-wave velocity profiles. The project is currently at the stage of data collection (over 4500 V S profiles) and prototype data model development. The database will be presented as an online map-based interface with downloadable V S profile and metadata information. This paper serves as a progress report to the geotechnical and earthquake engineering communities, as we seek community engagement and support.

Conference Paper↗
USGS2021

Changes in liquefaction severity in the San Francisco Bay Area with sea-level rise

This paper studies the impacts of sea-level rise on liquefaction triggering and severity around the San Francisco Bay Area, California, for the M 7.0 “HayWired” earthquake scenario along the Hayward fault. This work emerged from stakeholder engagement for the US Geological Survey releases of the HayWired earthquake scenario and the Coastal Storm Modeling System projects, in which local planners and engineers asked where, why, and by how much liquefaction hazards may change due to sea-level rise in the future. We assess the impacts of sea-level rise on liquefaction by computing changes in liquefaction potential index (LPI) for over 400 cone penetration test (CPT) soundings around the San Francisco Bay for groundwater table models developed for current and increased sea levels of up to 5 m. For the M 7.0 HayWired earthquake scenario, we find that while the majority of sites are insensitive to sea-level changes of less than 1 m, some sites are highly sensitive to small changes in water levels. We then repeat these analyses for a uniform shaking scenario to isolate the effects of sea-level rise and we find similar patterns of change. For both earthquake scenarios, modest changes in overall LPI are expected for increases in sea level, but individual sites may see significant increases in liquefaction likelihood and severity.

Conference Paper↗
USGS2022

The economic effects of the HayWired Scenario using the association of Bay Area governments regional growth forecast—A focus on network disruption and resilience

This paper describes how impacts to infrastructure networks within the San Francisco Bay Area may exacerbate the effects of building damage and how policies addressing these networks can improve resilience before and after the earthquake. The analysis uses existing modeling techniques that underlie the Association of Bay Area Government’s (ABAG) 2015 regional economic forecast of the San Francisco Bay region, California to estimate how a moment magnitude (MW) 7.0 earthquake scenario along the Hayward Fault, HayWired, would change the trajectory of that forecast. The ABAG forecast released in January 2015 is built on the framework of a Regional Economic Models, Inc. (REMI) model for the San Francisco Bay region and projects growth in the bay area through 2040. Using the simulation tools in the REMI model, the analysis applies the direct output losses flowing from building damages from the HayWired scenario (estimated using the FEMA Hazus model) to ABAG’s economic and demographic 2015 regional forecast. Also the analysis estimates direct, indirect, and induced effects on gross regional product (GRP), employment and population, and also highlights the effects of the physical infrastructure damage to roads, bridges, and rail to the region’s economy. Communications infrastructure, if resilient or restored, can help counteract the losses generated by building and transportation network damage. The REMI model results show that in the first year, employment would drop by almost half a million jobs, whereas GRP would decline by 8 percent. The two counties near the epicenter of the earthquake would have greater losses, of 15 percent in jobs and 13 percent in GRP. Counties with less physical damage may still have economic slowdowns due to transportation disruption. Much of the economy could recover within a few years, but a full return to the projected trajectory could take more than five years for the region and closer to a decade for the most severely affected counties. Recovery and rebuilding investments will be crucial to repairing the economic base of the region and returning it to its projected growth trajectory. State and local policies, as well as business and personal preparedness and employer flexibility in allowing remote work can reduce the length and severity of effects. Furthermore, sensitivity analyses using the model identify some critical factors that would lead to different levels of change. For example, a shortage of construction workers could result in a deeper, longer recession as rebuilding is postponed. Should major technology employers decide to relocate substantial portions of operations or expand outside of the region, the recovery period from the earthquake induced recession could stretch to six or seven years and the region’s trajectory could be permanently damped relative to the ABAG 2015 forecast for 2040.

Conference Paper↗
USGS2008

Seismic monitoring to assess performance of structures In near‐real time: Recent progress

Earlier papers have described how observed data from classical accelerometers deployed in structures or from differential GPS with high sampling ratios deployed at roofs of tall buildings can be configured to establish seismic health monitoring of structures. In these configurations, drift ratios 1 are the main parametric indicator of damage condition of a structure or component of a structure. Real‐time measurement of displacements are acquired either by double integration of accelerometer time‐series data, or by directly using GPS. Recorded sensor data is then related to the performance level of a building. Performance‐based design method stipulates that for a building the amplitude of relative displacement of the roof of a building (with respect to its base) indicates its performance. Usually, drift ratio is computed using relative displacement between two consecutive floors. When accelerometers are used, a specific software is used to compute displacements and drift ratios in realtime by double integration of accelerometer data from several floors. However, GPS‐measured relative displacements are limited to being acquired only at the roof with respect to its reference base. Thus, computed drift ratio is the average drift ratio for the whole building. Until recently, the validity of measurements using GPS was limited to long‐period structures ( T >1  s ) "> ( T >1 s ) because GPS systems readily available were limited to 10–20 samples per seconds (sps) capability. However, presently, up to 50 sps differential GPS systems are available on the market and have been successfully used to monitor drift ratios [1,2]—thus enabling future usefulness of GPS to all types of structures. Several levels of threshold drift ratios can be postulated in order to make decisions for inspections and/or occupancy. Experience with data acquired from both accelerometers and GPS deployments indicates that they are reliable and provide pragmatic alternatives to alert the owners and other authorized parties to make informed decisions and select choices for pre‐defined actions following significant events.

Conference Paper↗
USGS2005

The Ames MER microscopic imager toolkit

12The Mars Exploration Rovers, Spirit and Opportunity, have spent several successful months on Mars, returning gigabytes of images and spectral data to scientists on Earth. One of the instruments on the MER rovers, the Athena Microscopic Imager (MI), is a fixed focus, megapixel camera providing a ??3mm depth of field and a 31??31mm field of view at a working distance of 63 mm from the lens to the object being imaged. In order to maximize the science return from this instrument, we developed the Ames MI Toolkit and supported its use during the primary mission. The MI Toolkit is a set of programs that operate on collections of MI images, with the goal of making the data more understandable to the scientists on the ground. Because of the limited depth of field of the camera, and the often highly variable topography of the terrain being imaged, MI images of a given rock are often taken as a stack, with the Instrument Deployment Device (IDD) moving along a computed normal vector, pausing every few millimeters for the MI to acquire an image. The MI Toolkit provides image registration and focal section merging, which combine these images to form a single, maximally in-focus image, while compensating for changes in lighting as well as parallax due to the motion of the camera. The MI Toolkit also provides a 3-D reconstruction of the surface being imaged using stereo and can embed 2-D MI images as texture maps into 3-D meshes produced by other imagers on board the rover to provide context. The 2-D images and 3-D meshes output from the Toolkit are easily viewed by scientists using other mission tools, such as Viz or the MI Browser.This paper describes the MI Toolkit in detail, as well as our experience using it with scientists at JPL during the primary MER mission. ?? 2005 IEEE.

Conference Paper↗
USGS2009

Cacades: A reliable dissemination protocol for data collection sensor network

In this paper, we propose a fast and reliable data dissemination protocol Cascades to disseminate data from the sink(base station) to all or a subset of nodes in a data collection sensor network. Cascades makes use of the parentmonitor-children analogy to ensure reliable dissemination. Each node monitors whether or not its children have received the broadcast messages through snooping children's rebroadcasts or waiting for explicit ACKs. If a node detects a gap in its message sequences, it can fetch the missing messages from its neighbours reactively. Cascades also considers many practical issues for field deployment, such as dynamic topology, link/node failure, etc.. It therefore guarantees that a disseminated message from the sink will reach all intended receivers and the dissemination is terminated in a short time period. Notice that, all existing dissemination protocols either do not guarantee reliability or do not terminate [1, 2], which does not meet the requirement of real-time command control. We conducted experiment evaluations in both TOSSIM simulator and a sensor network testbed to compare Cascades with those existing dissemination protocols in TinyOS sensor networks, which show that Cascades achieves a higher degree of reliability, lower communication cost, and less delivery delay. ??2009 IEEE.

Conference Paper↗
USGS2009

Strategic analysis for the MER Cape Verde approach

The Mars Exploration Rover Opportunity has recently completed a two year campaign studying Victoria Crater. The campaign culminated in a close approach of Cape Verde in order to acquire high resolution imagery of the exposed stratigraphy in the cliff face. The close approach to Cape Verde provided significant challenges for every subsystem of the rover as the rover needed to traverse difficult, uncharacterised terrain and approach a cliff face with the potential of blocking out solar energy and communications with Earth. In this paper we describe the strategic analyses performed by the science and engineering teams so that we could successfully achieve the science objectives while keeping the rover safe. ??2009 IEEE.

Conference Paper↗
USGS2022

It’s time for focused in situ studies of planetary surface-atmosphere interactions

A critical gap in planetary observations has been in situ characterization of extra-terrestrial, present-day atmospheric and surface environments and activity. While some surface activity has been observed and some in situ meteorological measurements have been collected by auxiliary instruments on Mars, existing information is insufficient to conclusively characterize the natural processes via concurrent and high-resolution measurement of environmental drivers and activity. Thus, many atmospheric, aeolian, and other surface processes models – which are used to generate key constraints on science and exploration in many areas of planetary investigation—such as surface exposure/erosion estimates, landscape interpretation, and modeling dust storm development—remain untested under non-Earth conditions. Analogous terrestrial processes are often studied intensively via numerical modeling that integrates empirical results from laboratory and/or field studies of process-response interactions between the atmosphere and relevant surface landforms. Incorporation of such in situ measurements into model development has significantly advanced our understanding of atmosphere-surface interactions and related geomorphic processes on Earth, and is poised to do so on other planets. However, to date, such testing and refinement have not been possible in other planetary environments, partially because investigations of this sort require new technologies, mission architectures, and operations designs (e.g., different from large rovers focused on geochemical investigations) to fully address the key gaps in our understanding while keeping cost and risk low. Fortunately, technological developments in the areas of surface access, instrumentation, and onboard processing/memory now enable small spacecraft to accommodate meteorological and aeolian instrumentation that could collect the needed measurements to fill this critical gap while remaining within typical small spacecraft resource budgets. Furthermore, maturity of our understanding of the broader geologic and atmospheric context on Mars provides a ready framework for ingestion of discrete ground truth measurements into our understanding of the broader and multi-scale martian natural systems and processes. These advancements make addressing key science questions with novel mission concepts feasible, promising results that would significantly advance our understanding of extraterrestrial surface-atmosphere interactions. This summary follows from a community-generated white paper for the ongoing Planetary Science/Astrobiology Decadal Survey, small spacecraft concept development at JPL, and numerous JPL and community discussions.

Conference Paper↗
USGS2005

Steam injection pilot study in a contaminated fractured limestone (Maine, USA): Modeling and analysis of borehole radar reflection data

Steam-enhanced remediation (SER) has been successfully used to remove DNAPL and LNAPL contaminants in porous media. Between August and November 2002, SER was tested in fractured limestone at the former Loring Air Force Base, in Maine, USA. During the SER investigation, the U.S. Geological Survey conducted a series of borehole radar surveys to evaluate the effectiveness of radar methods for monitoring the movement of steam and heat through the fractured limestone. The data were collected before steam injection, 10 days after the beginning of injection, and at the end of injection. In this paper, reflection-mode borehole radar data from wells JBW-7816 and JBW-7817A are presented and discussed. Theoretical modeling was performed to predict the variation of fracture reflectivity owed to heating, to show displacement of water and to assess the effect of SER at the site. Analysis of the radar profile data indicates some variations resulting from heating (increase of continuity of reflectors, attenuation of deeper reflections) but no substantial variation of traveltimes. Spectral content analysis of several individual reflections surrounding the boreholes was used to investigate the replacement of water by steam in the fractures. Observed decrease in radar reflectivity was too small to be explained by a replacement of water by steam, except for two high-amplitude reflectors, which disappeared near the end of the injection; moreover, no change of polarity, consistent with steam replacing water, was observed. The decrease of amplitude was greater for reflectors near well JBW-7817A and is explained by a greater heating around this well.

Maine↗
USGS2014

A reference system for animal biometrics: application to the northern leopard frog

Reference systems and public databases are available for human biometrics, but to our knowledge nothing is available for animal biometrics. This is surprising because animals are not required to give their agreement to be in a database. This paper proposes a reference system and database for the northern leopard frog (Lithobates pipiens). Both are available for reproducible experiments. Results of both open set and closed set experiments are given.

Conference Paper↗
USGS2022

VIMTS: Variational-based Imputation for Multi-modal Time Series

Multi-modal time series data in real applications often contain data of different dimensionalities, e.g., high-dimensional modality such as image data series, and low-dimensional univariate time series. Multi-modal time series data with missing high-dimensional modal values are ubiquitous in real-world classification and regression applications. To accurately predict the target labels, it is important to appropriately impute the high-dimensional modal missing values. However, most existing imputation methods focus on multivariate time series, fail to simultaneously consider temporal dependencies within each series and the correlations across the series, and also lack a probabilistic interpretation. In this paper, we propose a novel method, which uses a new structured variational approximation technique for the imputation of missing values in multi-modal time series. Instead of directly imputing high-dimensional modal missing values, we use the variational approximation technique to impute intermediate lower-dimensional feature representations of high-dimensional modal missing values from simple modalities related to high-dimensional modality and then feed them into a dynamical model. The dynamical model captures the temporal dependencies of the feature representations and finally predicts the target labels. In order to address the optimization difficulties caused by the lack of ground truth values of lower-dimensional feature representations, we also propose a two-stage isolated optimization strategy for better convergence. We evaluate our method on a real-world stream monitoring dataset. Our extensive experiments demonstrate that the proposed method outperforms several state-of-the-art methods in both data imputation and prediction performance.

Conference Paper↗
USGS1978

Comparison of a few recording current meters in San Francisco Bay, CA

A team of research scientists in the U.S. Geological Survey uses San Francisco Bay, California, as an outdoor laboratory to study complicated interactions of physical, chemical, and biological processes which take place in an estuarine environment. A current meter comparison study was conceived because of the need to select a suitable current meter to meet field requirements for current measurements in the Bay. The study took place in south San Francisco Bay, California, in the spring of 1977. An instrument tower which was designed to support instruments free from the conventional mooring line motions was constructed and emplaced in south San Francisco Bay. During a period of two months, four types of recording current meters have been used in the tests. The four types were: (1) Aanderaa, (2) tethered shroud-impeller, (3) drag-inclinometer, and (4) electromagnetic current meters. With the exception of the electromagnetic current meter, one of each type was mounted on the instrument tower, and one of each type was deployed on moorings near the instrument tower. In addition, a wind anemometer and a recording tide gauge were also installed on the tower. This paper discusses the characteristics of each instrument and the accuracy that each instrument can provide when used in an estuarine environment. We pay special attention to our experiences in the field operation with respect to handling of the instruments and to our experiences working up the raw data in the post-deployment data analysis.

California↗
USGS2008

Validation of exposure time for discharge measurements made with two bottom-tracking acoustic doppler current profilers

Previous work by Oberg and Mueller of the U.S. Geological Survey in 2007 concluded that exposure time (total time spent sampling the flow) is a critical factor in reducing measurement uncertainty. In a subsequent paper, Oberg and Mueller validated these conclusions using one set of data to show that the effect of exposure time on the uncertainty of the measured discharge is independent of stream width, depth, and range of boat speeds. Analysis of eight StreamPro acoustic Doppler current profiler (ADCP) measurements indicate that they fall within and show a similar trend to the Rio Grande ADCP data previously reported. Four special validation measurements were made for the purpose of verifying the conclusions of Oberg and Mueller regarding exposure time for Rio Grande and StreamPro ADCPs. Analysis of these measurements confirms that exposure time is a critical factor in reducing measurement uncertainty and is independent of stream width, depth, and range of boat speeds. Furthermore, it appears that the relation between measured discharge uncertainty and exposure time is similar for both Rio Grande and StreamPro ADCPs. These results are applicable to ADCPs that make use of broadband technology using bottom-tracking to obtain the boat velocity. Based on this work, a minimum of two transects should be collected with an exposure time for all transects greater than or equal to 720 seconds in order to achieve an uncertainty of ??5 percent when using bottom-tracking ADCPs. ?? 2008 IEEE.

Conference Paper↗
USGS2011

2-D inner-shelf current observations from a single VHF WEllen RAdar (WERA) station

The majority of High Frequency (HF) radars used worldwide operate at medium to high frequencies (8 to 30 MHz) providing spatial resolutions ranging from 3 to 1.5 km and ranges from 150 to 50 km. This paper presents results from the deployment of a single Very High Frequency (VHF, 48 MHz) WEllen RAdar (WERA) radar with spatial resolution of 150 m and range 10-15 km, used in the nearshore off Cape Hatteras, NC, USA. It consisted of a linear array of 12 antennas operating in beam forming mode. Radial velocities were estimated from radar backscatter for a variety of wind and nearshore wave conditions. A methodology similar to that used for converting acoustically derived beam velocities to an orthogonal system is presented for obtaining 2-D current fields from a single station. The accuracy of the VHF radar-derived radial velocities is examined using a new statistical technique that evaluates the system over the range of measured velocities. The VHF radar velocities showed a bias of 3 to 7 cm/s over the experimental period explainable by the differences in radar penetration and in-situ measurement height. The 2-D current field shows good agreement with the in-situ measurements. Deviations and inaccuracies are well explained by the geometric dilution analysis.

North Carolina↗
USGS2015

Quality assurance testing of acoustic doppler current profiler transform matrices

The U.S. Geological Survey (USGS) Hydrologic Instrumentation Facility (HIF) is nationally responsible for the design, testing, evaluation, repair, calibration, warehousing, and distribution of hydrologic instrumentation in use within the USGS Water Mission Area (WMA). The HIF's Hydraulic Laboratory has begun routine quality assurance (QA) testing and documenting the performance of every USGS WMA acoustic Doppler current profiler (ADCP) used for making velocity and discharge measurements. All existing ADCPs are being registered and tracked in a database maintained by the HIF, and called for QA checks in the HIF's Hydraulic Laboratory on a 3- year cycle. All new ADCPs purchased directly from the manufacturer as well as ADCPs sent to the HIF or the manufacturer for repair are being registered and tracked in the database and QA checked in the laboratory before being placed into service. Meters failing the QA check are sent directly to the manufacturer for repairs and rechecked by HIF or removed from service. Although this QA program is specific to the SonTek 1 and Teledyne RD Instruments 1 , ADCPs most commonly used within the WMA, it is the intent of the USGS Office of Surface Water and the HIF to expand this program to include all bottom tracking ADCPs as they become available and more widely used throughout the WMA. As part of the HIF QA process, instruments are inspected for physical damage, the instrument must pass the ADCP diagnostic self-check tests, the temperature probe must be within ± 2 degrees Celsius of a National Institute of Standards and Technology traceable reference thermometer and the distance made good over a fixed distance must meet the manufacturer's specifications (+/-0.25% or +/-1% difference). The transform matrix is tested by conducting distance-made-good (DMG) tests comparing the straight-line distance from bottom tracking to the measured tow-track distance. The DMG test is conducted on each instrument twice in the forward and reverse directions (4 tows) at four orientations (16 total tows); with beam 1 orientated 0 degrees to the towing direction; turned 45 degrees to the towing direction; turned 90 degrees to the towing direction; and turned 135 degrees to the towing direction. All QA data files and summary results are archived. This paper documents methodology, participation and preliminary results of WMA ADCP QA testing.

Conference Paper↗
USGS2006

Managing large-scale workflow execution from resource provisioning to provenance tracking: The CyberShake example

This paper discusses the process of building an environment where large-scale, complex, scientific analysis can be scheduled onto a heterogeneous collection of computational and storage resources. The example application is the Southern California Earthquake Center (SCEC) CyberShake project, an analysis designed to compute probabilistic seismic hazard curves for sites in the Los Angeles area. We explain which software tools were used to build to the system, describe their functionality and interactions. We show the results of running the CyberShake analysis that included over 250,000 jobs using resources available through SCEC and the TeraGrid. ?? 2006 IEEE.

Conference Paper↗
USGS2008

United states national land cover data base development 1992-2001 and beyond

An accurate, up-to-date and spatially-explicate national land cover database is required for monitoring the status and trends of the nation's terrestrial ecosystem, and for managing and conserving land resources at the national scale. With all the challenges and resources required to develop such a database, an innovative and scientifically sound planning must be in place and a partnership be formed among users from government agencies, research institutes and private sectors. In this paper, we summarize major scientific and technical issues regarding the development of the NLCD 1992 and 2001. Experiences and lessons learned from the project are documented with regard to project design, technical approaches, accuracy assessment strategy, and projecti imiplementation.Future improvements in developing next generation NLCD beyond 2001 are suggested, including: 1) enhanced satellite data preprocessing in correction of atmospheric and adjacency effect and the topographic normalization; 2) improved classification accuracy through comprehensive and consistent training data and new algorithm development; 3) multi-resolution and multi-temporal database targeting major land cover changes and land cover database updates; 4) enriched database contents by including additional biophysical parameters and/or more detailed land cover classes through synergizing multi-sensor, multi-temporal, and multi-spectral satellite data and ancillary data, and 5) transform the NLCD project into a national land cover monitoring program. ?? 2008 IEEE.

Conference Paper↗