Browse
Submit Data
Databases
API
Help

Dataset Information

0 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

Constraining the kinematics of metropolitan Los Angeles faults with a slip-partitioning model.

ABSTRACT: Due to the limited resolution at depth of geodetic and other geophysical data, the geometry and the loading rate of the ramp-décollement faults below the metropolitan Los Angeles are poorly understood. Here we complement these data by assuming conservation of motion across the Big Bend of the San Andreas Fault. Using a Bayesian approach, we constrain the geometry of the ramp-décollement system from the Mojave block to Los Angeles and propose a partitioning of the convergence with 25.5 ± 0.5 mm/yr and 3.1 ± 0.6 mm/yr of strike-slip motion along the San Andreas Fault and the Whittier Fault, with 2.7 ± 0.9 mm/yr and 2.5 ± 1.0 mm/yr of updip movement along the Sierra Madre and the Puente Hills thrusts. Incorporating conservation of motion in geodetic models of strain accumulation reduces the number of free parameters and constitutes a useful methodology to estimate the tectonic loading and seismic potential of buried fault networks.

SUBMITTER: Daout S

PROVIDER: S-EPMC5267971 | biostudies-literature | 2016 Nov

REPOSITORIES: biostudies-literature

ACCESS DATA

Json Xml

Publications

Constraining the kinematics of metropolitan Los Angeles faults with a slip-partitioning model.

Daout S S Barbot S S Peltzer G G Doin M-P MP Liu Z Z Jolivet R R

Geophysical research letters 20161109 21

Due to the limited resolution at depth of geodetic and other geophysical data, the geometry and the loading rate of the ramp-décollement faults below the metropolitan Los Angeles are poorly understood. Here we complement these data by assuming conservation of motion across the Big Bend of the San Andreas Fault. Using a Bayesian approach, we constrain the geometry of the ramp-décollement system from the Mojave block to Los Angeles and propose a partitioning of the convergence with 25.5 ± 0.5 mm/y ...[more]

PMID: 28190902

Similar Datasets

Ambient noise differential adjoint tomography reveals fluid-bearing rocks near active faults in Los Angeles.

Project description:Water scarcity is a pressing issue in California. We develop ambient noise differential adjoint tomography that improves the sensitivity to fluid-bearing rocks by canceling bias caused by noise sources. Here we image the shallow S-wave velocity structure using this method beneath a linear seismic array (LASSIE) in Los Angeles Basin, which shows significant velocity reduction marking a major regional water producer, the Silverado aquifer, along with other fluid-bearing structures. Based on the S-wave tomography and previous P-wave studies, we derive the porosity in Long Beach and discover that the rock from 1-2 km depth surrounding the Newport-Inglewood Fault contains abundant fluids with pore-fluid fraction ~0.33. The high-porosity rock around the fault coincides with previously observed week-long shallow seismicity south of LASSIE array in Long Beach. The imaged S-wave velocity in the top layer shows a similar trend in the geotechnical layer Vs 30, suggesting additional applications to ground motion prediction.

| S-EPMC10613219 | biostudies-literature

Evidence for faulting and fluid-driven earthquake processes from seismic attenuation variations beneath metropolitan Los Angeles.

Project description:Seismicity in the Los Angeles metropolitan area has been primarily attributed to the regional stress loading. Below the urban areas, earthquake sequences have occurred over time showing migration off the faults and providing evidence that secondary processes may be involved in their evolution. Combining high-frequency seismic attenuation with other geophysical observations is a powerful tool for understanding which Earth properties distinguish regions with ongoing seismicity. We develop the first high-resolution 3D seismic attenuation models across the region east of downtown Los Angeles using 5,600 three-component seismograms from local earthquakes recorded by a dense seismic array. We present frequency-dependent peak delay and coda-attenuation tomography as proxies for seismic scattering and absorption, respectively. The scattering models show high sensitivity to the seismicity along some of the major faults, such as the Cucamonga fault and the San Jacinto fault zone, while a channel of low scattering in the basement extends from near the San Andreas fault westward. In the vicinity of the Fontana seismic sequence, high absorption, low scattering, and seismicity migration across a fault network suggest fluid-driven processes. Our attenuation and fault network imaging characterize near-fault zones and rock-fluid properties beneath the study area for future improvements in seismic hazard evaluation.

| S-EPMC11289358 | biostudies-literature

Seismic wave simulation using a 3D printed model of the Los Angeles Basin.

Project description:Studying seismic wave propagation through complex media is crucial to numerous aspects of geophysics and engineering including seismic hazard assessment. In particular, small-scale structure such as sedimentary basins and their edges can have significant effects on high-frequency earthquake ground motion, which is the main cause for the damage to buildings and infrastructure. However, such structural effects are poorly understood due to limitations in numerical and analytical methods. To overcome this challenge, for the first time, we utilize the 3D printing technique to build a scaled-down physical representation of geological structure and perform lab-scale seismic experiments on it. Specifically, a physical model based on the Los Angeles Basin is printed and used as synthetic medium to propagate ultrasonic waves, to mimic seismic wave propagation from local earthquakes. Our results show clear body and surface waves recorded at expected time and locations, as well as waves that are scattered from the basin edges. We find that high-frequency energies are significantly reduced at the basin, which is at odds with the conventional view of basins as ground motion amplifiers. This novel waveform modeling approach with 3D printed Earth models is largely automated and provides an effective means to tackle geophysical problems of significance.

| S-EPMC8931089 | biostudies-literature

The Impact of COVID-19 on CO<sub>2</sub> Emissions in the Los Angeles and Washington DC/Baltimore Metropolitan Areas.

Project description:Responses to COVID-19 have resulted in unintended reductions of city-scale carbon dioxide (CO2) emissions. Here, we detect and estimate decreases in CO2 emissions in Los Angeles and Washington DC/Baltimore during March and April 2020. We present three lines of evidence using methods that have increasing model dependency, including an inverse model to estimate relative emissions changes in 2020 compared to 2018 and 2019. The March decrease (25%) in Washington DC/Baltimore is largely supported by a drop in natural gas consumption associated with a warm spring whereas the decrease in April (33%) correlates with changes in gasoline fuel sales. In contrast, only a fraction of the March (17%) and April (34%) reduction in Los Angeles is explained by traffic declines. Methods and measurements used herein highlight the advantages of atmospheric CO2 observations for providing timely insights into rapidly changing emissions patterns that can empower cities to course-correct CO2 reduction activities efficiently.

| S-EPMC8206775 | biostudies-literature

Ultra-thin clay layers facilitate seismic slip in carbonate faults.

Project description:Many earthquakes propagate up to the Earth's surface producing surface ruptures. Seismic slip propagation is facilitated by along-fault low dynamic frictional resistance, which is controlled by a number of physico-chemical lubrication mechanisms. In particular, rotary shear experiments conducted at seismic slip rates (1 ms-1) show that phyllosilicates can facilitate co-seismic slip along faults during earthquakes. This evidence is crucial for hazard assessment along oceanic subduction zones, where pelagic clays participate in seismic slip propagation. Conversely, the reason why, in continental domains, co-seismic slip along faults can propagate up to the Earth's surface is still poorly understood. We document the occurrence of micrometer-thick phyllosilicate-bearing layers along a carbonate-hosted seismogenic extensional fault in the central Apennines, Italy. Using friction experiments, we demonstrate that, at seismic slip rates (1 ms-1), similar calcite gouges with pre-existing phyllosilicate-bearing (clay content ≤3 wt.%) micro-layers weaken faster than calcite gouges or mixed calcite-phyllosilicate gouges. We thus propose that, within calcite gouge, ultra-low clay content (≤3 wt.%) localized along micrometer-thick layers can facilitate seismic slip propagation during earthquakes in continental domains, possibly enhancing surface displacement.

| S-EPMC5429680 | biostudies-literature

Naturalizing unnatural death in Los Angeles County jails.

Project description:In this paper we use quantitative and qualitative methods to examine how death investigations in Los Angeles County jails disproportionately naturalize death among Black and Latino incarcerated people. Our study is based on an assessment of 58 autopsies, coroner investigator narratives, and toxicology reports produced between 2009 and 2018. We found that the Medical Examiner frequently arrived at natural or undetermined death determinations that minimized the culpability of carceral staff for loss of life that occurred within county jail. In our dataset, Black people were disproportionately classified as natural. Undetermined deaths were almost exclusively Latino. More than 75% of the cases in our study were deaths that occurred before standing trial. Our findings reveal how biomedical knowledge about incarcerated Black and Latino people is used to erase the life-diminishing effects of punishment, neglect, and maltreatment that are central to the project of mass incarceration.

| S-EPMC10922010 | biostudies-literature

Test-and-treat in Los Angeles: a mathematical model of the effects of test-and-treat for the population of men who have sex with men in Los Angeles County.

Project description:BackgroundThere is evidence to suggest that antiretroviral therapy (ART) and testing for human immunodeficiency virus (HIV) reduce the probability of transmission of HIV. This has led health officials across the United States to take steps toward a test-and-treat policy. However, the extent of the benefits generated by test-and-treat is debatable, and there are concerns, such as increased multidrug resistance (MDR), that remain unaddressed.MethodsWe developed a deterministic epidemiologic model to simulate the HIV/AIDS epidemic for men who have sex with men (MSM) in Los Angeles County (LAC). We calibrated the model to match the HIV surveillance data from LAC across a 10-year period, starting in 2000. We then modified our model to simulate the test-and-treat policy and compared epidemiologic outcomes under the test-and-treat scenario to the status quo scenario over the years 2012-2023. Outcome measures included new infections, deaths, new AIDS cases, and MDR.ResultsRelative to the status quo, the test-and-treat model resulted in a 34% reduction in new infections, 19% reduction in deaths, and 39% reduction in new AIDS cases by 2023. However, these results are counterbalanced by a near doubling of the prevalence of MDR (9.06% compared to 4.79%) in 2023. We also found that the effects of increasing testing and treatment were not complementary.ConclusionsAlthough test-and-treat generates substantial benefits, it will not eliminate the epidemic for MSM in LAC. Moreover, these benefits are counterbalanced by large increases in MDR.

| S-EPMC3658365 | biostudies-literature

Hepatitis E virus in rats, Los Angeles, California, USA.

Project description:The role of rats in human hepatitis E virus (HEV) infections remains controversial. A genetically distinct HEV was recently isolated from rats in Germany, and its genome was sequenced. We have isolated a genetically similar HEV from urban rats in Los Angeles, California, USA, and characterized its ability to infect laboratory rats and nonhuman primates. Two strains of HEV were isolated from serum samples of 134 wild rats that had a seroprevalence of antibodies against HEV of ≈80%. Virus was transmissible to seronegative Sprague-Dawley rats, but transmission was spotty and magnitude and duration of infection were not robust. Viremia was higher in nude rats. Serologic analysis and reverse transcription PCR were comparably sensitive in detecting infection. The sequence of the Los Angeles virus was virtually identical to that of isolates from Germany. Rat HEV was not transmissible to rhesus monkeys, suggesting that it is not a source of human infection.

| S-EPMC3311208 | biostudies-literature

Medication use and multiple myeloma risk in Los Angeles County.

Project description:BackgroundThe role of medication use in multiple myeloma (MM) risk remains unclear.MethodsThe Los Angeles County Multiple Myeloma Case-Control Study, comprising 278 MM cases and individually matched neighborhood controls, provided data to assess associations between medication use and MM risk. Odds ratios (OR) and 95 % confidence intervals (CI) were estimated using conditional logistic regression.ResultsErythromycin (ever) use was associated with increased MM risk (OR 1.85, 95 % CI 1.13-3.03). This association was restricted to men (OR 3.77, 95 % CI 1.72-8.29) and was especially apparent among men who took two or more courses of erythromycin (OR 4.68, 95 % CI 1.70-12.87).ConclusionsCompared to females, males have lower levels of cytochrome P450 3A4 (CYP3A4), for which erythromycin is both a substrate and inhibitor. Use of CYP3A4-inhibiting drugs such as erythromycin in men may thus result in even lower levels of CYP3A4 and, consequently, higher levels of CYP3A4-metabolized substances. These results could potentially provide clues to explain discrepancies in MM incidence by sex. Consortial efforts to confirm these associations are warranted.

| S-EPMC4156901 | biostudies-literature

Epstein-Barr virus-associated hemophagocytic lymphohistiocytosis in Los Angeles County.

Project description:Data on Epstein-Barr virus-related hemophagocytic lymphohistiocytosis (EBV-HLH) in adults in the United States remain very limited. A cluster of four cases of EBV-HLH was observed in a 4-month period at a tertiary center in Los Angeles County (LA County) and the clinical and molecular characteristics identified in these cases are being described. EBV typing, immunophenotypic and molecular genetic studies were performed. Diagnostic criteria that may be used to identify EBV as a cause of HLH in adults are also being suggested. Finally, the crude incidence rate for HLH in LA County was determined and was compared to the worldwide crude incidence rate for HLH. The cases each occurred in young male adult residents of California and were associated with evidence of EBV reactivation and ferritin levels of >20,000 µg/L. A higher rate of cases of EBV-HLH in 2010 was found at UCLA Medical Center than for 2007-2009 (4.9/10,000 hospital discharges vs. 0.14/10,000 hospital discharges, respectively; P = 0.0017). The cases were associated with EBV type 1, and the insertion of the codon CTC (leucine) was found in numerous of the EBNA-2 gene sequences. The annual incidence of secondary, non-familial HLH was estimated to be 0.9 cases per million persons >15 years of age in LA County. Although EBV-HLH is a rare disease, the incidence in adults in Western countries may be underestimated.

| S-EPMC8067666 | biostudies-literature

OmicsDI is part of the ELIXIR infrastructure

OmicsDI is an Elixir interoperability service. Learn more ›

Tweets

OmicsDI Databases

PRIDE
PeptideAtlas
MassIVE
JPOST Repository
Physiome Model Repository

EGA
EVA
ENA
LINCS
PAXDB
Cell Collective

MetaboLights
Metabolomics Workbench
MetabolomeExpress
GNPS
BioModels
FAIRDOMHub

ArrayExpress
dbGaP
ExpressionAtlas
GEO
NODE

Information

Databases
Help
API
Contact us
Code on GitHub
Terms of use
Submit Data