Abstract The Mission Creek fault strand (MCF) of the San Andreas Fault is proposed to be the primary strand accommodating slip between the Pacific and North American plates in Southern California, but its Holocene activity northwest of Indio is debated. This study presents new depositional ages for alluvial deposits near the mouth of the Mission Creek drainage to investigate potential Holocene activity of the MCF. We estimate a mean depositional age of 0.7 ± 0.2 ka for the alluvium deposited in the drainage valley, contradicting previously inferred ages of >3–18 ka. The young ages for alluvium, often indistinguishable from the age of modern alluvium, suggest that grains are transported during high-energy flash flood–like events. A comparison of luminescence and cosmogenic 10 Be ages from alluvial surfaces adjacent to the Mission Creek suggests a possible reworking event at ∼30 ka. Young alluvium ages, together with evidence for frequent flash floods, suggest that this site is rapidly resurfacing and therefore unlikely to preserve surficial rupture signatures older than a few hundred years. Therefore, the lack of observable offsets in deposits overlying the MCF does not imply Holocene inactivity.

Modeling community hydrogen sulfide exposure in an urban industrial area during routine and extreme events.

Abstract Lake sediments record past hydrologic variability, but natural lakes are often sparse in semiarid and arid regions, making the calibration of paleohydrologic models a challenge. At Lake Elsinore, the largest of the few natural lakes in Southern California, we explore and develop a novel transfer function approach for reconstructing lake depth. Using 32 modern surface sediment samples spanning Lake Elsinore’s littoral to profundal zones, we establish a statistical relationship between lake depth and sediment elemental geochemistry composition analyzed via X-ray fluorescence (XRF). We develop lake depth transfer functions using weighted averaging-partial least squares (WA-PLS) and modern analog technique (MAT). Application of the WA-PLS C5 elemental geochemistry-based transfer function to Lake Elsinore sediment cores reveals a climatically sensitive and variable lake hydrology over the past 32,000 years. The reconstruction suggests a prolonged shallowing during an early Marine Isotope Stage 2 (MIS 2) mega-drought between 28,000 and 25,000 cal yr BP, a deep lake spanning the last glacial maximum, a wet–dry response to the Younger Dryas, and a highly dynamic MIS 1/Holocene lake. This single-lake elemental geochemistry technique may be useful in similar settings for reconstructing lake depth and inferring past hydrologic changes.

Extreme weather events, such as tropical storms, can pose profound disruption to nearshore marine environments. Although coastal ecosystems are particularly vulnerable to storm impacts, research describing the response of marine taxa to extreme weather remains limited, especially for highly mobile marine predators. In this study, we use acoustic telemetry to investigate the behavioral responses of juvenile white sharks (Carcharodon carcharias) at a Southern California nursery aggregation site to Tropical Storm Hilary in 2023. To aid in these efforts, we developed a novel occupancy modeling approach to statistically account and correct for temporal variations in acoustic receiver performance during disruptive storm conditions. Using detection data from synchronization transmitters, we first estimated the effects of key environmental factors on transmitter detection efficiency, with ambient noise, receiver tilt, and the density of animal transmitters present inside the receiver array emerging as particularly influential predictors. We then leveraged these estimated effects to inform a Bayesian state space model designed to investigate nursery occupancy dynamics, including environmental drivers of nursery emigration. Our results provide evidence of partial nursery evacuation, with over half of tagged sharks temporarily leaving monitored nearshore habitats in response to peak storm conditions. However, most emigrations were short-lived, with all but one shark returning to the aggregation site within three weeks of the storm. Evacuations from nursery habitats were best predicted by falling sea surface temperatures, although increased wave height, declining barometric pressure, and drops in salinity may have served as important secondary flight cues. Our efforts provide a rare opportunity to document the storm response behaviors of a recovering top predator, while also presenting tangible analytical solutions to commonly encountered technical challenges in the field of acoustic telemetry.

Abstract This paper describes the synoptic and mesoscale meteorology associated with the strong Santa Ana event of January 7-12, 2025, which resulted in a catastrophic wildfire with over $150 billion in economic loss and 31 deaths. Strong northerly and northeasterly low-level winds, reaching record levels at some locations, resulted from an unusually intense mid-tropospheric low to the south of the Los Angeles basin. With higher pressure/heights over the northeast Pacific, strong crest-level flow developed over the Southern California Transverse Ranges, with intense downslope flow on the southern, lee slopes. High-resolution model simulations produced a highly realistic wind evolution over the region. The strongest winds, some exceeding 80 kt, occurred on the southwestern slopes of the San Gabriel Mountains and were associated with high-amplitude mountain wave activity. The predictability of the event was high, with substantial skill within three days of the start of the strong, dry winds. The prior autumn and early winter months were the driest on record in the region, ensuring surface fuels would be dry and flammable. Furthermore, the two previous winter seasons were considerably wetter than normal, producing large fuel loads.

Configurations of fuel break networks influence landscape-level fire-risk in Southern California

Silicosis, the most common form of pneumoconiosis, results from the inhalation of respirable crystalline silica dust, which is defined as silicon dioxide particles small enough to penetrate lung tissue (<5 μm). Once considered a historical occupational disease primarily affecting miners, silicosis is reemerging among workers who process engineered stone countertops because of the higher silica content of engineered stone compared with natural stone materials (often termed engineered stone pneumoconiosis). The authors discuss imaging features of engineered stone silicosis based on a cohort of patients employed as engineered stone countertop workers in Southern California, one of the largest cohorts in the United States. Historically, silicosis has been described as predominantly chronic silicosis with upper lung-predominant small solid nodules with or without fibrosis, occasional accelerated silicosis, and rarely, acute silicosis. In the engineered stone worker patient cohort described in this article, accelerated silicosis and atypical imaging features at presentation (such as diffuse centrilobular-predominant nodules, superimposed ground-glass opacities, lower lung or cavitary large opacities, and concomitant infections) were more common than expected, which contributed to the initial underdiagnosis and misdiagnosis of silicosis. Furthermore, many patients demonstrated relevant extrapulmonary disease, such as cardiovascular and autoimmune disease. The radiologist plays a pivotal role in recognizing silicosis and including it in their differential diagnosis at patient presentation. Early diagnosis is crucial to prevent further exposure, since silicosis is currently considered incurable. The authors highlight the imaging findings of silicosis to raise awareness among radiologists about this emerging occupational lung disease. ©RSNA, 2026.

Abstract Simultaneous analyses of complementary GNSS and InSAR measurements may lead to breakthroughs in our understanding of crustal deformation. We present an algorithm that combines InSAR with GNSS measurements, in which the GNSS data can be used either as original station velocities or as an interpolated and smoothed velocity field, to estimate continuous 3‐dimensional surface motions, horizontal strain rates and tilt in a self‐consistent way. This damped, weighted least‐squares inversion relies on physics‐based basis functions and provides a generalized tool for investigating the kinematics and dynamics of surface deformation. Through synthetic tests, we evaluate the performance of the algorithm. The results show that the algorithm reliably recovers a “true” synthetic field representing a complex horizontal interseismic signal mixed with a variable vertical signal in southern California. We also apply this algorithm to real GNSS and InSAR data from the same region to model an interseismic field and assess the final model by comparison with a GNSS‐only solution. The joint‐inversion model predicts narrower shear zones along faults and higher variations in off‐fault dilatational signals than the GNSS‐only model. In addition, the joint‐inversion model predicts vertical signals pertaining to hydrologic processes and step‐overs in small basin areas. We use k ‐fold cross‐validation to determine the optimal smoothness of the joint‐inversion model. Although widely used in geophysical inverse problems, it has been less frequently used in surface strain rate inversions. Our results show that the method reliably finds appropriate regularization strength for all tests in this study, indicating its potential for broader application in crustal deformation modeling.

Positive airway pressure therapy and cardiovascular events in obstructive sleep apnoea: an observational clinical cohort study.

The global prevalence of chronic hepatitis D virus (HDV) is estimated to be 4%-5%. Our aim was to determine the prevalence of HDV exposure in patients with chronic hepatitis B (CHB) in three different healthcare systems based in San Diego (SD) County and Los Angeles (LA) County of California. We retrospectively reviewed all adult CHB patients screened for anti-HDV IgG antibody (HDV Ab) who were seen from 2010 to 2024 in the hepatology clinics at Scripps Clinic (SC) in La Jolla, California, and La Maestra Clinic (LM) in SD, and from 2019 to 2023 at UCLA. We determined the median household income by ZIP Code to stratify all patients by socioeconomic status (SES). At SC, 593 of 2441 patients with CHB were screened for HDV. A total of 14 patients tested positive for HDV Ab (2.4%). Two of the 14 patients had detectable HDV RNA. At LM, 118 of 312 patients with CHB were screened for HDV and three patients had a positive HDV Ab (2.5%). None had detectable HDV RNA. At UCLA, 234 of 267 patients with CHB were screened for HDV, and 10 patients had a positive HDV Ab (4.3%). One patient had detectable HDV RNA. Most patients screened at LM, SC, and UCLA belonged to the lowest median yearly income ($75,281), middle ($101,105), and high ($123,271) categories, respectively. There was no statistically significant difference in the prevalence of HDV Ab among each cohort. Of almost a thousand CHB patients who were screened for HDV exposure across three healthcare systems, the prevalence of HDV Ab-positive patients was 2.4%-4.3% without statistically significant differences. Patients from LM, SC, and UCLA were representative of low, middle, and high socioeconomic groups, respectively. This suggests that SES may be less of a risk factor for HDV infection. The HDV PCR-positive (chronic infection) rates were low, ranging from 0% to 0.4%.

This article is a reprint of a curatorial essay written for the catalogue of Transformative Currents: Art and Action in the Pacific Ocean, a multi-venue exhibition presented as part of Art &amp;amp; Science Collide, Getty’s most recent PST ART initiative (2024–25). Transformative Currents featured work by twenty-one artists and collaborative teams from across the Pacific region at three venues in Southern California: Oceanside Museum of Art, Orange County Museum of Art (now UC Irvine Langson Orange County Museum of Art), and Crystal Cove Conservancy. The essay details how the show, while rooted in Southern California, attempted to suture the ways in which the Pacific has been divided by colonial and imperialist powers and, thus, is regularly presented in large-scale exhibitions. It argues that the work in Transformative Currents both disembarked from Southern California and seemingly always recalled it, the artists navigating the Pacific searching for points of solidarity, not places for subjugation.

Abstract Accurate representation of land use and urban morphological parameters (UMPs), particularly building height, road width, and roof width, is critical for urban climate/weather modeling. The Weather Research and Forecasting (WRF) coupled with the Single‐Layer Urban Canopy Model (SLUCM) has been widely used; however, few studies have quantified urban modeling uncertainties associated with UMPs in Los Angeles, a key metropolitan area. This study assesses the impact of UMPs on WRF–SLUCM simulations in Los Angeles and quantifies UMP‐induced uncertainties in 2‐m air temperature ( T 2 ), relative humidity (RH), wind speed and other outputs by integrating Polynomial Chaos Expansion, Sobol sensitivity analysis, and Monte Carlo methods. We apply urban Local Climate Zone (LCZ) land use data and find that incorporating accurate UMPs based on Los Angeles County improves wind speed simulations compared with default LCZ UMPs. Uncertainty analyses reveal strong sensitivities of urban meteorology to 50% UMP perturbation. The resulting average standard deviations of 2‐m air temperature are 0.02 K (day) and 0.23 K (night), while those of urban canyon temperature are 0.51 K (day) and 1.03 K (night). Wind speed uncertainties are also notable, reaching 0.42 m/s (day) and 0.27 m/s (night). Among UMPs, building height has the strongest influence on urban T2, RH, and wind speed. Furthermore, uncertainties in urban meteorology propagate into heat stress estimates, where different indices show different spatial patterns of uncertainty. These findings underscore the importance of accurately representing UMPs in urban climate/weather simulations and their implications for assessing urban heat stress.

The impact of oral nicotine product (ONP) use on e-cigarette use persistence among adolescents and young adults (AYA) remains unclear. We applied augmented inverse probability weighting (AIPW) with machine learning (ML) to reduce bias from model misspecification and improve precision of treatment effect estimates. We combined data from two Southern California cohorts of adolescents (n=269; M[SD]=16.3[0.6] years) and young adults (n=449; age M[SD]=23.4[0.4] years) who reported past 6-month e-cigarette use at baseline in 2022 and were re-assessed an average of 8 months later in 2023. We examined the effects of baseline ONP use on e-cigarette use persistence using AIPW with ML, with analyses stratified by age group. Among 718 AYAs (53.1% female; 58.4% Hispanic), 14.2% reported ONP use at baseline and 64.3% reported persistent e-cigarette use at follow-up. Adolescents who used ONPs had a lower risk of e-cigarette persistence compared with non-users (risk difference=-0.18, 95% CI=-0.31, -0.04; risk ratio=0.70, 95% CI=0.52, 0.95), whereas no association was observed among young adults. Findings suggest ONPs may serve as a partial substitute for e-cigarettes among adolescents, but not young adults. Regulatory policies should balance potential harm-reduction benefits with age-specific risks and address dual e-cigarette and ONP among young adults.

The goal of this study was to assess the effect of enteral feeding on aspiration risk and progression of respiratory failure in adults on high-flow nasal cannula (HFNC) oxygen therapy. Single-center retrospective cohort study. Keck Hospital of the University of Southern California, a tertiary care academic hospital. Hospitalized adults treated with HFNC between January 1, 2020, and December 31, 2022, were included. Exclusion criteria were chronic total parenteral nutrition, chronic tracheostomy, history of total laryngectomy, and "Do Not Intubate" code status. None. The primary outcome was the progression of respiratory failure from HFNC to noninvasive positive pressure ventilation, mechanical ventilation, or extracorporeal membrane oxygenation. We included 220 patients in the primary analysis. The median age was 62.6 years, 54.1% of patients were male, and 43.6% of patients were White. The primary outcome of progression of respiratory failure occurred in 57 patients, of whom 19 (33.3%) were feeding enterally and 38 (66.7%) were NPO at the time of progression. Patients feeding enterally were less likely than those who were NPO to have progression of respiratory failure in a multivariate mixed effects linear regression model (odds ratio [OR], 0.33; 95% CI, 0.18-0.58; p < 0.001). Patients feeding enterally remained less likely to have progression of respiratory failure in a propensity score-matched analysis (OR, 0.30; 95% CI, 0.15-0.58; p < 0.001). In this single-center, retrospective cohort, enteral nutrition in patients on HFNC was associated with lower risk of progression of respiratory failure and was not associated with increased risk of poor clinical outcomes. Prospective multicenter studies are needed to confirm these findings.

Latino populations in the United States have high levels of unmet mental health (MH) needs and MH-related stigma. Collaborative, community-based programming with predominately Latino churches is a promising approach for reducing MH stigma and unmet MH need in Latino communities. Project AMEN implemented MH workshops, homilies and text messages with Latino Catholic parishes to test this approach. We examined reach, satisfaction, effectiveness and fidelity for the overall intervention and individual activities. We collected baseline and one-year post-intervention data from n = 579 people at seven parishes in southern California. Variables included participation in and satisfaction with activities, MH stigma, sociodemographic characteristics, faith-related characteristics, MH needs, and fidelity measures for workshops. We used bivariate and multivariate modeling to describe intervention reach, satisfaction and effectiveness and to identify differences across subgroups. We describe fidelity for the MH workshop. Overall, 71% of the sample participated in at least one intervention activity. Participants were on average 48 years old, female, married, had less than high school education, and attended the parish for more than five years; 24% reported MH needs. Reach and satisfaction were greater for married individuals and those with strong connections to the parish. Individuals with MH problems had more barriers to participation. Activities most often participated in were text messages (42%), the introductory MH workshop (20%) and MH homily (20%). We observed high workshop fidelity. The number of AMEN activities predicted reduction in four types of MH stigma. AMEN showed promising results with respect to reach, satisfaction and effectiveness at reducing MH stigmaf.

Prior studies suggest positive associations of type 2 diabetes (T2D) with risk of non-Hodgkin lymphoma (NHL) and multiple myeloma (MM), but few studies had sufficient statistical power to evaluate associations for specific histologic subtypes. We pooled data from the Cancer Prevention Study-II Nutrition Cohort, California Teachers' Study, Health Professionals Follow-up Study, Nurses' Health Study (NHS), and NHSII cohorts and a sample of Kaiser Permanente Southern California members (585,114 total study participants). We confirmed incident diagnoses of NHL and MM using medical records or cancer registries. T2D history was assessed by self-report or clinical diagnosis. We estimated the associations of T2D history (yes/no) and T2D duration with risk of overall NHL, NHL subtypes, or MM using multivariable Cox regression models adjusted for age, sex, cohort, follow-up year, race, education, smoking, and body mass index. We confirmed 11,478 NHL and 2,783 MM diagnoses over a median follow-up of 20 years. T2D history was not associated with overall NHL risk but was positively associated with risk of diffuse large B-cell lymphoma (DLBCL; hazard ratio [HR]: 1.15, 95% confidence interval [CI]: 1.04-1.28) and MM (1.20, 1.07-1.35) and inversely associated with risk of lymphoplasmacytic lymphoma/Waldenström macroglobulinemia (0.45, 0.27-0.75), T-cell NHL (0.78, 0.62-0.97), and mycosis fungoides/Sezary syndrome (0.67, 0.46-0.98). T2D duration was positively associated with risk of DLBCL and MM. Our findings suggest a role for T2D in DLBCL and MM; thus, T2D prevention may be important in reducing their incidence. Some unexpected inverse associations require further investigation.

On 10 March 1933, an earthquake of roughly 6.4 on the Richter scale (retrospectively estimated) hit the City of Long Beach, California, and the counties surrounding it. Seismically, the quake was of moderate magnitude. However, to this day it remains one of the most destructive quakes in California history in terms of structural damage and fatalities, largely because of faults in building construction of the time that resulted in widespread collapses resulting from earth movement. This article tells the story of the quake itself in full detail; examines its role in the passage of the Field Act, tracing out how that act has impacted earthquake-resistant building design policy, law and practice in California and beyond; assesses the way in which the earthquake altered the trajectory of earthquake science; and details the economic policy response to the quake and the short-term stimulative effects this had on Long Beach and Southern California economies (referred to here as “Disaster Keynesianism”). While there is a large historiographical literature on the Long Beach quake and some of its singular impacts, this research is unique in that it describes and analyzes impacts across multiple dimensions and puts them in the context of contemporary literature on disaster studies, economic analysis, and the history of science, all based on extensive archival research. The paper concludes by positing that the policy, technical and economic response to the Long Beach earthquake represented a sort of “high modern” example of socially and institutionally constructed “disaster” that firmly set in place the notion that “natural disaster” could be managed and ultimately prevented by material and technical means. It is argued that such a view is still contained within more current and broader concepts of “Resilience” and “Anti-fragility”.

Abstract Southern California wildfires result in a significant loss for Los Angeles and San Diego County from January 7 to 31, 2025. Palisades Fire and Eaton fires, the two largest fires that caused most of that damage, were observed by the infrared sounder CrIS and microwave sounder ATMS aboard a polar‐orbit satellite of the National Oceanic and Atmospheric Administration, that is, NOAA‐20. The high spatial resolution Single Field‐of‐view Sounder Atmospheric Products (SiFSAP) retrieved from CrIS and ATMS measurement have been used to illustrate the emission and transport of the plume generated by the wildfires. The CO total column and UV aerosol index (UVAI) observed by TROPOMI, CO total column observed by AIRS, the aerosol optical thickness (AOT) provided by VIIRS, and wind provided by ERA5 were used to illustrate plume produced by wildfires. Furthermore, cloud optical depths and top pressures retrieved by SiFSAP and VIIRS were compared to assess the IR sounder's capability to retrieve clouds. Results indicated that the SiFSAP data products effectively capture not only large scale dry airmass transport but also the movement of wildfire‐generated plumes containing high CO concentrations. The study shows that the SiFSAP CO retrieved from IR measurements is less affected by aerosols as compared to solar measurements like TROPOMI. This study demonstrates that the SiFSAP products provides a high‐quality data set for wildfire observations and disaster observations.

In 2023, the PREVENT (Predicting Risk of CVD Events) equations were introduced to estimate 10-year risk of total cardiovascular disease (CVD). However, their accuracy in individual Asian or Native Hawaiian and Other Pacific Islander ethnic groups remains unknown. To evaluate the risk prediction accuracy of the PREVENT base and full equations in Asian and Native Hawaiian and Other Pacific Islander ethnic groups. This retrospective cohort study was conducted among adults aged 30 to 79 years without CVD who self-reported as being non-Hispanic White, Asian, or Native Hawaiian and Other Pacific Islander and were active Kaiser Permanente Southern California members as of September 30, 2009. Participants were followed up through 2019. Non-Hispanic Asian adults were further disaggregated into ethnic groups. Analysis was performed between February and June 2025. The main measures were the PREVENT base equation (age, total and high-density lipoprotein cholesterol, systolic blood pressure, body mass index, estimated glomerular filtration rate, diabetes, smoking, and lipid and antihypertensive medication) and the PREVENT full equation (base plus hemoglobin A1c, urine albumin-creatinine ratio, and Social Deprivation Index). The main outcome was the 10-year incidence of total CVD, atherosclerotic CVD, and heart failure. Estimated risks were compared with observed events using the Harrell C index and mean calibration (predicted to observed event ratios). The study cohort consisted of 542 848 adults, including 424 277 non-Hispanic White adults (mean [SD] age, 55.6 [11.8] years; 235 722 [55.6%] female), 110 855 non-Hispanic Asian adults (mean [SD] age, 52.5 [11.9] years; 66 292 [59.8%] female), and 7716 non-Hispanic Native Hawaiian and Other Pacific Islander adults (mean [SD] age, 51.4 [11.9] years; 4 398 [57.0%] female). A total of 31 556 CVD events occurred during 10 years. For total CVD, the PREVENT base equation demonstrated good discrimination across non-Hispanic White (C index, 0.764; 95% CI, 0.761-0.767), non-Hispanic Asian (C index, 0.773; 95% CI, 0.765-0.779) and non-Hispanic Native Hawaiian and Other Pacific Islander (C index, 0.757; 95% CI, 0.733-0.780) groups. Among Asian ethnic groups, C indexes for the PREVENT base equation ranged from 0.738 (95% CI, 0.701-0.774) in Vietnamese adults to 0.806 (95% CI, 0.787-0.826) in Chinese adults. The PREVENT full equations showed consistent results. The PREVENT base and full equations generally overestimated total CVD, atherosclerotic CVD, and heart failure risk in non-Hispanic Asian (mean calibration, 0.96-1.33) and underestimated risk in non-Hispanic Native Hawaiian and Other Pacific Islander (mean calibration, 0.74-0.96) and non-Hispanic White (mean calibration, 0.63-1.03) populations. In this retrospective cohort study, the PREVENT base and full equations demonstrated overall strong performance in predicting 10-year cardiovascular risk. However, notable differences were observed across disaggregated Asian and Native Hawaiian and Other Pacific Islander ethnic groups, underscoring the importance of recognizing heterogeneity within these populations when applying risk prediction models.

Live fuel moisture content (LFMC) strongly affects the behavior of wildland fire, resulting in its incorporation into wildfire spread models and danger ratings. In this study, over ten thousand LFMC observations are combined with predictor variables from Landsat imagery and the Weather Research and Forecasting model to train species-specific random forest models that predict the LFMC of four fuel types-chamise, old growth chamise, black sage, and bigpod ceanothus. These models are then utilized to create a historical, 32-year long, LFMC dataset in southern California chaparral. Additionally, the high spatial and temporal sampling frequency of chamise allowed for quantile mapping bias correction to be applied. The final chamise output, which is the most robust, has a mean absolute error of 9.68% and an R2 value of 0.76. The LFMC dataset successfully captures the variability in the annual cycle, the spatial heterogeneity, and the interspecies differences, which makes it applicable for better understanding varying fire season characteristics and landscape level flammability.