Final report on Task 12: Southern Great Basin seismic network operations

The Nevada Seismological Laboratory began seismic monitoring operations under the DOE-UCCSN Cooperative Agreement on 11/01/1999. This final report summarizes our activities and studies made in the four years up to 09/30/2003. Previously, NSL operated under the M&O for the Yucca Mountain Project from October 1995 through September 1999 and under the U. S. Geological Survey from October 1992 through September 1995. For purposes of this report, earthquakes occurring in the years FY1998 and FY1999 were analyzed in the first two years of the NSL’s involvement with the Cooperative Agreement, and they will be treated here, along with the data in the years FY2000, FY2001, and FY2002. During the four years of funding under the Cooperative Agreement, FY2000-FY2003, NSL has maintained a seismic network in the vicinity of Yucca Mountain; installed a strong-motion capability at 10 sites; installed a borehole array of strong-motion instruments near the ESF north portal; and has conducted various studies on seismic-wave attenuation, earthquake interactions, the character of the stress field, and seismotectonics, all within the southern Great Basin and mostly focused on the immediate vicinity of Yucca Mountain. This report will summarize these operational efforts and associated investigative studies. This report references many of the previous reports submitted under the Cooperative Agreement and does not present any new data itself

Measurement of the Parameter Kappa, and Reevaluation of Kappa for Small to Moderate Earthquakes at Seismic Stations in the Vicinity of Yucca Mountain, Nevada

The parameter kappa was defined by Anderson and Hough (1984) to describe the high-frequency spectral roll-off of the strong motion seismic spectrum. In the work of Su et al., (1996) the numerical value of kappa estimated for sites near Yucca Mountain was small (~20 ms). The estimate obtained from these events has been applied through a rigorous methodology to develop design earthquake spectra with magnitude over 5.0. Smaller values of kappa lead to higher estimated ground motions in the methodology used by the Probabilistic Seismic Hazard Analysis (PSHA) for Yucca Mountain. An increase of 10 ms in kappa could result in a substantial decrease in the high frequency level of the predicted ground motions. Any parameter that plays such a critical role deserves close examination. Here, we study kappa and its associated uncertainties. The data set used by Su et al (1996) consisted of 12 M 2.8 to 4.5 earthquakes recorded at temporary stations deployed after the June 1992 Little Skull Mountain earthquake. The kappa elements of that study were revisited by Anderson and Su (MOL.20071203.0134) and substantially confirmed. One weakness of those studies is the limited data used. Few of these stations were on tuff or on Yucca Mountain itself. A decade of Southern Great Basin Digital Seismic Network (SGBDSN) recording has now yielded a larger body of on-scale, well calibrated digital ground motion records suitable for investigating kappa. We use the SGBDSN data to check some of the original assumptions, improve the statistical confidence of the conclusions, and determine values of kappa for stations on or near Yucca Mountain. The outstanding issues in kappa analysis, as they apply to Yucca Mountain, include: 1. The number itself. The kappa estimate near 20 msec from Su et al. (1996) and Anderson and Su (MOL.20071203.0134) is markedly smaller than is considered typical in California (Silva, 1995). The low kappa value has engineering consequences because when it is applied in ground motions analyses used in PSHA, it contributes to the extreme values of peak ground acceleration that the PSHA predicts. Also, in some areas precarious rock evidence indicates that no such accelerations have occurred. 2. The disagreement among analyses in the value of kappa. Previous reports indicate that smallest earthquakes yield kappa estimate 12-20 msec larger than average values from M3 to M4.5 aftershocks of Little Skull Mountain earthquake. 3. The source of kappa. Classically and in engineering usage, kappa is attributed largely to the upper tens or hundreds of meters at the recording site. However, borehole recordings imply that a significant contribution to kappa originates below several hundred meters depth. Also, when earthquakes are considered from a small source region, a true site effect should be common to all recordings. In fact kappa observations of LSM aftershocks to stations on Yucca Mountain and at network stations appear to vary greatly, as though much of kappa actually derives from near the seismic source. 4. The repository overburden contribution to kappa. PSHA estimated ground motions to a free surface at 300 meters depth with properties of confined rock at that depth. Rock mechanical and borehole estimates suggest that several milliseconds of the total kappa accrue between 300 meters to the surface. If estimates of kappa are small at the surface, little is left to reduce incident ground accelerations from the seismic source to the repository level. 5. The variability of kappa. In most cases parametric estimates of kappa have some range of values that fit the data equally well in a statistical sense, so errors in kappa estimates must be addressed. As noted above, kappa at a station also varies significantly for events from the same source area. 6. Are kappa values from small to moderate magnitude earthquakes appropriately applied to the larger, potentially damaging earthquakes of engineering concern? Put another way, is there a significant magnitude dependence in kappa? Questions 1 and 6 are of primary importance, but we find answers to several others in the course of our study. Data from southern Nevada are capable of resolving only some of these questions. In a global search, we identified data from the Japanese borehole accelerometer array KiKNet as most likely to address the questions of the shallow site structural contribution to kappa and the usefulness of moderate earthquake kappa estimates to predict strong ground motion

Measurement of the parameter kappa, and reevaluation of kappa for small to moderate earthquakes at seismic stations in the vicinity of Yucca Mountain, Nevada

We address two primary questions. First, what are the values of seismic spectral decay parameter kappa at stations on and around Yucca Mountain. Second, can small and/or moderate earthquakes provide estimates of kappa that are valid for conditions of strong ground motion

Ground-Rupturing Earthquakes on the Northern Big Bend of the San Andreas Fault, California, 800 A.D. to Present

Paleoseismic data on the timing of ground-rupturing earthquakes constrain the recurrence behavior of active faults and can provide insight on the rupture history of a fault if earthquakes dated at neighboring sites overlap in age and are considered correlative. This study presents the evidence and ages for 11 earthquakes that occurred along the Big Bend section of the southern San Andreas Fault at the Frazier Mountain paleoseismic site. The most recent earthquake to rupture the site was the Mw7.7–7.9 Fort Tejon earthquake of 1857. We use over 30 trench excavations to document the structural and sedimentological evolution of a small pull-apart basin that has been repeatedly faulted and folded by ground-rupturing earthquakes. A sedimentation rate of 0.4 cm/yr and abundant organic material for radiocarbon dating contribute to a record that is considered complete since 800 A.D. and includes 10 paleoearthquakes. Earthquakes have ruptured this location on average every ~100 years over the last 1200 years, but individual intervals range from ~22 to 186 years. The coefficient of variation of the length of time between earthquakes (0.7) indicates quasiperiodic behavior, similar to other sites along the southern San Andreas Fault. Comparison with the earthquake chronology at neighboring sites along the fault indicates that only one other 1857-size earthquake could have occurred since 1350 A.D., and since 800 A.D., the Big Bend and Mojave sections have ruptured together at most 50% of the time in Mw ≥ 7.3 earthquakes

Late Holocene Rupture History of the Alpine Fault in South Westland, New Zealand

Abstract Strata and fault relationships revealed in five trenches excavated across the recent trace of the Alpine fault at the Haast, Okuru, and Turnbull Rivers, South Westland, New Zealand, record the three most recent surface-faulting events. Using back-stripping techniques to remove the three faulting events and the sedimentary units associated with the faulting restores the cross-sections to gravel-bed floodplains at the Haast and Okuru Rivers, at about A.D. 750. Horizontal and vertical offsets of stream channels and terrace risers reveal characteristic displacements of about 8–9 m dextral and up to 1 m vertical per event. Cumulative dextral displacement is 25 ± 3 m in the past three events. The most recent surface-rupture event was probably in A.D. 1717, and the next prior events were about A.D. 1230 ± 50 and about A.D.750 ± 50. The timing of these events is consistent with past large-great earth- quakes on the southern section of the Alpine fault inferred from off-fault data, but there are fewer events identified in trenches. Our three-event dataset indicates the aver- age surface-rupture recurrence interval for the South Westland section of the fault is about 480 years, much longer than the current elapsed time of 295 years. Therefore, the Alpine fault in South Westland may not be close to rupture as is often speculated

Southern Great Basin seismic network operations

Subtasks 1. Record and archive data from the permanent seismic network. 2. Process seismic data into a preliminary earthquake bulletin. 3. Maintain the seismic stations, the strong-motion stations, the telemetry network, and the computing lab. 4. Prepare and submit a seismicity report on a yearly basis 5. Maintain and collect data from 3 north-portal boreholes. 6. Report on borehole accelerometers. 7. Estimate Kappa at network stations. 8. Implement a recording system at borehole UZ16. 9. Prepare and submit high-quality papers to peer-reviewed journals on seismic data and interpretations in the YM region. 10. Perform a multi-year telemetry and station upgrade

Early goal-directed therapy using a physiological holistic view: the ANDROMEDA-SHOCK—a randomized controlled trial

Septic shock is a highly lethal condition. Early recognition of tissue hypoperfusion and its reversion are key factors for limiting progression to multiple organ dysfunction and death. Lactate‐targeted resuscitation is the gold‐standard under current guidelines, although it has several pitfalls including that non‐hypoxic sources of lactate might predominate in an unknown proportion of patients. Peripheral perfusion‐targeted resuscitation might provide a real‐time response to increases in ow that could lead to a more timely decision to stop resuscitation, thus avoiding uid overload and the risks of over‐resuscitation. This article reports the rationale, study design and analysis plan of the ANDROMEDA‐SHOCK Study. Methods: ANDROMEDA‐SHOCK is a randomized controlled trial which aims to determine if a peripheral perfusion‐ targeted resuscitation is associated with lower 28‐day mortality compared to a lactate‐targeted resuscitation in patients with septic shock with less than 4 h of diagnosis. Both groups will be treated with the same sequential approach during the 8‐hour study period pursuing normalization of capillary re ll time versus normalization or a decrease of more than 20% of lactate every 2 h. The common protocol starts with uid responsiveness assessment and uid loading in responders, followed by a vasopressor and an inodilator test if necessary. The primary outcome is 28‐day mortality, and the secondary outcomes are: free days of mechanical ventilation, renal replacement therapy and vasopressor support during the rst 28 days after randomization; multiple organ dysfunction during the rst 72 h after randomization; intensive care unit and hospital lengths of stay; and all‐cause mortality at 90‐day. A sample size of 422 patients was calculated to detect a 15% absolute reduction in mortality in the peripheral perfusion group with 90% power and two‐tailed type I error of 5%. All analysis will follow the intention‐to‐treat principle. Conclusions: If peripheral perfusion‐targeted resuscitation improves 28‐day mortality, this could lead to simpli ed algorithms, assessing almost in real‐time the reperfusion process, and pursuing more physiologically sound objec‐ tives. At the end, it might prevent the risk of over‐resuscitation and lead to a better utilization of intensive care unit resources

The practice of intensive care in Latin America: a survey of academic intensivists

Intensive care medicine is a relatively young discipline that has rapidly grown into a full-fledged medical subspecialty. Intensivists are responsible for managing an ever-increasing number of patients with complex, life-threatening diseases. Several factors may influence their performance, including age, training, experience, workload, and socioeconomic context. The aim of this study was to examine individual- and work-related aspects of the Latin American intensivist workforce, mainly with academic appointments, which might influence the quality of care provided. In consequence, we conducted a cross-sectional study of intensivists at public and private academic and nonacademic Latin American intensive care units (ICUs) through a web-based electronic survey submitted by email. Questions about personal aspects, work-related topics, and general clinical workflow were incorporated. RESULTS: Our study comprised 735 survey respondents (53% return rate) with the following country-specific breakdown: Brazil (29%); Argentina (19%); Chile (17%); Uruguay (12%); Ecuador (9%); Mexico (7%); Colombia (5%); and Bolivia, Peru, Guatemala, and Paraguay combined (2%). Latin American intensivists were predominantly male (68%) young adults (median age, 40 [IQR, 35-48] years) with a median clinical ICU experience of 10 (IQR, 5-20) years. The median weekly workload was 60 (IQR, 47-70) h. ICU formal training was between 2 and 4 years. Only 63% of academic ICUs performed multidisciplinary rounds. Most intensivists (85%) reported adequate conditions to manage patients with septic shock in their units. Unsatisfactory conditions were attributed to insufficient technology (11%), laboratory support (5%), imaging resources (5%), and drug shortages (5%). Seventy percent of intensivists participated in research, and 54% read scientific studies regularly, whereas 32% read no more than one scientific study per month. Research grants and pharmaceutical sponsorship are unusual funding sources in Latin America. Although Latin American intensivists are mostly unsatisfied with their income (81%), only a minority (27%) considered changing to another specialty before retirement. CONCLUSIONS: Latin American intensivists constitute a predominantly young adult workforce, mostly formally trained, have a high workload, and most are interested in research. They are under important limitations owing to resource constraints and overt dissatisfaction. Latin America may be representative of other world areas with similar challenges for intensivists. Specific initiatives aimed at addressing these situations need to be devised to improve the quality of critical care delivery in Latin America

Effects of very early start of norepinephrine in patients with septic shock: a propensity score-based analysis

BACKGROUND: Optimal timing for the start of vasopressors (VP) in septic shock has not been widely studied since it is assumed that fluids must be administered in advance. We sought to evaluate whether a very early start of VP, even without completing the initial fluid loading, might impact clinical outcomes in septic shock. METHODS: A total of 337 patients with sepsis requiring VP support for at least 6 h were initially selected from a prospectively collected database in a 90-bed mixed-ICU during a 24-month period. They were classified into very-early (VE-VPs) or delayed vasopressor start (D-VPs) categories according to whether norepinephrine was initiated or not within/before the next hour of the first resuscitative fluid load. Then, VE-VPs (n = 93) patients were 1:1 propensity matched to D-VPs (n = 93) based on age; source of admission (emergency room, general wards, intensive care unit); chronic and acute comorbidities; and lactate, heart rate, systolic, and diastolic pressure at vasopressor start. A risk-adjusted Cox proportional hazard model was fitted to assess the association between VE-VPs and day 28 mortality. Finally, a sensitivity analysis was performed also including those patients requiring VP support for less than 6 h. RESULTS: Patients subjected to VE-VPs received significantly less resuscitation fluids at vasopressor starting (0[0-510] vs. 1500[650-2300] mL, p < 0.001) and during the first 8 h of resuscitation (1100[500-1900] vs. 2600[1600-3800] mL, p < 0.001), with no significant increase in acute renal failure and/or renal replacement therapy requirements. VE-VPs was related with significant lower net fluid balances 8 and 24 h after VPs. VE-VPs was also associated with a significant reduction in the risk of death compared to D-VPs (HR 0.31, CI95% 0.17-0.57, p < 0.001) at day 28. Such association was maintained after including patients receiving vasopressors for < 6 h. CONCLUSION: A very early start of vasopressor support seems to be safe, might limit the amount of fluids to resuscitate septic shock, and could lead to better clinical outcomes

Effect of a Resuscitation Strategy Targeting Peripheral Perfusion Status vs Serum Lactate Levels on 28-Day Mortality Among Patients With Septic Shock The ANDROMEDA-SHOCK Randomized Clinical Trial

Importance Abnormal peripheral perfusion after septic shock resuscitation has been associated with organ dysfunction and mortality. The potential role of the clinical assessment of peripheral perfusion as a target during resuscitation in early septic shock has not been established. Objective To determine if a peripheral perfusion–targeted resuscitation during early septic shock in adults is more effective than a lactate level–targeted resuscitation for reducing mortality. Design, Setting, and Participants Multicenter, randomized trial conducted at 28 intensive care units in 5 countries. Four-hundred twenty-four patients with septic shock were included between March 2017 and March 2018. The last date of follow-up was June 12, 2018. Interventions Patients were randomized to a step-by-step resuscitation protocol aimed at either normalizing capillary refill time (n = 212) or normalizing or decreasing lactate levels at rates greater than 20% per 2 hours (n = 212), during an 8-hour intervention period. Main Outcomes and Measures The primary outcome was all-cause mortality at 28 days. Secondary outcomes were organ dysfunction at 72 hours after randomization, as assessed by Sequential Organ Failure Assessment (SOFA) score (range, 0 [best] to 24 [worst]); death within 90 days; mechanical ventilation–, renal replacement therapy–, and vasopressor-free days within 28 days; intensive care unit and hospital length of stay. Results Among 424 patients randomized (mean age, 63 years; 226 [53%] women), 416 (98%) completed the trial. By day 28, 74 patients (34.9%) in the peripheral perfusion group and 92 patients (43.4%) in the lactate group had died (hazard ratio, 0.75 [95% CI, 0.55 to 1.02]; P = .06; risk difference, −8.5% [95% CI, −18.2% to 1.2%]). Peripheral perfusion–targeted resuscitation was associated with less organ dysfunction at 72 hours (mean SOFA score, 5.6 [SD, 4.3] vs 6.6 [SD, 4.7]; mean difference, −1.00 [95% CI, −1.97 to −0.02]; P = .045). There were no significant differences in the other 6 secondary outcomes. No protocol-related serious adverse reactions were confirmed. Conclusions and Relevance Among patients with septic shock, a resuscitation strategy targeting normalization of capillary refill time, compared with a strategy targeting serum lactate levels, did not reduce all-cause 28-day mortality