Low potential for large intraslab earthquakes in the central Cascadia Subduction Zone

Abstract The Cascadia subduction zone (CSZ) can be divided into three distinct sections based on the characteristics of intraslab seismicity. Based on a 150-year historical record, no moderate-to-large intraslab earthquakes of moment magnitude (M) 5.5 or greater have occurred within the subducting Juan de Fuca plate of the central CSZ from south of the Puget Sound in northwestern Washington to the Oregon-California border. Also very few intraslab earthquakes as small as M 3 have been instrumentally located within the central CSZ since 1960, and a Wadati-Benioff zone is not apparent. In the southern CSZ beneath northwestern California, a WadatiBenioff zone is present to a depth of about 40 km, but no large Gorda block earthquakes have been observed in the downgoing slab, although large events have occurred near the trench axis. In contrast, the Puget Sound region within the northern CSZ has been repeatedly shaken by large intraslab earthquakes of M Ն6.5 in the depth range of 40 to 60 km, such as the recent 2001 M 6.8 Nisqually event. A critical question addressed in this article is what is the potential for such large, shallow intraslab earthquakes in the central CSZ beneath western Oregon and southwestern Washington? I have evaluated the available information on the thermal and physical properties, geometry, and historical and contemporary seismicity of the central CSZ, and performed thermal modeling. Based on these analyses and comparisons with other subduction zones worldwide, the lack of shallow intraslab earthquakes in the central CSZ is not unusual. The hot temperatures (Ͼ500ЊC) within the Juan de Fuca plate, particularly below a depth of 40 km where large events are expected, are not conducive to earthquake generation, resulting in either the complete absence of M Ն6.5 shallow intraslab earthquakes or long recurrence intervals (hundreds of years) between such events. Temperatures appear to be sufficiently high in the central CSZ so that no Wadati-Benioff zone can exist even at shallow depths (Ͻ40 km). The young plate age, slower convergence rate, and the insulating effect of the Siletz terrane above the plate are factors that probably lead to the hot temperatures in this portion of the slab. The variability in the maximum depth of the Wadati-Benioff zone along the CSZ, 60 km beneath the Puget Sound, 40 km within the subducting Gorda block, and essentially zero in the central CSZ, reflect the differing temperature conditions, that is, the cutoff temperature varies with depth and rock composition, and also the potential for large shallow intraslab earthquakes. In addition to the effects of temperature, the level of tectonic stresses, which vary along the length of the CSZ, must also be a factor in controlling the occurrence of large intraslab earthquakes. Large events can occur in the Puget Sound region, probably because of cooler intraslab temperatures and possibly because of a stress concentration or zone of weakness along the pronounced arch in the Juan de Fuca plate. A previous study has suggested an intraslab subduction zone origin for a M 7.3 earthquake that occurred in 1873 near the town of Brookings, in southernmost Oregon. However, analysis of its seismotectonic setting and comparison with other historical earthquakes in northernmost California suggest that the event probably had a very shallow origin within the Gorda block (southern CSZ) and was not a deep intraslab earthquake in the central CSZ

Shear-Wave Velocity Characterization of the USGS Hawaiian Strong-Motion Network on the Island of Hawaii and Development of an NEHRP Site-Class Map

To assess the level and nature of ground shaking in Hawaii for the purposes of earthquake hazard mitigation and seismic design, empirical ground-motion prediction models are desired. To develop such empirical relationships, knowledge of the subsurface site conditions beneath strong-motion stations is critical. Thus, as a first step to develop ground-motion prediction models for Hawaii, wspectral-analysis-of-surface-waves (SASW) profiling was performed at the 22 free-field U.S. Geological Survey (USGS) strong-motion sites on the Big Island to obtain shear-wave velocity (V(S)) data. Nineteen of these stations recorded the 2006 Kiholo Bay moment magnitude (M) 6.7 earthquake, and 17 stations recorded the triggered M 6.0 Mahukona earthquake. V(S) profiling was performed to reach depths of more than 100 ft. Most of the USGS stations are situated on sites underlain by basalt, based on surficial geologic maps. However, the sites have varying degrees of weathering and soil development. The remaining strong-motion stations are located on alluvium or volcanic ash. V(S30) (average V(S) in the top 30 m) values for the stations on basalt ranged from 906 to 1908 ft/s [National Earthquake Hazards Reduction Program (NEHRP) site classes C and D], because most sites were covered with soil of variable thickness. Based on these data, an NEHRP site-class map was developed for the Big Island. These new V(S) data will be a significant input into an update of the USGS statewide hazard maps and to the operation of ShakeMap on the island of Hawaii.George E. Brown, Jr. Network for Earthquake Engineering Simulation (NEES) under NSF CMS-0086605FEMA HSFEHQ-06-D-0162, HSFEHQ-04-D-0733U.S. Geological Survey, Department of the Interior 08HQGR0036Geotechnical Engineering Cente

Applications of the Band-Limited-White Noise Source Model for Predicting Site-Specific Strong Ground Motions

Since the Band-Limited-White-Noise (BLWN) source model coupled with random vibration theory (RVT) was first developed in the early 1980\u27s, it has been used successfully to predict strong ground motions at rock sites in different tectonic regimes. The BLWN-RVT methodology is appropriate for an engineering characterization of strong ground motions at a site since the method captures the important features of these motions in terms of peak acceleration and spectral composition and requires a minimum of input parameters. Recently, the capability to estimate strong ground motions at soil sites has been incorporated into the methodology by using RVT and plane-wave propagators in an equivalent-linear formulation. Thus, non-linear soil response that may occur at high strain levels can now be directly estimated and analyzed. Four cases in which the BLWN-RVT methodology has been applied to predict strong ground motions will be discussed: (l) a moment magnitude (M) 7.9 New Madrid earthquake located 10 km beneath a rock site and a deep soil site; (2) a M 6.9 event similar to the 1983 Borah Peak, Idaho earthquake at several rock and thin soil sites at source-to-site distances of 10 to 27 km; (3) a M 8.0 Cascadia subduction zone earthquake at both a deep alluvial and hypothetical hard rock site in Seattle, Washington at a source-to-site distance of 70 km; and (4) a M 7.0 earthquake occurring along the Hayward fault in the eastern San Francisco Bay region at an 18-m-thick soil site, 15 km from the fault. The effects of soil amplification or deamplification (possibly due to either non-linear soil response or soil damping) will be emphasized in these case histories

Tandem quadruplication of HMA4 in the zinc (Zn) and cadmium (Cd) hyperaccumulator noccaea caerulescens

Zinc (Zn) and cadmium (Cd) hyperaccumulation may have evolved twice in the Brassicaceae, in Arabidopsis halleri and in the Noccaea genus. Tandem gene duplication and deregulated expression of the Zn transporter, HMA4, has previously been linked to Zn/Cd hyperaccumulation in A. halleri. Here, we tested the hypothesis that tandem duplication and deregulation of HMA4 expression also occurs in Noccaea. A Noccaea caerulescens genomic library was generated, containing 36,864 fosmid pCC1FOSTM clones with insert sizes ~20–40 kbp, and screened with a PCR-generated HMA4 genomic probe. Gene copy number within the genome was estimated through DNA fingerprinting and pooled fosmid pyrosequencing. Gene copy numbers within individual clones was determined by PCR analyses with novel locus specific primers. Entire fosmids were then sequenced individually and reads equivalent to 20-fold coverage were assembled to generate complete whole contigs. Four tandem HMA4 repeats were identified in a contiguous sequence of 101,480 bp based on sequence overlap identities. These were flanked by regions syntenous with up and downstream regions of AtHMA4 in Arabidopsis thaliana. Promoter-reporter b-glucuronidase (GUS) fusion analysis of a NcHMA4 in A. thaliana revealed deregulated expression in roots and shoots, analogous to AhHMA4 promoters, but distinct from AtHMA4 expression which localised to the root vascular tissue. This remarkable consistency in tandem duplication and deregulated expression of metal transport genes between N. caerulescens and A. halleri, which last shared a common ancestor >40 mya, provides intriguing evidence that parallel evolutionary pathways may underlie Zn/Cd hyperaccumulation in Brassicaceae

Multicentric validation of proteomic biomarkers in urine specific for diabetic nephropathy

Background: Urine proteome analysis is rapidly emerging as a tool for diagnosis and prognosis in disease states. For diagnosis of diabetic nephropathy (DN), urinary proteome analysis was successfully applied in a pilot study. The validity of the previously established proteomic biomarkers with respect to the diagnostic and prognostic potential was assessed on a separate set of patients recruited at three different European centers. In this case-control study of 148 Caucasian patients with diabetes mellitus type 2 and duration >= 5 years, cases of DN were defined as albuminuria >300 mg/d and diabetic retinopathy (n = 66). Controls were matched for gender and diabetes duration (n = 82). Methodology/Principal Findings: Proteome analysis was performed blinded using high-resolution capillary electrophoresis coupled with mass spectrometry (CE-MS). Data were evaluated employing the previously developed model for DN. Upon unblinding, the model for DN showed 93.8% sensitivity and 91.4% specificity, with an AUC of 0.948 (95% CI 0.898-0.978). Of 65 previously identified peptides, 60 were significantly different between cases and controls of this study. In <10% of cases and controls classification by proteome analysis not entirely resulted in the expected clinical outcome. Analysis of patient's subsequent clinical course revealed later progression to DN in some of the false positive classified DN control patients. Conclusions: These data provide the first independent confirmation that profiling of the urinary proteome by CE-MS can adequately identify subjects with DN, supporting the generalizability of this approach. The data further establish urinary collagen fragments as biomarkers for diabetes-induced renal damage that may serve as earlier and more specific biomarkers than the currently used urinary albumin

The Hubble Space Telescope Wide Field Camera 3 Early Release Science data: Panchromatic Faint Object Counts for 0.2-2 microns wavelength

We describe the Hubble Space Telescope (HST) Wide Field Camera 3 (WFC3) Early Release Science (ERS) observations in the Great Observatories Origins Deep Survey (GOODS) South field. The new WFC3 ERS data provide calibrated, drizzled mosaics in the UV filters F225W, F275W, and F336W, as well as in the near-IR filters F098M (Ys), F125W (J), and F160W (H) with 1-2 HST orbits per filter. Together with the existing HST Advanced Camera for Surveys (ACS) GOODS-South mosaics in the BViz filters, these panchromatic 10-band ERS data cover 40-50 square arcmin at 0.2-1.7 {\mu}m in wavelength at 0.07-0.15" FWHM resolution and 0.090" Multidrizzled pixels to depths of AB\simeq 26.0-27.0 mag (5-{\sigma}) for point sources, and AB\simeq 25.5-26.5 mag for compact galaxies. In this paper, we describe: a) the scientific rationale, and the data taking plus reduction procedures of the panchromatic 10-band ERS mosaics; b) the procedure of generating object catalogs across the 10 different ERS filters, and the specific star-galaxy separation techniques used; and c) the reliability and completeness of the object catalogs from the WFC3 ERS mosaics. The excellent 0.07-0.15" FWHM resolution of HST/WFC3 and ACS makes star- galaxy separation straightforward over a factor of 10 in wavelength to AB\simeq 25-26 mag from the UV to the near-IR, respectively.Comment: 51 pages, 71 figures Accepted to ApJS 2011.01.2

Inhibition of HIV virus by neutralizing Vhh attached to dual functional liposomes encapsulating dapivirine

Although highly active antiretroviral therapy (HAART) has greatly improved the life expectancy of HIV/AIDS patients, the treatment is not curative. It is a global challenge which fosters an urgent need to develop an effective drug or neutralizing antibody delivery approach for the prevention and treatment of this disease. Due to the low density of envelope spikes with restricted mobility present on the surface of HIV virus, which limit the antibody potency and allow virus mutation and escape from the immune system, it is important for a neutralizing antibody to form bivalent or multivalent bonds with the virus. Liposome constructs could fulfil this need due to the flexible mobility of the membrane with its attached antibodies and the capacity for drug encapsulation. In this study, we evaluated the neutralization activity of a range of liposome formulations in different sizes coated with anti-gp120 llama antibody fragments (Vhhs) conjugated via either non-covalent metal chelation or a covalent linkage. The non-covalent construct demonstrated identical binding affinity to HIV-1 envelope glycoprotein gp120 and neutralizing ability for HIV virus as free Vhh. Although covalently linked Vhh showed significant binding affinity to gp120, it unexpectedly had a lower neutralization potency. This may be due to the comparability in size of the viral and liposome particles restricting the number which can be bound to the liposome surface so involving only a fraction of the antibodies, whereas non-covalently attached antibodies dissociate from the surface after acting with gp120 and free the remainder to bind further viruses. Covalently conjugated Vhh might also trigger the cellular uptake of a liposome-virion complex. To explore the possible ability of the antibody-coated liposomes to have a further function, we encapsulated the hydrophobic antiviral drug dapivirine into both of the non-covalently and covalently conjugated liposome formulations, both of which revealed high efficacy in reducing viral replication in vitro. Thus, dual function liposomes may lead to a novel strategy for the prophylaxis of HIV/AIDS by combining the neutralizing activity of Vhh with antiviral effects of high drug concentrations