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We present a newly developed three-dimensional seismic velocity model, high-precision earthquake relocations and focal mechanisms near the Geysers Geothermal Field in eastern California using seismic data recorded by the Northern California Earthquake Data Center from 1984 to 2015. The velocity model generally agrees with those in previous studies with the V p model mainly corresponding to rock composition and the V p / V s model more correlated with fluid content. The dominating low V p / V s anomalies observed from 0 to 4 km depth below sea level is a reflection of the geothermal reservoir. The waveform cross-correlation relocated seismicity shows both spatial and temporal correlations with the geothermal operations in the study area, indicating that they are induced seismicity. Although the focal solutions are dominated by normal and strike-slip regimes throughout our entire study time period, there has been an increase in reverse faulting since 2008, which may be caused by the thermal contraction associated with the Northwest Geysers Enhanced Geothermal System project between 2008 and 2012. Our study provides a groundwork for future seismological studies in The Geysers. [ABSTRACT FROM AUTHOR]

We develop a new three-dimensional local earthquake tomography algorithm with the inclusion of full topography (LETFT). We present both synthetic and real data tests based on the P- and S-wave arrival time data for Kīlauea volcano in Hawai'i. A total of 33,768 events with 515,711 P-picks and 272,217 S-picks recorded by 35 stations at the Hawaiian Volcano Observatory are used in these tests. The comparison between the new and traditional methods based on the synthetic test shows that our new algorithm significantly improves the accuracy of the velocity model, especially at shallow depths. In the real data application, the P- and S-wave velocity models of Kīlauea show several intriguing features. We observe discontinuous high Vp (> 7.0 km/s) and Vs (> 3.9 km/s) zones at 5–14 km depth below Kīlauea caldera, its East Rift Zone (ERZ) and the Southwest Rift Zone, which may represent consolidated intrusive gabbro-ultramafic cumulates. At Kīlauea caldera, Vp and Vs decrease from ~ 3.9 km/s and ~ 2.6 km/s from the surface to ~ 3.7 km/s and ~ 2.3 km/s at 2 km depth. We resolve a high Vp zone (> 7.0 km/s) at 5–14 km depth and high Vs zone (> 3.9 km/s) at 5–11 km depth. This high Vp and Vs zone extends to the north of the ERZ at 5–10 km depth and to the upper ERZ at 8–12 km depth. In the Hilina Fault System, there is a high Vp layer (~ 7.0 km/s) at 4–6 km depth and a low Vp body of ~ 5.7 km/s at 6–11 km depth. The high Vp layer could be associated with the intrusive ultramafic gabbro sills. The velocity contrast on the north and south sides of the Koa'e Fault System indicates that the intrusive activities mainly occur to the north of the fault. Our new LETFT method performs well in both the synthetic and real data tests and we expect that it will reveal more robust velocity structures in areas with larger topographic variations. [ABSTRACT FROM AUTHOR]

A new three-dimensional (3-D) seismic velocity model and high-precision location catalog for earthquakes between 1984 and 2014 are presented for Long Valley Caldera and its adjacent fault zones in eastern California. The simul2000 tomography algorithm is applied to derive the 3-D V p and V p / V s models using first-arrivals of 1004 composite earthquakes obtained from the original seismic data at the Northern California Earthquake Data Center. The resulting V p model reflects geological structures and agrees with previous local tomographic studies. The simultaneously resolved V p / V s model is a major contribution of this study providing an important complement to the V p model for the interpretation of structural heterogeneities and physical properties in the study area. The caldera is dominated by low V p anomalies at shallow depths due to postcaldera fill. High V p and low V p / V s values are resolved from the surface to ~ 3.4 km depth beneath the center of the caldera, corresponding to the structural uplift of the Resurgent Dome. An aseismic body with low V p and high V p / V s anomalies at 4.2–6.2 km depth below the surface is consistent with the location of partial melt suggested by previous studies based on V p models only and the inflation source locations based on geodetic modeling. The Sierran crystalline rocks outside the caldera are generally characterized with high V p and low V p / V s values. The newly resolved velocity model improves absolute location accuracy for the seismicity in the study area and ultimately provides the basis for a high-precision earthquake catalog based on similar-event cluster analysis and waveform cross-correlation data. The fine-scale velocity structure and precise earthquake relocations are useful for investigating magma sources, seismicity and stress interaction and other seismological studies in Long Valley. [ABSTRACT FROM AUTHOR]

We examine tidal asymmetry in a 100-km long coastal plain estuary, a 15-km long tidal creek closed at the end, and a small side channel of a coastal plain estuary closed at low water. Current meter and water depth data were harmonically analyzed for M2 and the M4 and M6 overtide. The results are displayed in a plot of tidal current versus water level and the effects of the M2, M2+M4, and M2+M4+M6 are compared in order to show how overtides affect tidal asymmetry in the different systems.The long estuary showed a gradual increase in tidal current asymmetry. The current takes on a more progressive nature as it goes into the estuary, as indicated by increasing lags between high or low water and the corresponding slack water. On the other hand, the tidal creek has its reflection point at the head, a relatively short distance from the observations, which reflects the incident tidal wave more efficiently.The tidal creek has a high salt marsh which is covered only an hour or so before high water. Since its intertidal areas flood and drain near the time of high water, maximum flood and ebb currents occur a short time before and after high water slack throughout the tidal creek. Most of the tidal energy is dissipated at the end of the creek where M6/M2 of the tidal current almost doubles.The small side channel has tidal flats that become covered soon after the time of low water. The relative time of maximum flood and ebb currents occurs much closer to the time of low-water-slack, which contrasts significantly to the timing in the tidal creek channel surrounded by high salt marsh. [Copyright &y& Elsevier]

The Salton Sea Geothermal Field is located on the southeastern shore of Salton Sea and has been facilitated with many geothermal units in the past few decades. In this study, I investigate possible effects of the long-term production process on seismic parameters by using a high-resolution approach to estimate the near-source compressional- to shear-wave velocity ratios (V p / V s). I apply this method to similar earthquake clusters based on waveform cross-correlation data and obtain robust results for six event clusters in the study area. The resulting in situ V p / V s ratios vary from 1.510 to 1.811 with the calculated uncertainties below 0.02. I examine possible relations between these V p / V s ratios and other types of data. The observed spatial correlation with the heat flow and temporal correlation with well production data indicate that the near-source V p / V s ratios strongly depend on the subsurface natural properties, but are influenced by the amount of extraction and injection volume throughout the operational period. This study suggests that the in situ estimation method can be used to detect changes in near-source V p / V s ratios caused by exploitation of geothermal areas and is a potentially valuable tool for geothermal resource monitoring. [ABSTRACT FROM AUTHOR]

Abstract: The crab-eating frog, Rana cancrivora, is one of only a handful of amphibians worldwide that tolerates saline waters. It typically inhabits brackish water of mangrove forests of Southeast Asia. A large amount of antimicrobial peptides belonging to different families have been identified from skins of amphibians inhabiting freshwater. No antimicrobial peptide from sea amphibians has been reported. In this paper, we firstly reported the antimicrobial peptide and its cDNA cloning from skin secretions of the crab-eating frog R. cancrivora. The antimicrobial peptide was named cancrin with an amino acid sequence of GSAQPYKQLHKVVNWDPYG. By BLAST search, cancrin had no significant similarity to any known peptides. The cDNA encoding cancrin was cloned from the cDNA library of the skin of R. cancrivora. The cancrin precursor is composed of 68 amino acid residues including a signal peptide, acidic spacer peptide, which are similar to other antimicrobial peptide precursors from Ranid amphibians and mature cancrin. The overall structure is similar to other amphibian antimicrobial peptide precursors although mature cancrin is different from known peptides. The current results reported a new family of amphibian antimicrobial peptide and the first antimicrobial peptide from sea amphibian. [Copyright &y& Elsevier]

Abstract: Group IIA secretory phospholipases A2 (sPLA2-II) is generally known to display potent gram-positive bactericidal activity, while group IA sPLA2 (sPLA2-I) reportedly is not. In this work, a novel sPLA2-I named BFPA was identified from Bungarus fasciatus venom, and its antimicrobial activity was studied as well. The amino acid sequence of the venomous protein precursor was 145-amino acid in length, and contained a predicted 27-amino acid signal peptide and a 118-amino acid mature protein. Unlike the well-known sPLA2-Is, which have 14 half-cysteines forming 7 intramolecular disulfide bridges, BFPA possesses 15 half-cysteines. The additional cysteine might contribute to the formation of an intermolecular disulfide bridge of the homodimeric protein. In the biological activities assays, BFPA displayed the activities of anticoagulation and bactericidal against Escherichia coli and Staphylococcus aureus. This study is the first report about gram-positive bactericidal activity of sPLA2-I. [Copyright &y& Elsevier]

Abstract: There are around 27 species of Amolops amphibian distributed in South-east of Asia. Seven antimicrobial peptides (AMPs) belonging to two different families were purified from skin of rufous-spotted torrent frog, Amolops loloensis, and designated brevinins-ALa, b, c, and d, and temporins-ALa, b, and c. The brevinins-AL family which is structurally related to brevinins-1 from skin secretions of the European frog, Rana brevipoda, is composed of 24 amino acids and has an intra-disulfide bridge at the C-terminus. The temporins-AL family, composed of 13 or 16 amino acid residues, is related with temporins from the skin secretions of R. temporaria. The findings of this study will facilitate the solutions to the taxonomic questions of the ranid genus Amolops and Staurois. In the work of this paper, both brevinins-ALb and temporin-Ma induced mast cell degranulation and histamine release, and had cytotoxic activity toward solid tumor cell line HepG2. Brevinins-ALb also exerted strong hemolytic activity while temporin-Ma had no such activity. [Copyright &y& Elsevier]