Consistent phase picking for regional tomography models: application to the greater Alpine region

The resolution and reliability of tomographic velocity models strongly depends on quality and consistency of available traveltime data. Arrival times routinely picked by network analysts on a day-to-day basis often yield a high level of noise due to mispicks and other inconsistencies, particularly in error assessment. Furthermore, tomographic studies at regional scales require merging of phase picks from several networks. Since a common quality assessment is not usually available for phase data provided by different networks, additional inconsistencies are introduced by the merging process. Considerable improvement in the quality of phase data can only be achieved through complete repicking of seismograms. Considering the amount of data necessary for regional high-resolution tomography, algorithms combining accurate picking with an automated error assessment represent the best tool to derive large suitable data sets. In this work, we present procedures for consistent automated and routine picking of P-wave arrival times at local to regional scales including consistent picking error assessment. Quality-attributed automatic picks are derived from the MPX picking system. The application to earthquakes in the greater Alpine region demonstrates the potential of such a repicking approach. The final data set consists of more than 13 000 high-quality first-arrivals and it is used to derive regional 1-D and preliminary 3-D P-wave models of the greater Alpine region. The comparison with a tomographic model based on routine phase data extracted from the ISC Bulletin illustrates effects on tomographic results due to consistency and reliability of our high-quality data se

Automatic seismic phase picking and consistent observation error assessment: application to the Italian seismicity

Accuracy of seismic phase observation and consistency of timing error assessment define the quality of seismic waves arrival times. High-quality and large data sets are prerequisites for seismic tomography to enhance the resolution of crustal and upper mantle structures. In this paper we present the application of an automated picking system to some 600 000 seismograms of local earthquakes routinely recorded and archived by the Italian national seismic network. The system defines an observation weighting scheme calibrated with a hand-picked data subset and mimics the picking by an expert seismologist. The strength of this automatic picking is that once it is tuned for observation quality assessment, consistency of arrival times is strongly improved and errors are independent of the amount of data to be picked. The application to the Italian local seismicity documents that it is possible to automatically compile a precise, homogeneous and large data set of local earthquake Pg and Pn arrivals with related polarities. We demonstrate that such a data set is suitable for high-precision earthquake location, focal mechanism determination and high-resolution seismic tomograph

Automatic seismic phase picking and consistent observation error assessment: application to Italian seismicity

Accuracy of seismic phase observation and consistency of timing error assessment define the quality of seismic waves arrival times. High-quality and large data sets are prerequisites for seismic tomography to enhance the resolution of crustal and upper mantle structures. In this paperwe present the application of an automated picking system to some 600000 seismograms of local earthquakes routinely recorded and archived by the Italian national seismic network. The system defines an observation weighting scheme calibrated with a hand-picked data subset and mimics the picking by an expert seismologist. The strength of this automatic picking is that once it is tuned for observation quality assessment, consistency of arrival times is strongly improved and errors are independent of the amount of data to be picked. The application to the Italian local seismicity documents that it is possible to automatically compile a precise, homogeneous and large data set of local earthquake Pg and Pn arrivals with related polarities. We demonstrate that such a data set is suitable for high-precision earthquake location, focal mechanism determination and high-resolution seismic tomography

Magnetic character of a large continental transform : an aeromagnetic survey of the Dead Sea Fault

Author Posting. © American Geophysical Union, 2007. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geochemistry Geophysics Geosystems 8 (2007): Q07005, doi:10.1029/2007GC001582.New high-resolution airborne magnetic (HRAM) data along a 120-km-long section of the Dead Sea Transform in southern Jordan and Israel shed light on the shallow structure of the fault zone and on the kinematics of the plate boundary. Despite infrequent seismic activity and only intermittent surface exposure, the fault is delineated clearly on a map of the first vertical derivative of the magnetic intensity, indicating that the source of the magnetic anomaly is shallow. The fault is manifested by a 10–20 nT negative anomaly in areas where the fault cuts through magnetic basement and by a <5 nT positive anomaly in other areas. Modeling suggests that the shallow fault is several hundred meters wide, in agreement with other geophysical and geological observations. A magnetic expression is observed only along the active trace of the fault and may reflect alteration of magnetic minerals due to fault zone processes or groundwater flow. The general lack of surface expression of the fault may reflect the absence of surface rupture during earthquakes. The magnetic data also indicate that unlike the San Andreas Fault, the location of this part of the plate boundary was stable throughout its history. Magnetic anomalies also support a total left-lateral offset of 105–110 km along the plate boundary, as suggested by others. Finally, despite previous suggestions of transtensional motion along the Dead Sea Transform, we did not identify any igneous intrusions related to the activity of this fault segment.The project was funded by U.S.-AID Middle Eastern Regional Cooperation grant TA-MOU-01-M21-012

Geometry and subsidence history of the Dead Sea basin : a case for fluid-induced mid-crustal shear zone?

This paper is not subject to U.S. copyright. The definitive version was published in Journal of Geophysical Research 117 (2012): B01406, doi:10.1029/2011JB008711.Pull-apart basins are narrow zones of crustal extension bounded by strike-slip faults that can serve as analogs to the early stages of crustal rifting. We use seismic tomography, 2-D ray tracing, gravity modeling, and subsidence analysis to study crustal extension of the Dead Sea basin (DSB), a large and long-lived pull-apart basin along the Dead Sea transform (DST). The basin gradually shallows southward for 50 km from the only significant transverse normal fault. Stratigraphic relationships there indicate basin elongation with time. The basin is deepest (8–8.5 km) and widest (~15 km) under the Lisan about 40 km north of the transverse fault. Farther north, basin depth is ambiguous, but is 3 km deep immediately north of the lake. The underlying pre-basin sedimentary layer thickens gradually from 2 to 3 km under the southern edge of the DSB to 3–4 km under the northern end of the lake and 5–6 km farther north. Crystalline basement is ~11 km deep under the deepest part of the basin. The upper crust under the basin has lower P wave velocity than in the surrounding regions, which is interpreted to reflect elevated pore fluids there. Within data resolution, the lower crust below ~18 km and the Moho are not affected by basin development. The subsidence rate was several hundreds of m/m.y. since the development of the DST ~17 Ma, similar to other basins along the DST, but subsidence rate has accelerated by an order of magnitude during the Pleistocene, which allowed the accumulation of 4 km of sediment. We propose that the rapid subsidence and perhaps elongation of the DSB are due to the development of inter-connected mid-crustal ductile shear zones caused by alteration of feldspar to muscovite in the presence of pore fluids. This alteration resulted in a significant strength decrease and viscous creep. We propose a similar cause to the enigmatic rapid subsidence of the North Sea at the onset the North Atlantic mantle plume. Thus, we propose that aqueous fluid flux into a slowly extending continental crust can cause rapid basin subsidence that may be erroneously interpreted as an increased rate of tectonic activity.Fieldwork was funded by U.S. AID Middle Eastern Regional Cooperation Program grant M21–012, with in-kind contributions by Al-Balqa’ Applied University (Jordan), the Geophysical Institute of Israel, and the U.S. Geological Survey

Vides piesārņotāju ietekme uz vairogdziedzera funkcijām

MedicīnaVeselības aprūpeMedicineHealth CareKOPSAVILKUMS IEVADS: Vairogdziedzerim un tā hormoniem ir daudzas svarīgas funkcijas, piemēram, uzturēt ķermeņa temperatūru, sirdsdarbības ātrumu un spēku, mitohondriju aktivitāti, normālu menstruālo ciklu, seksuālo funkciju, miegu, domāšanu un daudzas citas. Aizvien lielākas bažas rada dabā bieži sastopamo ķīmisko savienojumu iedarbība uz cilvēka vairogdziedzera funkcijām un to iespējamo kaitīgo ietekmi uz veselību. Tāpēc ir svarīgi pēc iespējas ātrāk noteikt iespējamos piesārņotājus, lai samazinātu vai pat pārtrauktu to ražošanu. MĒRĶIS: Veidot analītisku pārskatu par iespējamiem vides piesārņotājiem, kuri varētu negatīvi ietekmēt vairogdziedzera funkcijas, vienlaikus uzsverot to pieejamību vidē un viņu specifisko negatīvo ietekmi uz vairogdziedzeri. METODOLOĢIJA: Lai sasniegtu rezultātus, no visas pasaules tika savākti un pārskatīti dažādi medicīniskie raksti, grāmatas, žurnāli un zinātniskie darbi no PubMed reģistra. Vēlāk rezultāti un atklājumi tika salīdzināti ar uz pierādījumiem balstītās medicīnas datu bāzēm Lielbritānijā, Īrijā, ASV un Latvijā. GALVENIE REZULTĀTI: Perhlorāts, tiocianāts un nitrāts ir konkurējošie nātrija/joda simportera inhibitori. Polihlorēti bifenili, polibromēti difenilēteri, bisfenols-A un triklozāns var tieši ietekmēt vairogdziedzera hormonu receptorus. Polibromēti difenilēteri un hidroksilētie polihlorētie bifenili var aizstāt tiroksīnu no trantiretīna. Izoflavoni kavē vairogdziedzera peroksidāzes aktivitāti. Hloru saturošie pesticīdi un dioksīni var samazināt tiroksīna seruma eliminācijas pusperiodu, aktivizējot aknu enzīmus. Svina galvenais darbības mehānisms nav zināms, taču tas varētu ietekmēt hipofīzes vairogdziedzera asi. Dažos sauļošanās līdzekļos esošās sastāvdaļas var samazināt aknu 50-dejodināzes aktivitāti. Stirola iedarbība var kavēt tiroksīna pārvēršanu par trijodtironīnu. SECINĀJUMI: Vides piesārņotāji, kas negatīvi ietekmē vairogdziedzera funkcijas ir tiocianāts, nitrāts, polihlorēti bifenili, triklozāns, polibromēti difenilēteri, hidroksilētie polihlorētie bifenili, hloru saturošie pesticīdi, dioksīns, furāni, svins, stirols. Augsta deva un ilglaicīga iedarbība visvairāk izraisa negatīvās izmaiņas, bet zemai devai un īslaicīgai iedarbībai ir minimāla vai nav ietekmes uz vairogdziedzera funkcijām.ABSTRACT BACKGROUND: Thyroid gland and its hormones have many important functions, such as maintaining body's temperature, rate and strength of the heartbeat, activity of mitochondria, normal menstrual cycle, sexual function, sleep, thought patterns and many others. There is increasing concern about human exposure to commonly encountered chemical compounds on thyroid functions, due to their possible damaging effects on health. That’s why it is crucial to determinate possible pollutants as early as possible to decrease or even stop production of them. AIM: To compile an analytical overview of possible environmental pollutants that could negatively affect thyroid gland functions, while placing an emphasis on their availability in environment and their specific negative effects on thyroid. METHODOLOGY: In order to achieve results, different relevant medical articles, books, journals, and research papers from all over the world were collected and reviewed mainly from PubMed registry. Later results and findings were compared to commonly used evidence based medicine portals in United Kingdom, Ireland, United States and Latvia. KEY RESULTS: Perchlorate, thiocyanate and nitrate are all competitive inhibitors of sodium/iodine symporter. Polychlorinated biphenyls, polybrominated diphenyl ethers, bisphenol-A and triclosan, may have direct actions on the thyroid hormone receptors. Polybrominated diphenyl ethers and hydroxylated polychlorinated biphenyls may displace thyroxine from transthyretin. Isoflavones inhibit thyroid peroxidase activity. Organochlorine pesticides and dioxins may decrease serum thyroxine half-life by activating hepatic enzymes. Lead mechanism of action is unknown, but it could affect the pituitary–thyroid axis. Ingredients in some sunscreens may decrease hepatic 50-deiodinase activity. Styrene exposure may inhibit thyroxine to triiodothyronine conversion. CONCLUSIONS: Environmental pollutants that showed negative effects on thyroid gland functions were thiocynate, nitrates, polychlorinated biphenyls, triclosan, polybrominated diphenyl ethers, hydroxylated polychlorinated biphenyls, organochlorine pesticides, dioxin, furan, lead and styrene. High and long term exposure mostly provoked these negative effects, but low and short term exposure had minimal or no negative effect on thyroid gland functions

Physiological Mechanisms of Electrodermal Reactions

Available from VNTIC / VNTIC - Scientific & Technical Information Centre of RussiaSIGLERURussian Federatio

Consistent phase picking for regional tomography models: Application to the greater Alpine region

ISSN:0956-540XISSN:1365-246