Distinct control mechanism of fine-grained sediments from Yellow River and Kyushu supply in the northern Okinawa Trough since the last glacial

© 2017. American Geophysical Union. All Rights Reserved. High-resolution multiproxy records, including clay minerals and Sr-Nd-Pb isotopes of the clay-sized silicate fraction of sediments from IODP Site U1429 in the northern Okinawa Trough, provide reliable evidence for distinct control mechanism on fine-grained sediments input from the Yellow River and the southern Japanese Islands to the northern Okinawa Trough since 34 ka BP. Provenance analysis indicates that the sediments were mainly derived from the Yellow River and the island of Kyushu. Since the last glacial, clay-sized sediments transported from the Yellow River to the study site were strongly influenced by sea-level fluctuation. During low sea-level stage (∼34–14 ka BP), the paleo-Yellow River mouth was positioned closer to the northern Okinawa Trough, favoring large fluvial discharge or even direct input of detrital sediments, which resulted about four times more flux of clay-sized sediments supply to the study area as during the relatively high sea-level stage (∼14–0 ka BP). The input of Kyushu-derived clay-sized sediments to the study site was mainly controlled by the Kuroshio Current and Tsushima Warm Current intensity, with increased input in phase with weakened Kuroshio Current/Tsushima Warm Current. Our study suggests that the Kuroshio Current was very likely flowed into the Okinawa Trough and thus influenced the fine-grained sediment transport in the area throughout the last glacial and deglacial. During ∼34–11 ka BP, the Kyushu clay-sized sediment input was mainly controlled by the Kuroshio Current. Since ∼11 ka BP, the occurrence of Tsushima Warm Current became important in influencing the Kyushu fine-grained sediment input to the northern Okinawa Trough

Radon tides on an active volcanic island: Terceira, Azores

Se usaron 12 estaciones de monitoreo de radón sincrónicas, de registro continuo de radón en el volcán Pico Alto, en la isla Terceira, Azores, el cual se encuentra geotérmica y tectónicamente activo. Estas estaciones se utilizaron para identificar y cuantificar los movimientos subterráneos de radón. Se encontraron los siguientes resultados: (1) Las variaciones meteorológicas tienen efectos despreciables en las emanaciones subterráneas de radón.  (2) Las emanaciones de radón en función del mes lunar generan patrones repetitivos en tiempo y magnitud para varios meses consecutivos (al menos un año). Las desviaciones del patrón establecido indican eventos adicionales no sistemáticos en las emanaciones de radón.  (3) En radón del subsuelo se comporta como un cuerpo continuo, en gran parte como un acuífero. El radón presenta “mareas” distintas de la mareas marinas y terrestres. Las edades de las mareas de radón tienen una magnitud negativa, con máximos de emanación ocurriendo algunos días antes de la conjunción luni-solar y/o en oposición. Los máximos absolutos de radón están asociados con la Luna Llena, en contraste con el máximo de la marea marina, que ocurre en la Luna Nueva.  (4) Las emanaciones de radón tienen dos máximos por día, uno al amanecer y otro al anochecer. Las separaciones y tiempo de los picos varían con la estación, en función de las variaciones en la extensión del día.  (5) Las mareas marinas influyen en el cuerpo de radón a lo largo de fallas conectadas directamente al mar. Estos efectos de mareas están en forma de una acción física de bombeo en acuíferos y “masas” de radón. (6) Las estaciones de la isla de Terceira responden ya sea al sistema tectónico regional de esfuerzos Azores/Gibraltar (NO-SE), o al régimen local NE-SO del volcán Pico Alto. Se observó que los máximos de emanación cambiaron de un sistema al otro conforme predominaban diferentes regímenes tectónicos. doi: https://doi.org/10.22201/igeof.00167169p.2002.41.4.50

Radon Flux Variations as Earthquake Precursors

Scientific research leading to the successful prediction of large earthquakes, sufficiently in advance, has great significance to mankind. Unfortunately, to this date, no reliable method has been developed for the successful application of earthquake prediction based on a geological scale, when applied to a human scale; the latter requires precise timing, location and intensity, factors not easily defined geologically. Major, erratic changes in Radon concentration have been observed in many earthquake-prone zones a few months/days before, during and after a large earthquake. It is tempting to consider a sudden erratic fluctuation in Radon concentration as a potential signal for an earthquake. Here, a refinement of the Radon precursor method is proposed, based on results from a network of twelve multiple, synchronous underground monitoring station

Accidents in nuclear-powered submarines and their effect on environmental marine pollution

Since 1953, hundreds of nuclear-powered submarines (NPS) have been produced all over the world. Nowadays, about 160 nuclear submarines are in operation. In particular, USSR (then Russia) built 248 NPS between in the last 50 years. Most of them are now not operating anymore and have been dismantled only partially. Nowadays, Russia and USA have 75 and 52 operating NPS, while UK has 16, France has 10, and China has 6. Naval reactors have been in most cases pressurised water types, which differ from commercial reactors producing electricity (PWR) in that: - they deliver a lot of power from a very small volume and therefore run on highly-enriched uranium (>20% U-235, originally 93% but apparently now 20-25% in western vessels, and up to 45% in later Russian ones). This nuclear material has also proliferation problems. - the fuel is not UO2 but a U-Zr or U-Al alloy or a metal-ceramic. - they have long core lives, so that refuelling is needed only after 10 or more years, and new cores are designed to last 50 years in carriers and 30-40 years in submarines Decommissioning nuclear-powered submarines has become a major task for US and Russian navies. After defuelling, normal practice is to cut the reactor section from the vessel for disposal in shallow land burial as low-level waste. In Russia the whole vessels, or the sealed reactor sections, sometimes remain stored afloat indefinitely. Environmental consequences of such procedures may be very dangerous. Incidents and emergencies in atomic submarine fleet of USSR / RUSSIA have been many during their 50 years operational period of NPS: twelve nuclear and more 100 radiation emergencies have taken place. A nuclear emergency is such kind of emergency that concerns with the damage of fuel elements exceeding the established limits of safe operation, and/or irradiation of staff exceeding the permissible level for normal operation, caused by violation of control and managing of a chain nuclear reaction of fission in the reactor core, creation of a critical mass during reload, transportation and storage of fuel elements, or violation of heat elimination from fuel elements. Most of the emergencies were accompanied by serious radiological and ecological consequences. A relatively frequent event is the release of radioactive pollutants to the marine environment. In the Mediterranean sea, the effects of environmental marine pollution due to the presence of nuclear submarines has been recently studied. In particular, the most recent studies originated from the accident to the nuclear submarine "Hartford" that took place in 2003 close to the "La Maddalena" submarines base in Sardinia island (Italy). However it is not demonstrated that environmental release took place during the accident, findings about the presence of plutonium traces in certain types of algae close to the site have put into evidence the presence of artificial radioactive pollutants in that marine environment, a natural area of great ecological importance, designated by the Italian government as a natural marine park

Tensional fissures and crustal extension rates in the northern part of the Main Ethiopian Rift

This paper describes a swarm of tensional fissures located at the northern end of the Main Ethiopian Rift, and attempts to relate their dimensions and age to the overall rate of Rift widening. The fissures dissect an otherwise undisturbed welded tuff formation associated with the caldera complex of Mount Fantale. This tuff was dated by the fission track method to 168,000 ± 38,000 years. Examination of a comparable single fissure dissecting welded tuff and radiocarbon dated sediments at nearby K’one caldera complex suggests that the fissuring episode occurred within the last 7000 years. Detailed measurement of the total extension across the fissure swarm, taken in conjunction with these ages, indicates an average rate of widening of 0.01 cm per year across the 20 km width of the welded tuff. The overall extension rate of the rift at this latitude as determined by plate tectonic modelling is of the order of 0.5 cm per year, and by geodetic measurements between 0.1 and 0.45 cm per year. This marked discrepancy reflects the different scales of time and distance over which the various means of measurement operate. It indicates that the extension process is very variable over both time and space, and that surface evidence of extension may not be immediately apparent.F.M. Williams, M.A.J. Williams, and F. Aument

Nuclear Powered Submarines as Hazards For The Marine Environment

Hundreds of nuclear-powered submarines (NPS) have been manufactured since 1953; some 160 are still in operation. Decommissioning NPS is a major, delicate and costly task. There have been many incidents with NPS during their 50 years operational period: Most of these emergencies resulted in serious radiological and ecological consequences. In the Mediterranean, the effects of marine pollution due to NPS have been under recent investigation following the October 2003 accident to the US nuclear submarine Hartford in Sardinia (Italy). Preliminary studies indicated that no apparent environmental release had taken place as a direct result of the accident. However, further analyses detected traces of Pu-239 in several of the algal species, indicative of anthropogenic pollutants. Furthermore, several samples showed concentrations of radially distributed alpha tracks (forming "hot spots") emanating from micron-sized point sources. The concentrated, extremely localized occurrence of these nuclides cannot be explained in terms of left-over worldwide nuclear pollution. A local source seems more plausible. Our ongoing sampling programme has revealed that: some of the high alpha/hot spot levels measured in February 2004 have decreased markedly during subsequent months, others have decreased only slightly, and others still have remained unchanged: a clear indication that different nuclides are present. We are now analyzing 2005 samples

Nuclear powered submarines as hazards for the marine environment

Hundreds of nuclear-powered submarines (NPS) have been manufactured since 1953; some 160 are still in operation. Decommissioning NPS is a major, delicate and costly task. There have been many incidents with NPS during their 50 years operational period: Most of these emergencies resulted in serious radiological and ecological consequences. In the Mediterranean, the effects of marine pollution due to NPS have been under recent investigation following the October 2003 accident to the US nuclear submarine Hartford in Sardinia (Italy). Preliminary studies indicated that no apparent environmental release had taken place as a direct result of the accident. However, further analyses detected traces of Pu-239 in several of the algal species, indicative of anthropogenic pollutants. Furthermore, several samples showed concentrations of radially distributed alpha tracks (forming “hot spots”) emanating from micron-sized point sources. The concentrated, extremely localized occurrence of these nuclides cannot be explained in terms of left-over worldwide nuclear pollution. A local source seems more plausible. Our ongoing sampling programme has revealed that: some of the high alpha/hot spot levels measured in February 2004 have decreased markedly during subsequent months, others have decreased only slightly, and others still have remained unchanged: a clear indication that different nuclides are present. We are now analyzing 2005 samples