Gurung, D.; McHugh, C. M.; Ryan, W. B.; Giosan, L.; Mart, Y.; Cagatau, N.
Paleoenvironmental changes that document the reconnection of the Marmara Sea to the world's oceans were investigated from sediment cores and high-resolution CHIRP subbottom profiles acquired by the R/V Mediterranean Explorer in 2005. The transition from a glacial fresh/brackish water lake to a sea took place after global sea-level reached the Dardanelles outlet sill depth of -85m. We surveyed the continental shelf-slope boundary along the northern margin at Cekmece and the eastern margin at the Prince Islands in water depths extending from 80 to 135 m. Mollusk, ostracod, and foraminiferal faunal assemblages calibrated to radiocarbon chronology and sediment analyses reveal the mixing of marine and lake sediments, and very high sedimentation rates, 50 cm per 1000 years, from ~12 to 10.5 cal ka BP. Very high sedimentation rates (70 cm/1000 years) and an abrupt transition from lake stage to marine were documented along the southern shelf at Imrali from ~12.5 to 11.5 cal ka BP. This older age was derived from foraminifers. Marine mollusks Corbula sp., Lucinella sp., and Gouldia sp. are found in sand beds contained within stiff clays. The sands are rich in spherical, calcium carbonate, oolites commonly associated with shallow environments, agitated waters, and warm evaporative climates. The stiff clays contain low salinity 1-5 per mil bivalve Dreissena rostriformis, gastropod, Theodoxus fluviatilis, and fresh brackish ostracods and are interpreted as lake sediments. Paleoshorelines along the northern, eastern, and southern shelves were below the Dardanelles outlet sill of -85m at the time of marine reconnection. The drawdown of Marmara Lake prior to marine intrusion is also consistent with regional aridity. After 10.5 cal ka BP sediments and faunal assemblages are fully marine with mollusks (Corbula sp., Lucinella sp., Turritela sp., and Gouldia sp) and ostracods. Even though benthic foraminifers are rich after the marine conditions were established, planktonic
Ambraseys, N. N.; Jackson, J. A.
We use the earthquake history of the last 500 years to help evaluate the tectonic and hazard contexts of the 1999 earthquakes at Izmit and Düzce in western Turkey. The 20th century has been unusually active, but over the 500 year period the seismic moment release can account for the known right-lateral shear velocity across the Marmara region observed by GPS. Two areas of known late Quaternary faulting stand out as unusually quiet over this period: the northwest shore of the Sea of Marmara and the southern branch of the North Anatolian fault system between Bursa and Mudurnu.
Ozer Sozdinler, Ceren; Necmioglu, Ocal; Meral Ozel, Nurcan
Due to the very short travel times in Marmara Sea, a Tsunami Early Warning System (TEWS) has to be strongly coupled with the earthquake early warning system and should be supported with a pre-computed tsunami scenario database to be queried in near real-time based on the initial earthquake parameters. To address this problem, 30 different composite earthquake scenarios with maximum credible Mw values based on 32 fault segments have been identified to produce a detailed scenario database for all possible earthquakes in the Marmara Sea with a tsunamigenic potential. The bathy/topo data of Marmara Sea was prepared using GEBCO and ASTER data, bathymetric measurements along Bosphorus, Istanbul and Dardanelle, Canakkale and the coastline digitized from satellite images. The coarser domain in 90m-grid size was divided into 11 sub-regions having 30m-grid size in order to increase the data resolution and precision of the calculation results. The analyses were performed in nested domains with numerical model NAMIDANCE using non-linear shallow water equations. In order to cover all the residential areas, industrial facilities and touristic locations, more than 1000 numerical gauge points were selected along the coasts of Marmara Sea, which are located at water depth of 5 to 10m in finer domain. The distributions of tsunami hydrodynamic parameters were investigated together with the change of water surface elevations, current velocities, momentum fluxes and other important parameters at the gauge points. This work is funded by the project MARsite - New Directions in Seismic Hazard assessment through Focused Earth Observation in the Marmara Supersite (FP7-ENV.2012 6.4-2, Grant 308417 - see NH2.3/GMPV7.4/SM7.7) and supported by SATREPS-MarDim Project (Earthquake and Tsunami Disaster Mitigation in the Marmara Region and Disaster Education in Turkey) and JICA (Japan International Cooperation Agency). The authors would like to acknowledge Ms. Basak Firat for her assistance in
Polonia, A.; Cormier, M.-H.; Cagatay, N.; Bortoluzzi, G.; Bonatti, E.; Gasperini, L.; Seeber, L.; Gorur, N.; Capotondi, L.; McHugh, C.; Ryan, W. B. F.; Emre, Ö.; Okay, N.; Ligi, M.; Tok, B.; Blasi, A.; Busetti, M.; Eris, K.; Fabretti, P.; Fielding, E. J.; Imren, C.; Kurt, H.; Magagnoli, A.; Marozzi, G.; Ozer, N.; Penitenti, D.; Serpi, G.; Sarikavak, K.
The disastrous 1999 earthquakes in Turkey have spurred the international community to study the geometry and behavior of the North Anatolian Fault (NAF) beneath the Marmara Sea. While the area is considered mature for a large earthquake, the detailed fault geometry below the Marmara Sea is uncertain, and this prevents a realistic assessment of seismic hazards in the highly-populated region close to Istanbul.Two geological/geophysical surveys were recently conducted in the Marmara Sea: the first in November 2000 with the R/V Odin Finder, and the second in June 2001 with the R/V CNR-Urania. Both were sponsored and organized by the Institute of Marine Geology of the Italian National Research Council (CNR), in cooperation with the Turkish Council for Scientific and Technical Research (TUBITAK) and the Lamont-Doherty Earth Observatory of Columbia University Multi-beam bathymetry, multi-channel seismic reflection profiling, magnetometry high-resolution CHIRP sub-bottom profiling, and bottom imaging were carried out with a remotely operated vehicle (ROV). Over 60 gravity and piston cores were collected.
Aloisi, G.; Soulet, G.; Henry, P.; Wallmann, K.; Sauvestre, R.; Vallet-Coulomb, C.; Lécuyer, C.; Bard, E.
During the last glaciation the Marmara Sea was isolated from the Mediterranean Sea because global sea level was below the depth of the Dardanelles sill. Prior to the postglacial reconnection to the Mediterranean Sea (∼14.7 cal kyr BP), the surface waters of the Marmara Sea were brackish (Marmara Lake). Freshening of a previously saline Marmara Sea could have happened via spill-out of brackish to fresh water from the surface water of the Black Sea through the Bosphorus Strait. This hypothesis has not been tested against alternative possibilities (salt flushing by river run-off and precipitation). Here we use the dissolved Cl- and stable isotope composition (δ18O and δD) of Marmara Sea sediment pore water to estimate the salinity and stable isotope composition of Marmara Lake bottom water and to evaluate possible freshening scenarios. We use a transport model to simulate pore water Cl-, δ18O and δD in Marmara Sea sediments in the past 130 kyr, which includes the last interglacial (130-75 cal kyr BP), the last glacial (75-14 cal kyr BP) and the current postglacial period. Our results show that the bottom waters of the Marmara Lake were brackish (∼ 4 ‰ salinity) and isotopically depleted (δ18O ∼ - 10.2 ‰ and δD ∼ - 70 ‰, respectively) compared to modern seawater. Their salinity and stable isotope ratios show that they are a mixture of Mediterranean waters and Danube-like waters implying that the freshening took place via spill-out of freshwater through the Bosphorus. Our modelling approach indicates that the transit of fresh water from glacial Eurasia to the Mediterranean via the Marmara Sea started at least 50 cal kyr BP, was continuous throughout most of the last glaciation and persisted up to the post glacial reconnection to the Mediterranean through the Dardanelles sill (14.7 cal kyr BP). These results are consistent with previously published micropaleontological and geochemical investigations of sediment cores that indicate lacustrine
Yamamoto, Y.; Takahashi, N.; Citak, S.; Kalafat, D.; Pinar, A.; Gurbuz, C.; Kaneda, Y.
The North Anatolian Fault (NAF) extends 1600 km westward from a junction with the East Anatolian Fault at the Karliova Triple Junction in eastern Turkey, across northern Turkey and into the Aegean Sea, accommodating about 25 mm/yr of right-lateral motion between Anatolia and the Eurasian plate. Since 1939, devastating earthquakes with magnitude greater than seven ruptured NAF westward, starting from 1939 Erzincan at the eastern Turkey and including the latest 1999 Izmit-Golcuk and the Duzce earthquakes in the Marmara region. Considering the fault segments ruptured by the May 24th, 2014 Northern Aegean earthquake, the only un-ruptured segments left behind NAF locate beneath the Marmara Sea and those segments keep their mystery due to their underwater location. To clarify the detailed fault geometry beneath the western Marmara Sea, we started to operate a series of ocean bottom seismographic (OBS) observations. As a first step, we deployed 3 pop-up type OBSs on 20th of March 2014 as a trial observation, and recovered them on 18thof June 2014. Although one of the OBSs worked only 6 days from the start of the observation, other two OBSs functioned properly during the whole 3-month observation period. Only 8 earthquakes were reported near the OBS network in 3 months periods according to the Kandilli Observatory and Earthquake Research Institute catalogue. Thus, we first searched for the microearthquakes missing by the land seismic network and estimated their precious location by using the initial 6 days data. We could identify about 50 earthquakes with more than 5 picking data of P and S first arrivals, and half of them located near the NAF. We also tested the hypocenter relocation by combining the land and OBS seismic data for the 8 earthquakes, and found that these earthquakes are located in between 12-24 km depths. Next, we are planning to deploy 10 OBSs from September 2014 to June 2015 as a second step for our observation. At the AGU fall meeting, we will be able to
Elbaşı, Emre; Ozdemir, Hasan
The drainage basin, the fundamental unit of the fluvial landscape, has been focus of research aimed at understanding the geometric characteristics of the master channel and its tributary network. This geometry is referred to as the basin morphometry and is nicely reviewed by Abrahams (1984). A great amount of research has focused on geometric characteristic of drainage basins, including the topology of the stream networks, and quantitative description of drainage texture, pattern, shape, and relief characteristics. Evaluation of morphometric parameters necessitates the analysis of various drainage parameters such as ordering of the various streams, measurement of basin area and perimeter, length of drainage channels, drainage density (Dd), stream frequency (Fs), bifurcation ratio (Rb), texture ratio (T), basin relief (Bh), Ruggedness number (Rn), time of concentration (Tc), hypsometric curve and integral (Hc and Hi) (Horton, 1932, Schumn, 1956, Strahler, 1957; Verstappen 1983; Keller and Pinter, 2002; Ozdemir and Bird, 2009). These morphometric parameters have generally been used to predict flood peaks, to assess sediment yield, and to estimate erosion rates in the basins. River basins of the Marmara Sea, has an area of approximately 40,000 sqkm, are the most important basins in Turkey based on their dense populations, industry and transportation systems. The primary aim of this study is to determine and analyse of morphometric characteristics of the Marmara Sea river basins using 10 m resolution Digital Elevation Model (DEM) and to evaluate of the results. For these purposes, digital 10 m contour maps scaled 1:25000 and geological maps scaled 1:100000 were used as the main data sources in the study. 10 m resolution DEM data were created using the contour maps and then drainage networks and their watersheds were extracted using D8 pour point model. Finally, linear, areal and relief morphometries were applied to the river basins using Geographic Information Systems
Korkusuz Öztürk, Yasemin; Meral Özel, Nurcan; Özbakir, Ali Değer
We invert the present day states of stresses for five apparent earthquake clusters in the Northern branch of the North Anatolian Fault in the Sea of Marmara. As the center of the Sea of Marmara is prone to a devastating earthquake within a seismic gap between these selected clusters, sensitive analyses of the understanding of the stress and strain characteristics of the region are all-important. We use high quality P and S phases, and P-wave first motion polarities from 398 earthquakes with ML ≥ 1.5 using at least 10 P-wave first motion polarities (FMPs), and a maximum of 1 inconsistent station, obtained from a total of 105 seismic stations, including 5 continuous OBSs. We report here on large numbers of simultaneously determined individual fault plane solutions (FPSs), and orientations of principal stress axes, which previously have not been determined with any confidence from the basins of the Sea of Marmara and prominent fault branches. We find NE-SW trending transtensional stress structures, predominantly in the earthquake clusters of the Eastern Tekirdağ Basin, Eastern Çınarcık Basin, Yalova and Gemlik areas. We infer that a dextral strike-slip deformation exist in the Eastern Ganos Offshore cluster. Furthermore, we analyze FPSs of four ML ≥ 4.0 earthquakes, occurred in seismically quiet regions after 1999 Izmit earthquake. Stress tensor solutions from a cluster of small events that we have obtained, correlate with FPSs of these moderate size events as a demonstration of the effectiveness of the small earthquakes in the derivation of states of local stresses. Consequently, our analyses of seismicity and large numbers of FPSs using the densest seismic network of Turkey contribute to better understanding of the present states of the stresses and seismotectonics of the Sea of Marmara.
Quaiser, Achim; Zivanovic, Yvan; Moreira, David; López-García, Purificación
To extend comparative metagenomic analyses of the deep-sea, we produced metagenomic data by direct 454 pyrosequencing from bathypelagic plankton (1000 m depth) and bottom sediment of the Sea of Marmara, the gateway between the Eastern Mediterranean and the Black Seas. Data from small subunit ribosomal RNA (SSU rRNA) gene libraries and direct pyrosequencing of the same samples indicated that Gamma- and Alpha-proteobacteria, followed by Bacteroidetes, dominated the bacterial fraction in Marmara deep-sea plankton, whereas Planctomycetes, Delta- and Gamma-proteobacteria were the most abundant groups in high bacterial-diversity sediment. Group I Crenarchaeota/Thaumarchaeota dominated the archaeal plankton fraction, although group II and III Euryarchaeota were also present. Eukaryotes were highly diverse in SSU rRNA gene libraries, with group I (Duboscquellida) and II (Syndiniales) alveolates and Radiozoa dominating plankton, and Opisthokonta and Alveolates, sediment. However, eukaryotic sequences were scarce in pyrosequence data. Archaeal amo genes were abundant in plankton, suggesting that Marmara planktonic Thaumarchaeota are ammonia oxidizers. Genes involved in sulfate reduction, carbon monoxide oxidation, anammox and sulfatases were over-represented in sediment. Genome recruitment analyses showed that Alteromonas macleodii 'surface ecotype', Pelagibacter ubique and Nitrosopumilus maritimus were highly represented in 1000 m-deep plankton. A comparative analysis of Marmara metagenomes with ALOHA deep-sea and surface plankton, whale carcasses, Peru subsurface sediment and soil metagenomes clustered deep-sea Marmara plankton with deep-ALOHA plankton and whale carcasses, likely because of the suboxic conditions in the deep Marmara water column. The Marmara sediment clustered with the soil metagenome, highlighting the common ecological role of both types of microbial communities in the degradation of organic matter and the completion of biogeochemical cycles. PMID
Quaiser, Achim; Zivanovic, Yvan; Moreira, David; López-García, Purificación
To extend comparative metagenomic analyses of the deep-sea, we produced metagenomic data by direct 454 pyrosequencing from bathypelagic plankton (1000 m depth) and bottom sediment of the Sea of Marmara, the gateway between the Eastern Mediterranean and the Black Seas. Data from small subunit ribosomal RNA (SSU rRNA) gene libraries and direct pyrosequencing of the same samples indicated that Gamma- and Alpha-proteobacteria, followed by Bacteroidetes, dominated the bacterial fraction in Marmara deep-sea plankton, whereas Planctomycetes, Delta- and Gamma-proteobacteria were the most abundant groups in high bacterial-diversity sediment. Group I Crenarchaeota/Thaumarchaeota dominated the archaeal plankton fraction, although group II and III Euryarchaeota were also present. Eukaryotes were highly diverse in SSU rRNA gene libraries, with group I (Duboscquellida) and II (Syndiniales) alveolates and Radiozoa dominating plankton, and Opisthokonta and Alveolates, sediment. However, eukaryotic sequences were scarce in pyrosequence data. Archaeal amo genes were abundant in plankton, suggesting that Marmara planktonic Thaumarchaeota are ammonia oxidizers. Genes involved in sulfate reduction, carbon monoxide oxidation, anammox and sulfatases were over-represented in sediment. Genome recruitment analyses showed that Alteromonas macleodii ‘surface ecotype', Pelagibacter ubique and Nitrosopumilus maritimus were highly represented in 1000 m-deep plankton. A comparative analysis of Marmara metagenomes with ALOHA deep-sea and surface plankton, whale carcasses, Peru subsurface sediment and soil metagenomes clustered deep-sea Marmara plankton with deep-ALOHA plankton and whale carcasses, likely because of the suboxic conditions in the deep Marmara water column. The Marmara sediment clustered with the soil metagenome, highlighting the common ecological role of both types of microbial communities in the degradation of organic matter and the completion of biogeochemical cycles. PMID
Yamamoto, Yojiro; Takahashi, Narumi; Citak, Seckin; Kalafat, Doğan; Pinar, Ali; Gurbuz, Cemil; Kaneda, Yoshiyuki
The faults' geometry and their seismic activity beneath the Marmara Sea have been under debate for a couple of decades. We used data recorded by three ocean bottom seismographs (OBSs) over a period of 3 months in 2014 to investigate the relationship of fault geometry to microseismicity under the western Marmara Sea in Turkey. We detected a seismic swarm at 13 to 20 km depth beneath the main Marmara fault (MMF), and the maximum depth of seismogenic zone was 25 km within the OBS observation area. These results provided evidence that the dip of the MMF is almost vertical and that the seismogenic zone in this region extends into the lower crust. Our analysis of past seismicity indicated that the seismic swarm we recorded is the most recent of an episodic series of seismic activity with an average recurrence interval of 2-3 years. The repetitive seismicity indicates that the MMF beneath the western Marmara Sea is coupled and that some of the accumulated strain is released every 2 to 3 years. Our study shows that OBS data can provide useful information about seismicity along the MMF, but more extensive studies using more OBSs deployed over a wider area are needed to fully understand the fault geometry and stick-slip behavior of faults under the Marmara Sea.
Topcuoğlu, Sayhan; Kirbaşoğlu, Ciğdem; Yilmaz, Yusuf Ziya
Concentration of Cd, Co, Cr, Ni, Zn, Fe, Mn, Pb and Cu were determined in biota and sediment samples collected from the Marmara Sea in Turkey. The levels of Zn, Fe, Mn, Pb and Cu in the macroalgae are higher than previous studies in the Marmara Sea. Moreover, Cu and Zn concentrations at the present study are significantly high than Bosphorus and Black Sea algae. The order heavy metal concentrations in the mussel samples was: Fe > Zn > Ni > Mn > Cu > Pb > Cr > Cd > Co. The metal concentrations are generally lower when compared with the Black Sea mussels except Pb. At the same time, concentrations of Pb, Cu and Zn in the mussel species are lower when compared with the results in the Aegean Sea. The ranges of Mn and Cu in the tested fish samples are higher than Black Sea fish. On the other hand, Cd, Co, Cr, Zn and Pb concentrations are lower. The northern coast of the Marmara Sea having the highest metal concentrations in sediments as follows: Co, Cr, Ni, Fe at Sarköy; Pb, Cu at M. Ereğli; Cd, Zn, Mn at Menekşe. The heavy metal levels in the sediment samples are lower than other areas in the Marmara Sea. PMID:15327157
Çinar, Melih Ertan
Abstract During the implementation of a large project aimed to investigate the benthic community structures of the Sea of Marmara, specimens of the invasive ascidian species Styela clava were collected on natural substrata (rocks) at 10 m depth at one locality (Karamürsel) in İzmit Bay. The specimens were mature, containing gametes, indicating that the species had become established in the area. The Sea of Marmara seems to provide suitable conditions for this species to survive and form proliferating populations. PMID:27047235
Çinar, Melih Ertan
During the implementation of a large project aimed to investigate the benthic community structures of the Sea of Marmara, specimens of the invasive ascidian species Styela clava were collected on natural substrata (rocks) at 10 m depth at one locality (Karamürsel) in İzmit Bay. The specimens were mature, containing gametes, indicating that the species had become established in the area. The Sea of Marmara seems to provide suitable conditions for this species to survive and form proliferating populations. PMID:27047235
In this study, while discussing associated challenges such as contradictions between earthquake and tsunami mitigation activities in the Marmara Region, I suggest a conceptual design for a tsunami warning system in the Sea of Marmara upon an improved version of an applicable model for the near-field tsunami early warning and emergency planning in the Mediterranean Area presented by Papadopoulos and Fokaefs (2013). Due to the extreme short arrival times as a result of the close proximity of main fault lines to the coastal regions, and existence of potential submarine landslide sources, any tsunami early warning system in the Sea of Marmara has to be strongly coupled with the earthquake warning system and stakeholders of the tsunami mitigation activities, such as local and regional components of disaster and emergency management and civil protection units. Since 1900, around 90,000 people have lost their lives in 76 earthquakes in Turkey, with a total affected population of around 7 million and direct losses of around 25 billion USD (Erdik, 2013). Based on a time-dependent model that includes coseismic and postseismic effects of the 1999 Izmit earthquake with Mw = 7.4, the probability of an earthquake with Mw > 7 in the Sea of Marmara near Istanbul, as a mega-financial-city in the heart of the Marmara Region with a population around 13 million and 1,000,000 buildings, is 35% to 70% in the next 30 years (Parsons, 2004). Historical records indicate around 30 tsunamis in the Sea of Marmara until today (Altinok et al., 2011). Among those, catastrophic earthquakes such as 1509, 1766 and 1894 resulted in considerable tsunamis and some damage. Latest tsunami observed in Marmara was due to a triggered submarine landslide of 1999 Izmit earthquake which led to reported run-up heights of 1-3 m in most places (Tinti et al., 2006). Hence, the add-on impact of a tsunami generated by the anticipated next earthquake in the Sea of Marmara should not be neglected.
Kende, Julia; Henry, Pierre; Bayrakci, Gaye; Özeren, Sinan; Grall, Céline
With a width comparable to the brittle crust thickness, the Sea of Marmara strike-slip basin appears as an intermediate case between two much studied end-member cases of basin-width-to-brittle-crust-thickness ratio: the Dead Sea and the Death Valley. But geophysical studies have shown evidences of at least 5 km of mantle uplift under the Marmara Sea, much larger than in the two other cases. We compiled data from reflection, refraction and tomography seismic studies to correct satellite and survey vessel gravity data (acquired during MARSITE cruise of Ifremer R/V Pourquoi Pas ?) from the effect of topography and sedimentary basins. Assuming that no other crustal mass heterogeneity affects the gravity measurement, we inverted the residual, with constraints from seismic studies, to calculate the topography of the Moho. The 3D model obtained shows a mantle uplift broadly correlated with the Marmara deep basins, but the crustal thinning spreads southward further than the basin limits, This is explained by ductile flow in the lower crust between a northern zone where the thinning is closely related to the Marmara Fault strike-slip basins and a southern zone where extension appears associated with older crustal detachment systems. Finally, we estimated the extension budget in the area during the Marmara Sea formation by comparing our 3D crust volume with an initial crust of constant thickness. The increase in surface area, 2100±300 km2, is compatible with present day GPS velocity field measurement assuming steady state and an initiation of extension in the area about 5 Myr ago. We conclude that although the zone went through tectonic reorganizations during the Pliocene as the North Anatolian Fault system propagated westward, the overall extension rate in the area could have been stable, or decreasing with time, and thus should be understood in a broader geodynamic framework comprising the Aegean subduction.
The vertical distributions of the unicellular cyanobacteria Synechococcus were studied in several highly contrasting seas: the Black Sea, Sea of Marmara, Aegean Sea, and Mediterranean Sea. Cell abundances varied significantly on both vertical and horizontal scales in all physically and spatially discrete water masses. Epifluorescence microscope cell counts from all seas clearly showed that majority of the population remains suspended in the surface-mixed layer and decreases gradually towards the base of the euphotic zone. Surface spatial distributions in the Black Sea were heterogeneous. Salinity, rather than temperature, seemed to have the greatest impact on the surface distribution of cells in this highly eutrophic sea. Changes in abundance in the mixed layer were small compared to the abrupt changes below the halocline, especially in the Black Sea and the Sea of Marmara. In contrast to the Black Sea, the major population remains suspended above the depth of fluorescence maximum in the Aegean and eastern Mediterranean seas. Significant correlations ( r>P0.01) were observed between cell counts and physical and chemical parameters with depth in the Black Sea. In all seas, cells at subsurface chlorophyll- a maximum layer (SCML) reflected brighter and longer fluorescence than those present at the surface and below. Cell size derived from flow cytometry indicated the presence of larger cells at the surface mixed layer compared to those at depth.
Ucarkus, G.; Armijo, R.; Cakir, Z.; Schmidt, S.; Meyer, B.
appears to result from leveling by significant sediment transport. So, on the average the sedimentation rate must be low. Under such conditions, only the last earthquake break can be preserved across the canyon floor. The break continues for some kilometers to the west and appears to end at the junction with Cinarcik basin normal faulting. It corresponds probably to the western end of the 1999 Izmit earthquake rupture and is consistent with an underwater rupture extension of 20-30 km westward as inferred from SAR interferometry. The direct observations of submarine scarps in the Sea of Marmara are critical to define barriers that have arrested past earthquakes. Incorporating the submarine scarp evidence modifies substantially our understanding of the current state of loading along the NAF next to Istanbul.
Kolukirik, M; Ince, O; Cetecioglu, Z; Celikkol, S; Ince, B K
Spatial (10 different locations) and temporal (2 years) changes in characteristics of the Marmara Sea Sediments were monitored to determine interactions between the chemical and microbial diversity. The sediments were rich in terms of hydrocarbon, nitrate, Ni and microbial cell content. Denitrifying, sulfate reducing, fermentative and methanogenic organisms were co-abundant in 15 cm below the sea floor. The local variations in the sediments' characteristics were more distinctive than the temporal ones. The sulfate and nitrate contents were the main drivers of the changes in the microbial community compositions. N and P were limited for microbial growth in the sediments, and their levels determined the total cell abundance and activity. Seasonal shifts in temperatures of the shallow sediments were also reflected in the active cell abundances. It was concluded that the Marmara Sea is a promising ecosystem for the further investigation of the ecologically important microbial processes. PMID:21962921
Dursun, Fuat; Yurdun, Türkan; Ünlü, Selma
This study reports the first evidence of domoic acid (DA), an algal neurotoxin produced by the genus Pseudo-nitzschia, from plankton net samples collected in the Sea of Marmara in December, 2010 and February, 2011. DA concentrations of plankton net samples were analyzed by high-performance liquid chromatography (HPLC), using the fluorenylmethoxycarbonyl fluorescence derivatization technique (detection limit 0.2 ng DA). The biotoxin concentrations in samples from coastal waters varied between 0.96 and 5.25 µg DA/mL. We also investigated possible correlations between physicochemical parameters and DA concentration. The DA levels appear to be correlated negatively with silica and nitrite concentrations for both sampling periods. These data may be used to evaluate the probability of finding similar conditions in coastal waters of the Sea of Marmara in order to determine the potential risks to local aquaculture and fisheries. PMID:26615530
The early Holocene marine flooding of the Black Sea has been the subject of intense scientific debate since the "Noah's Flood" hypothesis was proposed in the late 1990s. The chronology of the flooding is not straightforward because the connection between the Black Sea and the Mediterranean Sea involves the intermediate Marmara Sea Basin via two sills (Dardanelles and Bosphorus). This study explores the chronology of late Pleistocene-Holocene flooding by examining sedimentary facies and molluscs from 24 gravity cores spanning shelf to slope settings in the southern Marmara Sea Basin. A late Pleistocene Ponto-Caspian (Neoeuxinian) mollusc association is found in 12 of the cores, comprising 14 mollusc species and dominated by brackish (oligohaline-lower mesohaline) endemic taxa (dreissenids, hydrobiids). The Neoeuxinian association is replaced by a Turritella- Corbula association at the onset of the Holocene. The latter is dominated by marine species, several of which are known to thrive under dysoxic conditions in muddy bottoms. This association is common in early Holocene intervals as well as sapropel intervals in younger Holocene strata. It is an indicator of low-salinity outflows from the Black Sea into the Marmara Sea that drive stratification. A marine Mediterranean association (87 species) represents both soft bottom and hard substrate faunas that lived in well-ventilated conditions and upper mesohaline-polyhaline salinities (ca. 25 psu). Shallower areas were occupied by hard substrate taxa and phytopdetritic communities, whereas deeper areas had soft bottom faunas. The middle shelf part of the northern Gemlik Gulf has intervals with irregular and discontinuous sedimentary structures admixed with worn Neoeuxinian and euryhaline Mediterranean faunas. These intervals represent reworking events (slumping) likely related to seismic activity rooted in the North Anatolian Fault system. The core data and faunas indicate an oscillating postglacial sea-level rise and
The early Holocene marine flooding of the Black Sea has been the subject of intense scientific debate since the "Noah's Flood" hypothesis was proposed in the late 1990s. The chronology of the flooding is not straightforward because the connection between the Black Sea and the Mediterranean Sea involves the intermediate Marmara Sea Basin via two sills (Dardanelles and Bosphorus). This study explores the chronology of late Pleistocene-Holocene flooding by examining sedimentary facies and molluscs from 24 gravity cores spanning shelf to slope settings in the southern Marmara Sea Basin. A late Pleistocene Ponto-Caspian (Neoeuxinian) mollusc association is found in 12 of the cores, comprising 14 mollusc species and dominated by brackish (oligohaline-lower mesohaline) endemic taxa (dreissenids, hydrobiids). The Neoeuxinian association is replaced by a Turritella-Corbula association at the onset of the Holocene. The latter is dominated by marine species, several of which are known to thrive under dysoxic conditions in muddy bottoms. This association is common in early Holocene intervals as well as sapropel intervals in younger Holocene strata. It is an indicator of low-salinity outflows from the Black Sea into the Marmara Sea that drive stratification. A marine Mediterranean association (87 species) represents both soft bottom and hard substrate faunas that lived in well-ventilated conditions and upper mesohaline-polyhaline salinities (ca. 25 psu). Shallower areas were occupied by hard substrate taxa and phytopdetritic communities, whereas deeper areas had soft bottom faunas. The middle shelf part of the northern Gemlik Gulf has intervals with irregular and discontinuous sedimentary structures admixed with worn Neoeuxinian and euryhaline Mediterranean faunas. These intervals represent reworking events (slumping) likely related to seismic activity rooted in the North Anatolian Fault system. The core data and faunas indicate an oscillating postglacial sea-level rise and
Italiano, Francesco; Woith, Heiko; Seyis, Cemil; Pizzino, Luca; Sciarra, Alessandra; Favali, Paolo
During two fluid sampling campaigns in 2013 and 2014, around 60 thermal and mineral water springs/wells in the wider Marmara region were visited jointly by INGV, TÜBITAK and GFZ scientists in the frame of MARsite (MARMARA Supersite, 7th FP EC-funded project, grant n° 308417). Gas samples were collected and analyzed for the main chemical composition as well as their isotopic composition (He and C). Gases were taken from thermal and cold springs located in coincidence of segments of the Northern and Southern branches of the Northern Anatolian Fault Zone (NAFZ). Bubbling gases were collected when available, in all the other cases the gas phase was extracted from water samples collected on that purpose. The results confirm that over the Marmara area the majority of the gases are a binary mixture of atmospheric and deep originated volatiles. CO2 is normally the main gas species. Its concentration decrease, due to GWI (gas-water interactions), increases the relative concentration of N2 and other less soluble gases. A high CO2 content indicates minor interactions, thus, the easier and faster is the path from the deep layers toward the earth's surface, the lower are the interactions. The volatiles keep their pristine composition. Faults represent a preferential way for rising volatiles due to local high permeability. The 3He/4He ratios ranging from 0.1 to 4.8Ra (Ra=3He/4He atmospheric ratio) indicate the presence of mantle contribution. The highest ratio was found at the eastern end of the Ganos fault. Mantle degassing is not obvious in non-volcanic areas, however the measured helium isotopic ratios indicate mantle degassing possibility through lithospheric faults. All the information indicate that the fluids circulating over this area are the result of fluid mixing at variable extents of three end-members: mantle, crust and atmosphere. We propose that while the composition of shallow fluids is a matter of the local geology (for example the hosting rocks where thermal
Since 1900, around 90,000 people have lost their lives in 76 earthquakes in Turkey, with a total affected population of around 7 million and direct losses of around 25 billion USD. Based on a time-dependent model that includes coseismic and post-seismic effects of the 1999 Kocaeli earthquake with moment magnitude Mw = 7.4, Parsons (J Geophys Res. 109, 2004) concluded that the probability of an earthquake with Mw > 7 in the Sea of Marmara near Istanbul is 35 to 70 % in the next 30 years. According to a 2011 study, an earthquake with Mw = 7.25 on the Main Marmara Fault is expected to heavily damage or destroy 2 to 4 % of around 1,000,000 buildings in Istanbul with a population around 13 million, with 9 to 15 % of the buildings receiving medium damage and 20 to 34 % of the buildings damaged lightly (Erdik, Science 341:72, 2013). In the absence of adequate post-earthquake assembly areas especially in the heavily urbanized Istanbul, it is evident that after a major earthquake, especially in the coastal parts of the city, citizens would be storming to landfill assembly and recreational areas. Besides earthquakes, around 30 tsunamis have been reported by Altınok et al. (Natural Hazards Earth System Science 11:273-293, 2011) in the Marmara Sea. Among those, catastrophic earthquakes such as 1509, 1766, and 1894 resulted in considerable tsunamis and some damage. The latest tsunami observed in Marmara was due to a triggered submarine landslide of the 1999 Mw = 7.4 Kocaeli earthquake which led to reported run-up heights of 1-3 m in most places (Tinti et al., Marine Geology 225:311-330, 2006). In this study, I propose a design for a tsunami warning system specific for the Marmara region that is strongly coupled with the earthquake early warning system (due to the short arrival times of tsunami) and stakeholders of the tsunami mitigation activities, such as local and regional components of disaster and emergency management and civil protection units, to ensure that the citizens
Nakano, Masaru; Citak, Seckin; Kalafat, Doğan
We determined the centroid moment tensor (CMT) solutions of earthquakes that occurred along the North Anatolian fault (NAF) beneath the Sea of Marmara and the Aegean Sea, using data obtained from Turkey's broad-band seismograph network. The CMT solution of the 2014 Aegean Sea earthquake ( Mw 6.9) represents a strike-slip fault, consistent with the geometry of the NAF, and the source-time function indicates that this event comprised several distinct subevents. Each subevent is considered to have ruptured a different fault segment. This observation indicates the existence of a mechanical barrier, namely a NAF segment boundary, at the hypocenter. CMT solutions of background seismicity beneath the Aegean Sea represent strike-slip or normal faulting along the NAF or its branch faults. The tensional axes of these events are oriented northeast-southwest, indicating a transtensional tectonic regime. Beneath the Sea of Marmara, the CMT solutions represent mostly strike-slip faulting, consistent with the motion of the NAF, but we identified a normal fault event with a tensional axis parallel to the strike of the NAF. This mechanism indicates that a pull-apart basin, marking a segment boundary of the NAF, is developing there. Because ruptures of a fault system and large earthquake magnitudes are strongly controlled by the fault system geometry and fault length, mapping fault segments along NAF can help to improve the accuracy of scenarios developed for future disastrous earthquakes in the Marmara region.
Géli, L.; Henry, P.; Zitter, T.; Dupré, S.; Tryon, M.; Çağatay, M. N.; de Lépinay, B. Mercier; Le Pichon, X.; Şengör, A. M. C.; Görür, N.; Natalin, B.; Uçarkuş, G.; Özeren, S.; Volker, D.; Gasperini, L.; Burnard, P.; Bourlange, S.; Marnaut Scientific Party
The submerged section of the North Anatolian fault within the Marmara Sea was investigated using acoustic techniques and submersible dives. Most gas emissions in the water column were found near the surface expression of known active faults. Gas emissions are unevenly distributed. The linear fault segment crossing the Central High and forming a seismic gap - as it has not ruptured since 1766, based on historical seismicity, exhibits relatively less gas emissions than the adjacent segments. In the eastern Sea of Marmara, active gas emissions are also found above a buried transtensional fault zone, which displayed micro-seismic activity after the 1999 events. Remarkably, this zone of gas emission extends westward all along the southern edge of Cinarcik basin, well beyond the zone where 1999 aftershocks were observed. The long term monitoring of gas seeps could hence be highly valuable for the understanding of the evolution of the fluid-fault coupling processes during the earthquake cycle within the Marmara Sea.
New earthquake probability calculations are made for the Sea of Marmara region and the city of Istanbul, providing a revised forecast and an evaluation of time-dependent interaction techniques. Calculations incorporate newly obtained bathymetric images of the North Anatolian fault beneath the Sea of Marmara [Le Pichon et al., 2001; Armijo et al., 2002]. Newly interpreted fault segmentation enables an improved regional A.D. 1500-2000 earthquake catalog and interevent model, which form the basis for time-dependent probability estimates. Calculations presented here also employ detailed models of coseismic and postseismic slip associated with the 17 August 1999 M = 7.4 Izmit earthquake to investigate effects of stress transfer on seismic hazard. Probability changes caused by the 1999 shock depend on Marmara Sea fault-stressing rates, which are calculated with a new finite element model. The combined 2004-2034 regional Poisson probability of M≥7 earthquakes is ~38%, the regional time-dependent probability is 44 ± 18%, and incorporation of stress transfer raises it to 53 ± 18%. The most important effect of adding time dependence and stress transfer to the calculations is an increase in the 30 year probability of a M ??? 7 earthquake affecting Istanbul. The 30 year Poisson probability at Istanbul is 21%, and the addition of time dependence and stress transfer raises it to 41 ± 14%. The ranges given on probability values are sensitivities of the calculations to input parameters determined by Monte Carlo analysis; 1000 calculations are made using parameters drawn at random from distributions. Sensitivities are large relative to mean probability values and enhancements caused by stress transfer, reflecting a poor understanding of large-earthquake aperiodicity.
Öksüz, I.; Güray, R. T.; Özkan, N.; Yalçin, C.; Ergül, H. A.; Aksan, S.
In order to determine the radioactivity level at Izmit Bay Marmara Sea, marine sediment samples were collected from five different locations. The radioactivity concentrations of naturally occurring 238U, 232Th and 40K isotopes and also that of an artificial isotope 137Cs were measured by using gamma-ray spectroscopy. Preliminary results show that the radioactivity concentrations of 238U and 232Th isotopes are lower than the average worldwide values while the radioactivity concentrations of the 40K are higher than the average worldwide value. A small amount of 137Cs contamination, which might be caused by the Chernobyl accident, was also detected.
Schaefer, Andreas; Daniell, James; Wenzel, Friedemann
Earthquake clusters are a worldwide observation, especially with respect to large events in terms of their respective aftershock sequences. These clusters contain a lot of information about the general seismicity of the region and follow various magnitude and location-dependent characteristics. Using the seismic record of smaller magnitudes in the aftermath of large earthquakes, these details can be used to extrapolate these characteristics and to simulate the unrecorded cluster activity of historic earthquakes. The Marmara Sea is prone to frequent strong seismicity, most recently experienced by the destructive Izmit earthquake in 1999 and several historic events with frequent return periods of only a few centuries. For the future, such an event is expected in the area of Istanbul. The city has already experienced several earthquakes over its long history, such as in 1509, when major parts of Constantinople were destroyed or severely damaged. The fault system in the Marmara Sea is very complex, but based on the distribution of fault ruptures during the last 500 years, a seismic gap is visible and experts around the world see an increased probability of a strong earthquake in the vicinity of Istanbul for the next decades. The seismicity and characteristics of clusters around the Marmara Sea and along the North Anatolian fault have been studied. The activity of these clusters, recorded during the last decades, is used to model the spatial and temporal distribution of aftershocks of historic events. In addition, a fault model is used and combined with the results of the cluster analysis to elongate the synthetic earthquake locations to active tectonics. The results are correlated and calibrated with the observed macroseismic intensity distribution of each historic event. With respect to recent ruptures, several scenarios are modelled for future events including and compared in terms of their respective ground accelerations. As a result, a new collection of possible
Çifçi, Günay; Barın, Burcu; Okay, Seda; Dondurur, Derman; Sorlien, Christopher; Suc, Jean-Pierre; Lericolais, Gilles
The Messinian Salinity Crisis widely accepted as one of the most interesting events concerning the Mediterranean marine environment in the earth's geological history. Late Miocene tectonic changes in Mediterranean-Atlantic connectivity caused this huge event. The Sea of Marmara region has been improperly considered as a gateway between the Paratethys and Mediterranean since the Middle Miocene. However, it is a very important location for paleoclimatic research including the sea level change associated with the Messinian Salinity Crisis. Although considerable work has been carried out on the Messinian Salinity Crisis, very little has been reported on the status of the Marmara Sea during the Messinian. The case study includes the southern shelf and North İmrali Basin of the Marmara Sea, which is in the region located from the Çanakkale Strait (Dardanelles) to İmralı Island. The structural and stratigraphic interpretation were carried out using high resolution multi-channel seismic reflection (MCS) data which were collected with the facilities of Seismic Laboratory (SeisLab) in the Institute of Marine Sciences and Technology and R/V K. Piri Reis belonging to Dokuz Eylül University under the frame of several projects including TUBİTAK-NSF. Seismic profiles acquired in southern shelf of the Marmara Sea suggest that Messinian fluvial erosion has occurred at the base of all the main sub-basins. The southern shoreline has provided well-preserved evidence of Messinian fluvial erosion followed by the post-crisis marine reflooding. Interpretation is focused on the nature of erosion related to this acoustic basement and to a major angular unconformity that may merge with it. The basement and erosionalsurface are interpreted in the Çanakkale outletandon the southern shelf of the Sea of Marmara. A buried East-West to NW-SE channel cut into acoustic basement that may belong to the Messinian period was interpreted on the MCS data. For instance, based on interpretation of
Tur, Huseyin; Hoskan, Nihan; Aktas, Gulten
This study is based on the geological interpretation of 250 km2 of multibeam bathymetric data coupled with 300 km of seismic profiles recorded on the northern shelf of the Marmara Sea offshore Büyükçekmece and Küçükçekmece Lagoons. The sea bottom morphology has a highly chaotic structure at the exit of the Büyükçekmece and Küçükçekmece lagoons. This chaotic surface structure is controlled by a basin-ridge system lying in the NE-SW direction at the exit of the Büyükçekmece Lagoon and by a relatively deep entrance observed at the exit of the Küçükçekmece Lagoon. In addition, the linear submarine slope parallel to the shoreline between the Istanbul Strait and the Küçükçekmece Lagoon is an important morphological structure of this area. The Istanbul Strait's canyon on the northern shelf of the Marmara Sea and the elevated submarine plain west of this canyon are other important morphological structures observed at the sea bottom. The geologic interpretation of seismic profiles has allowed us to distinguish two seismo-stratigraphic units. The lower one is separated from the overlying units by a seismic sequence having a seismic facies from chaotic to parallel and the top represented by a high amplitude seismic reflector. Since these units get close to the sea bottom rising landwards, they are inferred to be the seaward continuation of the Oligocene-Upper Miocene units widely exposed on land. The upper unit, overlying the acoustic basement, whose parallel internal reflections onlap and downlap on the top of the acoustic basement, is interpreted as a Quaternary basin fill. Two groups of faults have been identified on seismic profiles and identified based on their characteristics in the study area. The first group consists of dip-slip faults trending NNE-SSW. These faults border the western slope of the Bosporus and the NNE-SSW trending basins offshore of the Büyükçekmece Lagoon. The second group of faults consists of NW-SE oriented strike
Takahashi, Narumi; Shimizu, Satoshi; Maekawa, Takuya; Kalafat, Dogan; Pinar, Ali; Citak, Seckin; Kaneda, Yoshiyuki
We have carried out a collaboration study between Japan and Turkey since 2013, which is one of SATREPS projects, "Earthquake and Tsunami Disaster Mitigation in The Marmara Region and Disaster Education in Turkey". The main objective of this project is to reduce risk brought by earthquakes and tsunamis. In particular, the North Anatolian Fault system runs through the Marmara sea and it is expected that the seismic gap exists there according to past seismic studies. The details of seismicity distribution in the Marmara Sea is, however, still insufficient to construct fault model along the active faults. Therefore, we prepare ten ocean bottom seismographs (OBSs) to realize long term observation. We aim to identify size and depth of seismogenic zones using micro seismicity. In addition, we need to cover relative broad area from off-shore Istanbul city to the western end of the Marmara Sea. To clear these conditions, OBS specifications we need are high dynamic range and low instrument noise to observe micro seismicity, low electrical consumption to realize long term observation of over one year, high cost performance to cover the broad area for OBS installation, low cost implementation, and good operability to treat by relatively small number of persons. All items, which are three components velocity sensor, batteries, a recorder, a GPS receiver, a transponder and its transducer to control OBS retrieval, a flasher and a beacon, are installed in the 17 inches glass sphere. The natural frequency of the velocity sensor is 4.5 Hz and the frequency range of our OBS is from 4.5 Hz to 250 Hz. Data sampling is selectable among 100 Hz, 250 Hz and 500 Hz. Because our OBS is deployed by free fall, accuracy of the OBS clock is essentially one of important factors, and it is less than 0.1 ppm. And the resolution of A/D conversion performed on the recorder is 24 bit and we keep the dynamic range of over 135 dB. These data is stored on a semiconductor memory and the capacity is over
Matrullo, Emanuela; Lengliné, Olivier; Schmittbuhl, Jean; Karabulut, Hayrullah; Bouchon, Michel
After the 1999 Izmit earthquake, the Main Marmara Fault (MMF) represents a 150 km unruptured segment of the North Anatolian Fault located below the Marmara Sea. One of the principal issue for seismic hazard assessment in the region is to know if the MMF is totally or partially locked and where the nucleation of the major forthcoming event is going to take place. The area is actually one of the best-instrumented fault systems in Europe. Since year 2007, various seismic networks both broadband, short period and OBS stations were deployed in order to monitor continuously the seismicity along the MMF and the related fault systems. A recent analysis of the seismicity recorded during the 2007-2012 period has provided new insights on the recent evolution of this important regional seismic gap. This analysis was based on events detected with STA/LTA procedure and manually picked P and S wave arrivals times (Schmittbuhl et al., 2015). In order to extend the level of details and to fully take advantage of the dense seismic network we improved the seismic catalog using an automatic earthquake detection technique based on a template matching approach. This approach uses known earthquake seismic signals in order to detect newer events similar to the tested one from waveform cross-correlation. To set-up the methodology and verify the accuracy and the robustness of the results, we initially focused in the eastern part of the Marmara Sea (Cinarcik basin) and compared new detection with those manually identified. Through the massive analysis of cross-correlation based on the template scanning of the continuous recordings, we construct a refined catalog of earthquakes for the Marmara Sea in 2007-2014 period. Our improved earthquake catalog will provide an effective tool to improve the catalog completeness, to monitor and study the fine details of the time-space distribution of events, to characterize the repeating earthquake source processes and to understand the mechanical state of
Sinan Özeren, Mehmet; Postacioglu, Nazmi; Canlı, Umut; Gasperini, Luca
In this work we quantify the travel distance of edge waves created by submarine landslide over slopes of finite length. Edge waves, if generated, can constitute severe coastal hazard because they can travel long distances along the shores. In the Sea of Marmara there are several submarine masses susceptible to slide in case of a big earthquake on the Main Marmara Fault and some damage scenarios might involve edge waves. The edge waves generated by landslide Tsunamis over slopes of infinite lenghts are recently studied by Sammarco and Renzi (Landslide tsunamis propagating along a plane beach, 2008, Journal of Fluid Mech.). However the infinite slope length assumption causes a perfect confinement of the waves over the coastal slope, thereby overestimating the edge wave damage. Because of this, in their work there is no alongshore length scale over which these waves can lose their energy. In the real worls, the off-shore limiting depth will be finite and the off-shore direction wave vector will not be completely complex, pointing to radiation damping of these edge waves. In this work we analytically quantify the amount of this damping and we estimate the travel distance of the edge waves along the shoreline as a function of the limiting depth. We examine some some scenarios in the north coast of the Sea of Marmara and the northern shelf to quantify the edge waves. Since the method does not require high-resolution numerical computing, it can be used to calculate the edge-wave related risk factor anywhere with submarine landslide risk.
Gasperini, Luca; Cedro, Vincenzo; Polonia, Alina; Cruise Party, Marmara
Based on high-resolution multibeam and seismic reflection data recently collected and analysed in the frame of Marsite (New Directions in Seismic Hazard Assessment through Focused Earth Observation in the Marmara Supersite) EC FP7 Project, in conjunction with a large set of geophysical and geological data collected starting from 1999, we compiled a new morphotectonic map of the submerged part of the North-Anatolian Fault system (NAF) in the Sea of Marmara. Data analysis allowed us to recognize active fault segments and their activity at the scale of 10 ka, taking as stratigraphic reference the base of the latest marine ingression, which constitutes a clear marker in the sedimentary sequence of the Sea of Marmara. This is mainly due to the fact the Sea of Marmara was a fresh water lake during the Last Glacial Maximum, and switched to a marine environment when the global sea level reached to the -85 m relative to present day and crossed the Dardanelles sill during the transgression. The passage from lacustrine to marine environment is marked by a typical unconformity in high-resolution seismic profiles, which can be correlated over the entire Marmara basin. According to the average recurrence time for major earthquake along the NAF, the time interval of 10 ka should include several earthquake cycle and is representative of the seismotectonic behavior of the fault at geological time scales. Given the relatively high deformation rates relative to in relative to sediment supply, most active tectonic structures have a morphological expression at the seafloor. This allowed us to correlate deformations from a seismic section to the adjacent. Fault strands not affecting the Holocene sequence were considered inactive. Three types of deformation patterns were observed and classified: almost purely E-W oriented strike-slip segments; NE-SW oriented trans-pressional structures; NW-SE trending trans-tensional features. Segmentation of the so-called Main Marmara Fault in the Sea
Yamamoto, Yojiro; Takahashi, Narumi; Pinar, Ali; Kalafat, Doǧan; Citak, Seckin; Comoglu, Mustafa; Polat, Remzi; Çok, Özkan; Ogutcu, Zafer; Suvariklı, Murat; Tunc, Suleyman; Gürbüz, Cemil; Turhan, Fatih; Ozel, Nurcan; Kaneda, Yoshiyuki
The North Anatolian Fault (NAF) crosses the Marmara Sea in E-W direction, accommodating about 25 mm/yr of right-lateral motion between Anatolia and the Eurasian plate. There are many large earthquakes along the 1500 km long NAF repeatedly occurred and interacted each other. The recent large northern Aegean earthquake with Mw=6.9 filled one of the last two seismic gaps on NAF that experienced extraordinary seismic moment release cycle during the last century and confirmed a remained blank zone in the Marmara Sea. However, this segment keeps its mystery due to its underwater location. Earthquake hazard and disaster mitigation studies in Marmara region are sensitive to detailed information on fault geometry and its stick-slip behavior beneath the western Marmara Sea. We have started ocean bottom seismographic observations to obtain the detailed information about fault geometry and its stick-slip behavior beneath the western Marmara Sea, as a part of the SATREPS collaborative project between Japan and Turkey namely "Earthquake and Tsunami Disaster Mitigation in the Marmara Region and Disaster Education in Turkey". The target area spans from western Marmara Sea to offshore Istanbul along the NAF. In the beginning of the project, we deployed ten Ocean Bottom Seismographs (OBSs) between the Tekirdag Basin and the Central Basin (CB) in September 2014. Then, we added five Japanese OBSs and deployed them in the western end of the Marmara Sea and in the eastern CB to extend the observed area in March 2015. We retrieved all 15 OBSs in July 2015 and deployed them again in the same locations after data retrieve and battery maintenance. From continuous OBS records, we could detect more than 700 events near the seafloor trace of NAF during 10 months observation period whereas land-seismic network could detect less than 200 events. We estimated the micro-earthquake location using manual-picking arrival times incorporating station corrections. The tentative results show
Chiggiato, Jacopo; Jarosz, Ewa; Book, Jeffrey W.; Dykes, James; Torrisi, Lucio; Poulain, Pierre-Marie; Gerin, Riccardo; Horstmann, Jochen; Beşiktepe, Şükrü
During September 2008 and February 2009, the NR/V Alliance extensively sampled the waters of the Sea of Marmara within the framework of the Turkish Straits System (TSS) experiment coordinated by the NATO Undersea Research Centre. The observational effort provided an opportunity to set up realistic numerical experiments for modeling the observed variability of the Marmara Sea upper layer circulation at mesoscale resolution over the entire basin during the trial period, complementing relevant features and forcing factors revealed by numerical model results with information acquired from in situ and remote sensing datasets. Numerical model solutions from realistic runs using the Regional Ocean Modeling System (ROMS) produce a general circulation in the Sea of Marmara that is consistent with previous knowledge of the circulation drawn from past hydrographic measurements, with a westward meandering current associated with a recurrent large anticyclone. Additional idealized numerical experiments illuminate the role various dynamics play in determining the Sea of Marmara circulation and pycnocline structure. Both the wind curl and the strait flows are found to strongly influence the strength and location of the main mesoscale features. Large displacements of the pycnocline depth were observed during the sea trials. These displacements can be interpreted as storm-driven upwelling/downwelling dynamics associated with northeasterly winds; however, lateral advection associated with flow from the Straits also played a role in some displacements.
Köprülü, Kerem; Alpar, Bedri; Vardar, Denizhan
High resolution Chirp and Sparker data allowed definition and mapping of distinct seismic units in the shallow sediment record (~100 ms) acquired from the southern exit of the Bosphorus Strait; a dynamic depositional environment. The bottommost unit observed in the Chirp data (unit-3) is made up of marine-lacustrine sediments thinning seaward and onlaps the basement rocks which are represented by folded strata in the Sparker data, possibly lower to middle Pleistocene age. It is overlain by a series of prograding deposits along the shelf (unit-2) referring to sediment input from the northern sector depending on the water levels of the paleo Marmara lake's during MIS 3. The uppermost deposits (unit-1) close to the Bosphorus Strait were represented by three separate subunits, unlike to relatively thin drape of sediments observed at the other places in the surrounding regions. The detailed definition of these subunits deduced from the closely-spaced reflection profiles and available radiocarbon ages helped to explain the history of the latest stratigraphic development depending on the connections between the Black Sea and the Sea of Marmara. In addition to the previously proposed major conduits, which controlled the sedimentary deposition at the southern exit of the Bosphorus, namely the Bosphorus Strait and Kurbağalıdere River, another submarine sedimentary pathway at the eastern bank of the strait's channel seems to have delivered sediments directly into the basin.
Filikci, Betul; Çağatay, Namık; Kadir Eriş, Kürşad; Akyol, Mustafa; Yalamaz, Burak; Uçarkuş, Gülsen; Henry, Pierre
The Sea of Marmara (SoM) is located between the Aegean Sea and the Black Sea, to which it is connected via the Istanbul (Bosphorus) and Canakkale (Dardanelles) straits having sill depths of 65 and 35 m, respectively. It has a two-way water mass exchange with a permanent pycnocline located at 20-25 m water depth. With the objective of determining Holocene paleoenvironmental changes, we studied a 8.36 m-long piston core recovered from the Central High of the SoM at a water depth of 835 m, using multiproxy analyses such as total organic and inorganic carbon, high resolution µ-XRF core scanner analysis, grain size, magnetic susceptibility and density. A 2 cm-thick tephra layer with high K and Zr and relatively low magnetic susceptibility occurs at 2.1 meter below sea floor (mbsf), which is correlated with the Avellino (Somma-Vesuvius, Italy) eruption dated at 3.9 ka BP, according to the previous studies. Using this age and assuming a uniform sedimentation rate, the base of the core dates back to ca 8 ka BP. The core includes organic-rich (sapropelic) sediments with 1.5 % to 2.2%) in its top 3.5 m and bottom 1 m. Sapropelic layers are olive green and in part laminated, and contain occasional reddish brown spots and laminae formed by oxidation of iron monosulphides. The core also contains some few mm- to cm-thick sandy-silty mass-flow units below 2.4 mbsf, some of which could have been triggered by the earthquake activity on the Central High segment of the North Anatolian Fault, just a few km away from the core location. Variations in Ca-Ti ratio suggest millennial-scale climatic changes during the Holocene. Keywords: Sea of Marmara, Holocene paleoenvironmental records, tephra, turbidites, TOC analysis, XRF analysis, physical properties.
Mencin, David; Bohnhoff, Marco; Ozener, Haluk; Mattioli, Glen; Bilham, Roger; Johnson, Wade; Gottlieb, Mike; Van Boskirk, Elizabeth; Aracel, Digdem; Bulut, Fatih; Bal, Osman
Twice in the past 1000 years a sequence of damaging earthquakes has propagated during the course of a few decades along the North Anatolian fault (NAF) in Turkey towards Istanbul, with the final earthquake in the sequence catastrophically destroying the city. This occurred most recently in 1509 when the population was only about 200,000 yet ten thousand people died. The population of greater Istanbul is now 20 million, building stock more fragile, and the last earthquake of the current westward propagating sequence is considered geologically imminent. An opportunity to enhance the detection capability of a suite of deep seismometers installed near Istanbul has arisen, that will permit us to observe, characterize, and possibly predict the moment of imminent failure along the NAF, as well as monitor the tectonic processes leading to this failure. As an augmentation of the Geophysical Observatory at the North Anatolian Fault (GONAF), UNAVCO installed two continuous creepmeters and six borehole strainmeters between July 2014 and October 2015 into boreholes provided by the several international sponsors, including NSF, GFZ, AFAD and Bogazici University Kandilli Observatory. The entire geophysical sensor network is collectively referred to as GeoGONAF. The borehole strainmeters enhance the ability of the scientific instrumentation to monitor ultra-slow process near the probable source zone of the Mw>7 earthquake that is soon expected beneath the Marmara Sea. The strainmeters and creepmeters allow us to make geodetic observations of this segment of the fault before, during and after a large earthquake, which combined with the seismic data from GONAF will provide valuable data for understanding earthquake processes. Installed instruments have already recorded both local and teleseismic events and observed creep events on the on-shore segments of the NAF to the East of the Marmara. In addition we have seen typical hydrological loading signals associated with normal modes of
Yamamoto, Yojiro; Takahashi, Narumi; Citak, Seckin; Kalafat, Doǧan; Pinar, Ali; Gürbüz, Cemil; Kaneda, Yoshiyuki
The North Anatolian Fault (NAF) extends 1600 km westward from a junction with the East Anatolian Fault at the Karliova Triple Junction in eastern Turkey, across northern Turkey and into the Aegean Sea, accommodating about 25 mm/yr of right-lateral motion between Anatolia and the Eurasian plate. Since 1939, devastating earthquakes with magnitude greater than seven ruptured NAF westward, starting from 1939 Erzincan (Ms=7.9) at the eastern Turkey and including the latest 1999 Izmit-Golcuk (Ms=7.7) and the Duzce (Ms=7.4) earthquakes in the Marmara region. Considering the fault segments ruptured by the May 24th, 2014 Northern Aegean earthquake (Mw=6.9), the only un-ruptured segments left behind the 1600 km long NAF locate beneath the Marmara Sea and those segments keep their mystery due to their underwater location. To consider the earthquake hazard and disaster mitigation, the detailed information about fault geometry and its stick-slip behavior beneath the western Marmara Sea is very important. Thus, we started to operate a series of ocean bottom seismographic (OBS) observations to estimate the fault geometry from microearthquake distribution. As a first step, we deployed 3 pop-up type OBSs on 20th of March 2014 as a trial observation, and recovered them on 18th of June 2014. Although one of the OBSs worked only 6 days from the start of the observation, other two OBSs functioned properly during the whole 3-month observation period. We first searched for the microearthquakes missing by the land seismic network and estimated their precious location by using the initial 6 days data, i.e., using all the temporary OBS stations. Although there are only 3 earthquakes listed on the Kandilli Observatory and Earthquake Research Institute (KOERI) catalogue, we could identify 41 earthquakes with more than 5 picking data of P and S first arrivals, and two-third of them located within the OBS network. We found the earthquake cluster along the main NAF and whose depth interval is 12
Yıldız, Güliz; Namık Çaǧatay, M.
The Sea of Marmara is located on the North Anatolian Fault (NAF) fault zone that is a major continental transform plate boundary. It has ca. 1250 m-deep Tekirdag, Central and Cinarcik basins that are separated by two NE-SW trending Central and Western Highs. Extensive cold seeps occur along the active fault segments of the NAF in the deep basins and highs, which are associated with authigenic carbonate crusts, carbonate chimneys and mounds, black sulphidic sediments, and local gas hydrates and oil seepage. The cold seep sites were observed and sampled during the Nautile submersible and Victor 6000 Remotely Operated Vehicle (ROV) dives carried out during MARNAUT and MARSITE cruises in 2007 and 2014, respectively. Here, we report the mineralogical and stable isotopic composition of the authigenic carbonates and discuss their environmental conditions and mechanisms of formation. The carbonate crusts range up to 5 cm in thickness and the chimneys and mounds are up to 2 m high. Some chimneys are active emitting fresh to brackish water at ambient bottom water temperatures (˜ 14° C). The carbonate crusts occur as a pavements, and are commonly covered with black sulphidic sediments and bacterial mats that accommodate a rich chemosynthetic community of bivalves, sea urchins and marine annelid worms (Polychaeta). The authigenic carbonates commonly consist mainly of aragonite, but in a few instances contain subequal amounts of aragonite and calcite. High Mg-calcite is usually a minor to trace component, except in one sample in which it is present as a cement of mudstone. In the active methane emission zones, the sulphate/methane boundary occurs at or close to the seafloor, whereas elsewhere in the Sea of Marmara, the same boundary is located at 2-5 m below the seafloor. This, together with very light stable carbon isotope values (δ13C=-29.8 to - 46.3 ‰ V-PDB), indicates that the anaerobic oxidation of high methane flux emitted from the active faults is the major process
Arik Colakoglu, Fatma; Ormanci, Hasan Basri; Berik, Nermin; Kunili, Ibrahim Ender; Colakoglu, Serhat
The venerid clam Chamelea gallina is a popular and economic foodstuff around the Mediterranean countries especially in Italy, Spain, and France. The aim of this study is to evaluate the nutritional quality of striped venus of Southern Marmara. Samples were harvested seasonally at five stations and analyzed to determine meat yield, proximate, and elemental composition. According to the results, meat yield ranged from 20.24% to 29.94%. Means of water, protein, lipid, and ash content were 67%, 10.12%, 2.57%, and 1.66%, respectively. The mean concentrations (mg/kg wet weight) of elements in tissues are as follows: B: 2.37-4.24; Cr: 0-0.76; Co: 0-0.43; Cu: 0.71-5.30; Mn: 0.30-5.94; Zn: 13.08-77.76; Ni: 0-1.22; Fe: 2.46-114.22; Al: 1.23-75.49; Pb: 0.18-3.24; Ba: 0.66-15.97; Cd: 0.04-0.69. Among the reported metal levels, only Pb and Zn in two stations exceeded the maximum critical concentrations enforced by Turkish legislation and European Commission. Therefore, we report that striped venus from Southern Marmara Sea, in general, are safe for human consumption; nonetheless, Pb and Zn levels should be closely monitored in the future. PMID:21225478
Ritt, Bénédicte; Duperron, Sébastien; Lorion, Julien; Sara Lazar, Cassandre; Sarrazin, Jozée
Recently, small Idas-like mussels have been discovered living on carbonate crusts associated with cold-seeps in the Marmara Sea. These mussels, here referred to as Idas-like nov. sp., differ morphologically and genetically from another species identified as Idas aff. modiolaeformis, living in the same type of ecosystem in the Nile Deep-Sea Fan (eastern Mediterranean Sea). A phylogenetic analysis confirms the distinction between the two species, which belong to highly divergent lineages. Carbon stable isotope values, as well as the detection of thiotroph-related bacteria in the gill tissue, support the presence of a symbiotic, thiotroph-derived nutrition. In contrast, Idas aff. modiolaeformis displays six different types of symbionts. Finally our size-frequency data suggest that the recruitment is continuous in the examined area. The present study extends the documented distribution of symbiont-bearing mussels to the Marmara Sea, and contributes to the characterisation of biological communities in this recently explored area.
Ruffine, Livio; Germain, Yoan; Polonia, Alina; de Prunelé, Alexis; Croguennec, Claire; Donval, Jean-Pierre; Pitel-Roudaut, Mathilde; Ponzevera, Emmanuel; Caprais, Jean-Claude; Brandily, Christophe; Grall, Céline; Bollinger, Claire; Géli, Louis; Gasperini, Luca
Within the Sea of Marmara, the highly active North Anatolian Fault (NAF) is responsible for major earthquakes (Mw ≥ 7), and acts as a pathway for fluid migration from deep sources to the seafloor. This work reports on pore water geochemistry from three sediment cores collected in the Gulfs of Izmit and Gemlik, along the Northern and the Middle strands of the NAF, respectively. The resulting data set shows that anaerobic oxidation of methane (AOM) is the major process responsible for sulfate depletion in the shallow sediment. In the Gulf of Gemlik, depth concentration profiles of both sulfate and alkalinity exhibit a kink-type profile. The Sulfate Methane Transition Zone (SMTZ) is located at moderate depth in the area. In the Gulf of Izmit, the low concentrations observed near the seawater-sediment interface for sulfate, calcium, strontium, and magnesium result from rapid geochemical processes, AOM, and carbonate precipitation, occurring in the uppermost part of the sedimentary column and sustained by free methane accumulation. Barite dissolution and carbonate recrystallization have also been identified at deeper depth at the easternmost basin of the Gulf of Izmit. This is supported by the profile of the strontium isotope ratios (87Sr/86Sr) as a function of depth which exhibits negative anomalies compared to the modern seawater value. The strontium isotopic signature also shows that these carbonates had precipitated during the reconnection of the Sea of Marmara with the Mediterranean Sea. Finally, a first attempt to interpret the sulfate profiles observed in the light of the seismic activity at both sites is presented. We propose the hypothesis that seismic activity in the areas is responsible for the transient sulfate profile, and that the very shallow SMTZ depths observed in the Gulf of Izmit is likely due to episodic release of significant amount of methane.
Balkis, N; Müftüoğlu, E; Aksu, A; Sur, H I; Apak, R
The input of industrial and domestic waste to the horizontal circulation in the Golden Horn Estuary of Marmara Sea has resulted in one of the most polluted estuaries in the past. Consequently, the dissolved oxygen concentrations in both the surface and bottom waters decreased toward to the estuary head during 1998-2005. In contrast, the total suspended solids content of the surface water decreased toward to the estuary mouth. However, construction of the operational collector system surrounding the estuary during the process of rehabilitation projects, combined with the opening of the middle pontoons of the Valide Sultan Bridge, resulted in gradually improved water quality of the estuary with a concomitant decrease in pollution. However, phytoplankton blooms and eutrophication persist especially in the innermost part of the Golden Horn in 2005. The region from the estuary mouth up to Camialti has a dynamic structure, and sufficient circulation seemingly occurs in this part of the Golden Horn. PMID:19353286
Yalciner, A. C.; Aytore, B.; Cankaya, C.; Guler, H. G.; Suzen, L.; Zaytsev, A.; Arikawa, T.; Takashi, T.
Resilience of coastal utilities against earthquakes and tsunamis have major importance for efficient and proper rescue and recovery operations soon after disasters. Istanbul as a mega city have long coastline and strongly interact with Marmara sea with its dense coastal utilization. Yenikapi region and Haydarpasa port are two of major coastal utilities. Haydarpasa port has critical components such as the main transportation hub at Asian side of megacity Istanbul, cargo and container stock areas, ro-ro handling operations and passenger terminals. Yenikapi area serves different coastal activities and marine passenger transportation in the Marmara sea. High resolution GIS database of the Istanbul Metropolitan Municipality (IMM) is analyzed and detaled bathymetry and topography database is developed considering vulnerability of the near shore structures and buildings. Two different tsunami numerical models i) NAMIDANCE code (2-Dimensional, depth averaged shallow water model with dispersion hybrid model) and ii) STOC-CADMAS System (Quasi 3-Dimensional in large domains and 3-Dimensional in small domains hybrid model) are used in nested domain in simulations. In this study the accurate vulnerability assessments of these coastal utilities are performed by utilizing high performance computing technology with high resolution bathymetry and topography data for Haydarpasa and Yenikapi regions based on accurate GIS data. The results of computed 2D and 3D numerical models and also the achievements by high performance Computing systems are evaluated. As the result, the computed tsunami parameters inside the coastal utilities are compared and discussed to clarify the benefits of using high resolution data and using the 2D and 3D numerical models.
Bulut, Fatih; Bohnhoff, Marco; Ellsworth, William L.; Aktar, Mustafa; Dresen, Georg
The North Anatolian Fault Zone (NAFZ) below the Sea of Marmara forms a “seismic gap” where a major earthquake is expected to occur in the near future. This segment of the fault lies between the 1912 Ganos and 1999 İzmit ruptures and is the only NAFZ segment that has not ruptured since 1766. To monitor the microseismic activity at the main fault branch offshore of Istanbul below the Çınarcık Basin, a permanent seismic array (PIRES) was installed on the two outermost Prince Islands, Yassiada and Sivriada, at a few kilometers distance to the fault. In addition, a temporary network of ocean bottom seismometers was deployed throughout the Çınarcık Basin. Slowness vectors are determined combining waveform cross correlation and P wave polarization. We jointly invert azimuth and traveltime observations for hypocenter determination and apply a bootstrap resampling technique to quantify the location precision. We observe seismicity rates of 20 events per month for M < 2.5 along the basin. The spatial distribution of hypocenters suggests that the two major fault branches bounding the depocenter below the Çınarcık Basin merge to one single master fault below ∼17 km depth. On the basis of a cross-correlation technique we group closely spaced earthquakes and determine composite focal mechanisms implementing recordings of surrounding permanent land stations. Fault plane solutions have a predominant right-lateral strike-slip mechanism, indicating that normal faulting along this part of the NAFZ plays a minor role. Toward the west we observe increasing components of thrust faulting. This supports the model of NW trending, dextral strike-slip motion along the northern and main branch of the NAFZ below the eastern Sea of Marmara.
Cagatay, M.; Wulf, S.; Guichard, F.; Ozmaral, A.; Sancar; Akçer-Ön, S.; Henry, P.; Gasperini, L.
Sea of Marmara (SoM) is a gateway between the Mediterraean and Black seas, and a tectonically active basin located on a transform plate boundary. Tephra record in the SoM is therefore very important for dating palaeoceanographic, paleoclimatic and tectonic events. We report three tephra units in cores from the SoM extending back to ca 70 ka BP and including an upper marine and a lower lacustrine units separated by a 12 ka (uncalib.) boundary. The uppermost tephra unit is up to 8 mm thick layer in the marine unit. It is heterogenous phonolitic with high total alkali content of 12.4-15.7 wt % and K2O/Na2O of 0.9 to 1.2. The middle and lower tephra layers occur in the lacustrine unit in ca 29 m-long Core MD-01-2430. The middle tephra (MT-1) is a 70 mm-thick homogeneously rhyolitic layer. The lower tephra (MT-2) is 140 mm thick and has a phonolitic-trachytic composition with CaO content of 1.7-1.9 wt % and bimodal K2O/Na2O of 1.0-1.4. Using their geochemical composition and stratigraphic analysis, we assign the tephra units, from top to bottom, to Vesuvius AP2 Pumice, Santorini Cape Riva and Campanian Ignimbrite, which have been previously dated at 3.5 ka BP, 21.95 ka BP, and 39.3 ka BP (all calender ka). The continuous sedimentary record in the Core MD-01-2430 covering the last ca 70 ka indicates that the SoM was lacustrine, disconnected from the Mediterraean Sea during MIS4, MIS3 and most of MIS2. This implies that the sill depth of the Çanakkale Strait (Dardanelles) was shallower than the present-day -65 m sill depth during MIS3 and MIS4. Figure 1: Morphotectonic map of the Sea of Marmara showing location of the studied cores (red stars). Figure 2: Geochemical biplots of tephra glass composition. a) Total alkali silica diagram b) FeO versus total alkalies for allocating cryptotephras from core MNTKS34 and ML01 to the AP2 tephra from Vesuvius. c) FeO versus CaO for correlating tephra MT1 with the Y-2 tephra from Santorini. d) SiO2 versus CaO for discriminating the
Ozel, Oguz; Guralp, Cansun; Parolai, Stefano; Bouchon, Michel; Karabulut, Hayrullah; Aktar, Mustafa; Meral Ozel, Nurcan
The Istanbul-Marmara region of northwestern Turkey with a population of more than 15 million faces a high probability of being exposed to an hazardous earthquake. The 1999 Izmit earthquake in Turkey is one of the best recorded in the world. For the first time, researchers from CNRS and Kandilli Observatory (Istanbul) observed that the earthquake was preceded by a preparatory phase that lasted 44 minutes before the rupture of the fault. This phase, which was characterized by a distinctive seismic signal, corresponds to slow slip at depth along the fault. Detecting it in other earthquakes might make it possible to predict some types of earthquakes several tens of minutes before fault rupture. In an attempt to understand where and when large earthquakes will occur, and the physics of the source process prior to large earthquakes, we proposed to install multi-parameter borehole instruments in the western part of Marmara Sea in the frame of an EU project called MARSITE. This system and surrounding small-aperture surface array is planned to capable of recording small deformations and tiny seismic signals near the active seismic zone of the North Anatolian Fault passing through the Marmara Sea, which should enable us to address these issues. The objective is to design and build a multi-parameter borehole system for observing slow deformation, low-frequency noise or tremors, and high frequency signals near the epicentral area of the expected Marmara earthquake. Furthermore, it is also aimed to identify the presence of repeating earthquakes and rupture nucleation, to measure continuously the evolution of the state of stress and stress transfer from east to west with high resolution data, and to estimate the near-surface geology effects masking the source related information. The proposed location of the borehole system is right on the Ganos Fault and in a low ambient noise environment in Gazikoy in the western end of the North Anatolian Fault in the Marmara Sea, where the
Kinscher, J.; Krüger, F.; Woith, H.; Lühr, B. G.; Hintersberger, E.; Irmak, T. S.; Baris, S.
The Armutlu peninsula, located in the eastern Marmara Sea, coincides with the western end of the rupture of the 17 August 1999, İzmit MW 7.6 earthquake which is the penultimate event of an apparently westward migrating series of strong and disastrous earthquakes along the NAFZ during the past century. We present new seismotectonic data of this key region in order to evaluate previous seismotectonic models and their implications for seismic hazard assessment in the eastern Marmara Sea. Long term kinematics were investigated by performing paleo strain reconstruction from geological field investigations by morphotectonic and kinematic analysis of exposed brittle faults. Short term kinematics were investigated by inverting for the moment tensor of 13 small to moderate recent earthquakes using surface wave amplitude spectra. Our results confirm previous models interpreting the eastern Marmara Sea Region as an active transtensional pull-apart environment associated with significant NNE-SSW extension and vertical displacement. At the northern peninsula, long term deformation pattern did not change significantly since Pliocene times contradicting regional tectonic models which postulate a newly formed single dextral strike slip fault in the Marmara Sea Region. This area is interpreted as a horsetail splay fault structure associated with a major normal fault segment that we call the Waterfall Fault. Apart from the Waterfall Fault, the stress strain relation appears complex associated with a complicated internal fault geometry, strain partitioning, and reactivation of pre-existing plane structures. At the southern peninsula, recent deformation indicates active pull-apart tectonics constituted by NE-SW trending dextral strike slip faults. Earthquakes generated by stress release along large rupture zones seem to be less probable at the northern, but more probable at the southern peninsula. Additionally, regional seismicity appears predominantly driven by plate boundary
Isinibilir, Melek; Kideys, Ahmet E.; Tarkan, Ahmet N.; Yilmaz, I. Noyan
The monthly abundance, biomass and taxonomic composition of zooplankton of Izmit Bay (the northeastern Marmara Sea) were studied from October 2001 to September 2002. Most species within the zooplankton community displayed a clear pattern of succession throughout the year. Generally copepods and cladocerans were the most abundant groups, while the contribution of meroplankton increased at inner-most stations and dominated the zooplankton. Both species number ( S) and diversity ( H') were positively influenced by the increase in salinity of upper layers ( r = 0.30 and r = 0.31, p < 0.001, respectively), while chlorophyll a was negatively affected ( r = -0.36, p < 0.001). Even though Noctiluca scintillans had a significant seasonality ( F11,120 = 8.45, p < 0.001, ANOVA), abundance was not related to fluctuations in temperature and only chlorophyll a was adversely correlated ( r = -0.35, p < 0.001). In general, there are some minor differences in zooplankton assemblages of upper and lower layers. A comparison of the species composition and abundance of Izmit Bay with other Black Sea bays reveals a high similarity between them.
Pinar, Ali; Yamamoto, Yojiro; Comoglu, Mustafa; Polat, Remzi; Turhan, Fatih; Takahashi, Narumi; Kalafat, Dogan; Citak, Seckin
The fault segments of the North Anatolian fault (NAF) occurring between Tekirdag basin and Kumburgaz basin are investigated using 15 Ocean Bottom Seismic (OBS) stations. The OBS stations were deployed closely around the fault trace of NAF. During the observation period from September, 2014 until July, 2015 more than one thousand microearthquakes were determined. No uniform seismicity pattern was observed along strike and along dip of the fault segments in an area spanning 100 km from East to West of Marmara Sea. The western fault segments exhibit relatively higher and deeper seismic activity while the eastern segment show shallower and relatively lower seismic activity. Integrating the first motion polarity data from the land based stations of Kandilli Observatory and Earthquake Research Institute (KOERI) with the polarity data acquired from the OBS stations the focal mechanisms of 173 micro-earthquakes were determined. Most of the fault plane solutions indicate predominantly strike-slip mechanism. Several clusters of events are identified along the E-W extending NAF. We derive a focal mechanism for the individual events whenever the number of the polarities are sufficient. In addition, simultaneous inversion of the polarities in a cluster are done to retrieve a stress tensor along with focal mechanisms of the individual events in a cluster. A unique cluster of focal mechanisms was obtained from the events taking place in Western High (WH) region located between Tekirdag Basin (TB) and Central Basin (CB). Several features of this cluster are noticeable; 1) the site is the most seismically active part in Marmara Sea, 2) the site is the locus of the deepest events in the Sea of Marmara, 3) the shallower part of this segment is seismically less active, 4) two subgroups of P-axes of focal mechanisms exist; one oriented NW-SE and other oriented in N-S direction despite the proximity of the location of the events giving clues on the faulting dynamics. The N-S oriented P
Diao, Faqi; Wang, Rongjiang; Aochi, Hideo; Walter, Thomas R.; Zhang, Yong; Zheng, Yong; Xiong, Xiong
During the 20th century, a series of devastating earthquakes occurred along the North Anatolian Fault. These generally propagated westwards, such that the main fault segment beneath the Marmara Sea appears as a seismic gap. For the nearby megacity Istanbul, rapid seismic hazard assessment is currently of great importance. A key issue is how a strong earthquake in the Marmara Sea can be characterized reliably and rapidly using the seismic network currently operating in this region. In order to investigate this issue, several scenario earthquakes on the main Marmara fault are simulated through dynamic modelling based on a 3-D structure model. The synthetic datasets are then used to reconstruct the source processes of the causal events with a recently developed iterative deconvolution and stacking method based on simplified 1-D Earth structure models. The results indicate that, by using certain a priori information about the fault geometry and focal mechanism, the tempo-spatial slip patterns of the input scenarios can be well resolved. If reasonable uncertainties are considered for the a priori information, the key source parameters, such as moment magnitude, fault size and slip centroid, can still be estimated reliably, while the detailed tempo-spatial rupture pattern may reveal significant variations. To reduce the effect induced by employing the inaccurate event location and focal mechanism, a new approach for absolute source imaging is proposed and tested. We also investigate the performance of the new source imaging tool for near real-time source inversion under the current network configuration in the Marmara Sea region. The results obtained are meaningful particularly for developing the rapid earthquake response system for the megacity Istanbul.
Kido, Motoyuki; Takahashi, Narumi; Yamamoto, Yojiro; Kalafat, Dogan; Pinar, Ali; Ozeren, Sinan; Ohta, Yusaku; Kaneda, Yoshiyuki
Failure of the North Anatolian Fault (NAF) accompanied by a large earthquake is sequentially propagating to the west in Turley during the last century. However the region of the Marmara Sea, close to populous Istanbul, still remains unmoved and hence expected to have an impending devastating earthquake. In order to evaluate stress accumulation along the unmoved fault, which possibly controls the magnitude of the earthquake, it is crucial to know coupling ratio between the segments across the fault. The NAF is submerged beneath the Marmara Sea and inaccessible using onshore GNSS data. Therefore we have developed five seafloor extensometers and started their operation since September 2014 under SATREPS program between Japan and Turkey to directly measure the fault movement. The installation site is just on the Western High (~700m of depth), where strain partitioning is expected smaller (i.e., strain is concentrated at the main fault) because fewer sub-branches are observed. Four out of the five extensometers are alternately aligned across the fault in oblique direction with a baseline of roughly 1-km for each. The exact position of the fault is inferred from fine-scale bathymetric data based on multibeam surveys provided by Ifremer. The extensometers are designed that the main ranging data with associated information, such as temperature of sea water and etc., can be recovered through an acoustic modem at any time visiting the site without disruption of the measurement and is continuously worked at least 5 years with sampling rate of 12 hours. Based on the high-sampling (30 min.) preliminary data for 24 hours just after the installation, we found that the temporal variation of bottom temperature is quite stable due to strong density stratification in the Marmara Sea. Because of such stable condition, we confirmed that the system can potentially resolve 2-3 mm of shortening or extension along the 1-km-baseline. Maximum displacement across the fault is expected to be 2
Hori, Takane; Yalciner, Ahmet; Ozel, Nurcan; Kilic, Irfan; Miyazaki, Shin'ichi; Hyodo, Mamoru
In order to obtain comprehensive earthquake and tsunami scenarios for disaster assessment, numerical simulations of earthquake generation cycles and resultant tsunami generations have been performed in Japan. The occurrence of the 2011 Tohoku earthquake has realized us the necessity to consider all the possible scenarios without preconceptions. We have performed large-scale numerical simulations using Earth Simulator and K-computer for earthquake generation cycles along the Nankai trough, southwest Japan, where megathrust earthquakes with some segments have sequentially occurred. We have succeeded to reproduce various rupture pattern seen in historical data and geological evidences (such as tsunami deposit) being consistent with GEONET data during interseismic period. Using the results of such earthquake generation cycle simulations, we performed tsunami generation, propagation and inundation simulation. In Turkey, tsunami simulation methods and tsunami scenario database have been developed. In the research project of SATREPS -Earthquake and tsunami disaster mitigation in the Marmara region and disaster education in Turkey, we are applying such earthquake generation cycle and tsunami simulations to the North Anatolian fault system to obtain possible earthquake scenarios and to improve tsunami scenario data base for Sea of Marmara. For the modeling of the fault system, we will use observation results by the earthquake source modeling group in this project to improve the existing models. The earthquake scenarios will be used also for strong motion predictions by the group of seismic characterization and damage prediction. We will visualize the simulation results for disaster education. Furthermore, we will contribute to improve semi-realtime earthquake analyses and tsunami forecasting. In the presentation, we will show some recent simulation results of earthquake generation cycles and tsunamis for Turkey (Marmara sea) and Japan (Nankai trough and Japan trench
Diao, Faqi; Wang, Rongjiang; Aochi, Hideo; Zhang, Yong; Walter, Thomas R.
During the last century, the North Anatolian Fault (NAF) generated a series of devastating earthquakes, which generally propagated westwards, such that the main Marmara fault segment as a seismic gap. For the nearby megacity Istanbul, rapid seismic hazard assessment is currently of great importance. A key issue is how a strong earthquake in the Marmara Sea can be characterized reliably and rapidly using the seismic network currently operating in this region. In the frame of the MARsite project, several scenario earthquakes on the main Marmara fault are simulated through dynamic modelling based on a 3-D structure model. The synthetic datasets are then used to reconstruct the source processes of the causal events with a recently developed iterative deconvolution and stacking method based on simplified 1-D Earth structure models. The results indicate that, by using certain a priori information about the fault geometry and focal mechanism, the tempo-spatial slip patterns of the input scenarios can be well resolved robustly. If reasonable uncertainties are considered for the a priori information, the key source parameters, such as moment magnitude, fault size and slip centroid, can still be estimated robustly, while the detailed tempo-spatial rupture pattern may reveal significant variations. To reduce the effect induced by employing the inaccurate event location and focal mechanism, a new approach for absolute source imaging is proposed and tested for near real-time source inversion under the current network configuration in the Marmara Sea region. The results obtained are meaningful particularly for developing the rapid earthquake response system for the megacity Istanbul.
Chevalier, N; Bouloubassi, I; Birgel, D; Taphanel, M-H; López-García, P
Lipid biomarkers and their stable carbon isotopic composition, as well as 16S rRNA gene sequences, were investigated in sediment cores from active seepage zones in the Sea of Marmara (Turkey) located on the active North Anatolian Fault, to assess processes associated with methane turnover by indigenous microbial communities. Diagnostic (13) C-depleted archaeal lipids of anaerobic methane oxidizers were only found in one core from the South of Çinarcik Basin and consist mainly of archaeol, sn-2 hydroxyarchaeol and various unsaturated pentamethylicosenes. Concurrently, abundant fatty acids (FAs) and a substantial amount of monoalkylglycerolethers (MAGEs), assigned to sulphate-reducing bacteria, were detected with strong (13) C-depletions. Both microbial lipids and their δ(13) C values suggest that anaerobic oxidation of methane with sulphate reduction (AOM/SR) occurs, specially in the 10- to 12-cm depth interval. Lipid biomarker results accompanied by 16S rRNA-based microbial diversity analyses showed that ANME-2 (ANME-2a and -2c) archaea and Desulfosarcina/Desulfococcus and Desulfobulbus deltaproteobacterial clades are the major AOM assemblages, which indicate a shallow AOM community at high methane flux. Apart from the typical AOM lipid biomarker pattern, a (13) C-depleted diunsaturated hydrocarbon, identified as 7,14-tricosadiene, occurred in the inferred maximum AOM interval at 10-12 cm depth. Its isotopic fingerprint implies that its microbial precursor occurs in close association with the AOM communities. Interestingly, the presence of 7,14-tricosadiene coincides with the presence of the so-far uncultured bacterial Candidate Division JS1, often detected in AOM areas. We propose the hypothesis that the JS1 bacterial group could be the potential source of (13) C-depleted tricosadiene. Future testing of this hypothesis is essential to fully determine the role of this bacterial group in AOM. PMID:23205581
Yalçıner, A. C.; Kian, R.; Velioglu, D.; Zaytsev, A.
The movement of sea bottom or ground sediment material by tsunami cause erosion, deposition and hence bathymetry and topogrphy changes. The unexpected depth decrease at some parts of the enclosed basins and harbors may result in lack of movements of vessels. In order to understand the sediment movement inside the enclosed basins, Haydarpasa port in the sea of Marama is selected as a case study to understand the motion of tsunamis inside the port and identify their effects on harbor functions. The highest populated mega city Istanbul, located at north coast of the Sea of Marmara is one of the main centers of major economic activities in the region. In the study, the spatial and temporal changes of main tsunami parameters are investigated and their adverse effects on harbor performance are identified by analyzing the critical tsunami parameters (water elevation, current speed and momentum fluxes) in the port. Furthermore, the morphological changes due to tsunami induced flows are also considered. The morphological changes due to tsunamis can be governed by bathymetry and topography, tsunami current and the characteristics of ground material. Rouse number is one of the indicators to describe the initiation of sediment motion and transport modes under the flow. Therefore the morphological changes can be monitored by monitoring the change of the Rouse number. In this study the spatial and temporal change of Rouse number and hence modes of sediment transport in Haydarpasa port during a tsunami is investigated. Finally the functional loss of the port and the necessary strategies for reduction of tsunami impact and increase of resilience are also discussed. The research leading to these results has received funding from the European Union's Seventh Framework Programme (FP7/2007-2013) under grant agreement No. 603839 (Project ASTARTE - Assessment, Strategy and Risk Reduction for Tsunamis in Europe)".
Ulusoy, Şafak; Özden, Özkan; Päpke, Olaf
Mussel samples were collected monthly between October-2010 and October-2011 from four stations (Bosphorus, Bandırma, Gelibolu, Tekirdağ) in the Marmara Sea. Two consecutive months' samples were homogenized and combined as a single group for analysis. Mussel samples were analyzed for Organochlorine pesticides (OCPs); (total-DDT, total-HCH, Endrin, α-Endosulfan, β-Endosulfan, Heptachlor) and Polychlorinated biphenyls (PCBs); (PCB 28, PCB 52, PCB 138, PCB 153, and PCB 180). All analyses were done according to Eurofins house method in ERGO Laboratory in Germany. Concentrations of α-endosulfan and heptachlor in mussel tissues were below method detection limits. The annual average OCPs concentrations among the stations ranged between 0.02 and 1.45 ng/g (wet weight), 1.9-99.75 ng/g (lipid weight) whereas the annual average PCBs concentrations among the stations ranged between 0.03 and 0.40 ng/g (wet weight), 1.71-26.48 ng/g (lipid weight), respectively. There was no relation between fat content of mussels and residues of the contaminants. PCB 138 and PCB 153 were the most predominant PCBs, while total-DDT and total-HCH were the most predominant OCPs in the mussels. Total-DDT concentrations were higher compared to total-HCH and PCBs isomers. Measured levels were below the national and international committees' and institutions' limits for human consumption and protection of aquatic biota. PMID:27329111
Gasperini, L.; Polonia, A.; Del Bianco, F.; Etiope, G.; Marinaro, G.; Favali, P.; Italiano, F.; ćAǧAtay, M. N.
We carried out a combined geophysical and gas-geochemical survey on an active fault strand along the North Anatolian Fault (NAF) system in the Gulf of İzmit (eastern Sea of Marmara), providing for the first time in this area data on the distribution of methane (CH4) and other gases dissolved in the bottom seawater, as well as the CH4isotopic composition. Based on high-resolution morphobathymetric data and chirp-sonar seismic reflection profiles we selected three areas with different tectonic features associated to the NAF system, where we performed visual and instrumental seafloor inspections, including in situ measurements of dissolved CH4, and sampling of the bottom water. Starting from background values of 2-10 nM, methane concentration in the bottom seawater increases abruptly up to 20 nM over the main NAF trace. CH4 concentration peaks up to ˜120 nM were detected above mounds related probably to gas and fluids expulsion. Methane is microbial (δ13CCH4: -67.3 and -76‰ versus VPDB), and was found mainly associated with pre-Holocene deposits topped by a 10-20 m thick draping of marine mud. The correlation between tectonic structures and gas-seepages at the seafloor suggests that the NAF in the Gulf of İzmit could represent a key site for long-term combined monitoring of fluid exhalations and seismicity to assess their potential as earthquake precursors.
ÇUBUK, Y.; Fichtner, A.; Taymaz, T.
The Marmara and Northwestern Anatolia regions are known to be a transition zone from the strike-slip tectonics to the extensional tectonics. Although, the Sea of Marmara has been subjected to several active and passive seismic investigations, the accurate knowledge on the heterogeneity in the crust and upper mantle beneath the study area still remains enigmatic. On small-scale tomography problems, seismograms strongly reflect the effects of heterogeneities and the scattering properties of the Earth. Thus, the knowledge of high-resolution seismic imaging with an improved 3D radially anisotropic crustal model of the Northwestern Anatolia will enable better localization of earthquakes, identification of faults as well as the improvement of the seismic hazard assessment. For this purpose, 3D non-linear full waveform inversion methodology has been used to obtain an accurate image of the lithosphere and the upper-most mantle structure over an area of 37.5˚-42˚ N and 25˚-32˚ E and down to a depth of 471 km. The earthquake data were principally obtained from the Kandilli Observatory and Earthquake Research Institute (KOERI) and Earthquake Research Center (AFAD-DAD) database. In addition to this, some of the seismic waveform data extracted from the Hellenic Unified Seismic Network (HUSN) stations that are located within our study region were also used in this study. We have selected and simulated the waveforms of earthquakes with magnitudes Mw ≥ 4 occurred in the period of 2007-2014. In total, 3002 three-component regional seismograms from 95 events were used. The initial 3D earth model for the study region has been implemented from the multi-scale seismic tomography study of Fichtner et al. (2013). The synthetic seismograms were computed with forward modeling of seismic wave propagation by using spectral elements method (SEM). The complete waveforms were filtered at 8-100 seconds. The adjoint method is used to compute sensitivity kernels. The differences between
Aksu, Abdullah; Balkis, Nuray; Taşkin, Omer S; Erşan, Mahmut S
Toxic metals (Pb, Cd, As and Hg) and organochlorine residue levels were measured in hake (Merluccius merluccius) from the Marmara Sea. Biota samples were collected by a trawling cruise of the R/V ARAR in August and December 2009. The concentrations of toxic metals varied between Pb, 3.23-14.4; Cd, <0.01-2.14; Hg, 0.01-0.18 and As, 0.01-0.21 [Formula: see text]g g(-1) dry wt. Pb levels in the Marmara Sea were found to be higher than the critical limits set by the both Turkish Ministry of Environment for Aquatic Products (1 μg g(-1) wet wt.) and European countries (2.0 μg g(-1), UNEP 1985). In contrast, As and Hg levels were found to be lower than the critical limits for two periods. Cd contents of fish from the Marmara Sea were also comparable to or slightly lower than contents of fish from the Southern Black Sea Shelf. The results of organochlorine residues ranged between total HCH, <0.05 and 99 ng g(-1); endrin, <0.001 and 381 ng g(-1); alpha-endosulphan, <0.05 and 90 ng g(-1); beta-endosulphan, <0.05 and 15.3 ng g(-1); o,p DDE, 3.5 and 52.4 ng g(-1); p,p DDE, 7.4 and 139 ng g(-1); o,p DDD, 1.5 and 90.2 ng g(-1) and p,p DDD, 2.7 and 86 ng g(-1) wet weight. The rivers for the distribution of organochlorine levels in the Marmara Sea ordered from highest to lowest as Dil R. > Susurluk R. > Biga R. > Gönen R. The high levels of o,p and p,p DDE, and o,p and p,p DDD compounds, which are metabolites of DDT, indicate its illegal use. Toxic metal and organochlorine residue levels of fish are significantly higher than levels from the Mediterranean Sea. PMID:21336486
Murru, M.; Akinci, A.; Falcone, G.; Pucci, S.; Console, R.; Parsons, T.
We forecast time-independent and time-dependent earthquake ruptures in the Marmara region of Turkey for the next 30 years using a new fault segmentation model. We also augment time-dependent Brownian passage time (BPT) probability with static Coulomb stress changes (ΔCFF) from interacting faults. We calculate Mw > 6.5 probability from 26 individual fault sources in the Marmara region. We also consider a multisegment rupture model that allows higher-magnitude ruptures over some segments of the northern branch of the North Anatolian Fault Zone beneath the Marmara Sea. A total of 10 different Mw = 7.0 to Mw = 8.0 multisegment ruptures are combined with the other regional faults at rates that balance the overall moment accumulation. We use Gaussian random distributions to treat parameter uncertainties (e.g., aperiodicity, maximum expected magnitude, slip rate, and consequently mean recurrence time) of the statistical distributions associated with each fault source. We then estimate uncertainties of the 30 year probability values for the next characteristic event obtained from three different models (Poisson, BPT, and BPT + ΔCFF) using a Monte Carlo procedure. The Gerede fault segment located at the eastern end of the Marmara region shows the highest 30 year probability, with a Poisson value of 29% and a time-dependent interaction probability of 48%. We find an aggregated 30 year Poisson probability of M > 7.3 earthquakes at Istanbul of 35%, which increases to 47% if time dependence and stress transfer are considered. We calculate a twofold probability gain (ratio time dependent to time independent) on the southern strands of the North Anatolian Fault Zone.
Murru, Maura; Akinci, Aybige; Falcone, Guiseppe; Pucci, Stefano; Console, Rodolfo; Parsons, Thomas E.
We forecast time-independent and time-dependent earthquake ruptures in the Marmara region of Turkey for the next 30 years using a new fault-segmentation model. We also augment time-dependent Brownian Passage Time (BPT) probability with static Coulomb stress changes (ΔCFF) from interacting faults. We calculate Mw > 6.5 probability from 26 individual fault sources in the Marmara region. We also consider a multisegment rupture model that allows higher-magnitude ruptures over some segments of the Northern branch of the North Anatolian Fault Zone (NNAF) beneath the Marmara Sea. A total of 10 different Mw=7.0 to Mw=8.0 multisegment ruptures are combined with the other regional faults at rates that balance the overall moment accumulation. We use Gaussian random distributions to treat parameter uncertainties (e.g., aperiodicity, maximum expected magnitude, slip rate, and consequently mean recurrence time) of the statistical distributions associated with each fault source. We then estimate uncertainties of the 30-year probability values for the next characteristic event obtained from three different models (Poisson, BPT, and BPT+ΔCFF) using a Monte Carlo procedure. The Gerede fault segment located at the eastern end of the Marmara region shows the highest 30-yr probability, with a Poisson value of 29%, and a time-dependent interaction probability of 48%. We find an aggregated 30-yr Poisson probability of M >7.3 earthquakes at Istanbul of 35%, which increases to 47% if time dependence and stress transfer are considered. We calculate a 2-fold probability gain (ratio time-dependent to time-independent) on the southern strands of the North Anatolian Fault Zone.
Geli, L.; Henry, P.; Andre, C.; Zitter, T.; Cagatay, N.; Mercier de Lepinay, B.
For the first time, marine heat flow data were collected in the Sea of Marmara, in 2007, during the MarNaut cruise of R/V L'Atalante. A total of 45 heat flow measurements were carried out along three transects, respectively : the Tekirdag, the Central and the Cinarçik basins. The data were collected using 7 Micrel autonomous digital temperature probes fitted on a 10 cm-diameter gravity corer (the tube length was 10 m for the first 5 measurements ; 5 m for the remaining ones). The thermal profiles are linear, except near the very surface, where slight changes in water bottom temperature can be suspected. The measured heat flow values range between about 15 and 55 mW.m-2, except at one single location near the northern Cinarcik Basin escarpment, where heat flow reaches 120 mW.m-2, probably in response to deep, upward fluid flow. The measured values are lower than the published regional heat flow averages, which are of about 50 to 60 mW.m-2 and of about 100 mW.m-2 north and south of the Sea of Marmara, respectively. The lowest values correspond to the basins depocenters, where the syn-rift sediment cover is thickest, which suggests strong thermal sediment blanketing effects. Near the edges of the basins, effects resulting from basement topography are also suspected. Corrections are made to account for both effects, assuming different scenarii for the temporal and spatial evolution of the sedimentation rate. The computation results provide constraints to estimate the age of initiation of the North Anatolian Fault within what is now the Sea of Marmara.
Ülgen, S. C.; Okay, A. I.; Özcan, E.; Şengör, A. M. C.; Akbayram, K.
The study of a Ypresian flysch sequence, immediately southern of the Intra-Pontid suture zone and overlying the Upper Cretaceous basement rocks, permit us to comment on the late Cretaceous-early Tertiary tectonic history of the region This flysch sequence with a thickness 1500-2000 m consisting of sandstones, shales and conglomerates derived from the Upper-Cretaceous basement rocks. These clastics are intercalated with andesitic tuffs, pyroclasts, agglomerates and lenticular limestones. The flysch contains some larger foraminifera levels including Orbitoclypeus douvillei douvillei, O. douvillei yesilyurtensis, O. schopeni ex. interc. suvlukayensis-crimensis, O. schopeni crimensis, O.munieri munieri, Asterocyclina alticostata cf. gallica, , Discocyclina fortisi simferopolensis. The Ypresian flysch overlies a unit which consists of quartz conglomerate and boulders, chert, serpentinite , metamorphic rock blocks and conglomerates. Some think this unit to be a debris flow, but the range of rock types, the style of deformation and the its areal extent clearly shows it could be a mélange. Gravity flows like mudflows, slump folds and NW-SE trending anticline and synclines are observed and mapped in Ypresian flysch which suggest that it was tectonized during or soon after deposition. Anticlines, synclines and north-nortwest dipping thrust faults point SE vergance in the region. Also earlier published apatite fission track data from metamorphic rocks cropping out at south of Marmara Sea shows that nearby areas uplifted during Early Eocene (~ 52 Ma). We suggest that there are two probable sources for this tectonism in northwest Turkey; the compression related to the consumption of the Intra-Pontide Ocean in the north or the Late Cretaceous-Paleocene collision of Pontides and Taurides in the south.
Unlü, Selma; Alpar, Bedri
Seabottom sediments from Gemlik Bay, one of the most polluted spots in SW Marmara Sea, were analyzed for parent polycyclic aromatic hydrocarbons (PAHs) using gas chromatography-mass spectrometry. The concentration of 14 PAH compounds in sediment samples collected from 61 locations are distributed in a broad spectrum from low to very high concentration levels (50.8-13482 ng g-1). No significant correlation was found between summation operatorPAHs and organic carbon content while summation operatorPAHs increase slightly with silt/clay ratio. Therefore the distribution and concentrations of PAHs would be determined more by direct input, rather than by the type of sediment found locally. The most polluted areas are distributed nearshore eastern (Gemlik) and southern (Kursunlu, Mudanya and Trilye) coasts which are mainly influenced by rapid ecotourism development, direct discharges from rivers, surface run-off and drainage from port areas, domestic and industrial effluent discharges through outfalls and various contaminants from ships. Special PAH compound ratios, such as Phe/Anth, Flu/Py, B[a]A/Chry; LMWPAH/HMWPAH; Per/; Per/summation operatorPAH; Per/summation operator(penta-aromatics) and Flu/(Py+Flu), were calculated to evaluate different hydrocarbon origins and their relative importance. Pyrolytic activity is dominant along the highly-populated eastern and southern coasts. Meanwhile, petrogenic activity mixed with pyrolytic activity is a matter of fact in front of the main industrial-tourism ports and anchoring areas as well. Higher concentration of perylene are distributed along the mostly polluted eastern and southern coastal areas, however, the concentrations of perylene relative to the penta-aromatic isomers are dominant especially in the northern and deepest sectors of the bay, indicating diagenetic origin for the presence of perylene. PMID:16376968
Çağatay, M. N.; Erel, L.; Bellucci, L. G.; Polonia, A.; Gasperini, L.; Eriş, K. K.; Sancar, Ü.; Biltekin, D.; Uçarkuş, G.; Ülgen, U. B.; Damcı, E.
Sedimentary earthquake records of the last 2400 a, including that of the devastating 17 August 1999 İzmit earthquake (Mw = 7.4), were studied in cores from the 210 m-deep central Karamürsel Basin of the İzmit Gulf in the eastern Sea of Marmara, using laser grain-size, physical properties, stable O and C isotopes and XRF Core Scanner analyses, and dated by radionuclide and radiocarbon methods. The earthquake records are represented by turbidite-homogenite mass-flow units (THU) that commonly contain a basal coarse layer, a middle laminated silt layer and an overlying homogeneous mud layer. The coarse basal part has a sharp and sometimes scoured lower boundary, and includes multiple coarse (sand/silt) layers or laminae showing normal size grading. Multiple coarse layers and occasional bi-directional cross-bedding suggest deposition from a bed-load during water column oscillations, or seiche effect. The grain-size characteristics of the overlaying laminated silt and the homogeneous mud units indicate deposition from weak oscillating currents and homogeneous suspension, respectively. High Mn value just below the base of THUs suggests diagenetic enrichment at oxic/anoxic redox boundary before the mass-flow event. Sharp decrease in Mn with very low values within the THUs suggests transient redox conditions following the mass-flow. Variable geochemical compositions of the basal coarse layers indicate different sediment sources for different THUs. Eight sedimentary earthquake records observed in the last 2400 a in the İzmit Gulf can be confidently correlated with the historical earthquakes of 1999, 1509 AD (Ms = 7.2), 1296 AD (I = VII), 865 AD (I = VIII), 740 AD (I = VIII), 268 AD (I = VIII), 358 AD (I = IX), and 427 BC. This gives an earthquake recurrence time of ca. 300 a, with the interval between consecutive events ranging from 90 to 695 a.
Viana, M; Fann, N; Tobías, A; Querol, X; Rojas-Rueda, D; Plaza, A; Aynos, G; Conde, J A; Fernández, L; Fernández, C
Ship emissions degrade air quality and affect human health, and are increasingly becoming a matter of concern. Sulfur emission control areas (ECA), specific coastal regions where only low-sulfur fuels may be consumed by ocean-going ships, have proven to be useful tools to reduce ship-sourced air pollution along the North American, Canadian, and European North and Baltic Sea coastlines. The present work assesses the environmental and health benefits which would derive from designating an ECA in the Marmara Sea and the Turkish Straits (50 000 ships/year; 23 million inhabitants). Results show evidence that implementing an ECA would be technically viable and that it would reduce ship-sourced PM10 and PM2.5 ambient concentrations in Istanbul by 67%, and SO2 by 90%. The reduction of the air pollution burden on health was quantified as 210 hospital admissions from exposure to PM10, 290 hospital admissions from exposure to SO2, and up to 30 premature deaths annually due to ECA emission controls. Consequently, the designation of an ECA in the Marmara Sea and the Turkish Straits is evaluated as a positive, technically viable and real-world measure to reduce air pollution from ships in Turkey. PMID:25700153
Cagatay, M. Namik; Biltekin, Demet; Erel, Levent; Henry, Pierre; Gasperini, Luca; McHugh, Cecilia M.; Grall, Celine; Gungor, L. Nurdan; Gungor, Emin; Polonia, Alina; Zabci, Cengiz; Akkok, Remzi
Long-term paleoearthquake history of faults is important for probabilistic earthquake risk assessment. Such records can be obtained from the study of mass-transport units triggered by seismic activity in marine and lake basins. The Sea of Marmara (SoM), located on the North Anatolian Fault (NAF), is an important laboratory for the study of paleoearthquake records, mainly because it has: a) more than 2000 years of historical earthquake records with which radiometrically dated sedimentary earthquake records can be correlated, b) high sedimentation rates (≤3m/kyrs) so that individual events can be distinguished, and c) cold fluid and hydrocarbon seeps along active faults, leaving sedimentary and geochemical signatures of earthquake activity. After the destructive 1912 Mw 7.4 Mürefte and 1999 Mw 7.4 Izmit and Mw 7.2 Duzce earthquakes, the SoM represent a seismic gap. It is therefore crucial to obtain information on the long-term earthquake history of the NAF in the SoM. We have carried out a systematic study of the 24 cores recovered from the various Marmara basins and highs characterizing the different segments of the NAF, using high resolution digital X-Ray Radiography and µ-XRF Core Scanner, MSCL physical properties and grain-size analyses. The chronology was determined using AMS radiocarbon and radionuclide methods. Turbidite-homogenite deposits (TH) triggered by earthquakes are commonly characterized by multiple sand-silt laminae above a sharp and often erosional base and a homogeneous mud at the top. However, in shallow basins (<110 m) such as Gölcük and Gemlik, the TH units consists of red brown coarse to medium silt units having a sharp basal boundary. The basal TH parts have high gamma density and magnetic susceptibility, and are often enriched in one or more of elements, such as Si, Zr, Ca, Ti, K and Fe, indicative of coarse detrital silicate and carbonate shell input. Radionuclide and radiocarbon dated TH units in different basins of the SoM can be
Sabuncu, Asen; Kadir Eriş, K.; Kaslilar, Ayse; Namık Çaǧatay, M.; Gasperini, Luca; Filikçi, Betül
The Gulf of Gemlik is an E-W elongated trans-tensional basin with a maximum depth of 113 m, located on the middle strand of the North Anatolian Fault (NAF) in the south eastern part of the Sea of Marmara (SoM). While during the Holocene the sea level in the Gulf of Gemlik changed in tandem with the water level changes in the SoM, it may have been different in the late glacial when the Sea of Marmara was lacustrine. Beside the tectonic activity related to the NAFZ, eustatic sea level changes would have controlled the basin evolution and consequent sedimentary history during the different paleocanographic phases of the SoM. Considering the limited studies on the late glacial-Holocene stratigraph of the Gulf of Gemlik, this study aims to investigate the depositional units and their environments with respect to different allogenic and autogenic controls. For these purposes, we analyzed over 300 2 - 7 kHz bandwidth high-resolution gridded seismic sub-bottom CHIRP profiles together with 70 kHz high resolution multibeam bathymetry with backscatter data. Four seismic stratigraphic units were defined and correlated with chronstratigraphic units in five piston cores covering the last 15.8 ka BP according to radiocarbon ages (14C). The depth-scale accuracy of chronostratigraphic units in cores is of key importance for the precise calculation of sedimentation rates. Correlation between the seismic profiles and cores were made by matching Multi-Sensor Core-Logger (MSCL) data and seismic reflection coefficients and amplitudes for different stratigraphic units. The impedance data derived from the logger were used to generate a synthetic seismogram. We used an approach to display, estimate, and correct the depth-scale discrepancies due to oversampling affecting the upper part of sedimentary series during piston coring. The method is based on the resynchronization of synthetic seismograms computed from high-quality physical property logs to the corresponding CHIRP profiles. Each
Altinok, Y.; Alpar, B.; Cagatay, M. N.; Akcer, S.; Unlu, S.; Balkis, N.; Ozer, N.; Aykurt, H.
The coasts of the Sea of Marmara have been hit by numerous tsunami waves in the past, which might have surged up along its northern coastal strip and invaded inland more than 2 km. In order to understand and determine the tsunami potential and their possible effects along these coasts, detailed studies are needed on the past earthquake- and landslide-related tsunamis whose effects are presently unknown. These studies include gathering appropriate historical data, mapping out the underwater topography in detail, determining the active faults and underwater landslides and modeling. Marine geophysical works and numerical wave modeling applications show that three near surface faults out of six main structural elements outlined in the Sea of Marmara may trigger tsunami waves which may be effective along the northern coast. These are the west boundary fault of east Marmara ridge, the northern boundary fault of the middle Marmara ridge and the segment of Kumburgaz-Gaziköy. Ground motions on these fault segments may cause important wave runups along the coasts of Buyukcekmece and Kucukcekmece lagoons in the north with 2.5 to 4.5 m high waves depending on their source mechanism. Another indispensable study is to trace paleo-tsunami deposits in low-energy depositional environments such as coastal wetlands and places protected from the sea by sand barriers. The coasts of the Sea of Marmara, however, have been under rapid urbanization during last 50 years and only a very few areas preserve original coastal sediment successions. Meanwhile lagoons may also be important depositional areas for tsunami deposits and protect them from post-depositional erosion. The Kucukcekmece lagoon, which is separated from the sea by a narrow strip of sandbar (300-350 m), was investigated in the present study. A piston core (TKÇ-5) was recovered in the southern part. It is 463 cm long and composed by fine sediments, from clay to silt, with some distinctive thin coarse grained layers. An
Çolakoğlu, Serhat; Palaz, Mustafa
Ruditapes philippinarum, a venerid clam, is a dominant species in the sandy and muddy areas in the coastal waters of the Marmara Sea. Intensive commercial harvesting of this species is conducted in these regions. We studied the population dynamics of R. philippinarum on the southern coast of the Marmara Sea (Bandırma). Samples were collected on a monthly basis between September 2012 and August 2013. Seasonal von Bertalanffy growth parameters using the length-frequency distribution of R. philippinarum were estimated at L ∞ = 67.50 mm and K = 0.33 year-1, and the seasonal oscillation in growth rate was 0.53. The slowest growth period was in January. The growth performance index and potential lifespan were 3.182 and 8.06 years, respectively. The growth relationship was confirmed to have a positive allometric pattern. The average total mortality rate was estimated to be 0.777 year-1, whereas the natural and fishing mortality rates were 0.539 and 0.238 year-1, respectively. The current exploitation rate of R. philippinarum was 0.306. The recruitment pattern peaked during June-August, and spawning occurred between May and August. The results of this study provide valuable information on the status of R. philippinarum stocks.
The North Anatolian Fault (NAF) get across the mainland of Turkey is known as a quite active strike slip fault. The earthquake recurrence period for individual segment is estimated roughly 300 years based on historical records. The Marmara Segment is the major seismic gap since the last earthquake in 1766, while the Murefte earthquake occurred in 1912 at its west side and the Izmit earthquake in 1999 at its east side. The relative motion across the NAF is ~22 mm/yr based on the data from space geodesy. Investigating how much degree of this displacement is released by aseismic creep or accumulated by slip deficit in the Marmara Segment is crucial to know the total seismic risk in this region. Because the NAF is submerged in the Sea of Marmara and is inaccessible by space geodesy, we employed seafloor geodetic technique using extensometers, which acoustically monitor baseline length across a strain-localized zone, such as surface trace of a fault. In 2014, we installed five extensometers at the Western High crossing the NAF one after the other, where the surface trace of the NAF is prominent and gas emission from the seafloor is reported in. Totally four beselines of ~1 km range are successfully formed and quality of initial test data was promising. Based on the initial data, detectable level of the baseline change is estimated to be ~2mm, which owing to quite stable seawater near the bottom due to strong density stratification in the Sea of Marmara. The extensometers are designed that data can be recovered via acoustic modem without disrupt the monitoring. Since the installation, we have visited the site twice and have recovered the data for ten months in total. Temperature measured by thermistor equipped on each extensometer showed coherent change and gradual increase by 0.007 degree during the period. This reflects apparent beseline shortening due to the corresponding increase of the sound speed. In the preliminary temperature correction, difference of the change
Passarelli, Luigi; Seyis, Cemil; Woith, Heiko
Typically, the noble gas radon displays cyclic daily (S1), semidiurnal (S2) as well as seasonal variations in geological environments like soil air, groundwater, rock, caves, and tunnels. But there are also cases where theses cycles are absent. We present examples from a radon monitoring network of 21 sites around the Sea of Marmara. The works were carried out in the frame of MARsite, a project related to the EU supersite initiative (MARsite has received funding from the European Union's Seventh Programme for research, technological development and demonstration under grant agreement No 308417). Alpha-meters from the Canadian company alpha-nuclear are used to measure the radon concentration in counts per 15 minutes at a depth of 80 cm. The long-term average radon concentrations at 21 sites vary between 35 and 1,000 counts per 15 minutes. Typical seasonal variations are absent at more than 6 sites. Sites with seasonal variations have radon minima usually during winter (December to April), radon maxima during summer months (June to October). We carefully investigated radon time series for all the monitoring stations. We find that at some sites the empirical distribution of radon counts is clearly bimodal and in other bimodality is absent. In those stations we analysed the time series in different time intervals in order to highlight seasonal periodicity in the radon emission. The empirical distributions obtained by time-windowing of the radon signals results to be statistically different one another after applying a Kolmogorov-Smirnov test at significance level of 0.1. Usually the maxima in radon emission occur in summer time but, interestingly enough, two sites are characterized by radon maxima in winter periods. We further investigate the radon signals seeking for smaller scale periodicity. We calculated Fourier spectra of all 21 sites. Daily cycles are absent at 6 sites which is an unusual phenomenon. Daily cycles may disappear, if the local system is heavily
Filikci, Betül; Kadir Eriş, K.; Namık Çaǧatay, M.; Gasperini, Luca; Sabuncu, Asen; Acar, Dursun; Yalamaz, Burak
Gulf of Gemlik is an east-west oriented marine inlet with a maximum depth of 113 m in the south-eastern part of the Sea of Marmara. It is located on the middle branch of the North Anatolian Fault Zone. While the Gulf of Gemlik is separated from the SoM by a bedrock sill at -50 m, there were presumably several disconnections during the Late Pleistocene to Holocene, but the timing of the youngest connection around the onset of the Holocene is still controversial. Here, we attempt to elucidate the paleoceanographic and paleoenvironmental changes during the late glacial-Holocene using the multi-proxy analysis of a core extending back to 13 ka BP. The multi-proxy data include physical and geochemical properties together with AMS 14C ages. The core sediments covering the time period of the last 13 ka BP consists of two main lithostratigraphic units. The lower Unit L2 represents the lacustrine phase of the gulf prior to 10.6 ka BP, while the upper Unit L1 is an overlying transgressive mud drape deposited during the main part of the Holocene. Unit L2 deposited prior 10.6 ka BP represents Bølling-Allerød and Younger Dryas climatic periods, when prograding shelf edge sediments were deposited in the form of well sorted medium sands with brackish water bivalve shells (Dreissenapolymorpha). At the beginning of the Holocene, the rising sea level in the Sea of Marmara breached the -50 m sill at 10.6 ka BP, and therefore the Gulf of Gemlik was converted into a marine realm. Soon after, the water stratifications allowed to the formation of the previously studied two sapropels in the gulf, as shown by increased TOC contents. μ-XRF Ca/Ti and Sr/Ca profiles of Unit L1 provide evidence of rapid climatic changes at 8.2 ka BP and 4.2 ka BP, representing cold and dry short climatic periods which are well correlated with previous marine and lake studies in İznik Lake south of the Sea of Marmara. Keywords: Gemlik Gulf, core, paleoclimate, Late Pleistocene to Holocene
Ünal Yümün, Zeki; Murat Kılıç, Ali; Önce, Melike
In the area between Silivri (İstanbul) and Kumbagi (Tekirdag), NW of Marmara Sea, there is a considerable extent in marine pollution from industrial and settlements wastes, sea transports, and agricultural activities. The most important one of these pollutions is the spread of heavy metals. Our research investigated sediments in order to determine whether heavy minerals affected biota such as recent foraminifers, or not. Our investigation area starts from Marmara Ereglisi, in the east, continues to Tekirdag and Kumbagi, in the west. 10 sea-water samples, 10 sediment-core samples and one 10 m core-drilling sample, taken 250 m off-shore from coast line. As a result of this sampling geochemical analysis of the bottom-mud and water samples were done and the ratio of heavy metals and other contaminants determined. For heavy metal analyses, concentration analysis of 12 heavy metals (Cd, Fe, Cu, Pb, Zn, Al, Co, Cr, Mn, Ni, As, and Hg) has been conducted, as ppm, in sediment samples taken from the levels in which foraminifers are collected. Perpendicular (spatial) heavy metal concentration changes have been determined with off-shore drilling samples and horizontal changes (geochronological) have been determined with the help of core samples. Especially, it has been understood that heavy metal concentrations in recent sediments are higher compared to the past. In this research the samples have been taken from each 10 cm. of core and drilling samples to collect the benthic foraminifers. In this context, 15 grams of dry sediment sample taken from each level, have been washed in 125 μm sieves in order to determine its benthic foraminifer content. Benthic foraminifera from these samples have been identified taxonomically and their morphological differentiation has been determined after taking SEM photos. As a result of this study, the foraminifera types of "Adelosinacliarensis, Adelosinamediteranensis, Adelosinapulchella, Ammonia compacta, Ammonia parkinsonia, Ammonia tepida
Akinci, Aybige; Aochi, Hideo; Herrero, Andre; Pischiutta, Marta; Karanikas, Dimitris
The city of Istanbul is characterized by one of the highest levels of seismic risk in Europe and the Mediterranean region. The important source of the increased risk in Istanbul is the remarkable probability of the occurrence of a large earthquake, which stands at about 65% during the coming years due to the existing seismic gap and the post-1999 earthquake stress transfer at the western portion of the North Anatolian Fault Zone (NAFZ). In this study, we have simulated hybrid broadband time histories from two selected scenario earthquakes having magnitude M>7.0 in the Marmara Sea within 10-20 km of Istanbul believed to have generated devastating 1509 event in the region. The physics-based rupture scenarios, which may be an indication of potential future events, are adopted to estimate the ground motion characteristics and its variability in the region. Two simulation techniques (a full 3D wave propagation method to generate low-frequency seismograms, <~1 Hz and a stochastic technique to simulate high-frequency seismograms, >1Hz) are used to compute more realistic time series associated with scenario earthquakes having magnitudes Mw >7.0 in the Marmara Sea Region. A dynamic rupture is generated and computed with a boundary integral equation method and the propagation in the medium is realized through a finite difference approach (Aochi and Ulrich, 2015). The high frequency radiation is computed using stochastic finite-fault model approach based on a dynamic corner frequency (Motazedian and Atkinson, 2005; Boore, 2009). The results from the two simulation techniques are then merged by performing a weighted summation at intermediate frequencies to calculate broadband synthetic time series. The hybrid broadband ground motions computed with the proposed approach are validated by comparing peak ground acceleration (PGA), peak ground velocity (PGV), and spectral acceleration (SA) with recently proposed ground motion prediction equations (GMPE) in the region. Our
Armijo, R.; Meyer, B.; Navarro, S.; King, G.; Barka, A.
Between 1939 and 1999 the North Anatolian fault (NAF) experienced a westward pro- gression of eight large earthquakes over 800 km along its morphological trace. The 2000-km-long North Anatolian transform fault has also grown by westward propa- gation through continental lithosphere over a much longer time scale (~10 m.y.). As the Arabia/Europe collision progressed in eastern Turkey it caused Anatolia to move to the West and the North Anatolian Fault to propagate along the Pontides and into the northern Aegean. The early slow extension in the Aegean started to be modi- fied about 5 Ma ago. At 1 Ma the process of propagation dramatically increased the activity of the Corinth Rift in Greece, where Pleistocene marine terraces have been rapidly uplifted. The Sea of Marmara is a large pull-apart which appears to have been a geometrical/mechanical obstacle encountered by the NAF during its westward prop- agation. New high-resolution data (bathymetry, side-scan sonar, seismics) provide a precise image of the structure and the evolution of the submarine fault system that forms a smaller pull-apart beneath the Northern Sea of Marmara, between two well- known strike-slip faults on land (Izmit and Ganos faults). The outstandingly clear submarine morphology shows a segmented fault system including pull-apart features at a range of scales, which indicate a dominant transtensional tectonic regime. There is no evidence for a single, throughgoing, purely strike-slip fault. This result is criti- cal to our understanding of the seismic behaviour of this region of the NAF, close to Istanbul. There is morphological and geological evidence for a stable kinematics con- sistent both with the long-term displacement field determined for the past 5 m.y. and with the present-day Anatolia/Eurasia motion determined with GPS. However, within the Sea of Marmara region the fault kinematics involves asymmetric slip partitioning which appears to have extended throughout the evolution of the pull
Cros, Estelle; Géli, Louis; Bayrakci, Gaye; Cagatay, Namik; Gürbüz, Cemil
The Marmara Sea is located between the Agean Sea and the Black Sea, along the North Anatolian strike-slip fault, which experienced a sixty year sequence of earthquakes since 1940. Prior to this sequence, which ended with the Izmit and Duzce earthquakes in 1999, at the eastern end of the Sea of Marmara (SoM), the fault ruptured to the west in 1912 in Ganos, with an estimated moment magnitude of 7.4. Therefore, a major earthquake is expected within the SoM seismic gap. In order to better understand the seismicity and to reduce the threshold of detection, a network of ten OBS with four components was deployed by Ifremer with R/V Yunus of Istanbul Technical University, in the western and central parts of the Marmara Sea to record the micro-seismicity from the immediate vicinity of the main Marmara Fault, between April and August, 2011. The network was specifically designed to survey the segments crossing the Western High, where gas hydrates where recently found, the Central Basin and the Kumburgaz Basin. During this period more than one hundred earthquakes were detected by the EMSC (European-Mediterranean Seismological Centre) in the Sea of Marmara. Because the basins of the Sea of Marmara are filled with more than 5 km of Plio- Quaternary soft ("slow") sediments, it is of critical importance to take into account the velocity structure of the offshore domain, which is drastically different from the one onshore, and the bathymetry. To improve the localization of seismic events, a 3D velocity model was thus considered and implemented in the Sytmis software developed by INERIS. This model is based on the tomographic data collected in 2001 using a controlled source experiment and on the numerous multichannel seismic profiles that provide information on, respectively, the deeper structures and the upper, sedimentary layers. Preliminary results are presented. Special focus will be given on the clustering of the micro-seismicity in the Western High and on a swarm event. As a
We present here two data set composed of about 20 multichannel seismic data profiles, for a total of 1102 km of data acquired in the Sicilia Channel in Italy and Marmara Sea in Turkey. The data set of Multichannel seismic reflection profiles and well information acquired for commercial purpose by oil companies in the 1970's and 1980's. All profiles in Sicilia Channel, which are available on .pdf files were downloaded from VIDEPI website. Other profiles in Marmara Sea were taken from Turkish Petroleum Corporation. The first step was to convert the graphic files SEG-Y format files, using SeisTrans® software. Due to the great inhomogeneity of the various seismic lines, which have been recorded from different companies with different acquisition parameters, it has been necessary a great job of homogenization and noise reduction through the use of adequate band-pass filters. Then, for each reconstructed seismic line, SEG-Y header editing was necessary in order to assign the CDP (common-depth-points) and the SP (shot points) to the corresponding geographic coordinates. The SEG-Y files so created were uploaded and archived into a project using the Kingdom Suite® seismic package. To perform the calibration of seismic data with the stratigraphic wells, the classic problem is to identify on seismic profiles the reflections corresponding to the lithological variations identified in the wells. This is because the vertical scale of the seismic data is expressed in time, while that of the wells is expressed in meters. The main unknown is then the sound velocity within the different lithologies. In order to better correlate real data reflections with the corresponding stratigraphic discontinuities, synthetic seismogram have been created from the reflectivity series obtained through acoustic impedance calculations. They represent an example of forward modeling to match as closely as possible the real seismic data.
Eris, K. K.
Late Glacial to Holocene sedimentary record of the northern shelf of the Sea of Marmara (SoM) is documented by detailed stratigraphic analysis of sub-bottom (Chirp) profiles and sediment cores. The reflection profiles reveal the presence of four seismic stratigraphic units S4-S1 that are equivalent to lithostratigraphic units L4-L1, separated from each other by shelf-crossing unconformities of Q1 to Q3. The seismic profiles from the SoM entrance to the Strait of İstanbul (SoI) allow us to divide the Holocene sediments of Unit S1 into seven sub-units, therefore, we can estimate high-frequency sealevel fluctuations. The SoM was converted into freshwater lake in the beginning of the marine isotope stage 3 (MIS-3) due to global sealevel fall below the Dardanelles outlet (-83 m). During the MIS-3 and main part of the MIS-2, disconnection with the Mediterranean Sea and the forced regression in the SoM gave rise to deposition of progradational units (seismic units S4 and S3) as sediment wedges thickening towards the shelf edge. The maximum lowstand of the ‘Marmara lake' is associated with river incisions below to 105 m water depth, above which a prominent erosional surface formed on the shelf. In contrast to the LGM disconnection with the Mediterranean Sea, the SoM experienced a period of Black Sea outflow between 15-13.5 14C ka BP, when the Black Sea level rised above the sill depth (-35 m) of the SoI. This gave rise to a freshwater transgression in the lake leading to rise the water level to -85 m by 13 ka BP. Following the reconnection with the Mediterranean Sea at 12 ka BP, the Younger Dryas (YD) cold period in the SoM was associated by a Black Sea outflow at 11.5 ka BP leading to formation of a levee within the axis of the paleo Bosphorus shelf valley. During the YD, the sealevel increase was interrupted by stillstands at -76 m and -71 m. In the seismic profiles from the SoM entrance to the SoI, the colonization of algal-serpulid bioherms across the reflector
Atgın, O.; Çifçi, G.; Sorlien, C.; Seeber, L.; Steckler, M.; Sillington, D.; Kurt, H.; Dondurur, D.; Okay, S.; Gürçay, S.; Sarıtaş, H.; Küçük, H. M.
The Sea of Marmara is becoming a natural laboratory for structure, sedimentation, and fluid flow within the North Anatolian fault (NAF) system. Much marine geological and geophysical data has been collected there since the deadly 1999 M=7.2. Izmit earthquake. The Sea of Marmara occupies 3 major basins, with the study area located in the eastern Cinarcik basin near Istanbul. These basins are the results of an extensional component in releasing segments between bends in this right-lateral tranmsform. It is controversial whether the extensional component is taken up by partitioned normal slip on separate faults, or instead by oblique right-normal slip on the non-vertical main northern branch of the NAF. High resolution multichannel seismic reflection (MCS) and multibeam bathymetry data collected by R/V K.Piri Reis and R/V Le-Suroit as part of two different projects respectively entitled "SeisMarmara", "TAMAM" and "ESONET". 3000 km of multichannel seismic reflection profiles were collected in 2008 and 2010 using 72, 111, and 240 channels of streamer with a 6.25 m group interval. The generator-injector airgun was fired every 12.5 or 18.75 m and the resulting MCS data has 10-230 Hz frequency band. The aim of the study is to investigate continuation of North Anatolian Fault along the Sea of Marmara, in order to investigate migration of depo-centers past a fault bend. We also test and extend a recently-published age model, quantify extension across short normal faults, and investigate whether a major surface fault exists along the southern edge of Çınarcık Basin. MCS profiles indicate that main NAF strand is located at the northern boundary of Çınarcık Basin and has a large vertical component of slip. The geometry of the eastern (Tuzla) bend and estimated right-lateral slip rates from GPS data requires as much of ten mm/yr of extension across Çınarcık Basin. Based on the published age model, we calculate about 2 mm/yr of extension on short normal faults in the
Ergin, Mustafa; Yigit-Faridfathi, Füsun
This study forms part of a project (TUBITAK YDABCAG 101Y071) with the main purpose of investigation of late Quaternary slope stability, sediment mass movements and turbidite formations in the tectonically active Tekirdag Basin and its margins from the western Marmara Sea. The results were also intended to relate to the major earthquakes and sea-level changes. During this project, in 2001 aboard the former R/V MTA Sismik-1, a total of 100 km seismic reflection profiles were obtained along three tracklines representing from shelf to slope to deep basin environments. A multichannel airgun seismic system and well-known methods and principles of seismic stratigraphy was used for interpretations. At 11 sites from 29 to 1111 m water depths gravity sediment cores were taken having 100 to 359 cm recoveries and textural and structural characteristics were determined using standard petrographic methods. The NEE-SWW directed seismic profile (TKD-01) which runs parallel to the North Anatolian Fault zone displayed syntectonic sedimentation with negative flower structure that increased in thickness toward the Ganos Fault and pinched out in the east. ENE section of this profile also bears structures of underwater landslides with slump facies. Seismic profile TKD-02 which crosses the Tekirdag Basin in WNW-ESE direction most likely displays major 3 fault segments of the NAF zone. Many faults and syntectonic sedimentation structure can be recognized on this profile. A morphological feature of a sediment wedge or former lowstand delta at the present shelf edge can be related to the effects of last sea-level change. Mounded and chaotic seismic reflection configurations which indicate channel and slope-front fill as well as slump facies are thought to reflect submarine slides and slumps. Other morphological features such as incised submarine valleys or channels running E-W direction are also present on this profile. The seismic profile (TKD-03) runs from NNW to SSE across the basin and
Sile, Hande; Akin, Cansu; Ucarkus, Gulsen; Namik Cagatay, M.
The Sea of Marmara (NW Turkey), an intracontinental sea between the Mediterranean and Black Seas, is located in a tectonically active region with the formation of shallow gas hydrates and free gas. It is widely known that, Sea of Marmara sediments are organic-rich and conducive to production of methane, which is released on the sea floor through active fault segments of the North Anatolian Fault (Geli et al., 2008). Here we study the gas hydrate potential of the Çınarcık Basin using published data and our core analyses together with gas hydrate stability relations. The gas sampled in the Çınarcık Basin is composed mainly of biogenic methane and trace amounts of heavier hydrocarbons (Bourry et al., 2009). The seafloor at 1273 m depth on the Çınarcık Basin with temperature of 14.5oC and hydrostatic pressure of 127.3 atm corresponds to the physical limit for gas hydrate formation with respect to phase behavior of gas hydrates in marine sediments (Ménot and Bard, 2010). In order to calculate the base of the gas hydrate stability zone in Çınarcık Basin, we plotted T (oC) calculated considering the geothermal gradient versus P (atm) on the phase boundary diagram. Below the seafloor, in addition to hydrostatic pressure (10 Mpa/km), we calculated lithostatic pressure due to sediment thickness considering the MSCL gamma ray density values (~1.7 gr/cm3). Our estimations show that, gas hydrate could be stable in the upper ~20 m of sedimentary succession in Çınarcık Basin. The amount of gas hydrate in the Çınarcık Basin can be determined using the basinal area below 1220 m depth (483 km2) and average thickness of the gas hydrate stability zone (20 m) and the sediment gas hydrate saturation (1.2 % used as Milkov, 2004 suggested). The calculations indicate the potential volume of gas hydrate in Çınarcık Basin as ~11.6x107 m3. Such estimates are helpful for the consideration of gas hydrates as a new energy resource, for assessment of geohazards or their
Mert, Aydin; Fahjan, Yasin M.; Hutchings, Lawrence J.; Pınar, Ali
The main motivation for this study was the impending occurrence of a catastrophic earthquake along the Prince Island Fault (PIF) in the Marmara Sea and the disaster risk around the Marmara region, especially in Istanbul. This study provides the results of a physically based probabilistic seismic hazard analysis (PSHA) methodology, using broadband strong ground motion simulations, for sites within the Marmara region, Turkey, that may be vulnerable to possible large earthquakes throughout the PIF segments in the Marmara Sea. The methodology is called physically based because it depends on the physical processes of earthquake rupture and wave propagation to simulate earthquake ground motion time histories. We included the effects of all considerable-magnitude earthquakes. To generate the high-frequency (0.5-20 Hz) part of the broadband earthquake simulation, real, small-magnitude earthquakes recorded by a local seismic array were used as empirical Green's functions. For the frequencies below 0.5 Hz, the simulations were obtained by using synthetic Green's functions, which are synthetic seismograms calculated by an explicit 2D /3D elastic finite difference wave propagation routine. By using a range of rupture scenarios for all considerable-magnitude earthquakes throughout the PIF segments, we produced a hazard calculation for frequencies of 0.1-20 Hz. The physically based PSHA used here followed the same procedure as conventional PSHA, except that conventional PSHA utilizes point sources or a series of point sources to represent earthquakes, and this approach utilizes the full rupture of earthquakes along faults. Furthermore, conventional PSHA predicts ground motion parameters by using empirical attenuation relationships, whereas this approach calculates synthetic seismograms for all magnitudes of earthquakes to obtain ground motion parameters. PSHA results were produced for 2, 10, and 50 % hazards for all sites studied in the Marmara region.
Okay, Seda; Sorlien, Christopher; Cifci, Gunay; Cormier, Marie-Helene; Dondurur, Derman; Steckler, Michael; Barin, Burcu; Seeber, Leonardo; Gungor, Talip; Meriç İlkimen, Elif; Becel, Anne
The North Anatolian Fault (NAF), a major continental transform boundary, splays westward into three branches in the Sea of Marmara region of NW Turkey. The main northern branch passes only ~20 km from Istanbul and has been the subject of intense investigation, The central branch enters the sea of Marmara in Gemlik Bay and extends westward along the southern shelf of the Sea of Marmara. However, its detailed offshore geometry as well as its level of seismic activity have remained controversial. Under the SoMAR, bilateral TUBITAK-NSF Project, two geophysical cruises were carried out in 2013 and 2014 to map the major sedimentary basins and shallow fault patterns of the southern shelf of the Marmara Sea. Including our 2008 and 2010 acquisition, we acquired 4,430 km of high-resolution multichannel seismic, sparker, multibeam bathymetric and CHIRP data. We used the new data to correlate our published late Quaternary stratigraphic age model across the outer shelf, and a ~1/4 Ma horizon across the Inner Shelf, thus providing a chronology that can be applied to the tectonic history of the central branch. As it exits Gemlik Bay, the central branch itself diverges westward into strands in a fan pattern. A half dozen southern strands strike WSW and W, with one continuing onland near the Kocasu River delta between Bandırma and Mudanya, and others dying out offshore. The northern strand strikes WNW and splays again into the İmrali Ridge Fault and the Imrali Fault across respectively the mid-shelf and the shelf break. A middle fault, the Kapidag fault, is present between Kapidag Peninsula and Marmara Island. Most of the faults increase their vertical component with depth, suggesting activity during Pliocene through Holocene time. The Kapidag fault and Imrali Ridge fault each exhibit between 1 and 2 km of vertical separation of acoustic basement. Late Quaternary rates of vertical separation on these faults can accumulate the total vertical component after Miocene time. Thus
Vardar, Denizhan; Alpar, Bedri
High-resolution seismic survey was conducted to investigate acoustic characteristics of gassy sediments along the southern shelf of the Sea of Marmara. The acoustic turbidity zones outlined within the study area are generally below 2-9 m (2-10 ms TWT) the seafloor whilst this vertical distance varies between 9 and 21 m (10-25 ms TWT) for acoustic blanket type reflections. The gassy sediments cover an area of sea floor of about 45, 110, and 75 km2 in front of Gönen River, Kocasu River, and Gemlik Bay, respectively. The gassy sediments in the center of Gemlik Bay exhibited an elliptical geometry similar to its basin while the others have deltaic forms in front of the rivers. The sea bottom and near surface sedimentary units are made-up of organic-rich sediments, mostly transported by the southern rivers. The gas observed in sediments is thought to be of biogenic origin, which may be caused by degradation of organic matter in the sediment.
Otansev, Pelin; Taşkın, Halim; Başsarı, Asiye; Varinlioğlu, Ahmet
In this study, the natural and anthropogenic radioactivity levels in the sediment samples collected from the Marmara Sea in Turkey were determined. The average activity concentrations (range) of (226)Ra, (238)U, (232)Th, (40)K and (137)Cs were found to be 23.8 (13.8-34.2) Bq kg(-1), 18.8 (6.4-25.9) Bq kg(-1), 23.02 (6.3-31.1) Bq kg(-1), 558.6 (378.8-693.6) Bq kg(-1) and 9.14 (4.8-16.3) Bq kg(-1), respectively. Our results showed that the average activity concentrations of (226)Ra, (238)U and (232)Th in the sediment samples were within the acceptable limits; whereas the average activity concentration of (40)K in the sediment samples was higher than the worldwide average concentration. The average radium equivalent activity, the average absorbed dose rate and the average external hazard index were calculated as 100.01 Bq kg(-1), 48.32 nGy h(-1) and 0.27, respectively. The average gross alpha and beta activity in the seawater samples were found to be 0.042 Bq L(-1) and 13.402 Bq L(-1), respectively. The gross alpha and beta activity concentrations increased with water depth in the same stations. The average heavy metal concentrations (range) in the sediment samples were 114.6 (21.6-201.7) μg g(-1) for Cr, 568.2 (190.8-1625.1) μg g(-1) for Mn, 39.3 (4.9-83.4) μg g(-1) for Cu, 85.5 (11.0-171.8) μg g(-1) for Zn, 32.9 (9.1-73.1) μg g(-1) for Pb and 49.1 (6.8-103.0) μg g(-1) for Ni. S5 station was heavily polluted by Cr, Cu, Ni and Pb. The results showed that heavy metal enrichment in sediments of the Marmara Sea was widespread. PMID:27060635
Widespread gas emissions in the Sea of Marmara in relation with the tectonic and sedimentary environments: Results from shipborne multibeam echosounder water column imagery (MARMESONET expedition, 2009)
Dupré, Stéphanie; Scalabrin, Carla; Géli, Louis; Henry, Pierre; Grall, Céline; Tary, Jean-Baptiste; Ćaǧatay, Namık.; Imren, Caner
Acoustic systems in marine geosciences are mainly used to explore the seabed and image sub-bottom sedimentary units. However, side-scan sonars and echosounders can detect gas emissions from the seabed into the water column. Recently, advances in technology and computer processing allow carrying out large-scale 3D surveys of the entire water column with multibeam systems, so far dedicated to seabed imagery. A shipborne multibeam survey of the water column in the Sea of Marmara was performed with the R/V Le Suroit during the MARMESONET expedition (4-25 November 2009), that is part of the ESONET (European Seas Observatory NETwork) demonstration mission MarmaraDM. Data were acquired with a Simrad EM302 multibeam echosounder (27-33 kHz, 288 beams, 1°x2°, 2 or 5 ms pulse length) with automatic swath width control and equidistant sounding pattern over water depths varying from 300 to 1300 m. Volume backscattering coefficients were stored with <10 m depth bins along more than 2000 nm acoustic tracks. Gas bubble echoes were very well detected by the EM302 system within the water depth range of the Sea of Marmara, mostly with the central beams but also with the outer beams for the flares with strong backscatter intensity and large imprint. Geo-referenced gas flare 3D visualization is performed with Movies3D software developed for fish school echo description and biomass assessment (Trenkel et al., 2009). The distribution of water column acoustic echoes in the Sea of Marmara reveals that free gas emissions from the seabed are more widespread than expected from previous studies using ROVs, submersibles as well as acoustic methods (Géli et al., 2008; Zitter et al., 2008). Numerous acoustic gas flares were detected in association with the North Anatolian fault system and some appear to be localized on known active fault traces. However, gas emissions also spread around the edges of the sedimentary basins (e.g. Cinarcik and Tekirdag basins) and on structural highs (e
Unlü, Selma; Alpar, Bedri
The eastern and southern coasts of the Gulf of Gemlik, a resort in the Sea of Marmara, Turkey, are under the influence of rapid ecotourism development, direct domestic and industrial discharges via rivers and outfalls, surface run-off, drainage from ports and shipping. According to sediment quality criteria in use around the world, sediment quality in the gulf shows a broad spectrum. It is more related by direct input, rather than by the type of sediment, and excluding inner port and southern coasts, it does not exert adverse biological effects yet. The total PAH concentrations range from 51 to 13,482 ng/g dry weight with the mean value of 1,850 ng/g dry weight (n = 61). The elevated values of the total toxic Benzo[a]pyrene equivalency (TEQcarc), with a maximum of 1,838 ng/g dry weight, were found at the inner harbor of Gemlik, possibly posing hazard to benthic organisms. Among the different PAHs, the contribution to the total TEQcarc decreased as the following order: Benzo[a]pyrene (43.6%) > Benzo[k]fluoranthene (36.0%) > Indeno[1,2,3-cd]pyrene (35.1%) > Benzo[b]fluoranthene (20.0%) > Chrysene + Triphenylene (18.9%) > Benzo[a]anthracene (12.5%). PMID:19582364
Discussion: a critique of Possible waterways between the Marmara Sea and the Black Sea in the late Quaternary: evidence from ostracod and foraminifer assemblages in lakes İznik and Sapanca, Turkey, Geo-Marine Letters, 2011
Yaltırak, Cenk; Ülgen, Umut B.; Zabcı, Cengiz; Franz, Sven Oliver; Ön, Sena Akçer; Sakınç, Mehmet; Çağatay, M. Namık; Alpar, Bedri; Öztürk, Kurultay; Tunoğlu, Cemal; Ünlü, Selma
The identification of past connection routes between the Black Sea and the Sea of Marmara, other than the traditional one through to the Bosphorus Strait, would be of considerable interest to the international scientific community. Nazik et al. (Geo-Mar Lett 31:75-86 (2011) doi:10.1007/s00367-010-0216-9) suggest the possibility of two alternative waterway connections via lakes Sapanca and İznik. Their Black Sea to Sea of Marmara multi-connection hypothesis, which is based on undated marine fossils collected in both lakes from surficial grab samples, conflicts with many earlier studies. In this contribution, the hypothesis and the underlying data are discussed in the light of previous tectonic, sedimentological and limnological findings showing that it is impossible to have had marine connections through lakes Sapanca and İznik during the last 11.5 ka. Global sea-level trends and tectonic uplift rates would accommodate a connection between the Sea of Marmara and Lake İznik in the middle Pleistocene. Uplift rates for the northern block of the North Anatolian Fault, when compared with the global sea-level curve, clearly indicate that there cannot have been a connection through the İzmit Gulf-Lake Sapanca-Sakarya Valley for at least the past 500 ka. Moreover, borehole sediments along the western shores of Lake Sapanca, which reach down to the bedrock, do not contain any marine fossils.
Schmittbuhl, Jean; Karabulut, Hayrullah; Lengliné, Olivier; Bouchon, Michel
The North Anatolian Fault (NAF) poses a significant hazard for the large cities surrounding the Marmara Sea region particularly the megalopolis of Istanbul. Indeed, the NAF is presently hosting a long unruptured segment below the Sea of Marmara. This seismic gap is approximately 150 km long and corresponds to the Main Marmara Fault (MMF). The seismicity along the Main Marmara Fault (MMF) below the Marmara Sea is analyzed here during the 2007-2012 period to provide insights on the recent evolution of this important regional seismic gap. High precision locations show that seismicity is strongly varying along strike and depth providing fine details of the fault behavior that are inaccessible from geodetic inversions. The activity strongly clusters at the regions of transition between basins. The Central basin shows significant seismicity located below the shallow locking depth inferred from GPS measurements. Its b-value is low and the average seismic slip is high. Interestingly we found also several long term repeating earthquakes in this domain. Using a template matching technique, we evidenced two new families of repeaters: a first family that typically belongs to aftershock sequences and a second family of long lasting repeaters with a multi-month recurrence period. All observations are consistent with a deep creep of this segment. On the contrary, the Kumburgaz basin at the center of the fault shows sparse seismicity with the hallmarks of a locked segment. In the eastern Marmara Sea, the seismicity distribution along the Princes Island segment in the Cinarcik basin, is consistent with the geodetic locking depth of 10km and a low contribution to the regional seismic energy release. The assessment of the locked segment areas provide an estimate of the magnitude of the main forthcoming event to be about 7.3 assuming that the rupture will not enter significantly within creeping domains.
Italiano, Francesco; Woith, Heiko; Seyis, Cemil; Pizzino, Luca; Sciarra, Alessandra
Earthquake processes provoke modifications of the crust affecting the fluid regime with changes in water level in wells, in temperature and/or chemical composition of groundwaters, in the flow-rate of gas discharges and in their chemical and isotopic composition. In the frame of MARsite (MARsite has received funding from the European Union's Seventh Programme for research, technological development and demonstration under grant agreement No 308417) the relationship between fluids and seismogenesis has been approached collecting geochemical data of local significance and evaluating them in geochemical interpretative models of fluids circulation and interactions as well as defining their behaviour over a seismic-prone area. During three fluid sampling campaigns in 2013, 2014, and 2015 a suite of 120 gas samples were collected from 72 thermal and mineral water springs/wells in the wider Marmara region along the Northern and Southern branches of the North Anatolian Fault Zone (NAFZ). Bubbling gases were collected if available, in all other cases the gas phase was extracted from water samples collected on that purpose. Gas samples were analyzed for the main chemical composition as well as their isotopic composition (He and C). The results highlight that the vented gases are a binary mixture of two end-members having nitrogen and carbon dioxide as main components. The geochemical features of the gas phase are the result of several processes that have modified their pristine composition. Atmospheric and deep-originated volatiles mix at variable extents and interact with cold and hot groundwaters. CO2 is normally the main gas species. But it's concentration may decrease due to gas-water interactions (GWI) increasing the relative concentration of N2 and other less soluble gases. A high CO2 content indicates minor interactions. Thus, the easier and faster the pathways are from the deep layers toward the Earth's surface, the lower are the interactions. The volatiles keep
Reply to Discussion: a critique of Possible waterways between the Marmara Sea and the Black Sea in the late Quaternary: evidence from ostracod and foraminifer assemblages in lakes İznik and Sapanca, Turkey, Geo-Marine Letters, 2011
Nazik, Atike; Meriç, Engin; Avşar, Niyazi
In their discussion of our 2011 paper dealing with possible waterways between the Marmara Sea and the Black Sea in the "late" Quaternary, based on data from ostracod and foraminifer assemblages in lakes İznik and Sapanca, Turkey, Yaltırak et al. (Geo-Mar Lett 32:267-274, 2012) essentially reject the idea of any links whatsoever, be they between the Marmara Sea and the lakes İznik and Sapanca, or further to the Black Sea via the valley of the Sakarya River. The evidence they provide in support of their view, however, is essentially circumstantial, in part conjectural, and also inconclusive considering the findings in favour of linkage between the Marmara Sea and the lakes at the very least, while the proposed connection with the Sakarya River valley remains speculative because of the lack of unambiguous data. On the other hand, Yaltırak et al. (Geo-Mar Lett 32:267-274, 2012) do raise valid points of concern which deserve careful future investigation, the most important being the possibility of sample contamination from dumped marine sediment used for construction purposes along some parts of the shore of Lake İznik. We agree that a concerted multidisciplinary effort is required to address the many unresolved issues in connection with the potential waterways proposed by us and others before us.
Latcharote, P.; Suppasri, A.; Imamura, F.; Aytore, B.; Yalciner, A. C.
This study aimed to re-evaluate tsunami hazard in Marmara Sea from earthquake and submarine landslide focusing on the coastal area of Istanbul. For the fault-generated tsunami, the seismic rupture can be propagated along the North Anatolian Fault (NAF) which have evidenced historical tsunami in Marmara Sea. Based on previous research studies, future scenarios are expected to generate tsunami as well as submarine landslide could be triggered by seismic motion which consider fault-generated tsunami and landslide-generated tsunami individually. However, this study want to simulate tsunami propagation generated from the combining earthquake-landslide sources. Therefore, the evaluation of tsunami hazard was discussed in both of the individual case and the combining case of earthquake and submarine landslide through numerical modelling of tsunami wave with mesh size 90 m of bathymetry data. A two-layer numerical model was employed to simulate the landslide-generated tsunami by modeling the interaction between tsunami and submarine landslide with different volume of initial slide. First, tsunami propagation was generated from earthquake sources of Rupture E in the eastern basin and Rupture W in the western basin of Marmara Sea with fault slip 5 m. For Rupture E and Rupture W, maximum tsunami height at shore shoreline could reach 3.4 m and 2.8 m respectively along the coastal area of Istanbul. For combining Rupture E and Rupture W, maximum tsunami height could reach 3.8 m which was a little higher than that of Rupture E. Then, tsunami propagation was generated from landslide sources in the southern neighborhood of Istanbul near Rupture E. For landslide volume of 0.15 m3, 0.6 m3, and 1.5 m3, maximum tsunami height at shore shoreline could reach 3.7 m, 6.9 m and 8.7 m respectively along the coastal area of Istanbul. It was shown that maximum tsunami height from landslide sources was higher than that from earthquake sources depending on the volume of initial slide
Yakupoǧlu, Nurettin; Uçarkuş, Gülsen; Eriş, K. Kadir; Çaǧatay, M. Namık; Henry, Pierre; Yalamaz, Burak; Sabuncu, Asen; Acar, Dursun
Sediment sequences deposited in active transform basins provide valuable archives of earthquake-triggered co-seismic sedimentation. A better understanding of the relationship between offshore fault ruptures and Seismoturbidites would have direct implications for earthquake hazard assessment. Submerged section of the North Anatolian Fault in the northern Sea of Marmara basin, which experienced more than 55 (Ms>6.8) earthquakes in the last 2000 years, poses a unique laboratory to study such kind of sync-tectonic history. Following the devastating 1999 Izmit and Duzce earthquakes (Mw = 7.4/7.2 respectively), a major seismic gap is now along the offshore branch of the NAF in the Sea of Marmara. The segments that control the Cinarcik and Kumburgaz basins in the Sea of Marmara have not ruptured during the 20th century. This study focusses on the Kumburgaz basin, which is located along the central segment of the NAF, and its less-known linkage to historical earthquakes, particularly to Ms>7 1509 and 1766 earthquakes. The main objective of this study is to test the two alternative hypotheses of a creeping versus locked central High segment by determining the frequency and timing of earthquake triggered turbidite units in the Kumburgaz basin. A 21-m-long piston core recovered in Kumburgaz basin during the Marsite cruise in 2014 is analysed at high resolution in order to identify the discrete turbidite-homogenite units (T-H units). The piston core reveals 22 T-H units where several packages consist of a sharp basal contact and multiple fining upward beds of sand to coarse silt as characteristically seen in most Seismoturbidite units. We initiated a systematic study of T-H units with the objectives of establishing criteria for identification of Seismoturbidites by analysing the physical, mineralogical and chemical composition of the piston core. The density and magnetic susceptibility changes along the core are analysed by Multi-Sensor Core Logger (MSCL). High detrital input
Bayrakci, Gaye; Scalabrin, Carla; Dupré, Stéphanie; Leblond, Isabelle; Tary, Jean-Baptiste; Lanteri, Nadine; Augustin, Jean-Marie; Berger, Laurent; Cros, Estelle; Ogor, André; Tsabaris, Christos; Lescanne, Marc; Géli, Louis
A rotating, acoustic gas bubble detector, BOB (Bubble OBservatory) module was deployed during two surveys, conducted in 2009 and 2011 respectively, to study the temporal variations of gas emissions from the Marmara seafloor, along the North Anatolian Fault zone. The echosounder mounted on the instrument insonifies an angular sector of 7° during a given duration (of about 1 h). Then it rotates to the next, near-by angular sector and so forth. When the full angular domain is insonified, the "pan and tilt system" rotates back to its initial position, in order to start a new cycle (of about 1 day). The acoustic data reveal that gas emission is not a steady process, with observed temporal variations ranging between a few minutes and 24 h (from one cycle to the other). Echo-integration and inversion performed on the acoustic data as described in the companion paper of Leblond et al. (Mar Geophys Res, 2014), also indicate important variations in, respectively, the target strength and the volumetric flow rates of individual sources. However, the observed temporal variations may not be related to the properties of the gas source only, but reflect possible variations in sea-bottom currents, which could deviate the bubble train towards the neighboring sector. During the 2011 survey, a 4-component ocean bottom seismometer (OBS) was co-located at the seafloor, 59 m away from the BOB module. The acoustic data from our rotating, monitoring system support, but do not provide undisputable evidence to confirm, the hypothesis formulated by Tary et al. (2012), that the short-duration, non-seismic micro-events recorded by the OBS are likely produced by gas-related processes within the near seabed sediments. Hence, the use of a multibeam echosounder, or of several split beam echosounders should be preferred to rotating systems, for future experiments.
Oglesby, David D.; Mai, P. Martin
Using the 3-D finite-element method, we develop dynamic spontaneous rupture models of earthquakes on the North Anatolian Fault system in the Sea of Marmara, Turkey, considering the geometrical complexity of the fault system in this region. We find that the earthquake size, rupture propagation pattern and ground motion all strongly depend on the interplay between the initial (static) regional pre-stress field and the dynamic stress field radiated by the propagating rupture. By testing several nucleation locations, we observe that those far from an oblique normal fault stepover segment (near Istanbul) lead to large through-going rupture on the entire fault system, whereas nucleation locations closer to the stepover segment tend to produce ruptures that die out in the stepover. However, this pattern can change drastically with only a 10° rotation of the regional stress field. Our simulations also reveal that while dynamic unclamping near fault bends can produce a new mode of supershear rupture propagation, this unclamping has a much smaller effect on the speed of the peak in slip velocity along the fault. Finally, we find that the complex fault geometry leads to a very complex and asymmetric pattern of near-fault ground motion, including greatly amplified ground motion on the insides of fault bends. The ground-motion pattern can change significantly with different hypocentres, even beyond the typical effects of directivity. The results of this study may have implications for seismic hazard in this region, for the dynamics and ground motion of geometrically complex faults, and for the interpretation of kinematic inverse rupture models.
Bohnhoff, Marco; Dresen, Georg; Acarel, Digdem; Raub, Christina; Kilic, Tugbay; Kartal, Recai; Kadirioglu, Filiz; Nurlu, Murat; Bulut, Fatih; Malin, Peter
As part of the ICDP-GONAF project (Geophysical Observatory at the North Anatolian Fault) geophone arrays are being installed in 300 m deep boreholes around the eastern Sea of Marmara. The objectives of GONAF are to (1) monitor the NAFZ transition from the 1999 Izmit rupture to the Princes Islands offshore Istanbul, where a M ~ 7 earthquake can reasonably be expected to occur and (2) to determine ground-motion amplification and near-surface properties at the GONAF sites. Five geophone arrays are fully operational while two more are being completed in Spring 2015. The vertical arrays consist of one 1 Hz 3C Mark Products L4 seismometer at the surface, three 1 Hz vertical Mark Products L4 seismometers at 75 m depth-spacings, and 1 Hz, 2 Hz and 15 Hz 3C seismometers at 288 m depth. The 1Hz MARK 3C seismometer has been redesigned, gimble-mounted and deployed downhole to operate under low-noise conditions for the first time. During April-May 2013 the GONAF-Tuzla array in eastern Istanbul recorded a microearthquake swarm located ~ 3.5 km epicentral distance east of the site. By cross-correlating the continuous Tuzla data with the only swarm event detected by the regional network (20th of April 2013, Md 1.6) we retrieved an additional of 113 events confirming the expectations of a substantially lowered magnitude-detection threshold allowing for unprecedented fault-zone characterization along the Princes island fault segment offshore of Istanbul.
Aytore, Betul; Yalciner, Ahmet Cevdet; Zaytsev, Andrey; Cankaya, Zeynep Ceren; Suzen, Mehmet Lütfi
Turkey is highly prone to earthquakes because of active fault zones in the region. The Marmara region located at the western extension of the North Anatolian Fault Zone (NAFZ) is one of the most tectonically active zones in Turkey. Numerous catastrophic events such as earthquakes or earthquake/landslide-induced tsunamis have occurred in the Marmara Sea basin. According to studies on the past tsunami records, the Marmara coasts have been hit by 35 different tsunami events in the last 2000 years. The recent occurrences of catastrophic tsunamis in the world's oceans have also raised awareness about tsunamis that might take place around the Marmara coasts. Similarly, comprehensive studies on tsunamis, such as preparation of tsunami databases, tsunami hazard analysis and assessments, risk evaluations for the potential tsunami-prone regions, and establishing warning systems have accelerated. However, a complete tsunami inundation analysis in high resolution will provide a better understanding of the effects of tsunamis on a specific critical structure located in the Marmara Sea. Ports are one of those critical structures that are susceptible to marine disasters. Resilience of ports and harbors against tsunamis are essential for proper, efficient, and successful rescue operations to reduce loss of life and property. Considering this, high-resolution simulations have been carried out in the Marmara Sea by focusing on Haydarpaşa Port of the megacity Istanbul. In the first stage of simulations, the most critical tsunami sources possibly effective for Haydarpaşa Port were inputted, and the computed tsunami parameters at the port were compared to determine the most critical tsunami scenario. In the second stage of simulations, the nested domains from 90 m gird size to 10 m grid size (in the port region) were used, and the most critical tsunami scenario was modeled. In the third stage of simulations, the topography of the port and its regions were used in the two nested
Grall, Céline; Henry, Pierre; Kendé, Julia; Namık Çaǧatay, M.; Kadir Eriş, K.; Paillès, Christine; Sorlien, Christopher; Shillington, Donna; McHugh, Cecilia; Steckler, Michael; Çifçi, Günay; Géli, Louis
In the Sea of Marmara, glacio-eustatic cycles set the tempo of a complex history of disconnection and reconnection with the Black Sea and with the global ocean through the Mediterranean Sea. As a result, the sedimentary record consists of alternating high stand marine sediments and lowstand sea or lake sediments. The Sea of Marmara is also an active transtensional basin along the Northern branch of the North Anatolian Fault (NNAF), which accommodates most (~3/4) of the 21-27 mm/a dextral slip between Eurasia and Anatolia. This peculiar setting makes the Sea of Marmara an exceptional site to study the interplay of paleo-environmental factors and seismotectonic processes. Notably, Mass Transport Deposits (MTDs) crossing the faults provide offset markers although their age remains uncertain. A high resolution seismic stratigraphic model has been proposed for 100 ka glacial cycles, based on onlap sequences within basins, and paleo-deltas at shorelines. The sedimentation rate in basins decreases during episodes of sea-level rise and reach maximum values during low stands. Remarkably, seismic reflector sequences display nearly identical character for locations with similar sedimentation rate. The uppermost sequence boundary reflector (Red-H1) has been recently cored at several locations during MARSITECRUISE (Ifremer R/V Pourquoi Pas?, Oct-Nov. 2014), enabled us to correlate high resolution seismic data with core data. The Red-H1 reflector is regionally characterized by a high amplitude and a reverse polarity. Correlations between seismic data and piston core logs indicate that the reverse polarity of this reflector may be explained by a negative density contrast between lacustrine sediments above and a greenish sapropellic layer of several meters thickness below. On shelves, Red-H1 is on top of the low stand wedge. On slopes and topographic highs, Red-H1 appears as an erosional surface laterally correlative with an onlapping unit in basins and is frequently overlain by
Ergin, Mustafa; Sakitas, Alper; Sarikavak, Kerim; Keskin, Seref
The main purpose of this study was to determine and understand the impacts of the climatic changes, active tectonism, slope instability and sediment mass movements in the eastern Marmara Sea (Turkey) during the Holocene. Of these, sea level changes, earth quakes, slides, slumps and turbidites were considered to be the major causes to shape the seafloor in the region. With this in mind and within a framework of a larger Project (TÜBİTAK-YDABAG 101Y071), after the major earthquake of 17 August 1999 in Kocaeli-Turkey, both sediment samples and seismic reflection profiles were obtained during the August 2000 Cruise of the Research Vessel "MTA "SİSMİK 1" at water depths between 58 and 1249 meters in the Çınarcık Basin of the eastern Marmara Sea (NW Turkey). Offshore studies covered shelf, slope and basin-floor subenvironments. Onboard, airgun and multichannel seismic reflection system was used along 7 tracklines aligned to N-S and E-W directions. At 15 sites gravity cores were deployed and from 53 to 367 cm thick core sediments were obtained. Grain size analysis, visual core descriptions, and conventional radicarbon datings were also made. To interpret seismic profiles, well-known seismic facies analysis and stratigraphic methods were applied. Fine-grained and grayish-green colored siliciclastic mud was the dominant sediment type (also called "homogenite") deposited on the floor. The coarser-grained intervals and laminations would likely suggest effects of not only turbidites from active tectonism but they can also be related to the wind-driven offshore storm deposits and river floods after heavy rain-falls. Active normal faults on the shelves, fault scarps along the slopes and negative flower structure of syntectonic sedimentation in the deep basin floor observed on the seismic profiles all must indicate the consequences of westerly extension of the North Anatolian Fault Zone in the Marmara Sea. Seismic profiles displayed sediment structures of underwater
Crémière, Antoine; Pierre, Catherine; Blanc-Valleron, Marie-Madeleine; Zitter, Tiphaine; Çağatay, M. Namik; Henry, Pierre
The Marnaut cruise (May-June 2007) investigated the submerged part of the North Anatolian fault system, an active tectonic area in the Sea of Marmara. Already known and new fluid venting sites along the fault system were visited by submersible diving. Cold seeps present a considerable diversity of geochemical background associated with occurrences of authigenic carbonate crusts outcropping at the seafloor. Buried carbonate concretions were also recovered by coring within the sediments of the Tekirdağ Basin and of the Western-High ridge that separates the Tekirdağ and Central Basins. Interestingly, numerous of these early diagenetic carbonates were found within the transitional sediments from lacustrine to marine environment deposited after the late glacial maximum. The authigenic carbonates are mainly composed of aragonite, Mg-calcite and minor amounts of dolomite, and are often associated with pyrite and barite. The carbon isotopic compositions of carbonates present a wide range of values from -50.6‰ to +14.2‰ V-PDB indicating different diagenetic settings and complex mixtures of dissolved inorganic carbon from different sources. The low δ13C values of the seafloor crusts and of most buried concretions indicate that the carbon source was a mixture of microbial and thermogenic methane and possibly other hydrocarbons that were oxidized by anaerobic microbial processes. The positive δ13C values of a few buried concretions from the Western-High ridge reflect the mineralization of heavy CO2, which is thought to represent the residual by-product of oil biodegradation in a subsurface petroleum reservoir that migrated up with brines. Most of the oxygen isotopic compositions of seafloor carbonates are close to the isotopic equilibrium with the present-day bottom water conditions but a few values as low as -1.9‰ V-PDB indicate precipitation from brackish waters. In buried carbonate concretions, δ18O values as high as +4.9‰ V-PDB reflect the contribution of
Atgın, Orhan; Çifçi, Günay; Soelien, Christopher; Seeber, Leonardo; Steckler, Michael; Shillington, Donna; Kurt, Hülya; Dondurur, Derman; Okay, Seda; Gürçay, Savaş; Sarıtaş, Hakan; Mert Küçük, H.; Barın, Burcu
Marmara Sea is a limelight area for investigations due to its tectonic structure and remarkable seismic activity of North Anatolian Fault Zone (NAFZ). As NAFZ separates into 3 branches in the Marmara Sea, it has a complicated tectonic structure which gives rise to debates among researchers. Çınarcık Basin, which is close to Istanbul and very important for its tectonic activity is studied in this thesis. Two different multichannel seismic reflection data were used in this thesis. First data were acquired in 2008 in the frame of TAMAM (Turkish American Multichannel Project) and second data were in 2010 in the frame of TAMAM-2 (PirMarmara) onboard R/V K.Piri Reis. Also high resolution multibeam data were used which is provided by French Marine Institute IFREMER. In the scope of TAMAM project total 3000 km high resolution multi channel data were collected. 3000 km of multichannel seismic reflection profiles were collected in 2008 and 2010 using 72, 111, and 240 channels of streamer with a 6.25 m group interval. The generator-injector airgun was fired every 12.5 or 18.75 m and the resulting MCS data has 10-230 Hz frequency band. In this study, a detailed fault map of the basin is created and the fault on the southern slope of the basin which is interpreted by many researchers in many publications was investigated. And there is no evidence that such a fault exists on the southern part of the basin. With the multichannel seismic reflection data seismic stratigrafic interpretations of the basin deposits were done. The yearly cumulative north-south extension of the basin was calculated by making some calculations on the most active part of the faulting in the basin. In addition, the tilt angles of parallel tilted sediments were calculated and correlated with global sea level changes to calculate ages of the deposits in the basin. Keywords: NAFZ, multi channel seismic reflection, Çınarcık Basin
Aksu, A; Taşkin, O S
In this study, organochlorine and toxic metal (Pb, Cd and Cr) analyses have been done in the surface sediments. Sediment samples have been collected from 7 parts of the Marmara Sea and the coast of Istanbul during 2009. Total Pb, Cd and Cr contents vary between 32 μg g(-1) and 122 μg g(-1); 0.19 μg g(-1) and 1.16 μg g(-1); 62 μg g(-1) and 372 μg g(-1), respectively. EF values of Pb and Cr are higher than 1.5 in all the stations. EF value of Cd is considerably high at Station MY1 (Tuzla Port). Total organochlorine residue contents range between 4.33 ng g(-1) and 22.2 ng g(-1) in the surface sediments. PMID:22421429
Tarancioglu, Adil; Kocaoglu, Argun H.; Ozalaybey, Serdar
The objective of this study is to investigate the local seismicity and obtain a detailed three-dimensional crustal velocity structure beneath the Marmara Sea in an area surrounding the North Anatolian Fault Zone (NAFZ) by tomographic inversion using both controlled-source (air-gun) and earthquake data. The tomographic inversion is carried out by using the local earthquake tomography code SIMUL2000. Two sets of seismological data, collected in 2006 (EOSMARMARA experiment) and 2001 (SEISMARMARA experiment), are re-processed and used in this study. A total of 441 high quality earthquakes and 452 air-gun shots recorded by a total of 53 Ocean Bottom Seismometers (OBS) are selected for the simultaneous inversion for velocity and hypocentral parameters. The OBS location and time-drift errors are identified from air-gun shot records by a grid search method and required corrections are made on the travel time data. The initial (reference) velocity model and earthquake locations required for the three dimensional tomographic inversion are derived from the one-dimensional velocity model obtained by using the VELEST algorithm in which a subset of earthquakes are selected such that phase readings were made by at least five stations and maximum azimuthal gap was 180o. The inversion results are checked for initial model dependence and the effect of damping factor. The reliability of the results is also evaluated in terms of derivative-weighted-sum, resolution-diagonal-elements values and checkerboard tests. The hypocenter locations of the local earthquakes have been remarkably improved by the three-dimensional velocity model obtained from the tomographic inversion. The three-dimensional velocity model shows that the Tekirdag, Central and Cinarcik Basins are characterized generally by lower Vp (3.0 - 3.5 km/s) values and most of the earthquakes across these regions are located at the depths of 10 to 17 km, about 5 km deeper than those obtained from the one-dimensional reference
Dupré, Stéphanie; Scalabrin, Carla; Grall, Céline; Augustin, Jean-Marie; Henry, Pierre; Şengör, A. M. Celal; Görür, Naci; ćaǧatay, M. Namık.; Géli, Louis
Understanding of the evolution of fluid-fault interactions during earthquake cycles is a challenge that acoustic gas emission studies can contribute. A survey of the Sea of Marmara using a shipborne, multibeam echo sounder, with water column records, provided an accurate spatial distribution of offshore seeps. Gas emissions are spatially controlled by a combination of factors, including fault and fracture networks in connection to the Main Marmara Fault system and inherited faults, the nature and thickness of sediments (e.g., occurrence of impermeable or gas-bearing sediments and landslides), and the connectivity between the seafloor and gas sources, particularly in relation to the Eocene Thrace Basin. The relationship between seepage and fault activity is not linear, as active faults do not necessarily conduct gas, and scarps corresponding to deactivated fault strands may continue to channel fluids. Within sedimentary basins, gas is not expelled at the seafloor unless faulting, deformation, or erosional processes affect the sediments. On topographic highs, gas flares occur along the main fault scarps but are also associated with sediment deformation. The occurrence of gas emissions appears to be correlated with the distribution of microseismicity. The relative absence of earthquake-induced ground shaking along parts of the Istanbul-Silivri and Princes Islands segments is likely the primary factor responsible for the comparative lack of gas emissions along these fault segments. The spatiotemporal distribution of gas seeps may thus provide a complementary way to constrain earthquake geohazards by focusing the study on some key fault segments, e.g., the northern part of the locked Princes Islands segment.
In this study we have two main purposes. The first one is to simulate five midsize earthquakes (Mw≈5.0) recorded in the Marmara region, which has a geologically complex and heterogeneous crustal structure. We synthesize ground motion for the full wave train on three components, and applied a 'physics based' solution of earthquake rupture. The simulation methodology is based on the studies by Hutchings et al. (2007), Scognamiglio and Hutchings (2009). For each earthquake, we synthesized seismograms using by 500 different rupture scenarios that were generated by Monte Carlo selection of parameters within the range. Synthetic ground motion is a major challenge for seismic hazard assessment studies. Especially after the adoption of performance-based design approach with the Earthquake resistant design of engineering structures. To compute realistic time histories for different locations around Marmara region can be helpful for engineering design, retrofitting the existing structures, hazard and risk management studies and developing new seismic codes and standards.The second purpose is to validate synthetic seismograms with real seismograms. We follow the methodology presented by Anderson (2003) for validation. This methodology proposes a similarity score based on averages of the quality of fit measuring ground motion characteristics and uses a suite of measurements. Namely, the synthetics are compared to real data by ten representative ground motion criteria. The applicability of Empirical Green's functions methodology and physics based solution of earthquake rupture had been assessed in terms of modeling in complex geologic structure. Because the methodology produces source and site specific synthetic ground motion time histories and goodness-of-fit scores of obtained synthetics is between 'fair' to 'good' range based on Anderson's score, we concluded that it can be tried to produce ground motion that has not previously been recorded during catastrophic earthquake
Karimi, B.; McQuarrie, N.
On August 17th, 1999, a magnitude 7.4 earthquake shook Kocaeli (Izmit), Turkey killing over 17,000 people. The epicenter was 100-km east of Turkey's largest city, Istanbul, along the North Anatolian Fault (NAF) system. This 1600-km long, strike-slip boundary divides the Anatolian plate and the Eurasian plate. The NAF slips at an average rate of 2-3-cm/y, and has an estimated earthquake recurrence interval of approximately 300 years. To further understand the NAF system and its dynamics, a simplified 2-D mesh model was developed to evaluate the fault friction coefficient for various low cohesion values along an ~85-km stretch of the NAF system east of the Marmara Sea containing the Mudurnu valley between the cities of Izmit and Bolu (where the NAF splits). The NAF, in the region of interest, exhibits shorter recurrence intervals of 100-150 years over the last four centuries. In this region, two sets of faults within the NAF system converge and then diverge; one set diverges to the NW to bound the northern rim of the Marmara Sea, while the second set continues to the SW along the southern rim of the Marmara Sea. A 100 year seismic record of earthquakes between M3.0 and M9.0 supports the claim that the two sets of strike-slip faults near one another in the center of the region of interest, but do not intersect, thus defining three distinct geology provinces. A representational 2-D mesh separates the study area into three geologic provinces separated by these faults. The mesh was processed using PyLith, a finite element code tectonic deformation software. The PyLith software allows us to assign rock physics parameters of the surface geology, and relative plate motions as velocity boundary conditions. Surface geology was simplified into the three rock types, and rock physics parameters were assigned using general physical parameters for each rock type and extrapolating further data from the Canadian Rock Physics Database. An average value for density and P-wave velocity
Meral Ozel, N.; Necmioglu, O.; Ergintav, S.; Ozel, A.; Erdik, M. O.
The Marmara Region is one of the most active seismic regions in Turkey and also most densely populated and fast-developing part in the country. The region was effected with destructive earthquakes in its past, and the seismic hazard in Marmara Region has become a great concern especially after the Izmit and Duzce earthquakes in 1999 costing 18.000 people lives. Recent studies indicate that the region has a great potential to produce M≥7.0 earthquake within the next 30 years. Hence, a realistic assessment of the earthquake hazard in this area including Istanbul with more then 15 million inhabitants is a priority. MARsite project identifes the Marmara region as a ';Supersite' to aggregate on-shore, off-shore and space-based observations, comprehensive geophysical monitoring, improved hazard and risk assessments encompassed in an integrated set of activities. MARsite Consortium constitutes of 18 European research institutions with a long record of scientific history and success, and 3 SMEs, from 7 nations of the Euro-Mediterranean area. MARsite aims to harmonize geological, geophysical, geodetic and geochemical observations to provide a better view of the post-seismic deformation of the 1999 Izmit earthquake (in addition to the post-seismic signature of previous earthquakes), loading of submarine and inland active fault segments and transient pre-earthquake signals, related to stress loading with different tectonic properties in and around Marmara Sea. These studies are planned to contribute to high-quality rapid source-mechanism solutions and slip models, early warning and rapid-response studies. The project outputs will also be adapted to improve various phases of the risk management cycle with the creation of a link between the scientific community and end users. In this context, MARsite will develop novel geo-hazard monitoring instruments including high-resolution displacement meters, novel borehole instrumentation and sea-bottom gas emission and heat
Özmaral, A.; Çagatay, M. N.; Imren, C.; Gasperini, L.; Henry, P.
Gemlik Gulf is an oval-shaped transtensional basin with a maximum depth of 113 m, located on the middle strand of the North Anatolian Fault (NAF) in the eastern part of the Sea of Marmara (SOM). During the last glacial period until the Holocene marine transgression about 12 ka BP, the sea level was below the Çanakkale (Dardanelles) Strait's bedrock sill depth of -85 m, and the Gemlik Basin became a lake isolated lake from the rest of the Sea of Marmara "Lake" and the global ocean. The high resolution seismic profiles and the multi- beam bathymetric map of the basin show that the basin is characterized by NW-SE trending transtensional oblique faults, delta lobes of the Büyükdere (Kocadere) to the east and an erosional surface below an up to 15 m-thick Holocene mud drape. The Holocene mud drape was studied in up to 9.5 m-long gravity-piston and 0.84 m-long sediment/water interface cores located at -105 to -113 m in the basin's depocentre. The Holocene mud consists mainly of plastic gray green marine clayey mud that includes thick-red brown clay layers and a laminated organic-rich, dark olive green sapropel in the lower part, which was previously dated at 11.6-6.4 14Ckyr (uncalib) BP. Multi-proxy analyses of the Holocene mud drape in the sediment cores were carried out using Multisensor Core Logger, XRF Core Scanner equipped with digital X-Ray radiography, and laser particle size analyzer. Seismic-core correlation was made using seismic data of the chirp profiles at the core locations and the synthetic seismograms generated using the MSCL P-wave velocity and gamma density measurements. The long piston-gravity cores include five 20 to 100 mm-thick "red brown mud layers" in the top 2.5 m of the core. These layers have a sharp basal boundary and gradational upper boundary. The red brown layers consist of 55-75% clay-size material with an average grain size of 3-4 µm, and have relatively a high magnetic susceptibility. They are enriched in K, Fe, Ti and Zr that are
Pinar, Ali; Coskun, Zeynep; Mert, Aydin; Kalafat, Dogan
The general consensus based on historical earthquake data point out that the last major moment release on the Prince's islands fault was in 1766 which in turn signals an increased seismic risk for Istanbul Metropolitan area considering the fact that most of the 20 mm/yr GPS derived slip rate for the region is accommodated mostly by that fault segment. The orientation of the Prince's islands fault segment overlaps with the NW-SE direction of the maximum principle stress axis derived from the focal mechanism solutions of the large and moderate sized earthquakes occurred in the Marmara region. As such, the NW-SE trending fault segment translates the motion between the two E-W trending branches of the North Anatolian fault zone; one extending from the Gulf of Izmit towards Çınarcık basin and the other extending between offshore Bakırköy and Silivri. The basic relation between the orientation of the maximum and minimum principal stress axes, the shear and normal stresses, and the orientation of a fault provides clue on the strength of a fault, i.e., its frictional coefficient. Here, the angle between the fault normal and maximum compressive stress axis is a key parameter where fault normal and fault parallel maximum compressive stress might be a necessary and sufficient condition for a creeping event. That relation also implies that when the trend of the sigma-1 axis is close to the strike of the fault the shear stress acting on the fault plane approaches zero. On the other hand, the ratio between the shear and normal stresses acting on a fault plane is proportional to the coefficient of frictional coefficient of the fault. Accordingly, the geometry between the Prince's islands fault segment and a maximum principal stress axis matches a weak fault model. In the frame of the presentation we analyze seismological data acquired in Marmara region and interpret the results in conjuction with the above mentioned weak fault model.
Meral Ozel, Nurcan; Necmioglu, Ocal; Favali, Paolo; Douglas, John; Mathieu, Pierre-Philippe; Geli, Louis; Ergintav, Semih; Oguz Ozel, Asım; Tan, Onur; Gurbuz, Cemil; Erdik, Mustafa
MARSite Project was initiated in November 2012 under the EC/FP-7 framework as an initiative towards establishment of new directions in seismic hazard assessment through focused earth observation in Marmara Region. Within MARSite, collection of the first comprehensive data set of fluids composition around the Sea of Marmara has been accomplished and first insight in the geochemical features of the fluids are expelled from tectonic structures around the Sea of Marmara. GPS time series and velocity fields are periodically updated and a project proposal has been prepared for Supersite initiative to take SAR data and integrate the results with in-situ data sets, which is accepted by the scientific committee of GEOSS. In the meantime, special focus was given to develop the processing algorithms, starting from low level atmospheric correction to high level modeling routines. Considerable progress has been made in the novel design of a multiparameter borehole system consisting of very wide dynamic range and stable borehole (VBB) broad band seismic sensor also incorporating 3-D strain meter, tilt meter, and temperature and local hydrostatic pressure measuring devices. Borehole and surface array locations and borehole bedrock depth of 137 m has been identified. A modeling scheme for the scenario earthquake simulation has been set up in order to realize processing of real-time high-rate GPS data and simulating of scenario earthquakes. The probability of occurrence for the fault segmentation in the Marmara region were calculated using the Poisson, BPT and BPT with a stress interaction models for time intervals of 5-10-30 and 50 years. High resolution seismic reflection and multibeam data in the easternmost Cinarcik basin obtained during the cruise MARMARA 2013 carried out onboard the CNR R/V Urania ship provided information on diffuse gravitational failures. An in situ multi-parameter observational system for landslide monitoring, including displacement, rainfall and seismic
Royer, J. Y.; Deschamps, A.; Piete, H.; Sakic, P.; Ballu, V.; Apprioual, R.; Kopp, H.; Lange, D.; Ruffine, L.; Géli, L.
Located in the Marmara Sea, the Istanbul-Silivri segment of the North Anatolian Fault (NAF) is known to be a seismic gap since 1766, although, in the last century, the NAF has caused major devastating earthquakes over most of its extent. This fault segment, void of seismicity, may be either creeping aseismically or blocked and accumulating enough strain to produce an earthquake of magnitude 7 or greater. This section of the NAF may thus represent a major seismic and tsunamigenic hazard for the Istanbul megalopolis, located only 40 km away. The objective of the MARSITE project, funded by the European Union and coordinated by the Observatory of the University of Kandilli (KOERI), is to determine the blocking state of the Istanbul-Silivri fault segment. In this context, an array of 10 acoustic transponders has been deployed on either sides of the fault, in the eastern part of the Kumburgaz Basin, to measure the displacements of the fault over a period of 3 to 5 years. The telemetric beacons (4 from the University of Brest and 6 from the GEOMAR Institute in Kiel) form two arrays fitted in one another. The principle of the experiment is to repeatedly measure the distance (ie two-way-travel time of acoustic pings) between pairs of beacons and thus to monitor the deformation of an array of 9 baselines, 500m to 3000m long, of which 5 cross obliquely the assumed fault trace. The French and German arrays are independent but ensure a redundancy of rangings along common baselines. Each acoustic transponder also monitors the temperature, pressure, sound-velocity and attitude (tiltmeters), every one or two hours. Data are stored in each beacon and can be downloaded from the surface using an acoustic modem. We present here the first 6 months of recording by the French array, from November 1st, 2014 to April 25, 2015. All acoustic transponders worked nominally for 6 months and appear to have remained stable on the seafloor. Recorded sea-bottom temperatures provide evidence for
Sachpazi, M.; Vigner, A.; Laigle, M.; Hirn, A.; Roussos, N.
The North Aegean Trough (NAT), which is the deepest among Aegean marine troughs, is bordered by the termination of the North Anatolian Fault, and thus marks the interaction of this strike-slip fault with mainland Greece and the extensional Aegean domain. In the development of academic exploration of active regions at the scale of the whole crust, with marine multichannel seismics (MCS), the STREAMERS acquisition almost ten years ago provided a first hint of the feasibility there and in other parts of the Aegean and Ionian seas (Sachpazi et al., Tectonophysics 1996), and a template for later MCS and coincident wide-angle reflection surveying. These profiles were acquired by the French N/O Nadir, with an only 96-channel streamer 2.4 km length, and with an only 840 cu. in. generator capacity of a 8 gun array, but for the first time shot in the "single-bubble" mode that was developed in this survey. With respect to the present standard set by 2001 cruises in the Gulf of Corinth (US R/V Maurice Ewing, Taylor et al. this meeting) and in the Sea of Marmara (French N/O Nadir, Hirn et al., EGS 2002 and this meeting) this was a 2 to 3 times shorter streamer cable, a 2 to 4 times smaller number of hydrophone groups, and a 10 to 3 times smaller source. The SEISGREECE survey, with a source 3 times that of STREAMERS but other parameters as modest, explored the Gulf of Corinth and the Cyclades and added profiles in the North Aegean to this early attempt. A first result of merging the two surveys was to lend credence to possible structures detected by the first single profile. This revealed an active, recent normal-fault imaged down to 10 km depth, that cuts at a N 110°E strike the northern side of the NAT (Laigle et al., Geology, 2000). Indeed although processing has been hampered by the modest streamer length and only 16 or 24-fold coverage, the data now resolve clearly the sedimentary structure, image the basement, detect intra-basement faults, an upper crustal reflective zone
Accumulations of total metal in dominant shrimp species (Palaemon adspersus, Palaemon serratus, Parapenaeus longirostris) and bottom surface sediments obtained from the Northern Inner Shelf of the Sea of Marmara.
Kurun, A; Balkis, H; Balkis, N
The aim of this study is to determine the total metal (aluminum, copper, manganese, nickel, lead, zinc, cadmium, iron, mercury) contents of dominant shrimp species and sediments present at 1-50 m depths of the Northern Inner Shelf of the Sea of Marmara. Shrimp and sediment samples were collected from four regions (Büyükçekmece, Silivri, Tekirdağ, Sarköy) and from different depths (1, 5, 10, 20, 30, 50 m) at each region in September and November of 2003. Three shrimp species [Palaemon adspersus (Rathke, 1937), Palaemon serratus (Pennant, 1777), Parapenaeus longirostris (H. Lucas, 1846)] were identified to be dominant as a result of the examination on the obtained samples. Heavy metal contents of these three species were determined and the results were compared with the acceptable treshold values of the Seafood Standards and also with available literatures. The Cu contents were found to be higher than the treshold limits in all samples except P. longirostris from Silivri, also the Cd contents in all samples except P. adspersus from Büyükçekmece, the Zn contents only in P. adspersus and P. longirostris from Tekirdağ, and the Pb contents in all species from all regions. These high values are the indicator of industrial pollution. There is not any data in the Seafood Standards about Mn, Ni, Fe and Al contents in shrimp species. The values of these metal contents were given in the present study. The examination of total metal distributions in bottom surface sediment samples in the Northern Inner Shelf of the Sea of Marmara showed that the determined values were higher than the shale average at some depths of examined stations. PMID:17406997
Kalkan, E.; Gulkan, Polat; Yilmaz, N.; Celebi, M.
In 1999, the eastern coastline of the Marmara region (Turkey) witnessed increased seismic activity on the North Anatolian fault (NAF) system with two damaging earthquakes (M 7.4 Kocaeli and M 7.2 D??zce) that occurred almost three months apart. These events have reduced stress on the western segment of the NAF where it continues under the Marmara Sea. The undersea fault segments have been recently explored using bathymetric and reflection surveys. These recent findings helped scientists to understand the seismotectonic environment of the Marmara basin, which has remained a perplexing tectonic domain. On the basis of collected new data, seismic hazard of the Marmara region is reassessed using a probabilistic approach. Two different earthquake source models: (1) the smoothed-gridded seismicity model and (2) fault model and alternate magnitude-frequency relations, Gutenberg-Richter and characteristic, were used with local and imported ground-motion-prediction equations. Regional exposure is computed and quantified on a set of hazard maps that provide peak horizontal ground acceleration (PGA) and spectral acceleration at 0.2 and 1.0 sec on uniform firm-rock site condition (760 m=sec average shear wave velocity in the upper 30 m). These acceleration levels were computed for ground motions having 2% and 10% probabilities of exceedance in 50 yr, corresponding to return periods of about 2475 and 475 yr, respectively. The maximum PGA computed (at rock site) is 1.5g along the fault segments of the NAF zone extending into the Marmara Sea. The new maps generally show 10% to 15% increase for PGA, 0.2 and 1.0 sec spectral acceleration values across much of Marmara compared to previous regional hazard maps. Hazard curves and smooth design spectra for three site conditions: rock, soil, and soft-soil are provided for the Istanbul metropolitan area as possible tools in future risk estimates.
Tolun, L; Martens, D; Okay, O S; Schramm, K W
Izmit Bay and its coastal environment was strongly affected by the August 17th, 1999 Izmit Earthquake. The changes in the Bay ecosystem and its chemical oceanography have been studied in detail previously [Okay, O.S., Tolun, L, Telli-Karakoç, F., Tüfekçi, V., Tüfekçi, H. And Morkoç, E. 2001. Yzmit Bay ecosystem after Marmara earthquake and subsequent fire: The long-term data. Marine Pollution Bulletin 42, 361-369; Balkýs, N. 2003. The effect of Marmara (Izmit ) Earthquake on the chemical oceanography of Izmit Bay, Turkey. Marine Pollution Bulletin 46, 865-878.]. In this study surface sediments collected from the Izmit Bay before and after the earthquake have been analysed for total and individual (14 compounds) polycyclic aromatic hydrocarbons (PAH). Analyses have been performed by high performance liquid chromatography with fluorescence detection (HPLC/FD). Before the earthquake, total PAH concentrations in the Bay sediments ranged from 120 to 8900 ng/g while after the earthquake PAH concentrations varied between 240 and 11,400 ng/g. Molecular indices based on isomeric PAH ratios used to differentiate the pollution sources, clearly indicate the differences in molecular distribution of PAHs before and after the earthquake. Sediment data obtained before the earthquake shows that most of the contamination originated from high temperature pyrolytic inputs while after the earthquake it originated from petrogenic sources. This difference emphasises the environmental impact of uncontrolled discharges from petroleum industries after the earthquake. The LMW/HMW ratio (sum of the low molecular weight PAHs / the sum of higher molecular weight PAHs) predominance also changed after the earthquake as a result of the strong water movements. According to the characteristics of aromatic rings distributed in the bay sediments, the soluble parts of the total PAH were probably transferred to the water column after the earthquake as a result of resuspension process. The TEL
Baltacı, H.; Kındap, T.; Ünal, A.; Karaca, M.
In this study, regional patterns of precipitation in Marmara are described for the first time by means of Ward's hierarchical cluster analysis. Daily values of winter precipitation data based on 19 meteorological stations were used for the period from 1960 to 2012. Five clusters of coherent zones were determined, namely Black Sea-Marmara, Black Sea, Marmara, Thrace, and Aegean sub-regions. To investigate the prevailing atmospheric circulation types (CTs) that cause precipitation occurrence and intensity in these five different rainfall sub-basins, objective Lamb weather type (LWT) methodology was applied to National Centers of Environmental Prediction (NCEP)/National Center for Atmospheric Research (NCAR) reanalysis of daily mean sea level pressure (MSLP) data. Precipitation occurrence suggested that wet CTs (i.e. N, NE, NW, and C) offer a high chance of precipitation in all sub-regions. For the eastern (western) part of the region, the high probability of rainfall occurrence is shown under the influence of E (SE, S, SW) atmospheric CTs. In terms of precipitation intensity, N and C CTs had the highest positive gradients in all the sub-basins of the Marmara. In addition, although Marmara and Black Sea sub-regions have the highest daily rainfall potential during NE types, high daily rainfall totals are recorded in all sub-regions except the Black Sea during NW types.
Kaneda, Yoshiyuki; Ozener, Haluk; Meral Özel, Nurcan
Turkey is one of seismogenic countries with destructive earthquakes. In Turkey, the 1999 Izumit Earthquake as the destructive earthquake occurred along the North Anatolian fault. This fault is crossing the Marmara sea. In this SATREPS project, Marmara Sea should be focused on because of a seismic gap in the North Anatolian fault. Istanbul is located around the Marmara Sea, so, if next earthquake in the Marmara will occur near Istanbul, fatal damages will be generated as compound damages including Tsunami and liquefaction etc. The Japan and Turkey can share our own experiences during past damaging earthquakes and we can prepare for future large earthquakes in cooperation with each other. In earthquakes in Tokyo area and Istanbul area as the destructive earthquakes near high population cities, there are common disaster researches and measures in each country. For disaster mitigation, we are progressing multidisciplinary researches in this SATREPS project. Our goals of this SATREPS project are as follows, This project is composed of four research groups. 1) The first group is Marmara Earthquake Source region observationally research group. This group has 4 sub-themes such as Seismicity, Geodesy, Electromagnetics and Trench analyses. 2) The second group focuses on scenario researches of earthquake occurrence along the North Anatolia fault and precise tsunami simulation in the Marmara region. 3) Aims of the third group are improvements and constructions of seismic characterizations and damage predictions based on observation researches and precise simulations. 4) The fourth group is promoting disaster educations using research result visuals. In this SATREPS project, we will integrate these research results for disaster mitigation in Marmara region and disaster education in Turkey. Finally, these results and knowledges will be applied to Japanese disaster mitigation researches and disaster educations. We will have a presentation of the updated results of this SATREPS
Karpytchev, M.; Coulomb, A.; Vallee, M.
Estimations of sea level rise over the last centuries are mostly based on the rare historical sea level records from tide gauge stations usually designed for navigational purposes. In this study, we examine the quality of sea level measurements performed by a mean sea level gauge operated in Nice from 1887 to 1909 and transferred to the nearby town of Villefranche-sur-Mer in 1913 where it stayed in operation untill 1974. The mean sea level gauges, called medimaremetres, were invented for geodetic studies and installed in many French ports since the end of the XIX century. By construction, the medimaremetre was connected to the sea through a porous porcelain crucible in order to filter out the tides and higher frequency sea level oscillations. Ucontrolled properties of the crucible and some systematic errors made the medimaremetre data to be ignored in the current sea level researches. We demonstrate that the Nice-Villefranche medimaremetre measurements are coherent with two available historical tide gauge records from Marseille and Genova and a new century-scale sea level series can be build up by combining the medimaremetre data with the those recorded by a tide gauge operating in Nice since the 1980s. We analyse the low frequency variabilities in Marseille, Nice-Villefranche and Genova and get new insights on the decadal sea level variations in the Ligurian Sea since the end of the XIX century.
Behrendt, Axel; Dierking, Wolfgang; Witte, Hannelore
Sea ice has been routinely monitored by satellites since 1979. However, thickness measurements of sea ice are still very sparse, especially in the Southern Hemisphere. Satellite altimetry still provides relatively uncertain estimates of ice thickness. Today, the only tool for monitoring sea ice thickness over long time periods with highest accuracy (5-10 cm) are moored upward looking sonars (ULS). The instruments measure the subsurface portion (draft) of the ice, which can be converted into total ice thickness. We present a data set of ULS time series from 13 positions in the Atlantic sector of the Southern Ocean (Weddell Sea), which were made in different years between 1990 and 2010. Monthly mean sea ice draft shows high interannual variability and can reach more than 3 m in the dynamic coastal regions of the eastern and western Weddell Sea. The thinnest ice is found away from the coast in the eastern Weddell Sea and rarely exceeds 1 m in the monthly mean. In single years the ULS data allow for a clear discrimination between thermodynamic ice growth and dynamic ice growth due to rafting and ridging of the floes. We demonstrate that the thermodynamic ice thickness can reach its theoretical maximum value of 1 m in the central Weddell basin. Despite significant gaps, the presented data set provides an important validation tool for satellite algorithms and sea ice models.
Nasif, Aslıhan; Dondurur, Derman; Ergintav, Semih; Cifci, Gunay
The Marmara Sea is an inland sea located in the NW of Turkey with a maximum depth of 1270 m, and consists of a 3 major sub-basins. The active dextral North Anatolian Fault (NAF) passes through the basins, which shapes the general morphology and forms the tectonic settlement of the Marmara Sea. The investigations for the Marmara Sea are now important since İstanbul city, which is the most populous and economically the most important city of Turkey, is located just north of the Marmara Sea, quite close to the NAF. In order to define the morphology and structural state of the northern continental shelf of the Marmara Sea, we collected 224 km of multichannel high resolution seismic and 338 km of Chirp subbottom profiler data along the shallow shelf in 2007. A 600 m long, 96 channel digital seismic streamer, and a Generator-Injector (GI) gun was used to obtain high resolution seismic data. The Chirp data was collected a 2.75-6.75 kHz over-the-side-mount transducer system. The data have been processed using a conventional data processing flow. The scope of the present study is to re-process and to interpret the seismic and Chirp data between Silivri and Sarayburnu on the northern Marmara shelf up to 100 m water depth. The active tectonic characteristics of the area, especially its geological connection with the terrestrial area, are investigated using acoustic data. In addition, offshore continuity of the of the Çatalca Fault zone is investigated. The Çatalca Fault enters the shelf along the B. Çekmece Lake and can be tracked in the SSE direction on the seismic data. The seismic data is tied to North Marmara-1 well located on the central part of the shelf area, and distributions and thicknesses of the pre-Miocene sediments are mapped using a jump-correlation to the well information. The seismic data located at the southernmost part of the shelf along the shelf break also indicate the presence of active sediment erosion. Behind the shelf break, the slope inclination
Kreutz, K. J.; Mayewski, P. A.; Pittalwala, I. I.; Meeker, L. D.; Twickler, M. S.; Whitlow, S. I.
Using European Center for Medium-Range Weather Forecasts (ECMWF) numerical operational analyses, sea ice extent records, and station pressure data, we investigate the influence of sea level pressure variability in the Amundsen Sea region on a West Antarctic (Siple Dome) glaciochemical record. Empirical orthogonal function analysis of the high-resolution Siple Dome multivariate ice core chemical time series record (SDEOF1) documents lower tropospheric transport of sea-salt aerosols to the site. During 1985-1994 the SDEOF1 record of high (low) aerosol transport corresponds to anomalously low (high) sea level pressure (SLP) in the Amundsen Sea region. Spatial correlation patterns between ECMWF monthly SLP fields and the annual SDEOF1 record suggest that a majority of sea-salt aerosol is transported to Siple Dome during spring (September, October, and November). Analysis of zonal and meridional wind fields supports the SLP/SDEOF1 correlation and suggests the SDEOF1 record is sensitive to changes in regional circulation strength. No relationship is found between sea ice extent and the SDEOF1 record for the period 1973-1994. To investigate the SDEOF1 record prior to ECMWF coverage, a spring transpolar index (STPI) is created, using normalized SLP records from the New Zealand and South America/Antarctic Peninsula sectors, and is significantly correlated (at least 95% c.l.) with the SDEOF1 record on an annual (r = 0.32, p < 0.001) and interannual (3 years; r = 0.51, p < 0.001) basis. Dominant periodicities (3.3 and 7.1 years) in the annual SDEOF1 record (1890-1994 A.D.) suggest that a portion of the recorded interannual variability may be related tropical/extratropical ENSO teleconnections. Changes in the periodic structure of the full (850-1994 A.D.) Siple Dome record suggests a shift in SLP forcing during the Little Ice Age (˜1400-1900 A.D.) interval.
Chou, Ming-Dah; Chan, Pui-King; Wang, Menghua
Aerosol optical properties inferred from the Sea-viewing Wide Field-of-view Sensor (SeaWiFS) radiance measurements are used to compute the aerosol shortwave radiative forcing using a radiative transfer model. The aerosol optical thickness at the wavelength of 865-nm is taken from the SeaWIFS archive. It is found that the nominal optical thickness over oceans ranges from 0.1 to 0.2. Using a maritime aerosol model and the radiances measured at the various SeaWiFS channels, the Angstrom exponent is determined to be 0.2174, the single-scattering albedo to be 0.995, and the asymmetry factor to be 0.786. The radiative transfer model has eight bands in the visible and ultraviolet spectral regions and three bands in the near infrared. It includes the absorption due to aerosols, water vapor, carbon dioxide, and oxygen, and the scattering due to aerosols and gases (Rayleigh scattering). The radiative forcing is computed over global oceans for four months (January, April, July, and October, 1998) to represent four seasons. It is found that the aerosol radiative forcing is large and changes significantly with seasons near the continents with large-scale forest fires and desert dust. Averaged over oceans and the four months, the aerosol radiative forcing is approximately 7 W/sq m at the top of the atmosphere. This large radiative forcing is expected to have a significant cooling effect on the Earth's climate as implied from simulations of a number of general circulation models.
Pınar, Ali; Coşkun, Zeynep; Mert, Aydın; Kalafat, Doğan
Frequency distribution of azimuth and plunges of P- and T-axes of focal mechanisms is compared with the orientation of maximum compressive stress axis for investigating the frictional strength of three fault segments of North Anatolian fault (NAF) in eastern Marmara Sea, namely Princes' Islands, Yalova-Çınarcık and Yalova-Hersek fault segments. In this frame, we retrieved 25 CMT solutions of events in Çınarcık basin and derived a local stress tensor incorporating 30 focal mechanisms determined by other researches. As for the Yalova-Çınarcık and Yalova-Hersek fault segments, we constructed the frequency distribution of P- and T-axes utilizing 111 and 68 events, respectively, to correlate the geometry of the principle stress axes and fault orientations. The analysis yields low frictional strength for the Princes' Island fault segments and high frictional strength for Yalova-Çınarcık, Yalova-Hersek segments. The local stress tensor derived from the inversion of P- and T-axes of the fault plane solutions of Çınarcık basin events portrays nearly horizontal maximum compressive stress axis oriented N154E which is almost parallel to the peak of the frequency distribution of the azimuth of the P-axes. The fitting of the observed and calculated frequency distributions is attained for a low frictional coefficient which is about μ ≈ 0.1. Evidences on the weakness of NAF segments in eastern Marmara Sea region are revealed by other geophysical observations. Our results also show that the local stress field in Çınarcık basin is rotated ≈30° clockwise compared to the regional stress tensor in Marmara region derived from the large earthquakes, whereas the local stress tensor in Yalova-Çınarcık area is found to be rotated ≈30° counterclockwise. The rotation of the two local stress fields is derived in the area where NAF bifurcates into two branches overlaying large electrical conductor.
Meral Ozel, Nurcan; Necmioglu, Ocal; Oguz Ozel, Asım; Ergintav, Semih; Geli, Louis Louis; Favali, Paolo; Guralp, Cansun; Douglas, John; Mathieu, Pierre-Philippe; Tan, Onur; Gürbüz, Cemil; Erdik, Mustafa
This presentation provides a progress overview of the EC/FP-7 MARSite Project started in November 2012, which aims to coordinate research groups ranging from seismology to gas geochemistry in a comprehensive monitoring activity developed both in the Marmara Region based on collection of multidisciplinary data to be shared, interpreted and merged in consistent theoretical and practical models suitable for the implementation of good practices to move the necessary information to the end users in charge of seismic risk management of the region. In addition, processes involved in earthquake generation and the physics of short-term seismic transients, 4D deformations to understand earthquake cycle processes, fluid activity monitoring and seismicity under the sea floor using existing autonomous instrumentation, early warning and development of real-time shake and loss information, real- and quasi-real-time earthquake and tsunami hazard monitoring and earthquake-induced landslide hazard topics are also covered within MARSite. This presentation would provide a report on the progress achieved during the half-life of the project. In this respect, the main data server for the integration of real time network data has been finalized. Daily evaluation of online spring water and soil radon gas data in relation to seismic activity is in place, together with the continuous GPS data processing. A significant combination of postseismic (viscoelastic) deformation and afterslip was detected in the western segment of the 1999 Izmit rupture plane based on InSAR modeling. The optimum borehole depths have been identified based on seismic reflection studies and GURALP Systems is continuing its work on the manufacturing the borehole system. Seismic risk study for IGDAS Natural Gas Network including pipelines and its components has been carried out with several earthquake scenarios in Marmara Sea and an automatic shut-off algorithm has been developed for the automatic shut-off of the gas
Meral Ozel, N.; Necmioglu, O.; Ozel, A. O.; Ergintav, S.; Tan, O.; Geli, L. B.; Favali, P.; Guralp, C. M.; Douglas, J.; Mathieu, P. P.; Gurbuz, C.; Erdik, M. O.
MARSite Project, initiated in November 2012 under the EC/FP-7 framework, aims to coordinate research groups ranging from seismology to gas geochemistry in a comprehensive monitoring activity developed both in the Marmara Region based on collection of multidisciplinary data to be shared, interpreted and merged in consistent theoretical and practical models suitable for the implementation of good practices to move the necessary information to the end users in charge of seismic risk management of the region. In addition, processes involved in earthquake generation and the physics of short-term seismic transients, 4D deformations to understand earthquake cycle processes, fluid activity monitoring and seismicity under the sea floor using existing autonomous instrumentation, early warning and development of real-time shake and loss information, real- and quasi-real-time earthquake and tsunami hazard monitoring and earthquake-induced landslide hazard topics are also covered within MARSite. This presentation would provide a report on the progress achieved during the half-life of the project. In this respect, the main data server for the integration of real time network data has been finalized. Daily evaluation of online spring water and soil radon gas data in relation to seismic activity is in place, together with the continuous GPS data processing. A significant combination of postseismic (viscoelastic) deformation and afterslip was detected in the western segment of the 1999 Izmit rupture plane based on InSAR modeling. The optimum borehole depths have been identified based on seismic reflection studies and GURALP Systems is continuing its work on the manufacturing the borehole system. Seismic risk study for IGDAS Natural Gas Network including pipelines and its components has been carried out with several earthquake scenarios in Marmara Sea and an automatic shut-off algorithm has been developed for the automatic shut-off of the gas flow at the IGDAS district regulators
Büyükakpınar, Pınar; Gürbüz, Cemil; Zor, Ekrem
The Marmara region is a rapidly deforming area with high seismic activity in the northwestern Turkey. In order to further understand the crustal structure in the region, we present results from receiver function analysis using the permanent stations in the region by applying H-κ stacking algorithm which gives crustal thickness and Vp/Vs ratio beneath a station. 40 land stations between January of 2008 and April of 2012, and 5 cabled Sea Bottom Observatories which were deployed at the end of 2010 by KOERI located between 40.2°- 41.2° N and 26.5°- 30.5° E were included in the analysis. Approximately 250 teleseismic events from a wide range of epicentral distances with magnitudes greater than Mw 5.5 are used to obtain receiver functions. Furthermore, in order to calculate the receiver functions in time domain using iterative deconvolution technique suggested by Ligorria and Ammon (1999). Consequently, the crustal structure of the region has been reasonably defined and compared with the other studies. As a consequence of the receiver function analysis, the Moho depth variation map and Vp/Vs ratio map were plotted. The Moho depth on average is 31 km. There are no sharp changes in the crustal thickness of the Marmara Region except North Marmara Trough because basin structure of the Marmara Sea where crustal thickness reaches up to 26 km in the same region was not observed. Furthermore, we found overall average Vp/Vs ratio of 1.74, for the region but we obtained low Vp/Vs ratios in the stations located near Çınarcık Basin which varies between 1.64 - 1.74 indicating the effect of basin structure in the area and North Marmara where Vp/Vs ratios vary between 1.60 and 1.70 which is related to the sediment structure of the area. We also acquired higher Vp/Vs ratios which are between 1.86 and 1.96 in the Western Marmara Region. This can be due to increasing mafic content in this area. Additionally, an attempt has been made to invert the radial receiver function of the
Erkan Kideys, Ahmet; Yüksek, Ahsen; Sur, Halil Ibrahim
In this study, meteorological and hydrographical conditions as well as chemical and biological parameters have been examined for the period 2005-2009 to determine the impact and cause of the massive mucilage phenomenon observed in the Sea of Marmara in October 2007. Results showed that there is a decrease pattern in chl concentration as well as both phytoplankton and zooplankton abundances from August till October in 2007 whilst the jellyfish Liriope tetraphylla had bloom levels. This period coincided with the maximum intensity of pelagic fishing throughout the years. Nitrogen/phosphate ratio increased prior to the mucilage formation. Invasive Liriope tetraphylla abundance increased exponentially in August and died in masses as a result of starvation and meteorological / oceanographic conditions. In October, following the mucilage matter production another new species for the region Gonyaulax fragilis was observed in high abundance through the basin. It is worthy to note that during basin wide samplings conducted in the Sea of Marmara in both 2005 and 2006, high abundances of Liriope tetraphylla have been detected particularly at the northern parts where no mucilage event was observed. We suggest that overfishing in the Sea of Marmara provided a ground for the establishment of the invasive jellyfish and accompanying mucilage event was due to by synergic combinations of several factors.
O'Dowd, Colin D.; Lowe, Jason A.; Smith, Michael H.; Davison, Brian; Hewitt, C. Nicholas; Harrison, Roy M.
Accumulation mode aerosol properties and biogenic sulphur emissions over the South Atlantic and Antarctic Oceans are examined. Two contrasting air masses, polar and maritime, each possessing distinct aerosol properties, were encountered during the summer months. By examining aerosol volatile properties, polar air masses arriving from the Antarctic continent were shown to consist primarily Of H2SO4 in the accumulation mode size range, with inferred NH+4 to SO=4 molar ratios close to zero. By comparison, air masses of temperate maritime origin were significantly neutralized with molar ratios of ≈1. These results suggest a deficit of ammonia in polar air masses compared with that in maritime air masses. Dimethyl sulphide (DMS) exhibited no correlation with its putative aerosol oxidation products, although spatial coherence in atmospheric concentrations of DMS, methane sulphonic acid (MSA), and non-sea-salt (nss)-sulphate mass was observed. Volatility analysis, used to infer nss-sulphate cloud condensation nuclei (nss-sCCN) active at a supersaturation of ≈0.2%, indicates that nss-sCCN mass and number concentration were best correlated with MSA mass (r≈0.63). Aerosol volatility identified the presence of MSA in submicron non-sea-salt aerosol; however, its contribution to the aerosol mass was small relative to the contribution of sulphuric acid and ammonium bisulphate/sulphate aerosol. The marine sulphur cycle appears strongly coupled to the sea-salt cycle with, typically, 80-90% of nss-sulphate thought to be internally mixed with sea-salt aerosol. During the austral Summer of 1992/1993, a period of strong biological productivity in the Weddell Sea and sub-Antarctic Ocean, particularly during ice-melt, the cruise-average DMS flux of 61 μg m-2 d-1 corresponded to a very modest average nss-sCCN concentration of 21 cm-3. Observed peak values of DMS flux and inferred nss-CCN concentrations during the cruise were 477 μg m-2 d-1 and 64 cm-3, respectively. Events of new
Woith, Heiko; Caka, Deniz; Seyis, Cemil; Italiano, Francesco; Celik, Cengiz; Wang, Rongjiang; Baris, Serif
Since many years MAM and GFZ in co-operation with Kocaeli University (KU) operate fluid monitoring stations around the Sea of Marmara. In the frame of MARsite (MARsite has received funding from the European Union's Seventh Programme for research, technological development and demonstration under grant agreement No 308417) these networks were jointly evaluated for the first time. The on-land fluid monitoring networks continuously monitor the following parameters: soil radon (21 sites), temperature and conductivity of thermal springs (9 sites) operated by MAM covering the whole Marmara region; fluid pressure and water level/temperature (8 sites) within ARNET operated by GFZ/KU. ARNET is a combined seismological/hydrogeological monitoring network covering the Armutlu peninsula located SE of Istanbul. Additional to the geothermal wells and springs - our main target to detect transients of potentially seismo-tectonic origin - three shallow groundwater wells (tenth of meters deep) are being operated to identify and quantify seasonal variations, and meteorological influences like rainfall and snowmelt. But it turned out that these shallow aquifer systems showed very stable conditions with very small annual temperature amplitudes (0.2 - 0.3°C). One of these shallow monitoring wells is located just south of Lake Iznik (in the village of Sölöz) very close to the southern branch of the North Anatolian Fault Zone. Water level showed a steady decreasing trend since June 2012. This trend resulted in a data gap starting in January 2014, when the water level dropped below the sensor position. After adjusting the sensor position, positive spikes in the borehole temperature were recorded in June and August 2014, and again in 2015. The spikes are characterised by a sharp temperature increase followed by a decay lasting several days until the pre-event temperature was reached again. Since the spikes occurred on two independent logger systems, and since they lasted several days, a
Chandan, D.; Peltier, W. R.
The issue of tectonic contamination of geological inferences of relative sea level history is an important one. The issue arises on timescales that range from the 21-26 kyrs that have passed since the Last Glacial Maximum, to the most recent time when periods as warm as the present are expected to have existed, such as the mid-Pliocene. The coral based record from Barbados, for example, is known to be contaminated by continuing tectonic uplift of the island at a rate of approximately 0.34 mm/yr. For the Pliocene warm period at ~3 Myr, records from geological sites, such as the Orangeburg Scarp in North Carolina, have played a prominent role in arguments underpinning the design of the ongoing international PlioMIP program. In connection with the latter site, Rowley et al (2013) have recently argued that this record is contaminated by a tectonic imprint sufficiently strong to suggest that the usual inferences of Pliocene eustatic sea level based upon it (eg. Miller et al, 2012) must be seen as highly suspect. Here we employ a tomographically constrained model of the mantle convection process to revisit the issue of the tectonic imprint on relative sea level at the Orangeburg site, as well as other similar locations. Our analysis is based upon the inferred time dependence of dynamic topography forced by the mantle's internal density heterogeneities delivered by the S20RTS seismic tomography model. We begin by comparing the static, present day dynamic topography predicted by the (linear) internal loading theory based on the formalism of Pari and Peltier (2000) with that predicted using using a full three dimensional version of the nonlinear time-dependent mantle convection model of Shahnas and Peltier (2010, 2011). We demonstrate first that these two methodologies produce extremely similar results for the static field. We then proceed to run the nonlinear convection model in data assimilation mode while continuously nudging the internal density field back towards the
Meral Ozel, Nurcan; Necmioglu, Ocal; Favali, Paolo; Douglas, John; Mathieu, Pierre Philippe; Geli, Louis; Tan, Onur; Ergintav, Semih; Oguz Ozel, A.; Gurbuz, Cemil; Erdik, Mustafa
Among the regions around the Mediterranean Sea for which earthquakes represent a major threat to their social and economic development, the area around the Marmara Sea, one of the most densely populated parts of Europe, is subjected to a high level of seismic hazard. For this region the MARSITE project is proposed with the aim of assessing the "state of the art" of seismic risk evaluation and management at European level. This will be the starting point to move a "step forward" towards new concepts of risk mitigation and management by long-term monitoring activities carried out both on land and at sea. MARsite will serve as the platform for an integrated, multidisciplinary, holistic and articulated framework for dealing with fault zone monitoring, capable of developing the next generation of observatories to study earthquake generation processes. The main progress will be the fusion of ground- and space-based monitoring systems dedicated to geo-hazard monitoring. All data (space/sea-bottom/seismology/borehole/geochemistry) will flow to KOERI and hosted in and served via a secure server. The MARSITE project aims to coordinate research groups with different scientific skills (from seismology to engineering to gas geochemistry) in a comprehensive monitoring activity developed both in the Marmara Sea and in the surrounding urban and country areas. The project collects multidisciplinary data, to be shared, interpreted and merged in consistent theoretical and practical models suitable for the implementation of good practices to move the necessary information to the end users in charge of seismic risk management of the Istanbul-Marmara Sea area. Marsite is divided into eleven work packages that consider the processes involved in earthquake generation and the physics of short-term seismic transients, 4D deformations to understand earthquake cycle processes, fluid activity monitoring and seismicity under the sea floor using existing autonomous instrumentation, early warning
Radebach, Alexander; Donges, Jonathan F.; Donner, Reik V.; Barbosa, Susana; Lange, Holger; Kurths, Jürgen
Since the advent of the satellite era, global sea-level altimetry data sets are available. To study complex oceanographic processes and their coupling to atmospheric dynamics it is necessary to advance beyond analyzing global mean sea-level rise or local trends. We apply a wide range of methods from linear and nonlinear time series analysis for investigating the complex dynamics of observed sea-level altimetry time series at different locations around the globe. Employing this toolkit, linear and nonlinear autodependencies (autocorrelation and auto-mutual information functions), deterministic structure (recurrence quantification and recurrence network analysis), time-reversibility characteristics (visibility graph analysis) and the relative importance of stochastic vs. deterministic dynamics (complexity-entropy plane) are studied. Combining the complimentary information from all metrics, consistent spatial patterns of sea-level dynamics are detected. Classical statistical properties such as variance, skewness and Shannon entropy of the probability distribution of sea-level reveal the special importance of western boundary currents as well as parts of the Antarctic Circumpolar Current as regions of particularly complex sea-level dynamics. In turn, the nonlinear dynamics characteristics present a somewhat different pattern exhibiting particularly high complexity in the tropics as well as the Gulf Stream and Kuroshio regions. Notably, these are also the areas where missing values due to atmospheric processes are most prominent. Further research is required to fully disentangle the dynamic complexity of sea-level from potential artifacts in the underlying altimetry data.
Naoki, Kazuhiro; Ukita, Jinro; Nishio, Fumihiko; Nakayama, Masashige; Comiso, Josefino C.; Gasiewski, Al
Since microwave radiometric signals from sea-ice strongly reflect physical conditions of a layer near the ice surface, a relationship of brightness temperature with thickness is possible especially during the early stages of ice growth. Sea ice is most saline during formation stage and as the salinity decreases with time while at the same time the thickness of the sea ice increases, a corresponding change in the dielectric properties and hence the brightness temperature may occur. This study examines the extent to which the relationships of thickness with brightness temperature (and with emissivity) hold for thin sea-ice, approximately less than 0.2 -0.3 m, using near concurrent measurements of sea-ice thickness in the Sea of Okhotsk from a ship and passive microwave brightness temperature data from an over-flying aircraft. The results show that the brightness temperature and emissivity increase with ice thickness for the frequency range of 10-37 GHz. The relationship is more pronounced at lower frequencies and at the horizontal polarization. We also established an empirical relationship between ice thickness and salinity in the layer near the ice surface from a field experiment, which qualitatively support the idea that changes in the near-surface brine characteristics contribute to the observed thickness-brightness temperature/emissivity relationship. Our results suggest that for thin ice, passive microwave radiometric signals contain, ice thickness information which can be utilized in polar process studies.
Morishita, T.; Ichiyama, Y.; Tamura, A.; Arai, S.
Peridotite xenoliths are recovered in basaltic to andesitic lavas from several localities in the Japan Sea, a Miocene back-arc basin of the Western Pacific region. These peridotites are classified into two groups: two-pyroxene peridotitess and dunite-wehrlite groups. Although slight chemical modifications are observed in these peridotite samples, two-pyroxene peridotite group has retained their original residual mantle geochemical signatures left after partial melting. The dunite-wehrlite group is, on the other hand, probably formed by extensive interaction of the two-pyroxene peridotite group. We examined trace element characteristics of clinopyroxene in these xenoliths. Light REE-depleted clinopyroxenes that are usually interpreted as a simple residual mantle after anhydrous partial melting are similar to those of abyssal peridotite recovered from mid-ocean ridges and back-arc basins. Other samples show LREE-enriched patterns that are residues after influx melting caused by hydrous melt/supercritical fluids released from the subducted slab at high pressure conditions. The geotectonic and geochemical variations of the peridotite xenoliths from the Japan Sea (Shirabeshi Seamount, Seifu Seamount and Oshima-Oshima Island) suggest that the mantle beneath the Japan Sea are suffered from hydrous to anhydrous melting as the Japan Sea forms. This is consistent with the geochemical and isotopic results from Miocene basaltic rocks formed during opening of the Japan Sea (Sato et al., Jour. Petrol., 2013). The Japan Sea peridotite xenoliths also shed lights on the origin of ophiolites.
Aochi, Hideo; Ulrich, Thomas; Douglas, John
In the framework of the European project MARSite (2012-2016), one of the main contributions from our research team was to provide ground-motion simulations for the Marmara region from various earthquake source scenarios. We adopted a 3D finite difference code, taking into account the 3D structure around the Sea of Marmara (including the bathymetry) and the sea layer. We simulated two moderate earthquakes (about Mw4.5) and found that the 3D structure improves significantly the waveforms compared to the 1D layer model. Simulations were carried out for different earthquakes (moderate point sources and large finite sources) in order to provide shake maps (Aochi and Ulrich, BSSA, 2015), to study the variability of ground-motion parameters (Douglas & Aochi, BSSA, 2016) as well as to provide synthetic seismograms for the blind inversion tests (Diao et al., GJI, 2016). The results are also planned to be integrated in broadband ground-motion simulations, tsunamis generation and simulations of triggered landslides (in progress by different partners). The simulations are freely shared among the partners via the internet and the visualization of the results is diffused on the project's homepage. All these simulations should be seen as a reference for this region, as they are based on the latest knowledge that obtained during the MARSite project, although their refinement and validation of the model parameters and the simulations are a continuing research task relying on continuing observations. The numerical code used, the models and the simulations are available on demand.
Sadeh, M.; Hamiel, Y.; Ziv, A.; Bock, Y.; Fang, P.
We quantify the interseismic slip rates and locking depths along the Dead-Sea Transform (DST) in Israel using GPS observations and elastic modeling. Large-scale crustal deformation and earthquakes in Israel are mainly related to the Dead Sea Transform (DST) and the Carmel-Gilboa-Faria Fault System (CFS). The former is an active left lateral transform, bounding the Arabian plate and the Sinai sub-plate, and the latter branches out of the former and separates the Sinai sub-plate into two tectonic domains. GPS observations from 18 permanent GPS stations and 147 densely spaced stations that were surveyed in three campaigns between 1996 and 2008 are used in this study. The GPS data is processed using the GAMIT/GLOBK software package, providing station coordinates and velocities relative to a fixed Sinai reference frame. Using a simple 2-D elastic model, we infer a slip rate of 3-4.2 mm/yr and a locking depth of 6.7-15.4 km along the DST north of the CFS, and a slip rate of 4.4-5.1 mm/yr and a locking depth of 12.3-23 km south of the CFS. Additionally, we infer a left lateral slip rate of 0.5-1.3 along the CFS, and a rate of about 0.5 mm/yr of extension perpendicular to it. Near fault observations rule out the possibility of shallow creep along the Northern segment of the DST, but suggest that creep may occur along the Dead Sea West Boundary Fault.
Mauz, Barbara; Shen, Zhixiong
One of the responders to Milankovitch-scale climate changes is sea level which, in turn, is a driver of coastal change. In literature, the sedimentary sequences representing the coastal change are often linked to high sea-level stands, to intermediate sea-level positions or to regressive shorelines. We note apparent contradictions that indicate a lack of concept and inconsistent usage of sea level-related terms. To overcome this, we combine an integrated morpho-sedimentological concept for microtidal, mid-latitudinal coasts with chronologies based on Bayesian statistics. The concept regards the coastal sedimentary system as a depositional complex consisting of shallow-marine, aeolian and alluvial facies. These facies are in juxtaposition and respond simultaneously to external forcing. Bayesian statistics constrains the timing of the sequence based on optical or radiocarbon ages. Here, we present the site Hergla located on the North African coast of the central Mediterranean Sea as a case study to illustrate how the approach helps eliminating contradictions. The site has been cited frequently for confirming the hypothesis of a global two peak sea-level highstand during the last interglacial (MIS 5e). The ~2 km cliff exposure at Hergla was surveyed, mapped, logged and sampled for further describing the sediments and their depositional environment through thin section and Bayesian modelling of optical ages. Using our concept based on sequence stratigraphy tools, the section is interpreted as representing a coastal barrier with two bounding surfaces in the succession. Both surfaces mark the falling sea level of, first, MIS 5e and, second, MIS 5a and hence bound the falling stage system tract of a forced regression. Part of the deposits between the two surfaces are pulled up onto the shoulder of a small rising horst and the associated tectonic event coincided with the MIS 5a sea-level rise enhancing locally the accommodation space for a second foreshore environment. Our
Cazenave, A. A.; Llovel, W.; Becker, M.; Cretaux, J.
Global change in land water storage and its effect on sea level is estimated over a 6-year time span (mid-2002 to mid-2008) using satellite altimetry and space gravimetry data from GRACE. Satellite altimetry allows determination of surface water volume change while GRACE data provide vertically-integrated water storage change. The 32 largest river basins are considered as well as lakes not included in the 32 basins (Caspian and Aral seas). We focus on the year to year variability and construct a combined water storage time series that we further express in equivalent sea level time series. The mean trend in total water storage adjusted over this 6-year time span is positive and amounts to 114 +/- 24 km3/yr (net water storage excess). Most of the positive contribution arises from the Amazon and Siberian basins (Lena and Yenisei), followed by the Orinoco, Ob, Nile, Niger, Zambezi, Tocantins and Volga. The largest negative contributions (water deficit) come from the Mississippi, Yukon, Eyre, Brahmaputra, Ganges, Eyre, Murray and Mekong basins. Lakes volume change is slightly negative over the 2002-2008 time span (~ -16 km3/yr). Expressed in terms of equivalent sea level, total water volume change over 2002-2008 leads to a small negative contribution to sea level of -0.27 +/- 0.07 mm/yr. The time series for each basins clearly show that year to year variability dominates so that the value estimated in this study cannot be considered as representative of a long-term trend. Another interesting results of the study is the significant correlation (0.7) between (detrended) year-to- year variability in sea level (corrected for thermal expansion) and GRACE-based land water storage contribution.
Llovel, William; Becker, Mélanie; Cazenave, Anny; Crétaux, Jean-François; Ramillien, Guillaume
Global change in land water storage and its effect on sea level is estimated over a 7-year time span (August 2002 to July 2009) using space gravimetry data from GRACE. The 33 World largest river basins are considered. We focus on the year-to-year variability and construct a total land water storage time series that we further express in equivalent sea level time series. The short-term trend in total water storage adjusted over this 7-year time span is positive and amounts to 80.6 ± 15.7 km 3/yr (net water storage excess). Most of the positive contribution arises from the Amazon and Siberian basins (Lena and Yenisei), followed by the Zambezi, Orinoco and Ob basins. The largest negative contributions (water deficit) come from the Mississippi, Ganges, Brahmaputra, Aral, Euphrates, Indus and Parana. Expressed in terms of equivalent sea level, total water volume change over 2002-2009 leads to a small negative contribution to sea level of -0.22 ± 0.05 mm/yr. The time series for each basin clearly show that year-to-year variability dominates so that the value estimated in this study cannot be considered as representative of a long-term trend. We also compare the interannual variability of total land water storage (removing the mean trend over the studied time span) with interannual variability in sea level (corrected for thermal expansion). A correlation of ˜0.6 is found. Phasing, in particular, is correct. Thus, at least part of the interannual variability of the global mean sea level can be attributed to land water storage fluctuations.
Işık, S. E.; Gurbuz, C.
The 3D P wave velocity model of upper and lower crust of the Marmara Region between 40.200- 41.200N and 26.500- 30.500E is obtained by tomographic inversion (Simulps) of 47034 P wave arrivals of local earthquakes recorded at 90 land stations between October 2009 and December 2012 and 30 OBO stations and 14162 shot arrivals recorded at 35 OBO stations (Seismarmara Survey, 2001). We first obtained a 1D minimum model with Velest code in order to obtain an initial model for 3D inversion with 648 well located earthquakes located within the study area. After several 3D inversion trials we decided to create a more adequate initial model for 3D inversion. Choosing the initial model we estimated the 3D P wave velocity model representing the whole region both for land and sea. The results are tested by making Checkerboard , Restoring Resolution and Characteristic Tests, and the reliable areas of the resulting model is defined in terms of RDE, DWS, SF and Hit count distributions. By taking cross sections from the resulting model we observed the vertical velocity change along profiles crossing both land and sea. All the profiles crossing the basins showed that the high velocities of lower crust make extensions towards the basin area which looks like the force that gives a shape to the basins. These extensions of lower crust towards the basins appeared with an average velocity of 6.3 km/s which might be the result of the deformation due the shearing in the region. It is also interpreted that the development of these high velocities coincide with the development of the basins. Thus, both the basins and the high velocity zones around them might be resulted from the entrance of the NAF into the Marmara Sea and at the same time a shear regime was dominated due to the resistance of the northern Marmara Region (Yılmaz, 2010). The seismicity is observed between 5 km and 15 km after the 3D location of the earthquakes. The locations of the earthquakes improved and the seismogenic zone
Shackleton, Calvin; Bjarnadóttir, Lilja; Winsborrow, Monica; Esteves, Mariana; Andreassen, Karin
A large multibeam dataset acquired by the MAREANO programme covering over 24,000 km2 at 5 m horizontal resolution has uncovered abundant subglacial meltwater landforms in the central Barents Sea. These landforms provide unprecedented insights into the nature of hydrological systems operating at the bed of the former Barents Sea Ice Sheet, helping us to understand the subglacial environments of marine based ice sheets as a whole. Large sinuous features up to 3.5 km wide and over 40 km long, with depths up to 40 m are interpreted as braided tunnel valleys, which would have drained vast amounts of water at the base of the ice sheet. Dendritic channels are also common, up to 42 km long and 24 m deep, along with several anastomosing channels and numerous complex esker systems. These features document that a wide range of subglacial hydraulic conditions and a well-established meltwater system existed beneath the former Barents Sea Ice Sheet. In conjunction with mapping of glacial landforms, these meltwater features provide the basis for a reconstruction of the subglacial drainage systems in the central Barents Sea and their interaction with the dynamic activity of the overlying ice sheet.
Morin, Efrat; Ryb, Tamar; Gavrieli, Ittai; Enzel, Yehouda
The Dead Sea is a terminal lake of one of the largest watersheds in the Levant (~43,000 square km), draining sub-humid to hyperarid climate zones. The large size of the watershed and the synchronous regional pattern of annual precipitation are the main reasons that the Dead Sea lake levels are good proxies for the Levant precipitation. Since the mid-1960s intensive water diversions from this watershed caused a dramatic human-induced level drop (currently >1 m/year). Holocene lake levels were used to infer regional precipitation regimes. Previous studies have associated lake level rises and drops with past wet and dry periods in the region, but their quantitative assessment remains a challenge. Moreover, the attributing of lake levels alterations to changes in precipitation regime still misses natural precipitation variability and there is a need to identify and separate their effects. The current study confronts these basic challenges that underlie the transfer of proxy to climatic parameter procedures. It uses here a unique stochastic framework under which we link precipitation regime with the Dead Sea lake levels, considering changes and trends in both mean and variance. Then we infer Levant precipitation regime during the Holocene. The present mean and variance of annual precipitation and lake levels are represented by (a) Kfar Giladi rain station, determined as the best correlated with natural Dead Sea lake level changes, and, (b) using a water balance model; this allowed simulating mean and variance of annual lake levels. Stochastic simulations included scenarios of changes in precipitation regime considering both constant and trended mean annual precipitation. We assessed probabilities of obtaining specific rises and drops, derived from reconstructed Holocene lake levels, under diverse scenarios. The results suggest that late Holocene precipitation regime could be governed by periods of increasing and decreasing trends of mean annual precipitation in the
Paine, Jeffrey G.
Changes in sea level observed at tide gauges are caused by actual changes in water level and by changes in elevation at the observing station. Recent research has focused on the relationship between climatic change and sea level, but vertical land movement can be just as important, particularly in subsiding sedimentary basins. The purpose of this study is to compare long-term rates of subsidence estimated from upper Pleistocene strata along the central Texas coast with historical subsidence rates from the same area obtained from geodetic surveys and tide gauge data. This comparison shows that historical subsidence rates are much greater than long-term averages and are equal or greater than actual sea-level change along the Texas coast south of Galveston Bay. Long-term (~ 10 5 yr) subsidence rates were estimated by establishing the extent of marine, marine-influenced, and nonmarine strata within the upper Pleistocene Beaumont Formation in the Copano Bay area of the central Texas coast, and comparing the maximum elevation of in-place, marine-influenced deposits with published maximum sea level estimates of 5-8 m above mean sea level (MSL) from correlative, well-dated coral terraces from stable and uplifted areas. In-place, shell-bearing horizons deposited at or below sea level occur no higher than 2 m MSL in the Copano Bay area, suggesting that there has been no more than 6 m of subsidence since the probable time of deposition during the Sangamon interglacial at ~ 120 ka. The long-term, average subsidence rate for this part of the Texas coast is thus 0.05 mm/yr or less. Historical subsidence rates were obtained by: (1) calculating relative elevation changes between National Geodetic Survey first-order leveling surveys conducted in the early 1950s with those conducted in the late 1970s to early 1980s; (2) normalizing the relative elevation differences between surveys to annual rates of change relative to an arbitrarily chosen benchmark; (3) referencing these lines to
Kozlov, I. E.; Kudryavtsev, V. N.; Zubkova, E. V.; Zimin, A. V.; Chapron, B.
In this paper we present the results of short-period internal wave (SIW) observations in the Kara Sea on the basis of satellite ENVISAT ASAR data between July and October 2007. Altogether, 248 internal wave (IW) packets and solitons are identified in 89 SAR images. Detailed spatial statistics of IW signatures and their properties in the Kara Sea is presented. The primary regions of IW activity are the areas near the Kara Gates Strait, the southeastern part of the Novaya Zemlya Trough, and in the vicinity of Cape Zhelaniya. We identify the regions where large IW packets are observed with wavelengths up to 2-3 km and the front length exceeding 200 km. The mean interpacket distance for observed IWs is about 20 km, but it may reach 50-60 km. Consequent IW packets are observed to travel up to 500 km from the presumed generation points. The results of satellite observations are compared with results of previous studies.
He, Yunchang; Stanev, Emil V; Yakushev, Evgeniy; Staneva, Joanna
The long-term variability of the physical and biochemical structure of oxic and suboxic layers in the Black Sea was studied using a one-dimensional coupled hydrophysical and biogeochemical model. The focus was on the correlation between atmospheric forcing (2 m air temperature and dew point temperature, surface level pressure, surface wind) affected by the North Atlantic Oscillation in and the regional responses. The quality of model performance was demonstrated using observed vertical and temporal distribution of biogeochemical variables. It was shown that during 1960-2000, the long-term variability of simulated winter-mean SST in the Black Sea correlated reasonably well with the variability of 2 m air temperature. Furthermore, the thermal state of the upper ocean impacted largely on the variability of biogeochemical variables, such as oxygen, nitrate and phytoplankton concentration. The tele-connection between North Atlantic Oscillation and Black Sea biogeochemistry was manifested in a different way for the specific time-interval 1960-2000; the corresponding regime shifts were thus associated with the large scale forcing. One such extreme event occurred in 1976 leading to a pronounced shift in the oxygen and hydrogen sulfide state. PMID:22425506
Crusius, J.; Anderson, R. F.
Recently-published estimates for the age of the unit 1-unit 2 contact in Black Sea sediments based on accelerator mass spectrometry (AMS) 14C measurements [Jones, 1990; Calvert et al., 1991] appear to be older than those based on the previously published chronology based on lamina couplets [Degens et al., 1980; Hay, 1988] by a factor of 2 to 3. To help reconcile the differences, we compare sediment accumulation rates based on the 210Pb method with estimates based on lamina counts for two cores from the Black Sea abyssal plain. Accumulation rates estimated using the 210Pb technique have varied little over the last 150 years from the averages of 55 and 50 g m-2 yr-1 at stations in the western and eastern basins, respectively. These values are about a factor of 2 lower than accumulation rates derived by counting lamina couplets over the dated intervals. Close examination of the laminae suggests that the discrepancy exists both because it is difficult to count the very fine laminae and because a complete couplet is not deposited every year. In order to provide a useful stratigraphic horizon for future investigators studying sedimentary records of the Black Sea, we estimate the age of a distinct black marker horizon which can be easily identified across the entire abyssal plain to be 150±8 years (deposited in 1838±8 A.D.).
Polyak, L; Edwards, M H; Coakley, B J; Jakobsson, M
It has been proposed that during Pleistocene glaciations, an ice cap of 1 kilometre or greater thickness covered the Arctic Ocean. This notion contrasts with the prevailing view that the Arctic Ocean was covered only by perennial sea ice with scattered icebergs. Detailed mapping of the ocean floor is the best means to resolve this issue. Although sea-floor imagery has been used to reconstruct the glacial history of the Antarctic shelf, little data have been collected in the Arctic Ocean because of operational constraints. The use of a geophysical mapping system during the submarine SCICEX expedition in 1999 provided the opportunity to perform such an investigation over a large portion of the Arctic Ocean. Here we analyse backscatter images and sub-bottom profiler records obtained during this expedition from depths as great as 1 kilometre. These records show multiple bedforms indicative of glacial scouring and moulding of sea floor, combined with large-scale erosion of submarine ridge crests. These distinct glaciogenic features demonstrate that immense, Antarctic-type ice shelves up to 1 kilometre thick and hundreds of kilometres long existed in the Arctic Ocean during Pleistocene glaciations. PMID:11260709
Earthquake and Tsunami Disaster Mitigation in The Marmara Region and Disaster Education in Turkey (SATREPS Project: Science and Technology Research Partnership for Sustainable Development by JICA-JST)
Earthquake and Tsunami Disaster Mitigation in The Marmara Region and Disaster Education in Turkey (SATREPS Project: Science and Technology Research Partnership for Sustainable Development by JICA-JST) Yoshiyuki KANEDA Disaster mitigation center Nagoya University/ Japan Agency for Marine-Earth Science and Technology (JAMSTEC) Mustafa ELDIK Boğaziçi University, Kandilli Observatory and Earthquake Researches Institute (KOERI) and Members of SATREPS Japan-Turkey project The target of this project is the Marmara Sea earthquake after the Izmit (Kocaeli) Earthquake 1999 along to the North Anatolian fault. According to occurrences of historical Earthquakes, epicenters have moved from East to West along to the North Anatolian Fault. There is a seismic gap in the Marmara Sea. In Marmara region, there is Istanbul with high populations such as Tokyo. Therefore, Japan and Turkey can share our own experiences during past damaging earthquakes and we can prepare for future large Earthquakes and Tsunamis in cooperation with each other in SATREPS project. This project is composed of Multidisciplinary research project including observation researches, simulation researches, educational researches, and goals are as follows, ① To develop disaster mitigation policy and strategies based on Multidisciplinary research activities. ② To provide decision makers with newly found knowledge for its implementation to the current regulations. ③ To organize disaster education programs in order to increase disaster awareness in Turkey. ④ To contribute the evaluation of active fault studies in Japan. In this SATREPS project, we will integrate Multidisciplinary research results for disaster mitigation in Marmara region and .disaster education in Turkey.
Sprenk, D.; Weber, M. E.; Kuhn, G.; Wennrich, V.; Hartmann, T.; Seelos, K.
The Weddell Sea and the associated Filchner-Rønne Ice Shelf constitute key regions for global bottom-water production today. However, little is known about bottom-water production under different climate and ice-sheet conditions. Therefore, we studied core PS1795, which consists primarily of fine-grained siliciclastic varves that were deposited on contourite ridges in the southeastern Weddell Sea during the Last Glacial Maximum (LGM). We conducted high-resolution X-ray fluorescence (XRF) analysis and grain-size measurements with the RADIUS tool (Seelos and Sirocko, 2005) using thin sections to characterize the two seasonal components of the varves at sub-mm resolution to distinguish the seasonal components of the varves. Bright layers contain coarser grains that can mainly be identified as quartz in the medium-to-coarse silt grain size. They also contain higher amounts of Si, Zr, Ca, and Sr, as well as more ice-rafted debris (IRD). Dark layers, on the other hand, contain finer particles such as mica and clay minerals from the chlorite and illite groups. In addition, Fe, Ti, Rb, and K are elevated. Based on these findings as well as on previous analyses on neighbouring cores, we propose a model of enhanced thermohaline convection in front of a grounded ice sheet that is supported by seasonally variable coastal polynya activity during the LGM. Accordingly, katabatic (i.e. offshore blowing) winds removed sea ice from the ice edge, leading to coastal polynya formation. We suggest that glacial processes were similar to today with stronger katabatic winds and enhanced coastal polynya activity during the winter season. Under these conditions, lighter coarser-grained layers are likely glacial winter deposits, when brine rejection was increased, leading to enhanced bottom-water formation and increased sediment transport. Vice versa, darker finer-grained layers were then deposited during less windier season, mainly during summer, when coastal polynya activity was likely
Guilderson, T. P.; McCarthy, M. D.; Dunbar, R. B.; Englebrecht, A.; Roark, E. B.
δ15N and δ13C data obtained from samples of proteinaceous deep-sea corals collected from the North Pacific Subtropical Gyre (Hawaiian Archipelago) and the central equatorial Pacific (Line Islands) document multidecadal to century-scale variability in the isotopic composition of surface-produced particulate organic matter exported to the deep sea. Comparison of the δ13C data, where Line Islands samples are 0.6‰ more positive than the Hawaiian samples, supports the contention that the North Pacific Subtropical Gyre is more efficient than the tropical upwelling system at trapping and/or recycling nutrients within the mixed layer. δ15N values from the Line Islands samples are also more positive than those from the central gyre, and within the Hawaiian samples there is a gradient with more positive δ15N values in samples from the main Hawaiian Islands versus the French Frigate Shoals in the Northwestern Hawaiian Islands. The gradient in the Hawaiian samples likely reflects the relative importance of algal acquisition of metabolic N via dissolved seawater nitrate uptake versus nitrogen fixation. The Hawaiian sample set also exhibits a strong decrease in δ15N values from the mid-Holocene to present. We hypothesize that this decrease is most likely the result of decreasing trade winds, and possibly a commensurate decrease in entrainment of more positive δ15N-NO3 subthermocline water masses.
Guilderson, T. P.; McCarthy, M. D.; Dunbar, R. B.; Englebrecht, A.; Roark, E. B.
δ15N and δ13C data obtained from samples of proteinaceous deep-sea corals collected from the North Pacific Subtropical Gyre (Hawai'ian archipelago) and the central equatorial Pacific (Line Islands) document multi-decadal to century scale variability in the isotopic composition of surface-produced particulate organic matter exported to the deep sea. Comparison of the δ13C data, where Line Island samples are 0.6‰ more positive than the Hawai'ian samples, support the contention that the North Pacific Subtropical Gyre is more efficient than the tropical upwelling system at trapping and/or recycling nutrients within the mixed layer. δ15N values from the Line Island samples are also more positive than those from the central gyre, and within the Hawai'ian samples there is a gradient with more positive δ15N values in samples from the main Hawai'ian Islands versus French Frigate Shoals in the Northwestern Hawai'ian Islands. The gradient in the Hawai'ian samples likely reflects the relative importance of algal acquisition of metabolic N via dissolved seawater nitrate uptake versus nitrogen fixation. The Hawai'ian sample set also exhibits a strong decrease in δ15N values from the mid-Holocene to present. We hypothesize that this decrease is most likely the result of decreasing tradewinds, and possibly a commensurate decrease in entrainment of more positive δ15N-NO3 subthermocline water masses.
Dancause, Kelsey Needham; Chan, Chim W; Arunotai, Narumon Hinshiranan; Lum, J Koji
The origins of the Moken 'Sea Gypsies,' a group of traditionally boat-dwelling nomadic foragers, remain speculative despite previous examinations from linguistic, sociocultural and genetic perspectives. We explored Moken origin(s) and affinities by comparing whole mitochondrial genome and hypervariable segment I sequences from 12 Moken individuals, sampled from four islands of the Mergui Archipelago, to other mainland Asian, Island Southeast Asian (ISEA) and Oceanic populations. These analyses revealed a major (11/12) and a minor (1/12) haplotype in the population, indicating low mitochondrial diversity likely resulting from historically low population sizes, isolation and consequent genetic drift. Phylogenetic analyses revealed close relationships between the major lineage (MKN1) and ISEA, mainland Asian and aboriginal Malay populations, and of the minor lineage (MKN2) to populations from ISEA. MKN1 belongs to a recently defined subclade of the ancient yet localized M21 haplogroup. MKN2 is not closely related to any previously sampled lineages, but has been tentatively assigned to the basal M46 haplogroup that possibly originated among the original inhabitants of ISEA. Our analyses suggest that MKN1 originated within coastal mainland SEA and dispersed into ISEA and rapidly into the Mergui Archipelago within the past few thousand years as a result of climate change induced population pressure. PMID:19158811
Bourassa, Mark A.; Gille, Sarah T.; Jackson, Daren L.; Roberts, J. Brent; Wick, Gary A.
Air-sea turbulent fluxes determine the exchange of momentum, heat, freshwater, and gas between the atmosphere and ocean. These exchange processes are critical to a broad range of research questions spanning length scales from meters to thousands of kilometers and time scales from hours to decades. Examples are discussed (section 2). The estimation of surface turbulent fluxes from satellite is challenging and fraught with considerable errors (section 3); however, recent developments in retrievals (section 3) will greatly reduce these errors. Goals for the future observing system are summarized in section 4. Surface fluxes are defined as the rate per unit area at which something (e.g., momentum, energy, moisture, or CO Z ) is transferred across the air/sea interface. Wind- and buoyancy-driven surface fluxes are called surface turbulent fluxes because the mixing and transport are due to turbulence. Examples of nonturbulent processes are radiative fluxes (e.g., solar radiation) and precipitation (Schmitt et al., 2010). Turbulent fluxes are strongly dependent on wind speed; therefore, observations of wind speed are critical for the calculation of all turbulent surface fluxes. Wind stress, the vertical transport of horizontal momentum, also depends on wind direction. Stress is very important for many ocean processes, including upper ocean currents (Dohan and Maximenko, 2010) and deep ocean currents (Lee et al., 2010). On short time scales, this horizontal transport is usually small compared to surface fluxes. For long-term processes, transport can be very important but again is usually small compared to surface fluxes.
Martin, R.E.; Leorri, E.; McLaughlin, P.P.
Repeated marine invasions of the Black Sea during the Holocene have been inferred by many eastern scientists as resulting from episodes of marine inflow from the Mediterranean beneath a brackish outflow from the Black Sea. We support this scenario but a fundamental question remains: What caused the repeated marine invasions? We offer an hypothesis for the repeated marine invasions of the Black Sea based on: (1) the overall similarity of sea-level curves from both tectonically quiescent and active margins of the Black Sea and their similarity to a sequence stratigraphic record from the US mid-Atlantic coast. The similarity of the records from two widely-separated regions suggests their common response to documented Holocene climate ocean-atmosphere reorganizations (coolings); (2) the fact that in the modern Black Sea, freshwater runoff from surrounding rivers dominates over evaporation, so that excess runoff might have temporarily raised Black Sea level (although the Black Sea would have remained brackish). Following the initial invasion of the Black Sea by marine Mediterranean waters (through the Marmara Sea) in the early Holocene, repeated marine incursions were modulated, or perhaps even caused, by freshwater discharge to the Black Sea. Climatic amelioration (warming) following each documented ocean-atmosphere reorganization during the Holocene likely shifted precipitation patterns in the surrounding region and caused mountain glaciers to retreat, increasing freshwater runoff above modern values and temporarily contributing to an increase of Black Sea level. Freshwater-to-brackish water discharges into the Black Sea initially slowed marine inflow but upon mixing of runoff with more marine waters beneath them and their eventual exit through the Bosphorus, marine inflow increased again, accounting for the repeated marine invasions. The magnitude of the hydrologic and sea-level fluctuations became increasingly attenuated through the Holocene, as reflected by Black
Durukal, E.; Erdik, M.; Safak, E.; Ansal, A.; Ozel, O.; Alcik, H.; Mert, A.; Kafadar, N.; Korkmaz, A.; Kurtulus, A.
Istanbul has a 65% chance of having a magnitude 7 or above earthquake within the next 30 years. As part of the preparations for the future earthquake, strong motion networks have been installed in and around Istanbul. The Marmara Strong Motion Network, operated by the Department of Earthquake Engineering of Kandilli Observatory and Earthquake Research Institute, encompasses permanent systems outlined below. It is envisaged that the networks will be run by a single entity responsible for technical management and maintanence, as well as for data management, archiving and dissemination through dedicated web-based interfaces. • Istanbul Earthquake Rapid Response and Early Warning System - IERREWS (one hundred 18-bit accelerometers for rapid response; ten 24-bit accelerometers for early warning) • IGDAŞ Gas Shutoff Network (100 accelerometers to be installed in 2010 and integrated with IERREWS) • Structural Monitoring Arrays - Fatih Sultan Mehmet Suspension Bridge (1200m-long suspension bridge across the Bosphorus, five 3-component accelerometers + GPS sensors) - Hagia Sophia Array (1500-year-old historical edifice, 9 accelerometers) - Süleymaniye Mosque Array (450-year-old historical edifice,9 accelerometers) - Fatih Mosque Array (237-year-old historical edifice, 9 accelerometers) - Kanyon Building Array (high-rise office building, 5 accelerometers) - Isbank Tower Array (high-rise office building, 5 accelerometers) - ENRON Array (power generation facility, 4 acelerometers) - Mihrimah Sultan Mosque Array (450-year-old historical edifice,9 accelerometers + tiltmeters, to be installed in 2009) - Sultanahmet Mosque Array, (390-year-old historical edifice, 9 accelerometers + tiltmeters, to be installed in 2009) • Special Arrays - Atakoy Vertical Array (four 3-component accelerometers at 25, 50, 75, and 150 m depths) - Marmara Tube Tunnel (1400 m long submerged tunnel, 128 ch. accelerometric data, 24 ch. strain data, to be installed in 2010) - Air-Force Academy
Inglis, Gordon N.; Farnsworth, Alexander; Lunt, Daniel; Foster, Gavin L.; Hollis, Christopher J.; Pagani, Mark; Jardine, Phillip E.; Pearson, Paul N.; Markwick, Paul; Galsworthy, Amanda M. J.; Raynham, Lauren; Taylor, Kyle. W. R.; Pancost, Richard D.
The TEX86 proxy, based on the distribution of marine isoprenoidal glycerol dialkyl glycerol tetraether lipids (GDGTs), is increasingly used to reconstruct sea surface temperature (SST) during the Eocene epoch (56.0-33.9 Ma). Here we compile published TEX86 records, critically reevaluate them in light of new understandings in TEX86 palaeothermometry, and supplement them with new data in order to evaluate long-term temperature trends in the Eocene. We investigate the effect of archaea other than marine Thaumarchaeota upon TEX86 values using the branched-to-isoprenoid tetraether index (BIT), the abundance of GDGT-0 relative to crenarchaeol (%GDGT-0), and the Methane Index (MI). We also introduce a new ratio, %GDGTRS, which may help identify Red Sea-type GDGT distributions in the geological record. Using the offset between TEX86H and TEX86L (ΔH-L) and the ratio between GDGT-2 and GDGT-3 (/), we evaluate different TEX86 calibrations and present the first integrated SST compilation for the Eocene (55 to 34 Ma). Although the available data are still sparse some geographic trends can now be resolved. In the high latitudes (>55°), there was substantial cooling during the Eocene (~6°C). Our compiled record also indicates tropical cooling of ~2.5°C during the same interval. Using an ensemble of climate model simulations that span the Eocene, our results indicate that only a small percentage (~10%) of the reconstructed temperature change can be ascribed to ocean gateway reorganization or paleogeographic change. Collectively, this indicates that atmospheric carbon dioxide (pCO2) was the likely driver of surface water cooling during the descent toward the icehouse.
Tari, U.; Tuysuz, O.
The North Anatolian Fault, one of the longest and most active strike-slip faults of the world, is an important feature controlling the recent tectonic and morphological development of the northern part of Asia Minor. Along this 1500 km-long active dextral zone, best examples of pull-apart basins, push-up structures, and other strike-slip fault-related morphological features developed under the control of geometric and structural orientation of fault segments. The North Anatolian Fault splays into three main branches in the Northwestern Anatolia. According to GPS measurements, the northern branch is the most active one among the others. The Sea of Marmara and the Gulf of Izmit forming its eastern tip, were developed as pull-apart basins on this branch from Late Pliocene onward. The morphology and bathymetry of the region bear traces of the fault and fault-controlled morphological features. The morphometry of a landscape can be described as a function of the changes in elevation. Digital elevation models, and recently developed computer programs allow detailed analysis. In this study we evaluated morphometric analysis of an area between Gulf of Izmit and Adapazari pull-apart basin on the northern branch of the North Anatolian Fault. The area contains three east-west trending belts. The northern belt, the Kocaeli Peninsula, developed as a peneplain during the Late Miocene. The average height of this peneplain is about 150-200 m. The peneplain surface is delimited to the south by a degraded fault surface trending parallel to the recently active branch of the North Anatolian Fault. The peneplain has an asymmetric nature indicating a northward tilting, most probably due to the development of this fault. The valleys facing to the Gulf of Izmit are mainly short and immature, and degraded the fault surfaces. In contrast, the valleys facing to the Black Sea to the north are long, asymmetric and deeply incised into the peneplain. The southern belt, the Samanli Mountains which
Tripaldi, Alfonsina; Forman, Steven L.
The Pampean Sand Sea, which occurs from the Argentinian Pampas to the eastern Andean piedmont, hosts presently stabilized dune fields spanning the late Quaternary. This study integrates previous results and presents new geomorphic, stratigraphic, sedimentological, and chronologic data for nineteen >2 m-thick eolian successions for the San Luis paleo-dune field, western Pampas, to better constrain the depositional history. Six eolian depositional phases are identified spanning the past 50 ka, interposed with paleosols and/or bounded by erosive surfaces. Age control was from 61 OSL ages of small aliquots of quartz grains from eolian stratigraphic units. The inferred timing of eolian phases are at ca. 70 ± 10 yr, 190 ± 20 yr, 12 to 1 ka, 22 to 17 ka, 29 to 24 ka, and 40 to 32 ka. A maximum span for periods of pedogenesis at ca. 12 to 17 ka, 22 to 24 ka, and 29 to 32 ka was provided by bounding OSL ages, which broadly overlap with high stands of pluvial lakes and glacier advances in the central Andes. We infer that the added precipitation may reflect expansion of the Southern Hemisphere monsoon, associated with Northern Hemisphere Heinrich events, leading to episodes of significantly wetter conditions (>350 mm MAP) to at least 35° S. Most of the Holocene (12 ka to 0.8 ka) was characterized by sand sheet deposit under drier than present conditions (100-450 mm MAP), associated with Monte-type vegetation (shrub steppe). The latest two eolian depositional phases, occurred at ca. 190 and 70 yr ago, during the historic period with European settlement and are related to anthropogenic landscape disturbance, though the youngest phase was concomitant with 1930s drought. Wet conditions dominated since ca. AD 1970 with new lakes and rivers forming across this eolian terrain; an incongruous environmental response in reference to drier conditions for most of the Holocene.
Hamme, Roberta C.; Emerson, Steven R.
estimates of the budget of bioavailable nitrogen (fixed-N) suggest that the oceanic nitrogen cycle is grossly out of balance. We use observations of dissolved N2/Ar ratios along abyssal flow paths in the ocean to investigate fixed-N loss by benthic denitrification, one of the largest uncertainties. Dissolved N2/Ar in the deep-sea increases from the North Atlantic to the North Pacific. At depths >3500 m, this can be explained by the mixing of low N2/Ar source waters from the North Atlantic with high N2/Ar source waters from the Southern Ocean. Benthic denitrification in sediments bathed by these abyssal waters is below the detection limit. However, measureable increases in N2/Ar at depths of 2000-3000 m between the subtropical and subarctic North Pacific, regions that share the same source water, must be caused by benthic denitrification. The Cascadia Basin, with high denitrification rates and connection to the open North Pacific, is a likely source.
Rümpker, Georg; Ryberg, Trond; Bock, Günter
Lithospheric-scale transform faults play an important role in the dynamics of global plate motion. Near-surface deformation fields for such faults are relatively well documented by satellite geodesy, strain measurements and earthquake source studies, and deeper crustal structure has been imaged by seismic profiling. Relatively little is known, however, about deformation taking place in the subcrustal lithosphere--that is, the width and depth of the region associated with the deformation, the transition between deformed and undeformed lithosphere and the interaction between lithospheric and asthenospheric mantle flow at the plate boundary. Here we present evidence for a narrow, approximately 20-km-wide, subcrustal anisotropic zone of fault-parallel mineral alignment beneath the Dead Sea transform, obtained from an inversion of shear-wave splitting observations along a dense receiver profile. The geometry of this zone and the contrast between distinct anisotropic domains suggest subhorizontal mantle flow within a vertical boundary layer that extends through the entire lithosphere and accommodates the transform motion between the African and Arabian plates within this relatively narrow zone. PMID:14523443
Emery, William; Maslanik, James; Fowler, Charles
Synoptic observations of ice motion in the Arctic Basin are currently limited to those acquired by drifting buoys and, more recently, radar data from ERS-1. Buoys are not uniformly distributed throughout the Arctic, and SAR coverage is currently limited regionally and temporally due to the data volume, swath width, processing requirements, and power needs of the SAR. Additional ice-motion observations that can map ice responses simultaneously over large portions of the Arctic on daily to weekly time intervals are thus needed to augment the SAR and buoys data and to provide an intermediate-scale measure of ice drift suitable for climatological analyses and ice modeling. Principal objectives of this project were to: (1) demonstrate whether sufficient ice features and ice motion existed within the consolidated ice pack to permit motion tracking using AVHRR imagery; (2) determine the limits imposed on AVHRR mapping by cloud cover; and (3) test the applicability of AVHRR-derived motions in studies of ice-atmosphere interactions. Each of these main objectives was addressed. We conclude that AVHRR data, particularly when blended with other available observations, provide a valuable data set for studying sea ice processes. In a follow-on project, we are now extending this work to cover larger areas and to address science questions in more detail.
Posmentier, E. S.; Faiia, A.; Feng, X.; Michel, F. A.
Merlivat. Specifically, we include the effect of supersaturation in snow formation. We tune the steady state solutions to interannual means of observed precipitation and evaporation amounts at low latitudes, and to isotopic compositions of precipitation at low and high latitudes, with seasonal boundary conditions of temperature and circulation. By varying the Arctic sea ice area, which regulates surface evaporation, to obtain agreement with the constraints of precipitation isotope observations for one season in a specific year, we can extract from the model the amounts of Arctic precipitation that originated in subtropical and Arctic vapor source areas. We find that the Arctic vapor amount is significantly correlated with interannual variations of the sea-ice extent, which leads to inferences about the significance of the evaporation feedback. Furthermore, this study confirms that vapor sourcing can have an impact on isotopic ratios in ice cores and inherent implications for paleoclimatic interpretation.
Chou, Ming-Dah; Lindzen, Richard S.; Lee, Kyu-Tae; Einaudi, Franco (Technical Monitor)
High-level clouds have a significant impact on the radiation energy budgets and, hence, the climate of the Earth. Convective cloud systems, which are controlled by large-scale thermal and dynamical conditions, propagate rapidly within days. At this time scale, changes of sea surface temperature (SST) are small. Radiances measured by Japan's Geostationary Meteorological Satellite (GMS) are used to study the relation between high-level clouds and SST in the tropical western and central Pacific (30 S-30 N; 130 E-170 W), where the ocean is warm and deep convection is intensive. Twenty months (January 1998 - August, 1999) of GMS data are used, which cover the second half of the strong 1997-1998 El Nino. Brightness temperature at the 11-micron channel is used to identify high-level clouds. The core of convection is identified based on the difference in the brightness temperatures of the 11- and 12-micron channels. Because of the rapid movement of clouds, there is little correlation between clouds six hours apart. When most of deep convection moves to regions of high SST, the domain averaged high-level cloud amount decreases. A +2C change of SST in cloudy regions results in a relative change of -30% in high-level cloud amount. This large change in cloud amount is due to clouds moving from cool regions to warm regions but not the change in SST itself. A reduction in high-level cloud amount in the equatorial region implies an expanded dry upper troposphere in the off-equatorial region, and the greenhouse warming of high clouds and water vapor is reduced through enhanced longwave cooling to space. The results are important for understanding the physical processes relating SST, convection, and water vapor in the tropics. They are also important for validating climate simulations using global general circulation models.
Grall, C.; Henry, P.; Thomas, Y.; Westbrook, G. K.; ćaǧatay, M. N.; Marsset, B.; Saritas, H.; ćifçi, G.; Géli, L.
3-D seismic data acquired in the Sea of Marmara on the Western High, along the northwestern branch of the North Anatolian Fault (also known as the Main Marmara Fault), shed new light on the evolution of the deformation over the last 500-600 ka. Sedimentary sequences in ponded basins are correlated with glacioeustatic cycles and transitions between marine and low sea/lake environments in the Sea of Marmara. In the 3 × 11 km2 of the 3-D seismic survey, deformation over the last 405-490 ka is localized along the main fault branch and north of it, where N130°-N140° trending normal faults and N40°-N50° folding accommodated strike-slip deformation associated with active argillokinesis. There is some evidence that deformation was more distributed further back in the past, at least over the depth range (<600 m below seafloor) of our survey. A N110° basin and buried ridge system were eventually cut by the presently active fault. The southern part of the basin was then uplifted, while the northern part was folded but continued to subside along the fault. A mass transport deposits complex dated between 405-490 ka shows a lateral displacement of 7.7 ± 0.3 km, corresponding to an estimated slip rate of 15.1-19.7 mm/a. We conclude that this strand of the Main Marmara Fault on the Western High has taken up most of the strike slip motion between the Anatolian and Eurasian plates over the last 405 ka at least.
Wang, Juan; Xue, Dong-Xiu; Zhang, Bai-Dong; Li, Yu-Long; Liu, Bing-Jian; Liu, Jin-Xian
Next-generation sequencing and the collection of genome-wide single-nucleotide polymorphisms (SNPs) allow identifying fine-scale population genetic structure and genomic regions under selection. The spotted sea bass (Lateolabrax maculatus) is a non-model species of ecological and commercial importance and widely distributed in northwestern Pacific. A total of 22 648 SNPs was discovered across the genome of L. maculatus by paired-end sequencing of restriction-site associated DNA (RAD-PE) for 30 individuals from two populations. The nucleotide diversity (π) for each population was 0.0028±0.0001 in Dandong and 0.0018±0.0001 in Beihai, respectively. Shallow but significant genetic differentiation was detected between the two populations analyzed by using both the whole data set (FST = 0.0550, P < 0.001) and the putatively neutral SNPs (FST = 0.0347, P < 0.001). However, the two populations were highly differentiated based on the putatively adaptive SNPs (FST = 0.6929, P < 0.001). Moreover, a total of 356 SNPs representing 298 unique loci were detected as outliers putatively under divergent selection by FST-based outlier tests as implemented in BAYESCAN and LOSITAN. Functional annotation of the contigs containing putatively adaptive SNPs yielded hits for 22 of 55 (40%) significant BLASTX matches. Candidate genes for local selection constituted a wide array of functions, including binding, catalytic and metabolic activities, etc. The analyses with the SNPs developed in the present study highlighted the importance of genome-wide genetic variation for inference of population structure and local adaptation in L. maculatus. PMID:27336696
Demir, Turkay; Demir, Demet Eralp; Alkas, Leyla; Copur, Mazlum; Dogangun, Burak; Kayaalp, Levent
The Marmara earthquakes occurred in the Marmara Region (North West) of Turkey in 1999 and resulted in a death toll of approximately 20,000. This paper investigates the relationships between diagnoses and certain variables in children who developed emotional and/or behavioral disturbances in the aftermath of the Marmara earthquakes and were subsequently seen at a child psychiatry outpatient clinic. The variables evaluated are gender, age, the location where the earthquake was experienced, and the degree of losses, bodily injuries, and damage to the residence. Medical records of 321 children and adolescents ranging in age from 2 to 15 years who presented at the clinic due to problems associated with the earthquake between August 1999 and February 2000 were reviewed. Of the patients, 25.5% were diagnosed with post-traumatic stress disorder (PTSD), 16.5% with acute stress disorder (ASD) and 38% with adjustment disorder. No relationship is found between gender and diagnosis. Younger age groups tended to be diagnosed with adjustment disorder. Those who had lost relatives, friends or neighbors were more frequently diagnosed with ASD or PTSD. The same was true for children whose residence was heavily damaged. Children and adolescents constitute the age group that is most severely affected by natural disasters and display significant emotional-behavioral disturbances. The frequency of ASD and PTSD found in our study is considerably high. Although rarely mentioned in the literature, adjustment disorder appears to be one of the most common reactions of children to trauma. PMID:19639383
Auriac, Amandine; Whitehouse, Pippa L.; Bentley, Michael J.; Patton, Henry; Hubbard, Alun; Lloyd, Jerry M.
The Barents Sea, bordered by Norway to the south, Svalbard to the north and Novaya Zemlya to the east, was covered by ice during the last glacial cycle. The extent and thickness of the marine-based ice sheet as well as timing of glaciation / deglaciation are, however, difficult to constrain, partly due to the few terrestrial areas available. There are various models for the ice load history in this region, but large discrepancies remain between them depending on the dataset used as constraint (e.g. sea-level data, temperature record or geomorphology data). Our aim here is to compare and find the best ice load scenario for this region over the last glacial cycle and solve for the Earth structure in the area. To achieve this, we model the present-day crustal deformation and sea-level variations during the last deglaciation by solving the sea-level equation. We use a wide range of Earth models, where we vary the lithosphere thickness and the upper and lower mantle viscosities, as well as four ice load scenarios. The first three ice load scenarios come from published studies, and include the ICE-5G model as well as models from M. Siegert and J.-O. Näslund, while the last one is currently being developed at the University of Tromsø, Norway. We compare the modelled sea-level predictions to relative sea-level curves at key locations around the Barents Sea using chi square, which enables us to infer the best Earth structure and ice history. We also compare the predicted surface deformation from our best model with GPS observations from stations located around the Barents Sea. The GPS provides a constraint on the present-day evolution of deformation in the area and is complementary to the relative sea-level data, which constrain the long-term deformation. First results show that the published ice load scenarios are not accurate enough to reproduce the sea level curves around the Barents Sea, regardless of the Earth model tried. However, the last model, currently being
Ozel, A.; Yalcinkaya, E.; Guralp, C. M.; Tunc, S.; Meral Ozel, N.
The main objective of this study is to install a multi-parameter borehole system and surface array as close to the main Marmara Fault (MMF) in the western Marmara Sea as possible, and measure continuously the evolution of the state of the fault zone surrounding the MMF and to detect any anomaly or change which may occur before earthquakes by making use of the data from the arrays already running in the eastern part of the Marmara Sea. The multi-parameter borehole system will be composed of very wide dynamic range and stable borehole (VBB) broad band seismic sensor, and incorporate 3-D strain meter, tilt meter, and temperature and local hydrostatic pressure measuring devices. The borehole seismic station will use the latest update technologies and design ideas to record 'Earth tides' signals to the smallest magnitude -3 events. Bringing face to face the seismograms of microearthquakes recorded by borehole and surface instruments portrays quite different contents. The shorter recording duration and nearly flat frequency spectrum up to the Nyquist frequencies of borehole records are faced with longer recording duration and rapid decay of spectral amplitudes at higher frequencies of a surface seismogram. The main causative of the observed differences are near surface geology effects that mask most of the source related information the seismograms include, and that give rise to scattering, generating longer duration seismograms. In view of these circumstances, studies on microearthquakes employing surface seismograms may bring on misleading results. Particularly, the works on earthquake physics and nucleation process of earthquakes requires elaborate analysis of tiny events. It is obvious from the studies on the nucleation process of the 1999 earthquake that tens of minutes before the major rupture initiate noteworthy microearthquake activity happened. The starting point of the 1999 rupture was a site of swarm activity noticed a few decades prior the main shock
Yanchilina, A.; Ryan, W. B. F.; McManus, J. F.
This study presents a reconstruction of changes in the water column from the last glacial into the early Holocene using stable isotope, 87Sr/86Sr, 14C, and trace element ratios from mollusks from the shelf area and ostracods from the basin of the Black Sea. The stable isotope record is compared to a thoroughly U/Th dated terrestrial stable isotope record of a nearby cave, Sofular cave in northwestern Turkey. The combination of deep, surface, and terrestrial signals gives valuable insight towards the behavior of the lake water during the deglaciation in multiple dimensions, specifically the water column stratification and hydrological dynamics. The comparison of the stable isotope records of two independent proxies allows to make inferences on the changes in the 14C reservoir of the Black Sea-Lake. Results show that during the glacial period, water from the Black Sea-Lake was outflowing to the Sea of Marmara but the ventilation of the water column was weak as old 14C was not removed and allowed to accumulate giving the lake a large 14C reservoir age. A deglacial pulse of meltwater released from the Eurasian Fennoscandian pro-glacial lakes increased ventilation of the water column. This is seen in lighter δ18O and a spike in radiogenic 87Sr/86Sr in both deep and shallow parts of the water column. The dynamic ventilation and outflow of water into the Sea of Marmara continued until the onset of the Bolling/Allerod as the radiogenic 87Sr/86Sr was almost completely flushed out in a couple hundred years time. During the Bolling/Allerod and Preboreal warming, δ18O got heavier whereas the 87Sr/86Sr stayed constant and the 14C again accumulated and contributed to an older reservoir age. The Younger Dryas period, sandwiched in between the two warming periods, shows a return to glacial conditions in the δ13C and that the water outflowed to the Sea of Marmara as the δ18O only showed a slight change towards a more heavy value.
Polat, Gulten; Özel, Nurcan Meral; Koulakov, Ivan
We investigated the crustal structure beneath the Marmara region and the surrounding area in the western part of the North Anatolian fault zone. These areas have high seismicity and are of critical significance to earthquake hazards. The study was based on travel-time tomography using local moderate and micro-earthquakes occurring in the study area recorded by the Multi-Disciplinary Earthquake Research in High Risk Regions of Turkey project and Kandilli Observatory and Earthquake Research Institute. We selected 2131 earthquakes and a total of 92,858 arrival times, consisting of 50,044 P-wave and 42,814 S-wave arrival times. We present detailed crustal structure down to 50 km depth beneath the Marmara region for P- and S-wave velocities using the LOTOS code based on iterative inversion. We used the distributions of the resulting seismic parameters ( Vp, Vs) to pick out significant geodynamical features. The high-velocity anomalies correlate well with fracturing segments of the North Anatolian fault. High seismicity is mostly concentrated in these segments. In particular, low velocities were observed beneath the central Marmara Sea at 5 km depth.
Nakada, Masao; Inoue, Hiroshi
Tide gauge data at seven sites of the Permanent Service for Mean Sea Level (PSMSL), with information for relative sea-level during the past 140-200 yr, were analyzed to examine the rates and causes of the global sea-level rise (GSLR) during the twentieth century. By subtracting linear trends for relative sea-level rise during the past 100 yr from the observed data, we get the apparent GSLRs of ˜1 mm yr -1 for five sites around the Baltic Sea and Brest. The rate for San Francisco is significantly larger than this, with an optimum value ˜2 mm yr -1. The spatial difference of ˜1 mm yr -1 between these sites is reasonably explained by the recent melting of the Greenland ice sheet with an equivalent sea-level rise of ˜1 mm yr -1. The predicted relative sea-level change for this melting scenario is 0.5 mm yr -1 at sites around the Baltic Sea and Brest, and 1.5 mm yr -1 for San Francisco. The residuals between observations and predictions, ˜0.5 mm yr -1 at all sites, may be contributed by thermal expansion of seawater and/or other melting sources. These results suggest the rate of twentieth-century GSLR to be 1.5 mm yr -1.
Sabuncu, A.; Garagon Dogru, A.; Ozener, H.
Natural hazards are natural phenomenon occured in the Earth's system that include geological and meteorological events such as earthquakes, floods, landslides, droughts, fires and tsunamis. The metropolitan cities are vulnerable to natural hazards due to their population densities, industrial facilities and proporties. The urban layout of the megacities are complex since industrial facilities are interference with residential area. The Marmara region is placed in North-western Turkey suffered from natural hazards (earthquakes, floods etc.) for years. After 1999 Kocaeli and Duzce earthquakes and 2009 Istanbul flash floods, dramatic number of casualities and economic losses were reported by the authorities. Geographic information systems (GIS) have substantial capacity in order to develop natural disaster management. As these systems provide more efficient and reliable analysis and evaluation of the data in the management, and also convenient and better solutions for the decision making before during and after the natural hazards. The Earth science data and socio-economic data can be integrated into a GIS as different layers. Additionally, satellite data are used to understand the changes pre and post the natural hazards. GIS is a powerful software for the combination of different type of digital data. A natural hazard database for the Marmara region provides all different types of digital data to the users. All proper data collection processing and analysing are critical to evaluate and identify hazards. The natural hazard database allows users to monitor, analyze and query past and recent disasters in the Marmara Region. The long term aim of this study is to develop geodatabase and identify the natural hazard vulnerabilities of the metropolitan cities.
Earthquake and Tsunami Disaster Mitigation in The Marmara Region and Disaster Education in Turkey Part2 Yoshiyuki KANEDA Nagoya University Japan Agency for Marine-Earth Science and Technology (JAMSTEC) Haluk OZENER Boğaziçi University, Earthquake Researches Institute (KOERI) and Members of SATREPS Japan-Turkey project
Kaneda, Y.; Ozener, H.
The 1999 Izumit Earthquake as the destructive earthquake occurred near the Marmara Sea. The Marmara Sea should be focused on because of a seismic gap in the North Anatolian fault. Istanbul is located around the Marmara Sea, so, if next earthquake will occur near Istanbul, fatal damages will be generated. The Japan and Turkey can share our own experiences during past damaging earthquakes and we can prepare for future large earthquakes in cooperation with each other. In earthquakes in Tokyo area and Istanbul area as the destructive earthquakes near high population cities, there are common disaster researches and measures. For disaster mitigation, we are progressing multidisciplinary researches. Our goals of this SATREPS project are as follows, To develop disaster mitigation policy and strategies based on multidisciplinary research activities. To provide decision makers with newly found knowledge for its implementation to the current regulations. To organize disaster education programs in order to increase disaster awareness in Turkey. To contribute the evaluation of active fault studies in Japan. This project is composed of four research groups. The first group is Marmara Earthquake Source region observationally research group. This group has 4 sub-themes such as Seismicity, Geodesy, Electromagnetics and Trench analyses. The second group focuses on scenario researches of earthquake occurrence along the North Anatolia fault and precise tsunami simulation in the Marmara region. Aims of the third group are improvements and constructions of seismic characterizations and damage predictions based on observation researches and precise simulations. The fourth group is promoting disaster educations using research result visuals. In this SATREPS project, we will integrate these research results for disaster mitigation in Marmara region and .disaster education in Turkey. We will have a presentation of the updated results of this SATREPS project.
Mele, Salvatore; Pennino, M Grazia; Piras, M Cristina; Macías, David; Gómez-Vives, M José; Alemany, Francisco; Montero, Francisco E; Garippa, Giovanni; Merella, Paolo
Between 2008 and 2011, the head of 150 Euthynnus alletteratus (Osteichthyes: Scombridae) caught inshore off the southeastern Iberian coast (western Mediterranean Sea) were examined for parasites. Two monogeneans, four didymozoid trematodes and four copepods were found. Parasite abundance showed a positive relationship with the annual sea surface temperature, except for Pseudocycnus appendiculatus, but negative with the sea depth (Capsala manteri, Neonematobothrium cf. kawakawa and Caligus bonito). Prevalences and mean abundances differed significantly among sampling areas, except for C. manteri, Oesophagocystis sp. 2 and Ceratocolax euthynni, and sampling years (Melanocystis cf. kawakawa, N.cf. kawakawa, P. appendiculatus and Unicolax collateralis). Results indicate that the parasite abundances of E. alletteratus in the western Mediterranean Sea depend mainly on regional environmental variables, which can show interannual variations. The presence of pelagic parasites, i.e. didymozoids and P. appendiculatus, could indicate that E. alletteratus migrates between inshore and offshore pelagic domains. The different parasite faunas reported in E. alletteratus populations from the western Atlantic Ocean and the Mediterranean Sea appear to point out the geographical host isolation. These results suggest that E. alletteratus inhabiting the western Mediterranean Sea performs inshore-offshore small-scale migrations, and not transoceanic migrations between the western Atlantic Ocean and Mediterranean Sea. PMID:27173779
Miettinen, Arto; Divine, Dmitry; Koç, Nalan; Godtliebsen, Fred; Hall, Ian R.
A 2800-yr-long August sea surface temperature (aSST) record based on fossil diatom assemblages is generated from a marine sediment core Rapid 21-COM recovered in the Iceland Basin (northern subpolar North Atlantic). The record has a resolution of 2-10 years for interval 800-2004 AD representing the best resolved diatom SST reconstruction from the subpolar North Atlantic for this period, and 40 years for interval 800 BC-800 AD. The record is compared with the high-resolution (4-20 years) aSST record from core CR948/2011 from the Vøring Plateau, in the Norwegian Sea, to explore the variability of the aSST gradient between these areas during the late Holocene. The two aSST records show persistent opposite climate trends toward warming in the subpolar North Atlantic and cooling in the Norwegian Sea throughout the late Holocene. The wavelet analysis reveals an apparent tendency to coherent antiphased aSST variations between the sites for the shorter time scales too, implying a possible aSST seesaw between the northern subpolar North Atlantic and the Norwegian Sea to operate during the late Holocene. At the multicentennial scale of aSST variability of 600-900 years, the records are nearly in antiphase with warmer (colder) periods in the subpolar North Atlantic corresponding to the colder (warmer) periods in the Norwegian Sea. At the shorter time scale of 200-450 years the records display a nearly phase-locked behaviour with a tendency for the positive aSST anomalies in the Norwegian Sea to lead by ca. 30 years the negative aSST anomalies in the subpolar North Atlantic. This aSST seesaw might have had a strong effect, or be associated, with the two major climate anomalies in the northwest Europe during the past Millennium: Medieval Warm Period (MWP) and the Little Ice Age (LIA). During the MWP warming of the sea surface in the Norwegian Sea occurred in parallel with cooling in the northern subpolar North Atlantic, whereas the opposite pattern emerged during the LIA
Pujolar, J M; Zane, L; Congiu, L
The aim of our study is to examine the phylogenetic relationship, divergence times and demographic history of the five close-related Mediterranean and North-eastern Atlantic species/forms of Atherina using the full Bayesian framework for species tree estimation recently implemented in ∗BEAST. The inference is made possible by multilocus data using three mitochondrial genes (12S rRNA, 16S rRNA, control region) and one nuclear gene (rhodopsin) from multiple individuals per species available in GenBank. Bayesian phylogenetic analysis of the complete gene dataset produced a tree with strong support for the monophyly of each species, as well as high support for higher level nodes. An old origin of the Atherina group was suggested (19.2 MY), with deep split events within the Atherinidae predating the Messinian Salinity Crisis. Regional genetic substructuring was observed among populations of A. boyeri, with AMOVA and MultiDimensional Scaling suggesting the existence of five groupings (Atlantic/West Mediterranean, Adriatic, Greece, Black Sea and Tunis). The level of subdivision found might be consequence of the hydrographic isolation within the Mediterranean Sea. Bayesian inference of past demographic histories showed a clear signature of demographic expansion for the European coast populations of A. presbyter, possibly linked to post-glacial colonizations, but not for the Azores/Canary Islands, which is expected in isolated populations because of the impossibility of finding new habitats. Within the Mediterranean, signatures of recent demographic expansion were only found for the Adriatic population of A. boyeri, which could be associated with the relatively recent emergence of the Adriatic Sea. PMID:22425706
Basarir Basturk, Nilay; Meral Ozel, Nurcan
This study aimed at contributing to creation of a scenario database for tsunamigenic earthquakes occurred in Marmara Region through the investigation of the historical earthquakes under the frame of Marsite and also Mardim Projects for the work package 5 (WP5). Furthermore, this work provides an evaluation of earthquake history in Marmara Region which is important for seismic risk assesment in İstanbul and preparing an active fault map of the Sea of Marmara,which is one of the goals of the work package 7 (WP7) of Marmara Supersite Project. For this purpose, we have created a digital database containing 576 earthquakes with some parameters such as location and intensity, also including macroseismic explanations for Turkey between the dates of 2000 B.C. and 1900 A.D. by compiling over 20 available sources such as Ambraseys(2009), Ambraseys and Finkel(1995), Ergin et al. (1967 and 1971), Soysal et al. (1981), Guidoboni et al. (1994), Papazachos et al. (1997), Shebalin & Tatevossian (1997), Ambraseys & Jackson (1998), Kondorskaya & Ulomov (1999), Ambraseys & Jackson (2000), Guidoboni & Comastri(2005), Stucchi et al(2012), Papazachos&P.,(2003). Among these sources, the basic reference that we used for many earthquakes is the Soysal et al. (1981), including earthquake parameters such as macroseismic epicenter and intensity. Another important catalogue for the assessment of historical events is the Ambraseys (2009) which is a comprehensive review and contains macroseismic explanations of the earthquakes in Turkey from 2000 B.C. to 1900 A.D. Evaulation of every possible sources for the old earthquakes have enabled us to cross check differences among them , find dublicate events and debate the earthquakes in terms of their reliability. In the scope of this study, the historical earthquakes were classified to date, location, intensity, macroseismic explanations using available information. In addition, the coordinate and intensity were assigned to 343 and 114 events
Ozel, Oguz; Guralp, Cansun; Tunc, Suleyman; Yalcinkaya, Esref
The main objective of this study is to install a multi-parameter borehole system and surface array as close to the main Marmara Fault (MMF) in the western Marmara Sea as possible, and measure continuously the evolution of the state of the fault zone surrounding the MMF and to detect any anomaly or change, which may occur before earthquakes by making use of the data from the arrays already running in the eastern part of the Marmara Sea. The multi-parameter borehole system is composed of very wide dynamic range and stable borehole (VBB) broad band seismic sensor, and incorporate strain meter, tilt meter, and temperature and local hydrostatic pressure measuring devices. The borehole seismic station uses the latest update technologies and design ideas to record "Earth tides" signals to the smallest magnitude -3 events. Additionally, a surface microearthquake observation array, consisting of 8-10 seismometers around the borehole is established to obtain continuous high resolution locations of micro-seismicity and to better understand the existing seismically active structures and their roles in local tectonic settings.Bringing face to face the seismograms of microearthquakes recorded by borehole and surface instruments portrays quite different contents. The shorter recording duration and nearly flat frequency spectrum up to the Nyquist frequencies of borehole records are faced with longer recording duration and rapid decay of spectral amplitudes at higher frequencies of a surface seismogram. The main causative of the observed differences are near surface geology effects that mask most of the source related information the seismograms include, and that give rise to scattering, generating longer duration seismograms. In view of these circumstances, studies on microearthquakes employing surface seismograms may bring on misleading results. Particularly, the works on earthquake physics and nucleation process of earthquakes requires elaborate analysis of tiny events. It is
Earthquake and Tsunami Disaster Mitigation in The Marmara Region and Disaster Education in Turkey. (SATREPS Project: Science and Technology Research Partnership for Sustainable Development by JICA-JST)
Kaneda, Y.; Erdik, M. O.; Takahashi, N.; Meral Ozel, N.; Hori, T.; Hori, M.; Kumamoto, K.; Kalafat, D.; Pinar, A.; Ozel, A. O.; Yalciner, A. C.; Nurlu, M.; Tanircan, G.; Citak, S.; Ariyoshi, K.; Necmioglu, O.
Since 1900, around 90,000 people have lost their lives in 76 earthquakes occurred in Turkey, with a total affected population of ~7 million and direct estimated losses of ~25 billion USD. About half the lives lost were due to two earthquakes associated with the North Anatolian Fault in 1939 and 1999. During this time, seven large westward-migrating earthquakes created a 900-km-long continuous surface rupture along the fault zone from Erzincan to the Marmara Sea, stopping just short of Istanbul. Based on a time-dependent model that includes coseismic and postseismic effects of the 1999 Kocaeli earthquake with moment magnitude (Mw) = 7.4, Parsons concluded that the probability of an earthquake with Mw >7 in the Sea of Marmara near Istanbul is 35% to 70% in the next 30 years. This high probability is shared by Tokyo and San Francisco; however, the earthquake fragility of the pre-2000 building stock in Turkey is much higher than that of California or Japan. (Erdik, 2013). All of the arguments described above provide a sound basis for a Japanese-Turkish partnership enabling each partner to share experiences gained from past destructive earthquakes and prepare for expected large earthquakes. The SATREPS project aims to address this need, also focusing on the tsunami hazard. The project's main objectives are i) to develop disaster mitigation policies and strategies based on multidisciplinary research activities; ii) to provide decision makers with newly found knowledge for its implementation to the current regulations; iii) to organize disaster education programs in order to increase disaster awareness in Turkey; iv) to contribute the evaluation of active fault studies in Japan. To achieve successfully these objectives, 4 research groups have been set specializing on observations, simulations, civil engineering and disaster education and the results will be integrated for disaster mitigation in the Marmara region and disaster education in Turkey.
Ulses, Caroline; Kessouri, Fayçal; Estournel, Claude; Marsaleix, Patrick; Beuvier, Jonathan; Somot, Samuel; Touratier, Frank; Goyet, Catherine; Coppola, Laurent; Diamond, Emilie; Metzl, Nicolas
The semi-enclosed Mediterranean Sea characterized by short residence times is considered as a region particularly sensitive to natural and anthropogenic forcing. Due to scarce CO2 measurements in the whole basin, the CO2 system, for instance the air-sea CO2 exchanges and the effects of the increase of atmospheric CO2, are poorly characterized. 3D physical-biogeochemical coupled models are unique tools that can provide integrated view and gain understanding in the temporal and spatial variation of the CO2 system variables (dissolved inorganic carbon, total alkalinity, partial pressure of CO2 and pH). An extended version of the biogeochemical model Eco3m-S (Auger et al., 2014), that describes the cycles of carbon, nitrogen, phosphorus and silica, was forced by a regional circulation model (Beuvier et al., 2012) to investigate the CO2 system in the Mediterranean Sea over a 13-years period (2001-2013). First, the quality of the modelling was evaluated through comparisons with satellite and in situ observations collected in the whole basin over the study period (Touratier and Goyet, 2009; 2011 ; Rivaro et al., 2010 ; Pujo-Pay et al., 2011 ; Alvarez et al, 2014). The model reasonably reproduced the various biological regimes (north-western phytoplanctonic bloom regime, oligotrophic eastern regime, etc.) as well as the recorded spatial distribution and temporal variations of the carbonate system variables. The coupled model was then used to estimate the air-sea pCO2 exchanges and the transport of DIC and TA towards the Atlantic Ocean at the Strait of Gibraltar.
Chiba, T.; Fujino, S.; Kobori, E.
The average recurrence interval of the interplate earthquakes along the Nankai Trough is estimated from historical literature and archaeological data. However, the details of tectonic movements by past Nankai earthquakes are mostly left unclear from historical literature, therefore, we need to obtain the geological evidence of the tectonic movements. Yuki city, Tokushima prefecture, located in north part of the Nankai Trough, has been subsided and many tsunamis attacked along the coast of the Shikoku islands accompanied by the previous Nankai earthquakes. Therefore, some historical documents and memorial monuments written about the past Nankai earthquakes and tsunamis remain in the city. The study purposed to reveal tectonic movements of the earthquakes from Nankai Trough during the late Holocene at Tainohama in Minami city which is adjacent to the southwest of Yuki city by fossil diatom analysis. We obtained a 700cm long core at a marsh behind a barrier spit probably be not affected directly from sea waves in Tainohama. The core includes more than 13 sand layers in organic-rich muddy or peaty sedimentary succession up to 500cm depth in the core. And the diatom assemblages included in the peat and peaty mud deposits were dominated by fresh and brackish water species, especially Pseudostaurosira brevistriata, P. subsalina and Tabellaria fenestrate. In contrast to the above mentioned sand layers, brackish and marine species, such as Diploneis smithii increased. The diatom assemblages from the organic rich muddy sediments and radiocarbon ages indicate that freshwater marsh or saltmarsh formed in this region during the late Holocene. On the other hand, the sandy layers include the diatoms living in environments where salinities are higher than freshwater or salt marsh, so the assemblages suggest that the sand layers were transported from seaside by past tsunamis. In addition, changes of diatom assemblages in the peaty or peaty mud sediments show increase or decrease of
Meral OZel, Nurcan; Necmioǧlu, Öcal; Ergintav, Semih; Ozel, Oǧuz; Favali, Paolo; Bigarre, Pascal; Çakır, Ziyadin; Ozeren, Sinan; Geli, Louis; Douglas, John; Aochi, Hideo; Bossu, Remy; Zülfikar, Can; Şeşetyan, Karin; Erdik, Mustafa
The MARsite Project, which started in November 2012,funded by the EC/ FP7-ENV.2012 6.4-2 (Grant 308417) identifies the Marmara region as a 'Supersite' within European initiatives to aggregate on-shore, off-shore and space-based observations, comprehensive geophysical monitoring, improved hazard and risk assessments encompassed in an integrated set of activities. MARsite aimed to harmonize geological, geophysical, geodetic and geochemical observations to provide a better view of the post-seismic deformation of the 1999 Izmit earthquake (in addition to the post-seismic signature of previous earthquakes), loading of submarine and inland active fault segments and transient pre-earthquake signals, related to stress loading with different tectonic properties in and around Marmara Sea. This presentation provides an overview of the achievements of MARSite which aimed to coordinate research groups ranging from seismology to gas geochemistry in a comprehensive monitoring activity developed in the Marmara Region based on collection of multidisciplinary data to be shared, interpreted and merged in consistent theoretical and practical models suitable for the implementation of good practices to move the necessary information to the end users in charge of seismic risk management of the region. In addition, processes involved in earthquake generation and the physics of short-term seismic transients, 4D deformations to understand earthquake cycle processes, fluid activity monitoring and seismicity under the sea floor using existing autonomous instrumentation, early warning and development of real-time shake and loss information, real- and quasi-real-time earthquake and tsunami hazard monitoring and earthquake-induced landslide hazard topics are also covered within MARSite. In particular, achievements and progress in the design and building of a multi-parameter borehole system consisting of very wide dynamic range and stable borehole (VBB) broad band seismic sensor, with
Lougheed, Bryan C.; Snowball, Ian; Moros, Matthias; Kabel, Karoline; Muscheler, Raimund; Virtasalo, Joonas J.; Wacker, Lukas
these sediments. An inferred marine reservoir age offset (ΔR) is calculated by comparing the foraminifera 14C determinations to a PSV & Pb age model. This ΔR is found to trend towards younger values upwards in the core, possibly due to a gradual change in hydrographic conditions brought about by a reduction in marine water exchange from the open sea due to continued isostatic rebound.
Xu, Dongdong; Li, Sanlei; Lou, Bao; Zhang, Yurong; Zhan, Wei; Shi, Huilai
Japanese flounder is one of the most important commercial species in China; however, information on the genetic background of natural populations in China seas is scarce. The lack of genetic data has hampered fishery management and aquaculture development programs for this species. In the present study, we have analyzed the genetic diversity in natural populations of Japanese flounder sampled from the Yellow Sea (Qingdao population, QD) and East China Sea (Zhoushan population, ZS) using 10 polymorphic microsatellite loci and cytochrome c oxidase subunit I (COI) sequencing data. A total of 68 different alleles were observed over 10 microsatellite loci. The total number of alleles per locus ranged from 2 to 9, and the number of genotypes per locus ranged from 3 to 45. The observed heterozygosity and expected heterozygosity in QD were 0.733 and 0.779, respectively, and in ZS the heterozygosity values were 0.708 and 0.783, respectively. Significant departures from Hardy-Weinberg equilibrium were observed in 7 of the 10 microsatellite loci in each of the two populations. The COI sequencing analysis revealed 25 polymorphic sites and 15 haplotypes in the two populations. The haplotype diversity and nucleotide diversity in the QD population were 0.746±0.072 8 and 0.003 34±0.001 03 respectively, and in ZS population the genetic diversity values were 0.712±0.047 0 and 0.003 18±0.000 49, respectively. The microsatellite data ( F st =0.048 7, P <0.001) and mitochondrial DNA data ( F st =0.128, P <0.001) both revealed significant genetic differentiation between the two populations. The information on the genetic variation and differentiation in Japanese flounder obtained in this study could be used to set up suitable guidelines for the management and conservation of this species, as well as for managing artificial selection programs. In future studies, more geographically diverse stocks should be used to obtain a deeper understanding of the population structure of Japanese
Blanco Gonzalez, Enrique; Aritaki, Masato; Sakurai, Shigeru; Taniguchi, Nobuhiko
Since 1978, millions of hatchery-reared red sea bream (Pagrus major) juveniles have been released in Sagami Bay and Tokyo Bay in Kanagawa Prefecture, Japan. The stock enhancement program has contributed to total catch; however, no information regarding the genetic interactions with wild counterparts is available. Here, we combined 15 microsatellite loci and mitochondrial D-loop sequencing to characterize the genetic resources of red sea bream in Sagami Bay and Tokyo Bay and to elucidate the potential harmful genetic effects associated with fish releases. Both types of markers evidenced higher levels of genetic diversity in wild samples (SB and TB) compared with offspring before stocking (H07 and H08) as well as a hatchery-released sample recaptured in Sagami Bay (HR). Microsatellite F (ST) estimates and Bayesian clustering analysis found significant genetic differences among samples (F (ST) = 0.013-0.054), except for the two wild samples (F (ST) = 0.002) and HR vs. H07 (F (ST) = 0.007). On the other hand, mitochondrial-based Ф (ST) suggested haplotypic similarity between SB, H07, and HR. The low effective number of females contributing to the offspring over multiple generations may be responsible for the lack of haplotypic differentiation. Moreover, the putative hatchery origin to three fish (8 %) without deformity in the inter-nostril epidermis was inferred for the first time. Our results showed the usefulness of combining nuclear and mitochondrial markers to elucidate genetic interactions between hatchery-released and wild red sea bream and warned about potential harmful genetic effects should interbreeding takes place. PMID:22855399
Sadeh, M.; Hamiel, Y.; Ziv, A.; Bock, Y.; Fang, P.; Wdowinski, S.
Large-scale crustal deformation in the Levant is mainly related to the DST and the CFS. The former is an active left lateral transform, bounding the Arabian plate and the Sinai sub-plate, and the latter branches out of the former and separates the Sinai sub-plate into two tectonic domains. In this study we obtain the velocities of 33 permanent GPS stations and 145 survey stations that were surveyed in three campaigns between 1996 and 2008. We use a simple 1-D elastic dislocation model to infer the slip rate and locking depth along various segments of the DST. We infer a 3.1-4.5 mm/yr slip rate and a 7.8-16.5 km locking depth along the DST north of the CFS, and a slip rate of 4.6-5.9 mm/yr and locking depth of 11.8-24 km along the Jericho Valley, south of the CFS. Further south, along the Arava Valley we obtain a slip rate of 4.7-5.4 mm/yr and a locking depth of 12.1-23 km. We identify an oblique motion along the Carmel Fault with ˜0.7 mm/yr left-lateral and ˜0.6 mm/yr extension rates, resulting in N-S extension across the Carmel Fault. This result, together with the decrease in DST slip velocity from the Jericho Valley to the segment north of the CFS, confirms previous suggestions, according to which part of the slip between Arabia and Sinai is being transferred from the DST to the CFS.
Bourdeau, Céline; Lenti, Luca; Martino, Salvatore
Turkey is one of the geologically most active regions of Europe prone to natural hazards in particular earthquakes and landslides. Detailed seismological studies show that a catastrophic event is now expected in the Marmara region along the North Anatolian Fault Zone (NAFZ). On the shores of the Marmara sea, about 30km East of Istanbul and 15km North from the NAFZ, urbanization is fastly growing despite the presence of pre-existing large landslides. Whether such landslides could be reactivated under seismic shaking is a key question. In the framework of the MARsite European project, we selected one of the most critical landslides namely the Büyükçekmece landslide in order to assess its local seismic response. Based on detailed geophysical and geotechnical field investigations, a high-resolution engineering-geological model of the landslide slope was reconstructed. A numerical modeling was carried out on a longitudinal cross section of this landslide with a 2D finite difference code FLAC in order to assess the local seismic response of the slope and to evaluate the consistency of conditions suitable for the earthquake-induced reactivation of the landslide. The obtained ground-motion amplification pattern along the slope surface is very complex and is strongly influenced by properties changes between the pre-existing landslide mass and the surrounding material. Further comparisons of 2D versus 1D ground-motion amplifications on the one hand and 2D versus topographic site effects on the other hand will shed light on the parameters controlling the spatial variations of ground-motion amplifications along the slope surface.
Oguz, Temel; La Violette, Paul E.; Unluata, Umit
Quasi-synoptic hydrographic data and satellite imagery are used to describe the circulation and the structural variability of the Black Sea with particular emphasis on the Turkish coast. The circulation is indicated to involve a variable cyclonic circulation with no apparent central locus and a well-defined cyclonic 'Rim Current' containing meanders and interacting eddy fields confined to the shelf slope. Interspersed between the coastal eddies are filaments and intense jets, often with dipole eddies at their termina. The extension of these features across the shelf-slope into the central basin offshore waters implies important dynamical processes related to the shell-deep basin exchanges. These features are often steered by the topography and evolve continuously through the mixed baroclinic-barotropic instability of the Rim Current.
Lopes, Elinia Medeiros; Ventura, Carlos Renato Rezende
We describe the development and juvenile morphology of the sea star Echinaster (Othilia) brasiliensis in order to explore evolutionary developmental modes and skeletal homologies. This species produces large, buoyant eggs (0.6 ± 0.03 mm diameter), and has a typical lecithotrophic brachiolaria larva. The planktonic brachiolaria larva is formed 2-4 days after fertilization, when cilia cover the surface. Early juveniles are completely formed by 18 days of age. Initial growth is supported by maternal nutrients while the stomach continues to develop until 60 days after fertilization, when juveniles reach about 0.5 mm of radius length. The madreporite was observed 88 days after fertilization. In the youngest juvenile skeleton of E. (O.) brasiliensis, the madreporite and odontophore are homologous to those of other recent, non-paxillosid asteroids, and follow the Late Madreporic Mode. The emergence of plates related to the ambulacral system follows the Ocular Plate Rule. The development and juvenile skeletal morphology of this species are similar to those of the few other studied species in the genus Echinaster. This study corroborates the notion that the mode of development--including a short-lived lecithotrophic brachiolaria larva--in all Echinaster species shares a similar pattern that may be conserved throughout the evolutionary history of the group. PMID:26896175
Shailaja, M. S.; Narvekar, P. V.; Alagarsamy, R.; Naqvi, S. W. A.
Vertical distributions of the potential activities of some key enzymes mediating nitrification and denitrification were investigated within the oxygen (O 2) minimum zone of the Arabian Sea at a number of locations between latitudes 17°N and 21°N and longitudes 63°E and 68°E so as to get an insight into the predominant biochemical mode(s) of production and consumption of nitrous oxide (N 2O). Results revealed that the dissimilatory nitrate (NO -3) reduction activity was generally very low or absent within the σ θ range 26.6-26.8, which corresponds to the Persian Gulf Watermass (PGW). Depth profiles of nitrate reductase (NaR), nitrite reductase (NiR) and ammonia monooxygenase (AMO) activities were compared with those of O 2, NO -3, nitrite (NO -2) and N 2O, and it is concluded that nitrifier denitrification rather than heterotrophic denitrification is active within the core of PGW. The presence of multiple peaks of AMO activity coinciding with distinct maxima in the O 2 profile and with a trend opposite to that of NaR activity indicates that the two processes, viz., classical and nitrifier denitrification, occur in discrete layers, probably determined by the variations in the ambient O 2 concentrations at various depths surrounding the PGW core. Further, it appears that at the depths where nitrifier denitrification is active in the absence of heterotrophic denitrification, N 2O builds up as its consumption may be inhibited by O 2. Possible reasons for the occurrence of appreciable nitrate deficit within the core of PGW, where dissimilatory NO -3 reduction is lacking, are discussed.
Akuhara, Takeshi; Mochizuki, Kimihiro
Exploring the hydrous state of subducting oceanic crust is intriguing because it is considered to affect the strength of megathrust faults that cause various types of earthquakes; however, its state beneath offshore regions remains unclear. In this study, we investigated fluid contents along the subducting Philippine Sea plate around the Kii Peninsula by receiver function (RF) analysis using data from both on-land stations and ocean bottom seismometers (OBSs). The vertical component of OBS records contains dominant water reverberations, and thus, conventional methods fail to estimate RFs correctly. We therefore developed a method to calculate RFs that removes such reverberations. The RFs calculated by our method showed considerable improvement for later phase identification, compared with those obtained using a conventional method. Resultant RF amplitudes suggest the existence of low-velocity zones directly beneath the plate interface of both onshore and offshore regions. We interpreted this as evidence of hydrous oceanic crust, which extends from 5 km to 35 km depth to the plate interface. Reduction of RF amplitudes beneath the Kii Peninsula suggests that dehydration of the oceanic crust increases the seismic velocity, and the accompanying densification makes the plate interface permeable. This permeable plate interface may characterize the location of non-volcanic tremors. This contrasts with long-term slow slip events because it is believed that they occur along the sealed plate interface. Comparison between the plate geometry and local earthquakes reveals the paucity of earthquakes in the oceanic crust below a certain depth, which provides further insight into the dehydration process in the oceanic crust.
Biri, Stavroula; Serra, Nuno; Scharffenberg, Martin G.; Stammer, Detlef
Frequency and wavenumber spectra of sea surface height (SSH) and surface geostrophic velocity are presented, as they result for the Atlantic Ocean from a 23 year long altimeter data set and from a hierarchy of ocean model simulations with spatial resolutions of 16, 8, and 4 km. SSH frequency spectra follow a spectral decay of roughly f-1 on long periods; toward higher frequencies a spectral decay close to f-2 is found. For geostrophic velocity spectra, a somewhat similar picture emerges, albeit with flatter spectral relations. In terms of geostrophic velocity wavenumber spectra, we find a general relation close to k-3 in the high-resolution model results. Outside low-energy regions all model spectra come close to observed spectra at low frequencies and wavenumbers in terms of shape and amplitude. However, the highest model resolution appears essential for reproducing the observed spectra at high frequencies and wavenumbers. This holds especially for velocity spectra in mid and high latitudes, suggesting that eddy resolving ocean models need to be run at a resolution of 1/24° or better if one were to fully resolve the observed mesoscale eddy field. Causes for remaining discrepancies between observed and simulated results can be manifold. At least partially, they can be rationalized by taking into account an aliasing effect of unresolved temporal variability in the altimetric observations occurring on periods smaller than the 20 days Nyquist period of the altimetric data, thereby leading to an overestimate of variability in the altimetric estimates, roughly on periods below 100 days.
Andreev, Andrei A.; Schirrmeister, Lutz; Tarasov, Pavel E.; Ganopolski, Andrey; Brovkin, Viktor; Siegert, Christine; Wetterich, Sebastian; Hubberten, Hans-Wolfgang
Paleoenvironmental records from a number of permafrost sections and lacustrine cores from the Laptev Sea region dated by several methods ( 14C-AMS, TL, IRSL, OSL and 230Th/U) were analyzed for pollen and palynomorphs. The records reveal the environmental history for the last ca 200 kyr. For interglacial pollen spectra, quantitative temperature values were estimated using the best modern analogue method. Sparse grass-sedge vegetation indicating arctic desert environmental conditions existed prior to 200 kyr ago. Dense, wet grass-sedge tundra habitats dominated during an interstadial ca 200-190 kyr ago, reflecting warmer and wetter summers than before. Sparser vegetation communities point to much more severe stadial conditions ca 190-130 kyr ago. Open grass and Artemisia communities with shrub stands ( Alnus fruticosa, Salix, Betula nana) in more protected and moister places characterized the beginning of the Last Interglacial indicate climate conditions similar to present. Shrub tundra ( Alnus fruticosa and Betula nana) dominated during the middle Eemian climatic optimum, when summer temperatures were 4-5 °C higher than today. Early-Weichselian sparse grass-sedge dominated vegetation indicates climate conditions colder and dryer than in the previous interval. Middle Weichselian Interstadial records indicate moister and warmer climate conditions, for example, in the interval 40-32 kyr BP Salix was present within dense, grass-sedge dominated vegetation. Sedge-grass- Artemisia-communities indicate that climate became cooler and drier after 30 kyr BP, and cold, dry conditions characterized the Late Weichselian, ca 26-16 kyr BP, when grass-dominated communities with Caryophyllaceae, Asteraceae, Cichoriaceae, Selaginella rupestris were present. From 16 to 12 kyr BP, grass-sedge communities with Caryophyllaceae, Asteraceae, and Cichoriaceae indicate climate was significantly warmer and moister than during the previous interval. The presence of Salix and Betula reflect
Andreev, A.; Schirrmeister, L.; Tarasov, P.
. Mostly grass conenoses with some Caryophyllaceae, Asteraceae, Cichoriaceae, Selaginella rupestris predominated during the late Weichselian (Sartan), ca 26-16 ka BP. Climate was very cold and dry. Later, 16-12 ka BP, grass and sedge associations with Caryophyllaceae, Asteraceae, and Cichoriaceae dominated the vegetation. Climate was significantly warmer and moister than during the previous interval. Accumulation of Ice Complex sediments stopped ca 12 ka BP, at the beginning of Allerød. Higher pollen concentration, the presence of willow and birch pollen points to a relatively warm climate between 12 and 11 ka BP reflecting significant climate amelioration. Pollen of shrubs disappeared from the Younger Dryas spectra pointing to the harsher climate. Early Holocene spectra are dominated by alder, birch, Poaceae, and Cyperaceae. Climate reconstruction inferred a temperature substantially warmer than present (up to 12°C). Shrubs gradually disappeared from the area after 7.6 14C ka BP and vegetation cover became similar to modern tundra.
Geographic genetic structure in two laticaudine sea kraits, Laticauda laticaudata and Laticauda semifasciata (Serpentes: Elapidae), in the Ryukyu-Taiwan region as inferred from mitochondrial cytochrome b sequences.
Tandavanitj, Nontivich; Ota, Hidetoshi; Cheng, Yuan-Cheng; Toda, Mamoru
The Ryukyu-Taiwan region is an island arch with intervening waters of varying distances and depths. This study examines the geographic genetic structure of two sympatric sea kraits, Laticauda laticaudata and L. semifasciata, in the region, to infer factors affecting the extent of dispersal and other biogeographical traits of these amphibious reptiles. Sequence analyses of the mitochondrial cytochrome b gene revealed four and 16 haplotypes for L. laticaudata (136 individuals) and L. semifasciata (177 individuals), respectively. For both species, population pairwise F ST analyses revealed significant genetic differentiations among islands and island groups, which are separated by deep straits, suggesting that deep waters serve as obstacles for dispersal in both species. Significant genetic differentiation was detected even among islands of the same basin in L. laticaudata, but not in L. semifasciata, and the isolation by distance analyses revealed no significant correlation between geographic and genetic distances in the former species. These results further suggest that L. laticaudata has stronger site fidelity or degree of philopatry than L. semifasciata. Based on the geographic genetic patterns, the historical biogeography of the two species in the Ryukyu-Taiwan region is also discussed. PMID:23915156
Demircioglu, M.; Sesetyan, K.; Erdik, M.; Durukal, E.
As a consequence of the change of paradigm in earthquake resistant design stronger design earthquakes now control the seismic design of important structures. These stronger earthquakes include the effects of near-field pulses, fault-normal motions, and near-field deep soil site motions. As a consequence, there is a strong need for the development of robust and reliable techniques for the assessment of long period earthquake ground motions especially for near field conditions. To provide an example to the assessment of long period ground motion a comparative study has been carried out for the Marmara Region, Turkey. The probabilistic earthquake hazard has been investigated using PEER-NGA (2007) and older generation attenuation relationships for PGA and SA (0.2s, 1s, 2s, 4s, 6s, 8s and 10s) corresponding to 50, 10 and 2 percent probabilities of exceedance in 50 years. PGA values were used to obtain the EuroCode whereas, SA(0.2s and 1s) were used to obtain the NEHRP (2003) based response spectra. SA (0.2s, 1s, 2s, 4s, 6s, 8s and 10s) values were used to plot the equi-hazard spectrum. Furthermore associated hazard deaggregation has been conducted for several selected sites to obtain rational estimates of the deterministic long period spectral accelerations and the deterministic spectral shapes. Comparison of the findings indicate significant variation of long period spectral accelerations. The accuracy of seismic design spectra given in current codes is not sufficient at these periods. There is also a need to develop guidelines for the selection of design basis ground motion for long period or highly nonlinear (softening) structure.
Jennifer, W.; Feuillet, N.; Robert, H.; Brian, A.; Ten Brink, U. S.; Deschamps, P.; Tuttle, M. P.; Wei, Y.; Fuentes, Z.
Coral boulders deposited on Anegada, an island 120 km south of the Puerto Rico Trench, record overwash dated to AD 1200-1450 and relative sea-level changes that preceded it. Composed largely of Pleistocene limestone, Anegada is less than 8 m above sea level and is fringed on the north and east by a coral reef where Atlantic Ocean waves break. The lowest parts of the island were washed over from the north in AD 1650-1800, as judged from landforms and deposits reported previously (doi:10.1007/s11069-010-9622-6). The coral boulders indicate overwash of higher elevation and earlier age. The boulders were apparently torn from the adjacent reef by a tsunami of nearby origin, as inferred in companion abstracts on geology and modeling. We found the corals scattered in five areas inland from the north shore. Two of the areas show solitary coral heads 1500 m from the reef. The boulders are more numerous in the three other areas, where they are up to 500-700 m from the reef and up to 4 m above sea level. Some were transported over beach ridges or through breaches cut into them. Others are hundreds of meters inland from a modern storm berm. Most rest on the Pleistocene limestone. Many are overturned. Most are broken but few are whole. The largest measured diameter is 2 m and the greatest measured height is 1 m. Most of the boulders are of the brain coral Diploria strigosa, but smaller Porites asteroides and Montastrea annularis are also present. Some of the D. strigosa retain the rounded shape typical of living heads and are dimpled with holes perhaps left by feather-duster worms. The preservation of these features suggests that many of the boulders came ashore alive. We avoided dating a head that shows field evidence for death before transport; an erosional surface cuts across its youngest growth bands and is covered with the remains of encrusting marine organisms. Among the 18 coral boulders dated, 13 form a young group with ages in the range 890±25 to 1020±25 14C yr BP
King, Gary; Rosen, Ori; Tanner, Martin A.
This collection of essays brings together a diverse group of scholars to survey the latest strategies for solving ecological inference problems in various fields. The last half-decade has witnessed an explosion of research in ecological inference--the process of trying to infer individual behavior from aggregate data. Although uncertainties and information lost in aggregation make ecological inference one of the most problematic types of research to rely on, these inferences are required in many academic fields, as well as by legislatures and the Courts in redistricting, by business in marketing research, and by governments in policy analysis.
Yağmur, Ersen Aydın; Tropea, Gioele
Abstract A new species of the genus Euscorpius Thorell, 1876 is described based on specimens collected from Bursa Province, in Marmara Region of Turkey. It is characterized by a mesotrichous trichobothrial pattern (Pv= 8, et= 6, em=4, eb= 4), medium size and light coloration. Euscorpius (Euscorpius) rahsenae sp. n. is the second species of the subgenus Euscorpius recognizedin Turkey. PMID:23794835
Ozel, Oguz; Guralp, Cansun; Tunc, Suleyman; Yalcinkaya, Esref; Meral Ozel, Nurcan
The main objective of this study is to install a multi-parameter borehole system and surface array consisting of eight broadband sensors as close to the main Marmara Fault (MMF) in the western Marmara Sea as possible, and measure continuously the evolution of the state of the fault zone surrounding the MMF and to detect any anomaly or change which may occur before earthquakes by making use of the data from these arrays. The multi-parameter borehole system is composed of very wide dynamic range and stable borehole (VBB) broad band seismic sensor, and incorporate 3-D strain meter, tilt meter, and temperature and local hydrostatic pressure measuring devices. All these sensors are installed in 146m-deep borehole. All the sensor outputs are digitized; total of 11*24 bit-channels and 6*20 bit-channels. Real-time data transmission to the main server of the Marsite Project at Kandilli Observatory in Istanbul is accomplished. The multi-parameter borehole seismic station uses the latest update technologies and design ideas to record "Earth tides" signals to the smallest magnitude -3 events, as the innovative part of the Marsite Project. Bringing face to face the seismograms of microearthquakes recorded by borehole and surface instruments portrays quite different contents. The shorter recording duration and nearly flat frequency spectrum up to the Nyquist frequencies of borehole records are faced with longer recording duration and rapid decay of spectral amplitudes at higher frequencies of a surface seismogram. The main causative of the observed differences are near surface geology effects that mask most of the source related information the seismograms include, and that give rise to scattering, generating longer duration seismograms. In view of these circumstances, studies on microearthquakes employing surface seismograms may bring on misleading results. Particularly, the works on earthquake physics and nucleation process of earthquakes requires elaborate analysis of tiny
Özgür, Evren; Koçak, Kasım
Persistence is a measure of continuity of a variable over a period of time at any location. This definition implies that wind speed persistence means a positive serial correlation in a time series. In literature, there are numerous methods for measuring wind speed persistence. In this study, wind speed persistence were obtained for 19 stations located in Marmara Region by using two different methods. Daily wind speed data, taken from Turkish State Meteorological Service, were used in the study. The observation period was taken to be 1965-2014 for all stations. The methods used in the study are directional statistical method and wind speed duration curves approach. In directional statistical method, individual dates of winds are defined as directional variables; then, directional mean and variance are calculated. Wind dates are being converted to angular values and these days are being considered as a unit vector which has direction θ. In polar coordinate, the measures of directional mean and variance have been expressed as a vector with direction θmean and magnitude r. The r value can be considered as a measure of persistence. The wind speed duration curve is simply the cumulative distribution function of the wind speed in a certain period of time. In other words, it is the graphical representation of wind speed and percentage of exceedence time for a predefined threshold wind speed value in the same graphic. As a threshold wind speed, lower quartile (q0.25) value of ranked wind speed data were selected. In application, total time period was divided into five subperiods and changes of persistence in wind speeds as far as subperiods were presented. Persistence can be used in different kinds of study areas such as control of forest fires, dispersion of air pollutants, calculation of wind energy potential, ventilation of a city, etc. The results of this analysis showed that the proposed methods can be used as an alternative approach to determine whether a given time
Onur Karslioglu, Mahmut; Yeganehsahab, Amir; Durmaz, Murat
It is generally known that extreme ionospheric density associated with severe magnetic storm degrades the Global Navigation satellite Systems (GNSS) measurements also at mid - to high latitudes. Strong solar activity can cause large local spatial and temporal gradients in the delays induced on the GNSS signals by the ionosphere. The local nature of gradients can result in significant decorrelation between Ground Based Augmentation System (GBAS) Ground Stations and the GNSS receiver on board the aircraft. For the mitigation of this effect either a special functional architecture is established to monitor the ionosphere on the basis of so called Extended GBAS or ionospheric threat models can be constructed for a certain region. In this work two different techniques have been evaluated for the estimation of ionospheric threat model parameters consisting of width, slope and velocity of the ionospheric wave front by using real ground-based observations from both GPS and GLONASS in the Marmara Region. The data collected between 2012 and 2015 also containing high ionospheric activities are pre-processed to extract ionospheric gradients. Ionospheric delays at each ionospheric piercing point are determined by applying a local ionospheric Total Electron Content (TEC) modeling and filtering techniques on the basis of raw carrier-phase observations. The ionospheric fronts are searched by looking at high ionospheric gradients which result from ionospheric delay differences between ionospheric piercing points. The first technique of the threat model evaluation is based on the propagation of an ideal plane wave as a wave front, velocity of which is estimated on the basis of a Gauss Markov Model using an ordinary least square estimation procedure. The remaining parameters namely slope and width are calculated afterwards using rate of change gradients and the duration of the wave front in context with the estimated front velocity. In the second technique both the magnitude of the
Yavuz, Evrim; Çaka, Deniz; Tunç, Berna; Serkan Irmak, T.; Woith, Heiko; Cesca, Simone; Lühr, Birger-Gottfried; Barış, Şerif
The most active fault system of Turkey is North Anatolian Fault Zone and caused two large earthquakes in 1999. These two earthquakes affected the eastern Marmara region destructively. Unbroken part of the North Anatolian Fault Zone crosses north of Armutlu Peninsula on east-west direction. This branch has been also located quite close to Istanbul known as a megacity with its high population, economic and social aspects. A new cluster of microseismic activity occurred in the direct vicinity southeastern of the Yalova Termal area. Activity started on August 2, 2014 with a series of micro events, and then on August 3, 2014 a local magnitude is 4.1 event occurred, more than 1000 in the followed until August 31, 2014. Thus we call this tentatively a swarm-like activity. Therefore, investigation of the micro-earthquake activity of the Armutlu Peninsula has become important to understand the relationship between the occurrence of micro-earthquakes and the tectonic structure of the region. For these reasons, Armutlu Network (ARNET), installed end of 2005 and equipped with currently 27 active seismic stations operating by Kocaeli University Earth and Space Sciences Research Center (ESSRC) and Helmholtz-Zentrum Potsdam Deutsches GeoForschungsZentrum (GFZ), is a very dense network tool able to record even micro-earthquakes in this region. In the 30 days period of August 02 to 31, 2014 Kandilli Observatory and Earthquake Research Institute (KOERI) announced 120 local earthquakes ranging magnitudes between 0.7 and 4.1, but ARNET provided more than 1000 earthquakes for analyzes at the same time period. In this study, earthquakes of the swarm area and vicinity regions determined by ARNET were investigated. The focal mechanism of the August 03, 2014 22:22:42 (GMT) earthquake with local magnitude (Ml) 4.0 is obtained by the moment tensor solution. According to the solution, it discriminates a normal faulting with dextral component. The obtained focal mechanism solution is
Lühr, B.-G.; Bariş, Ş.; Grosser, H.; Irmak, T. S.; Woith, H.; Donner, S.; Özer, M. F.; Çaka, D.; Zschau, J.
The North Anatolian Fault Zone (NAFZ) represents one of the most prominent continental transforms and slips at an average rate of 20-30 mm/yr. During the 20th century, the NAFZ has ruptured over about 900 km of its more than 1,500 km length by ten devastating earthquakes with magnitudes above Ms > 6.5. Today, a segment inside the Marmara Sea just south of the megacity of Istanbul represents a seismic gap that is believed being capable of generating a M â¥7 earthquake within the next decades. East of this segment the western end of the 1999 Kocaeli earthquake rupture is located next to the northern shoreline of the Armutlu Peninsula depicted by distinct clusters of micro-seismic activity. As a contribution to hazard assessment the local seismic network ARMNET had been set-up in 2005 in co-operation between Kocaeli University, and GFZ, to monitor the chronological evolution of seismicity, and to investigate the deformation of the Armutlu Peninsula, as well as possible interactions between seismic waves and pore-pressure variations in geothermal systems. The installation was strongly supported by local governments, and lead to a strong interest and an increasing knowledge transfer to local authorities. The ARMNET contributes to the implementation of an Anatolian plate boundary observatory (PBO) belonging to a series of GFZ-operated Earth System Observatories to systemically study coupled Earth processes, and is imbedded in the framework of the CEDIM (CEnter for DIsaster Management and Risk Reduction Technology) project "Megacity Istanbul", which involves the analysis of the seismicity of the Greater Istanbul region. At present, ARMNET consist of 12 short period and 10 broadband stations. Additionally, a borehole seismometer has been installed in a 100 m borehole close to Yalova. Most of the detected events occurred in a depth range of 5 to 15 km, and determined duration magnitudes are in a range 0.4 and 5.3 with a magnitude of completeness of 1.3. Besides seismic
In this tutorial we review the essential arguments behing entropic inference. We focus on the epistemological notion of information and its relation to the Bayesian beliefs of rational agents. The problem of updating from a prior to a posterior probability distribution is tackled through an eliminative induction process that singles out the logarithmic relative entropy as the unique tool for inference. The resulting method of Maximum relative Entropy (ME), includes as special cases both MaxEnt and Bayes' rule, and therefore unifies the two themes of these workshops—the Maximum Entropy and the Bayesian methods—into a single general inference scheme.
Aggelopoulos, Nikolaos C
Perceptual inference refers to the ability to infer sensory stimuli from predictions that result from internal neural representations built through prior experience. Methods of Bayesian statistical inference and decision theory model cognition adequately by using error sensing either in guiding action or in "generative" models that predict the sensory information. In this framework, perception can be seen as a process qualitatively distinct from sensation, a process of information evaluation using previously acquired and stored representations (memories) that is guided by sensory feedback. The stored representations can be utilised as internal models of sensory stimuli enabling long term associations, for example in operant conditioning. Evidence for perceptual inference is contributed by such phenomena as the cortical co-localisation of object perception with object memory, the response invariance in the responses of some neurons to variations in the stimulus, as well as from situations in which perception can be dissociated from sensation. In the context of perceptual inference, sensory areas of the cerebral cortex that have been facilitated by a priming signal may be regarded as comparators in a closed feedback loop, similar to the better known motor reflexes in the sensorimotor system. The adult cerebral cortex can be regarded as similar to a servomechanism, in using sensory feedback to correct internal models, producing predictions of the outside world on the basis of past experience. PMID:25976632
Chierici, Francesco; Pignagnoli, Luca; Iannaccone, Giovanni; Guardato, Sergio; Locritani, Marina; Embriaco, Davide; Donnarumma, Gian Paolo; La Rocca, Adriano; Pinto, Salvatore; Beranzoli, Laura
The vertical component of sea floor displacement in tectonic or volcanically active areas can be observed using sea bottom pressure recorders. These measurements are usually acquired in areas affected by strong dynamics with large vertical displacement and in deep water, where the noise induced by the sea state is low. Under these conditions the contribution of the variation of sea water density and the contribution of the instrumental drift - a typical feature of the bottom pressure recorders - can be negligible. We have developed a new methodology to monitor vertical sea floor displacement both in areas with small and slow deformation, and in shallow water. We take advantage of bottom pressure recorder data, augmented with ancillary sea level, barometric and water physical parameters measurements. We have applied this method to the data collected by a bottom pressure recorder deployed at 100 m w.d. in the Campi Flegrei Caldera as part of CUMAS multiparameter monitoring system. During several months of 2011 we have observed a small uplift episode related to the bradiseismic activity of the area. These observations are compatible with other geodetic data recorded in the region and provide unprecedented measurements of the vertical deformation in the marine area.
Earthquake-triggered landslides have an increasing disastrous impact in seismic regions due to the fast growing urbanization and infrastructures. Just considering disasters from the last fifteen years, among which the 1999 Chi-Chi earthquake, the 2008 Wenchuan earthquake, and the 2011 Tohoku earthquake, these events generated tens of thousands of coseismic landslides. Those resulted in amazing death toll and considerable damages, affecting the regional landscape including its hydrological main features. Despite a strong impetus in research during past decades, knowledge on those geohazards is still fragmentary, while databases of high quality observational data are lacking. These phenomena call for further collaborative researches aiming eventually to enhance preparedness and crisis management. As one of the three SUPERSITE concept FP7 projects dealing with long term high level monitoring of major natural hazards at the European level, the MARSITE project gathers research groups in a comprehensive monitoring activity developed in the Sea of Marmara Region, one of the most densely populated parts of Europe and rated at high seismic risk level since the 1999 Izmit and Duzce devastating earthquakes. Besides the seismic threat, landslides in Turkey and in this region constitute an important source of loss. The 1999 Earthquake caused extensive landslides while tsunami effects were observed during the post-event surveys in several places along the coasts of the Izmit bay. The 6th Work Package of MARSITE project gathers 9 research groups to study earthquake-induced landslides focusing on two sub-regional areas of high interest. First, the Cekmece-Avcilar peninsula, located westwards of Istanbul, is a highly urbanized concentrated landslide prone area, showing high susceptibility to both rainfalls while affected by very significant seismic site effects. Second, the off-shore entrance of the Izmit Gulf, close to the termination of the surface rupture of the 1999 earthquake
Bergeron, Myriam; Tremblay, Jean-Éric
This paper reports the first in situ evidence of change in the net biological productivity of high-latitude western Arctic seas. Estimates of seasonal drawdown for major plant nutrients show that net community production (NCP) shifted differently in two contrasted Canadian oceanographic settings. In the stratified southeast Beaufort Sea, seasonal nitrate consumption increased 1.6-fold between 2003-2004 and 2010-2011. The concomitant thickening of the nitrate-depleted layer in summer/fall implies that subsurface chlorophyll maxima now consume nutrients over a larger extent of the water column. Meanwhile, nitrate consumption in the once productive North Water Polynya declined by 65% and is now nearly on par with the oligotrophic coastal Beaufort Sea. This decline is attributed to freshening and increased stratification. Commensurate changes in silicate and phosphate drawdown in the two regions indicate that diatoms drove the spatial and temporal shifts in NCP.
Balcıoğlu, Esra Billur
In this study, PAH analyses have been conducted on indigenous mussels. Mussel samples (Mytilus galloprovincialis) have been collected from seven stations of Prince Islands during September 2015. Concentrations of total determined PAHs (sum of 16 compounds) ranged between 664 and 9083ngg(-1). The origin of PAHs has been found to be pyrolytic according to the PHE/ANT and FA/PYR ratios in Büyükada. For other islands, PAH origins have been observed as pyrolytic and petrogenic together according to the PHE/ANT, FA/PYR and BaA/CHR ratios. PMID:27237036
Kılıç, Önder; Belivermiş, Murat; Gözel, Furkan; Carvalho, Fernando P
The Golden Horn is an estuary located in the center of İstanbul receiving freshwater discharges from two creeks and connecting to the Bosphorus Strait. Activity concentrations of natural and artificial radionuclides were determined in mussels (Mytilus galloprovincialis) and sediments from the Golden Horn sampled in February 2012. Mean activity concentrations of (137)Cs, (40)K, (226)Ra, (228)Ra, (210)Po and (210)Pb in the mussels were determined at 1.03±0.23, 389±41.6, 2.61±1.23, not detected (ND), 91.96±37.88 and 11.48±4.85 Bq kg(-1), respectively. In sediments, it was observed that (137)Cs, (40)K, (226)Ra, (228)Ra, (210)Po and (210)Pb activity concentrations in<63 μm particle fraction of sediment were generally higher than those determined in mussels. Po-210 and (210)Po/(210)Pb ratios in mussels from the Golden Horn were much lower than in mussels from other coastal regions and this was related to low plankton productivity and eutrophication of the Golden Horn. PMID:25023437
Shirodkar, P V; Xiao, Y K; Sarkar, A; Dalal, S G; Chivas, A R
The behaviors of chlorine isotopes in relation to air-sea flux variables have been investigated through multivariate statistical analyses (MSA). The MSA technique provides an approach to reduce the data set and was applied to a set of 7 air-sea flux variables to supplement and describe the variation in chlorine isotopic compositions (delta37Cl) of ocean water. The variation in delta37Cl values of surface ocean water from 51 stations in 4 major world oceans--the Pacific, Atlantic, Indian and the Southern Ocean has been observed from -0.76 to +0.74 per thousand (av. 0.039+/-0.04 per thousand). The observed delta37Cl values show basic homogeneity and indicate that the air-sea fluxes act differently in different oceanic regions and help to maintain the balance between delta37Cl values of the world oceans. The study showed that it is possible to model the behavior of chlorine isotopes to the extent of 38-73% for different geographical regions. The models offered here are purely statistical in nature; however, the relationships uncovered by these models extend our understanding of the constancy in delta37Cl of ocean water in relation to air-sea flux variables. PMID:16214214
Lambertian equivalent reflectivity (LER) ultraviolet (UV) data are routinely retrieved from many satellite-based instruments. Besides their original primarily function related to the retrieval of the ozone data, they also demonstrated to be useful as a cloudiness proxy comparable with data recorded from ground-based instruments, as well as for tracking ice/snow changes at high latitudes. LER time series spanning more than three decades can be retrieved from TOMS/OMI instruments although concerns related to the EP TOMS scan mirror degradation exist. Therefore, recently additional multi-satellite-based LER datasets have been created from SBUV instruments in the frame of the NASA MEaSUREs Program (Herman et al. 2013). In this presentation we report some recent applications of both datasets over southern middle and high latitudes focusing on cloudiness, surface UV and sea-ice. LER data have been analyzed over eight locations spanning from about 18° (north of Chile) to 62° S (Antarctic peninsula) covering years 1978-2011. Generally the distribution of the reflectivity of both TOMS datasets is similar. On the other hand, OMI LER data differ from TOMS ones in almost all locations. Daily CMF values from ground-based global solar irradiance measurements have been compared with OMI LER-based CMF data. The northernmost and southernmost locations characterized by prevalent clear sky and winter snow conditions, respectively, showed the worse agreement while the other stations showed a better correlation. For one location clear sky ground UV index values for have been estimated for years 1979-2011 by means of an empirical reconstruction model based on data recorded by a multichannel radiometer. Then, we exploit satellite LER data for computing actual surface UV by correcting clear sky UV with LER-based CMF data. Besides we also evaluated the cloud cover and the sea ice influence on the reflectivity in the Southern Ocean by comparing the MEaSUREs LER dataset with satellite
Ozener, H.; Garagon Dogru, A.; Aktug, B.; Ergintav, S.; Yilmaz, O.; Turgut, B.; Halicioglu, K.; Sabuncu, A.; Havazli, E.; Gurkan, O.; Reilinger, R. E.
North Anatolian Fault System (NAFS) is a well-known transform boundary between the Eurasian and Anatolian plates. The western part of the fault has a remarkable history of seismic activity and quantification of the deformation is needed especially for the northern strand, which consists of Izmit segment, Prince's Islands segment, and Ganos segment. Space geodetic data provide valuable information to constrain the seismic potential of the area. The Geodesy Department of Kandilli Observatory and Earthquake Research Institute at Bogazici University has conducted GPS surveys since 1994 on near-fault geodetic networks. Annually surveyed GPS data from 24 stations of 3 geodetic networks and continuous data from permanent stations are combined to study both the spatial and the temporal variations of crustal strain in the area. These small-aperture geodetic networks include three different sites and were deployed across the North Anatolian Fault System in 1990. Both trilateration and triangulation measurements along with GPS observations were carried out periodically. These measurements allow us to characterize the deformation and fault kinematics near the fault, and they also provide the opportunity to quantify the co-seismic and post-seismic deformation of the 1999 Izmit Earthquake along the coseismic fault break. The continuous GPS measurements are well suited to detect aseismic strain transients and the small-aperture geodetic networks are useful for monitoring systematic variations in the near-fault strain rate (creep events). The geodetic observations from these observations, covering the period 1994-2013 will be presented and used to investigate the mechanism of these transient strain events and their relationship to earthquake activity.
Douville, E.; Paterne, M.; Feuillet, N.; Noury, C.; Bordier, L.; Thil, F.
Global warming and ocean acidification caused by the rising levels of anthropogenic CO2 in the atmosphere need to be better constrained by long-term studies of high resolution natural archives, especially at inter-annual and decadal scales. In the framework of the French INSU program LEFE/CYBER ACID-Antilles, here we developed a 200-year long interannual time series of sea surface temperature and pH based on the geochemical composition of tropical reef forming coral. The selected tropical coral called CHANCEL-1 is a colony of genus Siderastrea Siderea which was collected in 2008 from a living micro-atoll off Martinique in the Lesser Antilles, facing the eastern side of the Caribbean Sea. The colony of 1-meter extension presents a mean growth rate of 4 - 5 mm/yr. Along the growth axis, we measured the boron isotopic composition (delta11B) and trace element ratios (Li/Mg, Sr/Ca), which reveal a progressive decrease of the surface water pH and increase of temperature during the past 200 years. These observations cooperate the anthropogenic forcing, i.e. rising atmospheric CO2 and rising sea surface temperatures due to global warming. However, other processes apparently affect the geochemical records, as indicated by sub-decadal variations of pH and temperature reconstruction overprinting the long term global trend. Possible drivers of such most likely regional variability might be decadal changes of oceanographic conditions (upwelling, freshwater runoff, seawater masse changes, etc.) as well as species dependent biological controls.
A strong ‘filter’ effect of the East China Sea land bridge for East Asia’s temperate plant species: inferences from molecular phylogeography and ecological niche modelling of Platycrater arguta (Hydrangeaceae)
Background In East Asia, an increasing number of studies on temperate forest tree species find evidence for migration and gene exchange across the East China Sea (ECS) land bridge up until the last glacial maximum (LGM). However, it is less clear when and how lineages diverged in this region, whether in full isolation or in the face of post-divergence gene flow. Here, we investigate the effects of Quaternary changes in climate and sea level on the evolutionary and demographic history of Platycrater arguta, a rare temperate understorey shrub with disjunct distributions in East China (var. sinensis) and South Japan (var. arguta). Molecular data were obtained from 14 P. arguta populations to infer current patterns of molecular structure and diversity in relation to past (Last Interglacial and Last Glacial Maximum) and present distributions based on ecological niche modelling (ENM). A coalescent-based isolation-with-migration (IM) model was used to estimate lineage divergence times and population demographic parameters. Results Combining information from nuclear/chloroplast sequence data with nuclear microsatellites, our IM analyses identify the two varieties as genetically distinct units that evolved in strict allopatry since the mid-Pleistocene, c. 0.89 (0.51–1.2) Ma. Together with Bayesian Skyeline Plots, our data further suggest that both lineages experienced post-divergence demographic growth, followed by refugial isolation, divergence, and in the case of var. arguta post-glacial admixture. However, past species distribution modelling indicates that the species’ overall distribution has not greatly changed over the last glacial cycles. Conclusions Our findings highlight the important influence of ancient sea-level changes on the diversification of East Asia’s temperate flora. Implicitly, they challenge the notion of general temperate forest expansion across the ECS land bridge, demonstrating instead its ‘filter’ effect owing to an unsuitable environment
Matsuno, Tetsuo; Nogi, Yoshifumi; Seama, Nobukazu
The western Cosmonauts Sea, off the coast of East Antarctica, was a site of rifting of the Gondwana supercontinent and subsequent early seafloor spreading. To improve our understanding of the breakup of Gondwana, we conducted a marine magnetotelluric experiment to determine the electrical resistivity structure within the uppermost several hundred kilometers beneath the western Cosmonauts Sea. Magnetotelluric response functions at two sites, obtained after considering possible influences of non-plane magnetic field sources, suggest that these responses include distortions by topographic variations and conductive anomalies around the observation sites. Three-dimensional forward modeling confirmed that these distortions due to topographic variations and a thin (∼2-km thick) conductive layer immediately under the sites (mostly sediments) are severe. Furthermore, three-dimensional forward modeling to investigate the resistivity structure at deeper depths revealed an upper resistive layer (≥300 Ω-m), with a thickness of <100 km, and an underlying conductive half-space (∼10 Ω-m). The upper resistive layer and the underlying conductive structure most likely represent dry and water/melt-rich oceanic upper mantle, respectively. The upper resistive layer may be thinner than anticipated under the old seafloor of the study area (likely >90 Ma), and may suggest a conductive anomaly in the upper mantle produced by mantle convection and/or upwelling.
Guilderson, T. P.; Mccarthy, M. D.; Dunbar, R. B.; Englebrecht, A.; Roark, E.
δ15N and δ13C data obtained from samples of proteinaceous deep-sea corals collected from the North Pacific Subtropical Gyre (Hawai'ian archipelago) and the central equatorial Pacific (Line Islands) document multi-decadal to century scale variability in the isotopic composition of surface-produced particulate organic matter exported to the deep sea. Comparison of the δ13C data, where Line Island samples are 0.6‰ more positive than the Hawai'ian samples, support the contention that the North Pacific Subtropical Gyre is more efficient than the tropical upwelling system at trapping and/or recycling nutrients within the mixed layer. δ15N values from the Line Island samples are also more positive than those from the central gyre, and within the Hawai'ian samples there is a gradient with more positive δ15N values in samples from the main Hawai'ian Islands versus French Frigate Shoals in the Northwestern Hawai'ian Islands. The gradient in the Hawai'ian samples likely reflects the relative importance of algal acquisition of metabolic N via dissolved seawater nitrate uptake versus nitrogen fixation. The Hawai'ian sample set also exhibits a strong decrease in δ15N values from the mid-Holocene to present. We hypothesize that this decrease is most likely the result of decreasing tradewinds, and possibly a commensurate decrease in entrainment of more positive δ15N-NO3 subthermocline water masses.
Spagnuolo, E.; Akinci, A.; Herrero, A.; Pucci, S.
In this study, we attempt to incorporate the rupture directivity effects into seismic hazard analysis in the Marmara region, Turkey. We introduce information about the fault segments by focusing on the fault rupture characteristics, near source directivity effects and its influence on the probabilistic seismic hazard analyses (PSHA) accounting for the azimuthal variations of the ground motion spatial distribution. An analytical model developed by Spudich and Chiou (2008) is used as a corrective factor that modifies four ground motion predictive equations (GMPEs) (Abrahamson & Silva 2008; Boore & Atkinson 2008; Campbell & Bozorgnia 2008; Chiou &Youngs 2008) and accounts for rupture related parameters that generally lump together into the term directivity effect. In this paper, we only use the relation calibrated for the Abrahamson & Silva (2008) and Boore & Atkinson (2008). In order to evaluate the impact of the rupture directivity effects to ground motion hazard in the near source we attempt to calculate the fault-based probabilistic seismic hazard maps (PSHA) of mean Peak Ground Acceleration (PGA) having 10% probability of exceedance in 50 years on rock site condition. Therefore the PSHMs for the Marmara region is produced incorporating detailed knowledge of active faulting and tectonic rates in earthquake recurrence models using the available database and the most innovative approaches. In order to test the impact of the corrective factor on seismic hazard we first considered its effect on a normal fault and on a strike slip fault as a function of magnitude. Seismic hazard is given in terms of Spectral Acceleration (SA) at seven different periods. We also report the percentage ratio between the seismic hazards computed with the directivity model and without it, over the seismic hazard resulting from the standard practice. Finally, we improve the seismic hazard maps in the near fault source incorporating the directivity effects in the ground motion prediction in
Abdeldayem, A.L.; Ikehara, K.; Yamazaki, T.
A magnetic fabric analysis has been carried out on standard cube samples from one gravity and three multiple cores extracted from the Shiribeshi trough and Okushiri basin in the southern margin of the Japan sea north basin. It is aimed at tracing the flow path of turbidites that are assumed to have deposited in response to the 1993 Hokkaido-Nansei-oki earthquake. Magnetic remanence was used for reorientation to the geographic coordinates. Magnetomineralogical investigations including low-temperature magnetometry, magnetic hysteresis loops and isothermal remanent magnetization (IRM) acquisition experiments indicate that pseudosingle domain to multidomain magnetite is the principal magnetic carrier and is, therefore, capable of providing reliable anisotropy of magnetic susceptibility (AMS) palaeocurrent direction estimates. A well-developed near-horizontal magnetic foliation and minimum susceptibility axes lying close to vertical are recorded at all sites reflecting an original depositional fabric. Clearly defined magnetic lineation was observed at all sites and is considered to reflect the palaeocurrent direction. Down-core changes of susceptibility and key AMS parameters show good correspondence to occurrences of turbidite layers marking the increase of input of influx materials. In agreement with results from recent marine surveys and IZANAGI side-scan sonar images, an NNE transportation trend has been estimated for sediments at sites from the Shiribeshi trough with a possible depositing path initiating from the slope bounding the south and southeastern margin down to the trough floor. Similarly, a SSE palaeocurrent direction has been estimated for sediments from the Okushiri basin with evidence for a relatively strong transporting current flowing through the canyons along the steep slope bounding the north and northeastern margins of the basin. The present results agree with the view that slope failure is the most probable mechanism for the down-slope transport
Gama, C.; Jalobeanu, A.
Monitoring the sediment budget of coastal systems is essential to understand the costal equilibrium, and is an important aspect to be considered in coastal management. Thus, the identification and the quantitative evaluation of sedimentary sources and sinks are the first steps towards a better understanding of the dynamics of coastal morphology. The Tróia-Sines Embayed Coast (TSEC) in the southwest Portuguese coast corresponds to a continuous sandy beach that extends for approximately 65 km. It is limited at north by the Sado river estuary and at south by the Sines cape. Beaches are discontinuously limited landward by dunes (≈42 km) and by sea cliffs (≈18 km) made of poorly consolidated Plio-Plistocene detrital deposits. Cliff erosion by subaerial processes or gullying is a continuous phenomenon that contributes a significant amount of sediment to the TSEC coastal system, which is what we want to measure. Mainly due to winter rainfall, sea cliffs develop debris fans at the backshore inner limit, therefore we chose to make morphological measurements at one year interval. Thus, two series digital aerial images at 20 cm resolution were acquired in Oct 2008 and July 2009, supported by a collection of ground control points (GCP) to constrain the sensor orientation. Digital aerial stereo image pairs are used as main data source to reconstruct digital surface models (DSM). A new stereo photogrammetric method is used, based on dense disparity maps and Bayesian inference (Jalobeanu et al, 2010 and Jalobeanu, 2011). The originality of this method is in the computation of the spatial distribution of elevation errors in the DSM using stochastic modelling and probabilistic inference, which helps to detect the statistically significant changes in the estimated topography. The difference between the two generated DSMs is used to characterize the variability of the main subaerial beach morphodynamics parameters, such as: i) the alongshore beach configuration; ii) the beach
Laws, Edward A.; Landry, Michael R.; Barber, Richard T.; Campbell, Lisa; Dickson, Mary-Lynn; Marra, John
Estimates of photosynthesis based on the incorporation of 14C-labeled inorganic carbon into particulate carbon were compared to estimates of gross photosynthesis based on net O 2 production and the production of 18O2 from H218O during the US Joint Global Ocean Flux Study (US JGOFS) Arabian Sea process cruises. For samples incubated below the surface and at optical depths<3, the 14C uptake : gross photosynthesis ratio averaged 0.45±0.1. This result is in accord with theoretical considerations of the combined effects of the Mehler reaction, photorespiration, dark respiration, excretion, and grazing effects on the two estimates of photosynthesis. The 14C uptake : gross photosynthesis ratio was distinctly higher (0.62) for samples incubated at the surface. This result is likely due to UV light effects, since the O 2 and 14C incubations were done in quartz and polysulfone bottles, respectively. The 14C uptake : gross photosynthesis ratio was lower (0.31) for bottles incubated at optical depths>3. This result probably reflects an increase in the ratio of dark respiration to net photosynthesis in the vicinity of the compensation light level.
Ostrovskii, Alexander; Zatsepin, Andrey
This presentation introduces a new ocean autonomous profiler for multiparametric surveys at fixed geographical locations. The profiler moves down and up along a mooring line, which is taut vertically between a subsurface flotation and an anchor. This observational platform carries such modern oceanographic equipment as the Nortek Aquadopp-3D current meter and the Teledyne RDI Citadel CTD-ES probe. The profiler was successfully tested in the northeastern Black Sea during 2007-2009. By using the profiler, new data on the layered organization of the marine environment in the waters over the upper part of the continental slope were obtained. The temporal variability of the fine-scale structure of the acoustic backscatter at 2 MHz was interpreted along with biooptical and chemical data. The patchy patterns of the acoustic backscatter were associated with physical and biological processes such as the advection, propagation of submesoscale eddy, thermocline displacement, and diel migration of zooplankton. Further applications of the multidisciplinary moored profiler technology are discussed.
Hernández-Carrasco, Ismael; Sudre, Joel; Garçon, Veronique; Yahia, Hussein; Dewitte, Boris; Garbe, Christoph; Illig, Séréna; Montes, Ivonne; Dadou, Isabelle; Paulmier, Aurélien; Butz, André
In recent years the role of submesoscale activity is emerging as being more and more important to understand global ocean properties, for instance, for accurately estimating the sources and sinks of Greenhouse Gases (GHGs) at the air-sea interface. The scarcity of oceanographic cruises and the lack of available satellite products for GHG concentrations at high resolution prevent from obtaining a global assessment of their spatial variability at small scales. In this work we develop a novel method to reconstruct maps of CO2 fluxes at super resolution (4km) using SST and ocean colour data at this resolution, and CarbonTracker CO2 fluxes data at low resolution (110 km). The responsible process for propagating the information between scales is related to cascading properties and multiscale organization, typical of fully developed turbulence. The methodology, based on the Microcanonical Multifractal Formalism, makes use, from the knowledge of singularity exponents, of the optimal wavelet for the determination of the energy injection mechanism between scales. We perform a validation analysis of the results of our algorithm using pCO2 ocean data from in-situ measurements in the upwelling region off Namibia.
Cox, C.; Au, A.; Klosko, S.; Chao, B.; Smith, David E. (Technical Monitor)
The upcoming GRACE mission promises to open a window on details of the global mass budget that will have remarkable clarity, but it will not directly answer the question of what the state of the Earth's mass budget is over the critical last quarter of the 20th century. To address that problem we must draw upon existing technologies such as SLR, DORIS, and GPS, and climate modeling runs in order to improve our understanding. Analysis of long-period geopotential changes based on SLR and DORIS tracking has shown that addition of post 1996 satellite tracking data has a significant impact on the recovered zonal rates and long-period tides. Interannual effects such as those causing the post 1996 anomalies must be better characterized before refined estimates of the decadal period changes in the geopotential can be derived from the historical database of satellite tracking. A possible cause of this anomaly is variations in ocean mass distribution, perhaps associated with the recent large El Nino/La Nina. In this study, a low-degree spherical harmonic gravity time series derived from satellite tracking is compared with a TOPEX/POSEIDON-derived sea surface height time series. Corrections for atmospheric mass effects, continental hydrology, snowfall accumulation, and ocean steric model predictions will be considered.
Roark, B.; Guilderson, T. P.; Fallon, S.; Dunbar, R. B.; McCulloch, M.
Deep-sea corals are an important archive of intermediate and deep-water variability, and provide the means to explore decadal to century-scale ocean dynamics in regions and time periods heretofore unexplored. We present a reconstruction of pre to post-bomb surface and interior water Δ14C based on analysis of deep-sea Isididae (bamboo) corals collected live at ~700 meters in June 2002 at Warwick Seamount, Gulf of Alaska. Concurrent isotope analyses of polyp/tissue and outermost portion of the hard horny proteinaceous gorgonin nodes compared with in situ dissolved inorganic carbon indicates that the gorgonin portion is derived exclusively from recently fixed/exported particulate organic carbon and thus a record of the surface water 14C/12C history. This is in contrast to the carbonate internode portion which is primarily derived from in situ dissolved inorganic carbon, and thus a record of the in situ 14C/12C. Radiocarbon analysis of gorgonin nodal sections captures the surface water D14C evolution. Pre-bomb values are -105‰ reaching a maximum of 100‰ before decreasing to collection values of 20‰. We anticipate that the post-bomb maximum will be in the early 1970s consistent with other mid to high latitude records and that the pre/post bomb transition initiates near 1956. If we utilize the gorgonin pre/post bomb transition as a tie-point and assume a linear growth rate the Isididae used in this study are 75- 125 years old. Carbonate Δ14C shows a 25‰ increase from -215 to -190‰ reflecting the penetration of bomb-14C in the sub-polar North Pacific. To place the carbonate time-series on a fixed timescale we determined the minor element chemistry and tested the inter-species reproducibility. The distribution of Sr is quite homogenous whereas Mg is not with higher Mg concentrations associated with centers of calcification. Age estimates using what appear to be annual Sr/Ca cycles, which we hypothesize are related to biomineralization cycles associated with a
Cahyarini, Sri Yudawati; Pfeiffer, Miriam; Nurhati, Intan Suci; Aldrian, Edvin; Dullo, Wolf-Christian; Hetzinger, Steffen
The Indonesian Throughflow (ITF), which represents the global ocean circulation connecting the Pacific Warm Pool to the Indian Ocean, strongly influences the Indo-Pacific climate. ITF monitoring since the late 1990s using mooring buoys have provided insights on seasonal and interannual time scales. However, the absence of longer records limits our perspective on its evolution over the past century. Here, we present sea surface temperature (SST) and salinity (SSS) proxy records from Timor Island located at the ITF exit passage via paired coral δ18O and Sr/Ca measurements spanning the period 1914-2004. These high-resolution proxy based climate data of the last century highlights improvements and cautions when interpreting paleoclimate records of the Indonesian region. If the seasonality of SST and SSS is not perfectly in phase, the application of coral Sr/Ca thermometry improves SST reconstructions compared to estimates based on coral δ18O only. Our records also underline the importance of ocean advection besides rainfall on local SSS in the region. Although the El Niño/Southern Oscillation (ENSO) causes larger anomalies relative to the Indian Ocean Dipole (IOD), Timor coral-based SST and SSS records robustly correlate with IOD on interannual time scales, whereas ENSO only modifies Timor SST. Similarly, Timor SST and SSS are strongly linked to Indian Ocean decadal-scale variations that appear to lead Timor oceanographic conditions by about 1.6-2 years. Our study sheds new light on the complex signatures of Indo-Pacific climate modes on SST and SSS dynamics of the ITF. This article was corrected on 8 AUG 2014. See the end of the full text for details.
Cukur, D.; Kim, S. P.; Kong, G. S.; Yoon, Y.; Kim, J. K.; Choi, J. G.
Submarine landslides form very complex features on the seafloor and the associated geological processes are yet to be known completely. Various researches are still undergoing not only for their profound academic significance but also for their hazardous impact potential to seafloor infrastructures and coastal areas. In order to investigate the morphology and cause of landslides along the western margin of the Ulleung Basin in the East Sea, we collected multiple geophysical datasets in the summer of 2015, including sparker, subbottom profiler, and multibeam echosounder. The preliminary analysis of the bathymetric data shows a number of U-shaped scarps that occur on a rather steep slope (up to 10°) in water depths of ~600 m. The scarps cover an area of ~100 km2 and have reliefs of up to 50 m. Seismic data clearly image erosional headwalls and the basal gliding plane which is characterized by a prominent high-amplitude reflector. Chaotic- to transparent-seismic facies, located immediately downslope of the headwall scarps, represent landslide deposits of about 20 m in thickness. At the base of slope, the slides form lens-shaped transparent bodies, resting on well-stratified turbidite deposits. Several V-shaped seafloor depressions near the head of these scarps are seen on the subbottom profiles. These depressions, which are ~5 m deep and ~150 m wide, are interpreted to be representing pockmarks, resulted from upward migration of gas in the sediment layers beneath. The presence of these pockmarks directly above the scars may suggest that the gases and/or gas fluids might be playing an important role for destabilizing slope sediments. Furthermore, subbottom profiles suggest the presence of numerous faults in close vicinity of headwall scarps; some are extending to the seafloor suggesting their recent activity. Earthquakes associated with tectonic activity are indicated to be the cause of these faults. Thus the fault-related earthquakes might be the final triggering
Chang, N. N.; Shiao, J. C.; Gong, G. C.; Kao, S. J.; Hsieh, C. H.
Coastal areas adjoining rivers are nourished by both the riverborne nutrients and organic matters. Annually, the East China Sea (ECS) receives large quantities of particulate organic carbon transported from the Changjiang (Yangtze River), as well as nutrients, which have brought about high primary production in the ECS. This study evaluated the respective contributions of terrigenous organic matters (allochthonous food source) and nutrient-induced marine production (autochthonous food source) to the ECS benthic ecosystem by analyzing the stable isotope compositions for zooplankton, benthic crustacea and demersal fish. Zooplankton exhibited consistently higher δ13C values (-21.31‰ ~ -19.22‰) in the inner shelf than in the outer shelf. The δ13C signals of fish (-19.64‰ ~ -13.46‰) and crustacea (-18.87‰ ~ -15.00‰) showed strong reliance on the marine production across the ECS continental shelf, regardless of distance from the shore. Moreover, the benthic crustacea and fish exhibited significantly higher δ13C values in the highly productive inshore sites and the δ13C values decreased seawards, implying a higher intrusion of atmospheric CO2 and lower photosynthetic fractionation due to algal blooming in the inner shelf. The δ13C values of fish also showed significant positive correlations with the concentration of surface chlorophyll a and nitrogen. Riverborne nutrients closely linked marine benthic consumers to the terrestrial watershed and tightly coupled the pelagic and benthic ecosystems in the ECS. The stable isotope compositions of benthic consumers can act as an indicator for pelagic trophic status. The future research combining analyses of stable isotope and community structure may improve assessment on the balance between contribution and risk of phytoplankton blooms.
Furumura, T.; Padhy, S.; Maeda, T.
A detailed structure of the subducting Philippine Sea plate (PHP) along the Nankai trough in western Japan was studied by analyzing waveforms recorded at dense Hi-net stations in Japan. It is well recognized that the waveforms from intraplate earthquakes dominate in high-frequency (f >1 Hz) signals due to the waveguide effect of the subducting slab (Furumura and Kennett, 2005; 2008). This results in distorted pattern of intensity and peak ground acceleration (PGA) above the hypocenter with a substantial elongation of isoseismic contours correlated with the configuration of the isodepth contours of the subducting PHP beneath western Japan. A detailed analysis of the dense Hi-net waveform data from the intermediate-depth PHP event shows that the high-frequency S-wave signals suddenly disappear as the waves propagate the zone away from the Kii Channel to the boundary of Hyogo and Okayama prefectures and large S-to-P conversion occurs before the arrival of S-wave. Such anomalies do not occur for shallow and deep earthquakes occurring outside the PHP. These observations support the recent debate on the complexities of the configuration of the PHP subducting beneath western Japan such as that shown by Shiomi et al. (2008) based on receiver function images and the PHP-split model beneath the Kii channel shown by Ide et al.(2010) based on the analysis of comprehensive geophysical data. In order to explain the observations associated with sudden lateral change in the PHP structure, we conducted finite difference method (FDM) simulations of seismic wave propagation taking the detailed PHP model into account. It is confirmed that high-frequency guided wave energy decouple from waveguide where the shape of the PHP is suddenly deformed, which results in dramatic attenuation of high-frequency signals associating with large S-to-P conversions developed at sharp plate boundary. The present results also support the recently proposed complicated PHP-split model, however, further
Sud, Y. C.; Walker, G. K.; Zhou, Y.; Lau, W. K.-M.
Two parallel sets of 10-year long: January 1, 1982 to December 31, 1991, simulations were made with the finite volume General Circulation Model (fvGCM) in which the model integrations were forced with prescribed sea-surface temperature fields (SSTs) available as two separate SST-datasets. One dataset contained naturally varying monthly SSTs for the chosen period, and the oth& had the 12-monthly mean SSTs for the same period. Plots of evaporation, precipitation, and atmosphere-column moisture convergence, binned by l C SST intervals show that except for the tropics, the precipitation is more strongly constrained by large-scale dynamics as opposed to local SST. Binning data by SST naturally provided an ensemble average of data contributed from disparate locations with same SST; such averages could be expected to mitigate all location related influences. However, the plots revealed: i) evaporation, vertical velocity, and precipitation are very robust and remarkably similar for each of the two simulations and even for the data from 1987-ENSO-year simulation; ii) while the evaporation increased monotonically with SST up to about 27 C, the precipitation did not; iii) precipitation correlated much better with the column vertical velocity as opposed to SST suggesting that the influence of dynamical circulation including non-local SSTs is stronger than local-SSTs. The precipitation fields were doubly binned with respect to SST and boundary-layer mass and/or moisture convergence. The analysis discerned the rate of change of precipitation with local SST as a sum of partial derivative of precipitation with local SST plus partial derivative of precipitation with boundary layer moisture convergence multiplied by the rate of change of boundary-layer moisture convergence with SST (see Eqn. 3 of Section 4.5). This analysis is mathematically rigorous as well as provides a quantitative measure of the influence of local SST on the local precipitation. The results were recast to
Wang, Xiujuan; Lee, Myung W.; Collett, Timothy S.; Yang, Shengxiong; Guo, Yiqun; Wu, Shiguo
Downhole wireline log (DWL) data was acquired from eight drill sites during China's first gas hydrate drilling expedition (GMGS-1) in 2007. Initial analyses of the acquired well log data suggested that there were no significant gas hydrate occurrences at Site SH4. However, the re-examination of the DWL data from Site SH4 indicated that there are two intervals of high resistivity, which could be indicative of gas hydrate. One interval of high resistivity at depth of 171–175 m below seafloor (mbsf) is associated with a high compressional- wave (P-wave) velocities and low gamma ray log values, which suggests the presence of gas hydrate in a potentially sand-rich (low clay content) sedimentary section. The second high resistivity interval at depth of 175–180 mbsf is associated with low P-wave velocities and low gamma values, which suggests the presence of free gas in a potentially sand-rich (low clay content) sedimentary section. Because the occurrence of free gas is much shallower than the expected from the regional depth of the bottom simulating reflector (BSR), the free gas could be from the dissociation of gas hydrate during drilling or there may be a local anomaly in the depth to the base of the gas hydrate stability zone. In order to determine whether the low P-wave velocity with high resistivity is caused by in-situ free gas or dissociated free gas from the gas hydrate, the surface seismic data were also used in this analysis. The log analysis incorporating the surface seismic data through the construction of synthetic seismograms using various models indicated the presence of free gas directly in contact with an overlying gas hydrate-bearing section. The occurrence of the anomalous base of gas hydrate stability at Site SH4 could be caused by a local heat flow conditions. This paper documents the first observation of gas hydrate in what is believed to be a sand-rich sediment in Shenhu area of the South China Sea.
Shibata, T.; Yoshikawa, M.; Itoh, J.; Ujike, O.; Miyoshi, M.; Takemura, K.
geochemical data, including Sr, Nd, and Pb isotope ratios, were restricted to Kuju and Yufu-Tsurumi volcanoes (Kita et al., 2001; Sugimoto et al., 2007), and hence we present new geochemical and Sr-Nd-Pb isotope ratios of lavas from Himeshima and Futagoyama volcanoes and Nd-Pb isotope ratios of Aso volcano. The Sr/Y ratios of the arc lavas decrease from north to south along the volcanic front. Mixing relations in Sr-Nd-Pb isotope space suggest recycling of the subducted slab materials from the Philippine Sea Plate to the arc. The 87Sr/86Sr ratios decrease with increasing Sr/Y and SiO2, which argues against a genetic link of fractional crystallization between adakites and basaltic magmas. The observations further suggest that partial melting of the hot and young Shikoku Basin slab produces the high Sr/Y component visible in the arc magmas in the north, whereas dehydration of the older West Philippine Basin slab produces the low Sr/Y arc magmas in the south. References Hunter, 1998, Chemical Geology, 201: 19-36. Kita et al., 2001, Journal of Volcanology and Geothermal Research, 111, 99-109. Mahony et al., 2011, Geological Society of America Bulletin, 123, 2201-2223. Sugimoto et al., 2007, Journal of Mineralogical and Petrological Sciences, 101: 270-275. Zellmer et al., 2012, Geology, 40: 487-490.
Herrero, Andre; Spagnuolo, Elena; Akinci, Aybige; Pucci, Stefano
In the present study we attempted to improve the seismic hazard assessment taking into account possible sources of epistemic uncertainty and the azimuthal variability of the ground motions which, at a particular site, is significantly influenced by the rupture mechanism and the rupture direction relative to the site. As a study area we selected Marmara Region (Turkey), especially the city of Istanbul which is characterized by one of the highest levels of seismic risk in Europe and the Mediterranean region. The seismic hazard in the city is mainly associated with two active fault segments which are located at about 20-30 km south of Istanbul. In this perspective first we proposed a methodology to incorporate this new information such as nucleation point in a probabilistic seismic hazard analysis (PSHA) framework. Secondly we introduced information about those fault segments by focusing on the fault rupture characteristics which affect the azimuthal variations of the ground motion spatial distribution i.e. source directivity effect and its influence on the probabilistic seismic hazard analyses (PSHA). An analytical model developed by Spudich and Chiou (2008) is used as a corrective factor that modifies the Next Generation Attenuation (NGA, Power et al. 2008) ground motion predictive equations (GMPEs) introducing rupture related parameters that generally lump together into the term directivity effect. We used the GMPEs as derived by the Abrahamson and Silva (2008) and the Boore and Atkinson (2008); our results are given in terms of 10% probability of exceedance of PSHA (at several periods from 0.5 s to 10 s) in 50 years on rock site condition; the correction for directivity introduces a significant contribution to the percentage ratio between the seismic hazards computed using the directivity model respect to the seismic hazard standard practice. In particular, we benefited the dynamic simulation from a previous study (Aochi & Utrich, 2015) aimed at evaluating the
Bayrakci, G.; Laigle, M.; Bécel, A.; Hirn, A.; Taymaz, T.; Yolsal-Çevikbilen, S.; Seismarmara Team
A 3-D tomographic inversion of first arrival times of shot profiles recorded by a dense 2-D OBS network provides an unprecedented constraint on the P-wave velocities heterogeneity of the upper-crustal part of the North Marmara Trough (NMT), over a region of 180 km long by 50 km wide. One of the specific aims of this controlled source tomography is to provide a 3-D initial model for the local earthquake tomography (LET). Hence, in an original way, the controlled source inversion has been performed by using a code dedicated to LET. After several tests to check the results trade-off with the inversion parameters, we build up a 3-D a priori velocity model, in which the sea-bottom topography, the acoustic and the crystalline basements and the Moho interfaces have been considered. The reliability of the obtained features has been checked by checkerboard tests and also by their comparison with the deep-penetration multichannel seismic profiles, and with the wide-angle reflection and refraction modelled profiles. This study provides the first 3-D view of the basement topography along the active North Anatolian fault beneath the Marmara Sea, even beneath the deepest part of three sedimentary basins of NMT. Clear basement depressions reaching down 6 km depth below the sea level (bsl) have been found beneath these basins. The North Imrali Basin located on the southern continental shelf is observed with a similar sedimentary thickness as its northern neighbours. Between Central and Çinarcik basins, the Central High rises up to 3 km depth below (bsl). Its crest position is offset by 10 km northwestward relatively to the bathymetric crest. On the contrary, Tekirdağ and Central basins appear linked, forming a 60-km-long basement depression. Beneath the bathymetric relief of Western High low velocities are observed down to 6 km depth (bsl) and no basement high have been found. The obtained 3-D Vp heterogeneity model allows the consideration of the 3-D supracrustal heterogeneity
The Marmara region (Turkey) along the North Anatolian fault is known as a high potential of large earthquakes in the next decades. For the purpose of seismic hazard/risk evaluation, kinematic and dynamic source models have been proposed (e.g. Oglesby and Mai, GJI, 2012). In general, the simulated earthquake scenarios depend on the hypothesis and cannot be verified before the expected earthquake. We then introduce a probabilistic insight to give the initial/boundary conditions to statistically analyze the simulated scenarios. We prepare different fault geometry models, tectonic loading and hypocenter locations. We keep the same framework of the simulation procedure as the dynamic rupture process of the adjacent 1999 Izmit earthquake (Aochi and Madariaga, BSSA, 2003), as the previous models were able to reproduce the seismological/geodetic aspects of the event. Irregularities in fault geometry play a significant role to control the rupture progress, and a relatively large change in geometry may work as barriers. The variety of the simulate earthquake scenarios should be useful for estimating the variety of the expected ground motion.
Turhal, Nazim S; Efe, Basak; Gumus, Mahmut; Aliustaoglu, Mehmet; Karamanoglu, Ayla; Sengoz, Meric
Background We conducted a survey to find out how patients feel about the care they receive in the outpatient chemotherapy unit of Marmara University Hospital. Methods The American College of Physicians Patient Satisfaction survey translated into Turkish was used. A meeting was held with all involved staff, before conducting the survey, to review the purpose and determine the process. The study was conducted with 100 random patients. Results Consistent with cancer frequency, most patients had either lung, colorectal or breast cancer. Their insurance was government sponsored in close to 90%. The educational levels were above Turkish median but consistent with the area the hospital is serving. They were coming to the unit on average 8.5 months. The responses were not influenced by the surveyed diagnosis, age, sex or educational status (p > 0,05). Particularly health care team's attention, trust and courtesy came forward as strong points. The weaknesses noted as difficulties in booking an outpatient doctor visit appointment because the phone line was busy or the secretary was not courteous, the excessive amount of time and effort it required to get laboratory and radiology results. Conclusion The health care system is basically a service based industry and customer satisfaction is at utmost importance just as in other service-oriented sectors. We hope this study will shed light in that area and Turkish health care providers will pay closer attention to how their patients feel about the services that they are getting. PMID:12443536
Finson, Kevin D.
Learning about what inferences are, and what a good inference is, will help students become more scientifically literate and better understand the nature of science in inquiry. Students in K-4 should be able to give explanations about what they investigate (NSTA 1997) and that includes doing so through inferring. This article provides some tips…
Coccia, Stella; Bigarré, Pascal; Ergintav, Semih; Ozel, Oguz; Yalcinkaya, Esref; Ozalabey, Serdar; Bourdeau, Céline; Martino, Salvatore; Lenti, Luca; Zucca, Francesco; Moro, Marco
The MARsite project (Nov 2012-Avril 2016), one of the three SUPERSITE concept FP7 projects, deals with the definition of new directions in seismic hazard assessment through focused earth observation in the Marmara Supersite. This project gathers different research groups in a comprehensive monitoring activity developed in the Sea of Marmara Region. This region is one of the most densely populated parts of Europe and rated at high seismic risk level since the 1999 Izmit and Duzce devastating earthquakes. The 6th Work Package of MARsite project offered a very valuable frame to undertake simultaneous and complementary scientific investigations and studies to get deeper insight in the seismic and rainfall landslide topic, ranging from methodology to hazard assessment tool. This package focused on two sub-regional areas of high interest. First, the Avcilar-Beylikdüzü peninsula, located westwards of Istanbul, is a highly urbanized concentrated landslide prone area, showing high susceptibility to both rainfalls while affected by very significant seismic site effects. Second, the off-shore entrance of the Izmit Gulf, close to the termination of the surface rupture of the 1999 earthquake, that shows an important slump mass facing the Istanbul coastline. For the on-shore area, after refining the landslide inventory of the peninsula, one of the nine inventoried rototranslational landslides was chosen as pilot site, the Büyükçekmece landslide. This landslide has a continuous activity and a composite mechanism (including several secondary sliding surfaces); it moves at low velocity and involves sandy and clayey deposits of a local Cenozoic Succession damaging several infrastructures, such as buildings and roads. Various geophysical campaigns were carried out and then a field temporary multi-parameter monitoring was set up, composed of GPS-RTK, two seismic probes, thermometer, rain-gauge, moisture, etc.. Hyperspectral and Dinsar imagery technologies were also deployed to
Ozener, H.; Aktug, B.; Karabulut, H.; Ergintav, S.; Dogru, A.; Yilmaz, O.; Turgut, B.; Ahiska, B.; Mencin, D.; Mattioli, G. S.
Dense continuous GPS networks quantify the time-dependent deformation field of the earthquake cycle. However the strainmeters can capture signals with superior precision at local spatial scales, in particular in the short-period, from minutes to a month. Many relatively small-scale events (e.i. SSEs, creeps) have been successfully determined on the subduction zones. Istanbul located near the most active parts of the North Anatolian Fault (NAF) has been monitored by different observing techniques such as seismic networks and continuous/survey-mode GPS networks for decades. However, it is still essential to observe deformation in a broad range of temporal and spatial scales (from seismology to geodesy and to geology). Borehole strainmeters are very sensitive to deformation in the range of less than a month. In this study, we present a new project, financially and technically supported by Istanbul Development Agency (ISTKA) and UNAVCO, respectively, which includes the installation of two borehole strainmeters are being deployed in European side of Istanbul in Marmara Region. Since these instruments can also respond to non-tectonic processes, it is necessary to have more instruments to increase spatial coherence and to have additional sensors to detect and model noise (such as barometric pressure, tides, or precipitation). The introduced monitoring system will provide significant insight about the creeping phenomenon and the possible SSE to our understanding of seismic hazards in active zones and possible precursors. Our long term objective is to build a borehole monitoring system in the region. By integrating various data obtained from borehole observations, we expect to get a better understanding of dynamics in the western NAF. In this presentation, we introduce data and ongoing analysis obtained with strainmeters.
Lüleci, Nimet Emel; Kaya, Eda; Aslan, Ece; Şenkal, Ece Söylem; Çiçek, Zehra Nadide
Background: Historically, sexual assault is a common issue in Turkey. As doctors are one of the steps to help sexually assaulted women, medical students should have basic knowledge of and sensitivity regarding this subject. Another common women’s public health issue is induced abortion. In countries where access to abortion is restricted, there is a tendency towards unhealthy abortion. Aims: The aims of this study are: (1) to determine the attitudes and opinions of Marmara University Medical Faculty students about sexual assault against women and induced abortion and (2) to propose an educational program for medical students about sexual assault and abortion. Study Design: Cross-sectional study. Methods: The questionnaires were self-administered and the data were analyzed using SPSS v.15.0. First, the descriptive statistics were analyzed, followed by Chi-square for contingency tests assessing differences in attitudes toward sexual assault and induced abortion by factors such as gender and educational term. Differences were considered statistically significant at p<0.05. Results: About 89.6% of the participants (n=266) reported that they had never been sexually assaulted and about 11.5% of the women (n=19) had been sexually assaulted. There was no significant relationship between previous sexual assault and gender (p>0.05). Although there was no significant difference regarding the extent of punishment by victim’s status as a virgin, 21.3% (n=63) agreed that punishment should be more severe when the victim was a virgin. About 40.7% (n=120) agreed that the legal period of abortion in Turkey (10 weeks) should be longer. The majority (86.1%, n=255) agreed that legally prohibiting abortions causes an increase in unhealthy abortions. Conclusion: An educational program on these issues should be developed for medical students. PMID:27403386
Ryan, William B. F.
Decades of seabed mapping, reflection profiling, and seabed sampling reveal that throughout the past two million years the Black Sea was predominantly a freshwater lake interrupted only briefly by saltwater invasions coincident with global sea level highstand. When the exterior ocean lay below the relatively shallow sill of the Bosporus outlet, the Black Sea operated in two modes. As in the neighboring Caspian Sea, a cold climate mode corresponded with an expanded lake and a warm climate mode with a shrunken lake. Thus, during much of the cold glacial Quaternary, the expanded Black Sea's lake spilled into to the Marmara Sea and from there to the Mediterranean. However, in the warm climate mode, after receiving a vast volume of ice sheet meltwater, the shoreline of the shrinking lake contracted to the outer shelf and on a few occasions even beyond the shelf edge. If the confluence of a falling interior lake and a rising global ocean persisted to the moment when the rising ocean penetrated across the dividing sill, it would set the stage for catastrophic flooding. Although recently challenged, the flood hypothesis for the connecting event best fits the full set of observations.
Wolpert, David H.
We show that physical devices that perform observation, prediction, or recollection share an underlying mathematical structure. We call devices with that structure “inference devices”. We present a set of existence and impossibility results concerning inference devices. These results hold independent of the precise physical laws governing our universe. In a limited sense, the impossibility results establish that Laplace was wrong to claim that even in a classical, non-chaotic universe the future can be unerringly predicted, given sufficient knowledge of the present. Alternatively, these impossibility results can be viewed as a non-quantum-mechanical “uncertainty principle”. The mathematics of inference devices has close connections to the mathematics of Turing Machines (TMs). In particular, the impossibility results for inference devices are similar to the Halting theorem for TMs. Furthermore, one can define an analog of Universal TMs (UTMs) for inference devices. We call those analogs “strong inference devices”. We use strong inference devices to define the “inference complexity” of an inference task, which is the analog of the Kolmogorov complexity of computing a string. A task-independent bound is derived on how much the inference complexity of an inference task can differ for two different inference devices. This is analogous to the “encoding” bound governing how much the Kolmogorov complexity of a string can differ between two UTMs used to compute that string. However no universe can contain more than one strong inference device. So whereas the Kolmogorov complexity of a string is arbitrary up to specification of the UTM, there is no such arbitrariness in the inference complexity of an inference task. We informally discuss the philosophical implications of these results, e.g., for whether the universe “is” a computer. We also derive some graph-theoretic properties governing any set of multiple inference devices. We also present an
Triantaphyllou, Maria V.; Gogou, Alexandra; Dimiza, Margarita D.; Kostopoulou, Sofia; Parinos, Constantine; Roussakis, Grigoris; Geraga, Maria; Bouloubassi, Ioanna; Fleitmann, Dominik; Zervakis, Vassilis; Velaoras, Dimitris; Diamantopoulou, Antonia; Sampatakaki, Angeliki; Lykousis, Vassilis
Combined micropaleontological and geochemical analyses of the high-sedimentation gravity core M-4G provided new centennial-scale paleoceanographic data for sapropel S1 deposition in the NE Aegean Sea during the Holocene Climatic Optimum. Sapropel layer S1a (10.2-8.0 ka) was deposited in dysoxic to oxic bottom waters characterized by a high abundance of benthic foraminiferal species tolerating surface sediment and/or pore water oxygen depletion (e.g., Chilostomella mediterranensis, Globobulimina affinis), and the presence of Uvigerina mediterranea, which thrives in oxic mesotrophic-eutrophic environments. Preservation of organic matter (OM) is inferred based on high organic carbon as well as loliolide and isololiolide contents, while the biomarker record and the abundances of eutrophic planktonic foraminifera document enhanced productivity. High inputs of terrigenous OM are attributed to north Aegean borderland riverine inputs. Both alkenone-based sea surface temperatures (SSTs) and δO18 G. bulloides records indicate cooling at 8.2 ka (S1a) and ~7.8 ka (S1 interruption). Sapropelic layer S1b (7.7-6.4 ka) is characterized by rather oxic conditions; abundances of foraminiferal species tolerant to oxygen depletion are very low compared with the U. mediterranea rise. Strongly fluctuating SSTs demonstrate repeated cooling and associated dense water formation, with a major event at 7.4 ka followed by cold spells at 7.0, 6.8, and 6.5 ka. The prominent rise of the carbon preference index within the S1b layer indicates the delivery of less degraded terrestrial OM. The increase of algal biomarkers, labile OM-feeding foraminifera and eutrophic planktonic species pinpoints an enhanced in situ marine productivity, promoted by more efficient vertical convection due to repeated cold events. The associated contributions of labile marine OM along with fresher terrestrial OM inputs after ~7.7 ka imply sources alternative/additional to the north Aegean riverine borderland sources for
Languages with a solvable implication problem but without complete and consistent systems of inference rules (`poor` languages) are considered. The problem of existence of finite complete and consistent inference rule system for a ``poor`` language is stated independently of the language or rules syntax. Several properties of the problem arc proved. An application of results to the language of join dependencies is given.