Multi-disciplinary earthquake researches in Western Turkey: Hints to select sites to study geochemical transients associated to seismicity     

Sedat İnan  Kadriye Ertekin  Cemil Seyis  Şakir Şimşek  Furkan Kulak  Aynur Dikbaş  Onur Tan  Semih Ergintav  Rahşan Çakmak  Ahmet Yörük  Muhiddin Çergel  Hakan Yakan  Hüseyin Karakuş  Ruhi Saatçilar  Zafer Akçiğ  Yıldız İravul  Bekir Tüzel 《Acta Geophysica》2010,58(5):767-813

Warm and hot spring water as well as soil gas radon release patterns have been monitored in the Aegean Extensional Province of Western Turkey, alongside regional seismic events, providing a multi-disciplinary approach. In the study period of 20 months, seven moderate earthquakes with M _L between 4.0 and 4.7 occurred in this seismically very active region; two earthquakes with magnitude 5.0 also occurred near the study area. Seismic monitoring showed no foreshock activity. By contrast, hydro-geochemical anomalies were found prior to these seismic events, each lasting for weeks. The anomalies occurred foremost in conjunction with dip-slip events and seem to support the dilatancy and water diffusion hypothesis. Increased soil gas radon release was recorded before earthquakes associated with strike-slip faults, but no soil radon anomalies were seen before earthquakes associated with dip-slip faults. Geochemical anomalies were also noticeably absent at some springs throughout the postulated deformation zones of impending earthquakes. The reason for this discrepancy might be due to stress/strain anisotropies.  相似文献   

Robust representation of dry cells in single-layer MODFLOW models   总被引：1，自引：0，他引：1  

Painter S  Başağaoğlu H  Liu A 《Ground water》2008,46(6):873-881

Dewatered or "dry" grid cells in the USGS ground water modeling software MODFLOW may cause nonphysical artifacts, trigger convergence failures, or interfere with parameter estimation. These difficulties can be avoided in two dimensions by modifying the spatial differencing scheme and the iterative procedure used to resolve nonlinearities. Specifically, the spatial differencing scheme is modified to use the water level on the upstream side of a pair of adjacent cells to calculate the saturated thickness and hence intercell conductance for the pair. This makes it possible to explicitly constrain the water level in a cell to be at or above the cell bottom elevation without introducing nonphysical artifacts. Thus constrained, all initially active cells will remain active throughout the simulation. It was necessary to replace MODFLOW's Picard iteration method with the Newton-Raphson method to achieve convergence in demanding applications involving many dry cells. Tests using a MODFLOW variant based on the new method produced results nearly identical to conventional MODFLOW in situations where conventional MODFLOW converges. The new method is extremely robust and converged in scenarios where conventional MODFLOW failed to converge, such as when almost all cells dewatered. An example application to the Edwards Aquifer in south-central Texas further demonstrates the utility of the new method.  相似文献   

Optimum parameter selection in offset-dependent predictive deconvolution: testing on multichannel marine seismic data     

Güney  Recep  Karslı  Hakan  Dondurur  Derman 《Marine Geophysical Researches》2019,40(4):601-617

Marine Geophysical Research - Predictive deconvolution is an effective way to suppress multiple reflections, especially short path multiples, in seismic data. However, the effectiveness of the...  相似文献   

Seasonal variations and distributions of dissolved free and total carbohydrates at the İzmir Bay, Aegean Sea     

ALYURUK Hakan  KONTAS Aynur 《海洋学报(英文版)》2018,37(8):6-14

Seasonal variations and distributions of dissolved carbohydrate concentrations at the İzmir Bay were investigated with salinity, chlorophyll a (Chl a), and dissolved organic carbon (DOC) levels to understand their relationships. Samples were collected from surface, subsurface and bottom depths at seven stations. DOC concentrations ranged from 32.2 to 244.2 μmol/L, and in general, DOC levels increased from winter to summer, then slightly decreased in autumn. Monosaccharide (MCHO), polysaccharide (PCHO) and total dissolved carbohydrate (TDCHO) levels were found between 0.7-8.3, 0.7-19.5, and 2.6-24.6 μmol/L. DOC, MCHO, PCHO and TDCHO levels were found higher in middle-inner bays, under the influence of anthropogenic inputs, compared to outer bay. Seasonal changes of MCHO/DOC, PCHO/DOC and TDCHO/DOC ratios were statistically significant (p<0.05) and the ratios showed decrease trends from winter to summer-autumn seasons. Distributions of TDCHO/DOC ratios at wide ranges (2.5%-42.3%) indicated the presence of newly forming and degrading fractions of DOM. According to results of factor analysis, Chl a, MCHO and TDCHO were explained in the same factor groups. In conclusion, the results showed that dissolved carbohydrate levels in the İzmir Bay might be influenced by biological processes and terrestrial/anthropogenic inputs.  相似文献   

Determination of optimum kernel bandwidth for northern Marmara region,Turkey     

Hakan Karaca 《Acta Geophysica》2018,66(4):633-642

As a relatively recent development, spatial smoothing methods have been introduced to identify seismic patterns. Among the methods developed to model the spatial variation, methods based on utilization of 3-D Gaussian isotropic kernels have a wide reception. The most important question remaining to be answered in the application of these methods is the determination of the optimum kernel bandwidth. At the present, researchers’ efforts to clarify the subject have still not yet finalized, this study aims to provide insightful knowledge for future efforts. In this study, for the region bounded by 27°–33° longitudes and 39°–41° latitudes, where the western section of the famous Northern Anatolian fault lies, smoothing techniques are implemented to determine the optimum smoothing kernel bandwidth for point sources. The influence of the modeling of seismicity through the computation of the optimum smoothing kernel bandwidth is examined. In addition, the sensitivity of each smoothing technique to the seismic patterns, whether densely clustered or scarcely populated, is investigated. In the end, the smoothing method based on optimum neighbor number is identified as highly sensitive to the density of seismicity and seismic clusters, and better in modeling high seismicity compared to the model based on single optimum smoothing distance used for the entire region of interest.  相似文献   

Correction to: Observational Investigation of the Statistical Properties of Surface-Layer Turbulence in a Suburban Area of São Paulo,Brazil: Objective Analysis of Scaling-Parameter Accuracy and Uncertainties     

da Silveira  Lucas Cardoso  de Oliveira  Amauri Pereira  Sánchez  Maciel Piñero  Codato  Georgia  Ferreira  Maurício Jonas  Filho  Edson Pereira Marques  Božnar  Marija Zlata  Mlakar  Primož 《Boundary-Layer Meteorology》2022,185(2):197-197

Boundary-Layer Meteorology -  相似文献   

Reply to the comment on “Prediction of ground vibrations resulting from the blasting operations in an open pit mine by adaptive neuro-fuzzy inference system” by Tarkan Erdik     

Iphar  Melih  Yavuz  Mahmut  Ak  Hakan 《Environmental Earth Sciences》2009,59(2):473-476

Environmental Earth Sciences -  相似文献   

The distribution and sources of heavy metals in Izmit Bay surface sediments affected by a polluted stream   总被引：20，自引：0，他引：20  

Pekey H 《Marine pollution bulletin》2006,52(10):1197-1208

Dil Deresi stream is a highly contaminated stream passing through the most heavily industrialized area of Izmit Bay. In this research, surface sediments in the <63-microm fraction collected from 34 sites at western part of Izmit Bay, Northeastern Marmara Sea, Turkey were analyzed by ICP-AES for Al, As, Cd, Co, Cr, Cu, Fe, Mg, Mn, Ni, Pb, Sn and Zn. Metal concentrations were compared with the marine sediment quality standards (SQS) and literature data to assess the pollution status of the sediments. Enrichment factors (EFs) were calculated to assess whether the concentrations observed represent background or contaminated levels. The analysis revealed three groups of elements: (1) Sn is the most enriched element; (2) As, Cd, Pb and Zn are minor enriched elements; and (3) Co, Cr, Cu, Fe, Mg, Mn and Ni are at background concentrations. The distribution maps of the concentrations and enrichment factors for all heavy metals were also produced as a contour plot based on Geographic Information System (GIS) technology.  相似文献   

Determining and modeling tectonic movements along the central part of the North Anatolian Fault (Turkey) using geodetic measurements     

Hakan Yavaolu  Ergin Tar&#x;  Okan Tüysüz  Ziyadin ak&#x;r  Semih Ergintav 《Journal of Geodynamics》2011,51(5):339-343

The North Anatolian Fault (NAF), which extends from Karl?ova in Eastern Turkey to the Gulf of Saros in the Northern Aegean Sea, is one of the longest active strike-slip faults in the world with a length of about 1500 km. Within the North Anatolian Shear Zone (NASZ) there are long splays off the main trunk of the NAF veering towards the interior parts of Anatolia. Although the whole shear zone is still seismically active, the major seismicity is concentrated along the main branch of the NAF. Splays of the NAF dissect the shear zone into different continental blocks. The largest splay of the NAF was selected to analyze the distribution of movements between the faults delimiting these blocks. Four years of GPS measurements and modeling results indicate that the differential motion between the Anatolian collage and the Eurasian plate along the central part of the NAF is partitioned between fault splays and varies between 18.7 ± 1.6 and 21.5 ± 2.1 mm/yr with the main branch taking ∼90% of the motion.  相似文献   

Sensitivity of the strong ground motion time histories to a finite source model: A case study for the January 12, 2010 Haiti earthquake (M_w=7.0)     

Nurcan Meral Özel  Ebru Harmandar  Ali Pınar 《Soil Dynamics and Earthquake Engineering》2011

We analyze the waveforms generated by the January 12, 2010 Haiti earthquake (M_w=7.0) for its source characteristics. A 60 to 25 km source model is retrieved by the Kikuchi and Kanamori finite source inversion technique that uses broadband teleseismic body wave records. The derived rupture model points out unilateral rupture propagation commenced at the eastern side of the fault plane where the major seismic moment release occurred. The rupture front propagated westward and terminated at a site where the largest aftershocks occurred. Our estimates yield a seismic moment of M_o=8.17×10¹⁹ N m released on a 60 km-long fault plane. A patch at the eastern side of the ruptured fault plane inferred as a region of maximum moment release.  相似文献