Applications of cumulative absolute velocity to urban earthquake early warning systems     

Yasin M. Fahjan  Hakan Alcik  Ali Sari 《Journal of Seismology》2011,15(2):355-373

An early warning system forewarns an urban area of the forthcoming strong shaking, normally with a few seconds to a few tens of seconds of early warning time before the arrival of the destructive S-wave part of the strong ground motion. For urban and industrial areas susceptible to earthquake damage, where the fault rupture system is complex and the fault-site distances are short, there is usually insufficient time to compute the hypocenter, focal parameters and the magnitude of an earthquake. Therefore, simpler and robust early warning algorithm is needed. The direct (engineering) early warning systems are based on algorithms of the exceedance of specified threshold time domain amplitude levels. The continuous stations’ data are processed to compute specific engineering parameters robustly and compared with specified threshold levels. The parameters can be chosen as band-pass filtered peak ground accelerations and/or the bracketed cumulative absolute velocity (BCAV). In this paper, an enhancement to bracket cumulative absolute velocity for the application of online urban early warning systems results in a new parameter called window based bracketed cumulative absolute velocity (BCAV-W). The BCAV-W allows computation of cumulative absolute velocity in a specified window size and to include the vertical component of the motion. The importance of choosing optimum window size for the cumulative absolute velocity BCAV-W is discussed and the correlations between BCAV-W and the macro-seismic intensity are studied for three combinations of horizontal and vertical components of the motion. Empirical relationship is developed to estimate BCAV-W as a function of magnitude, distance, fault mechanism, and site category based on 1,208 recorded ground motion data from 75 earthquakes in active plate-margins.  相似文献   

Landform effect on rockfall and hazard mapping in Cappadocia (Turkey)   总被引：2，自引：0，他引：2  

Kivanc Zorlu  M. Celal Tunusluoglu  Tolga Gorum  Hakan A. Nefeslioglu  Ali Yalcin  Dilek Turer  Candan Gokceoglu 《Environmental Earth Sciences》2011,62(8):1685-1693

The Cappadocia region has unique geomorphological features resulting from differential erosional processes which make it very attractive to tourists. Besides the fairy chimneys for which the area is best known, there are also impressive buttes and mesas. Buttes and mesas are formed in regions having flat-lying strata in which the uppermost levels are composed of well-cemented limestones and granular ignimbrites, whereas the lower parts and slopes consist of low-durability tuff and ignimbrites. This durability difference results in serious rockfall events. This study involves two-dimensional rockfall analyses in and near the Avanos, Zelve, and Çavusini areas, where volcano-sedimentary units of Neogene age outcrop, to provide a rockfall hazard map in which areas of tourism activity are also considered.  相似文献   

Seismological and engineering characteristics of strong motion data from 24 and 26 September 2019 Marmara Sea earthquakes     

Malcioglu  Fatma Sevil  S&#;leyman  Hakan  &#;akt&#;  Eser 《Bulletin of Earthquake Engineering》2022,20(11):5567-5599

Bulletin of Earthquake Engineering - An MW 4.5 earthquake took place on September 24, 2019 in the Marmara Sea. Two days after, on September 26, 2019, Marmara region was rattled by an MW5.7...  相似文献   

Incorporation of silica into the goethite structure: a microscopic and spectroscopic study     

Abdullah Musa Ali  Eswaran Padmanabhan  Hassan Baioumy 《中国地球化学学报》2018,37(6):911-921

Quartz and iron (hydr)oxide are reactive surface phases that are often associated with one another in soils and sediments. Despite the several studies on the coating of quartz with iron oxides, the reactivity of dissolved species (Si) leached from quartz with iron (hydr)oxides has received limited attention. In this study, goethite synthesized on quartz substrates were characterized using field emission scanning electron microscopy, X-ray diffraction (XRD), transmission electron microscopy, and Fourier-transform infrared (FT-IR) spectroscopy. The SEM characterization revealed that bundles of thin parallel aligned goethite rods were formed at pH?>?10, while large pseudohexagonal crystals of twinned goethite needles were synthesized at pH?≤?10 after dehydration and hydration in the alkaline media. TEM analysis showed expanded and distorted lattice spacing of the crystal structure of iron (hydr)oxide due to silica incorporation. The characterization showed that silica increased the crystallite size of the goethite and transformed its acicular texture to a larger, twinned needle structure. FT-IR and XRD analyses revealed band shifts in crystal bonds as well as new bond formations, which indicate the presence of changes in the chemical environment of Fe–O and Si–O bonds. Thus, the presence of sorbed silicates modifies the crystal and lattice structure of goethite.  相似文献   

Estimation of the soil strength parameters in Tertiary volcanic regolith (NE Turkey) using analytical hierarchy process     

Hakan Ersoy  Melek Betül Karsli  Seda Çellek  Bilgehan Kul  İdris Baykan  Robert L Parsons 《Journal of Earth System Science》2013,122(6):1545-1555

  相似文献   

Magnetic gradient techniques on digitized aeromagnetic data of Ibadan area, south-western Nigeria     

Biodun Suraj Badmus  Musa Olufemi Awoyemi  Olukayode Dewunmi Akinyemi  Ganiyu Adekunle Saheed  Oluwaseun Tolutope Olurin 《Central European Journal of Geosciences》2013,5(3):387-393

Locations and depths to magnetic contacts were estimated from the total intensity magnetic field using the Horizontal Gradient Magnitude (HGM), Analytic Signal Amplitude (ASA) and Local Wavenumber (LWN) methods. Aeromagnetic data from the Ibadan area, in south-western Nigeria, were analyzed to estimate depths to magnetic sources as well as source locations. The minimum/maximum depth limits of the HGM and LWN are relatively close and comparable, while shallow source depths limits are greater than expected in the ASA method when compared with the HGM and LWN functions.  相似文献   

Post-stack high-resolution deconvolution using Cauchy norm regularization with FX filter weighting     

Hakan Karslı  Recep Güney  Mustafa Senkaya 《Arabian Journal of Geosciences》2017,10(24):551

High-resolution deconvolution can mathematically be viewed as a regularized inverse problem. Besides, the result of the high-resolution deconvolution is generally accepted as reflectivity series of the layered media. On the other hand, lateral continuity is frequently poorer than vertical resolution on post-stack seismic section after application of any high-resolution deconvolution. However, because of the ill-posed inherent of the deconvolution problem, the Cauchy norm regularization term, a non-quadratic prior-information is widely used to provide the stability and uniqueness of the problem. But, it does not provide adequate quality of deconvolution if the noise in the data is strong. In this study, a stable and high-resolution deconvolution of post-stack seismic data was accomplished by an iterative inversion algorithm incorporating the Cauchy norm regularization with FX filter weighting. Cauchy norm regularization was utilized to force the solution to a spikiness structure, while the effective random noise reduction was performed by using the FX filter. Applications to synthetic and real post-stack data showed that the resolution in the vertical direction and continuity in the lateral direction are better improved. Thus, we think that this process makes seismic sections obtained especially from thin layered sedimentary basins more interpretable.  相似文献   

Rapid assessment for seismic vulnerability of low and medium rise infilled RC frame buildings     

Hanan Al-Nimry  Musa Resheidat  Saddam Qeran 《地震工程与工程振动(英文版)》2015,14(2):275-293

An indexing method for rapid evaluation of the seismic vulnerability of infi lled RC frame buildings in Jordan is proposed. The method aims at identifying low and medium rise residential buildings as safe or in need of further detailed evaluation. Following a rapid visual screening, the building is assigned a Basic Capacity Index(BCI); fi ve performance modifi ers are identifi ed and multiplied by the BCI to arrive at the Capacity Index(CI) of the building. A Capacity Index lower than a limit CI value indicates that the screened building could experience moderate earthquake damage whereas a higher value implies that minor damage, if any, would take place. To establish the basic evaluation parameters; forty RC frame buildings were selected, designed and analyzed using static nonlinear analysis and incorporating the effect of infi ll walls. Effects of seismicity, local site conditions, horizontal irregularities(setbacks and re-entrant corners), vertical irregularities(soft story at ground fl oor level) and overhangs on the seismic performance of local buildings were examined. Assessment forms were designed and used to evaluate and rank 112 sample buildings. About 40% of the surveyed buildings were found to be in need of detailed evaluation to better defi ne their seismic vulnerabilities.  相似文献   

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