Ergin Ulutas | Kocaeli University (original) (raw)

Papers by Ergin Ulutas

EGU General Assembly Conference Abstracts, Apr 1, 2016

The aim of this study is the simulation and visualization of the initial and maximum tsunami wave... more The aim of this study is the simulation and visualization of the initial and maximum tsunami wave heights in 2D and 3D along the Mediterranean coasts inferred from the five largest earthquakes in history in this region. The earthquakes considered in the study are 21 July 365 Crete, 8 August 1303 Crete, 3 May 1481 Rhodes, 28 December Messina and 21 May 2003 Algeria. All these earthquakes spawned tsunamis and inflicted damage in coastal regions. The study was conducted to explain which could be the potential Tsunami consequences caused by similar earthquakes occurring in the region in the future. The methodology used for the calculation of tsunami wave heights from the earthquakes includes the determination of earthquake parameters, modeling of the initial wave height, simulation of the wave propagation and calculation of the maximum wave heights near coastal areas. The parameters of the earthquakes are based on previously published fault mechanism solutions and known tectonic features of the regions. Static dislocation algorithm for the initial wave height is used from the parameters of focal mechanism solutions. The study was conducted also to understand the reliability of the previously published focal mechanism solutions for the earthquakes by using the principal stress axis in the regions. The 2D and 3D visualized models of tsunamis from the earthquakes include isometric grid representing the sea surface for the purpose of a better understanding of the initial tsunami mechanism compared to 1D visualizations. In many studies, the earthquake locations, tectonic features of the regions, initial heights and tsunami simulations are shown on maps as bird’s eye in 1D visualization. However these kinds of features are related in depths and bathymetric features. For that reason, our approaches will contribute to have better understanding where the uplift- subsidence of initial heights and crests-troughs of simulated wave heights and thus provide a better insight of the tsunami features. The results of the simulations show the endangered coastal areas from the historically largest earthquakes in Mediterranean Region. Furthermore, these results may enable to construct early warning systems and may help to reduce the tsunami risk along the Mediterranean coasts.

9th Congress of the Balkan Geophysical Society, 2017

Summary The crustal compensation rate can be estimated from the differences gravimetric Moho and ... more Summary The crustal compensation rate can be estimated from the differences gravimetric Moho and isostatic Moho with respect to gravimetric Moho, and allow the establishment of the relationship between isostatic compensation and seismicity in the central Anatolian region. The compensation rates range between 92% and 108%. What is surprising about the most of events are aligned in the zones that encompass seismic activity with the rates between 99% and 101% that are almost fully compensated. It is understood that the pattern of seismicity is also dependence of rheological structure of crustal blocks. The areas where compansation rate less than 100% and greater than 100% correspond to undercompensation and overcompensation, respectively. The results in undercompensation provide aseismic zones where preseismic locking is high and a major role for accommodating the stress evaluation of crustal blocks, and may then be related to preseismic activity. The crustal thickening obtained from gravity inversion in the eastern part of the central Anatolian region suggests overcompensated crust and the buoyant forces that result from subsidence, controlled by the density contrast between crust and lithospheric mantle. The overcompensation areas are almost aseismic, and indicates isostatic readjustment.

In this study, The numerical simulations of November 13, 2016 Kaikoura, New Zealand eaerthquake (... more In this study, The numerical simulations of November 13, 2016 Kaikoura, New Zealand eaerthquake (M w : 7.8) have been performed. The earthquake occurred at a depth of 15 km at the transition between the Alpine fault in the South Island and the Kermadec-Tonga subduction zone. The approximation of non-linear long wave equations is performed and adopted to simulate tsunami propagations with an initial displacement of the ocean bottom deformation due to faulting. Co-seismic source models proposed by United States Geological Survey (USGS) are further used to represent the effects of various slip models on tsunami prediction along the coastal regions of New Zealand. The maximum value of the initial heights are calculated as 1.18 and -0.2 meters for uplift and subsidence areas from uni-form point source models. However, these maximum values are 1.01 and -0.1 meters from finite-fault source models. We have also compared our simulated tsunami waveforms with the observed tide gauge records. T...

Journal of Asian Earth Sciences, 2019

In this study, the regional components of global model EGM08 Bouguer anomalies obtained by low pa... more In this study, the regional components of global model EGM08 Bouguer anomalies obtained by low pass filtering were inverted to map the geometries of Moho and Lithosphere-Asthenosphere Boundary (LAB) of the central Anatolian region. It was determined the Moho and LAB depths in the region to be 35.8-41.2 km and 67-91 km, respectively. The results from rheological modeling indicate mechanical decoupling of the crust and uppermost lithospheric mantle in eastern part and coupling in the western part of the study area. We also compare the rheological stratification with the focal depth distribution of earthquakes to examine the possible discrepancies between the brittle-ductile transition zone and the maximum depths of earthquakes along the selected profiles. The spatial variations of effective elastic thicknesses (EET) of the lithosphere have been estimated from the strength of the crust and lithospheric mantle by implying deformation gradient at Moho and LAB. The EET values vary in the range of 19-24.3 km. Although the EET values are relatively high in the eastern part of the region, lower EET values are directly underlain by thinned lithosphere of northwestern and southwestern part of central Anatolian region. We also analyze the crustal rheologies obtained from the lithospheric strength by delineating the pattern of crustal seismic activities.

2273-2285The 27 February 2010 Maule (Chile) tsunami was numerically modeled using the SWAN (Simul... more 2273-2285The 27 February 2010 Maule (Chile) tsunami was numerically modeled using the SWAN (Simulating WAves Near-Shore) code which solves the non-linear long wave equations of fluid flow by a finite difference algorithm. The computational area is divided into two computational domains with a grid of 2 arc min and 0.5 arc min. Bathymetry data for the domains are interpolated from the General Bathymetry Chart of the Ocean (GEBCO) 30 arc-seconds grid data. Results from uniform and non-uniform slip models are compared with available tide gauges and Deep-ocean Assessment and Reporting of Tsunami (DART) buoy records

A new attenuation relation for peak ground acceleration (PGA) in the Marmara region of northweste... more A new attenuation relation for peak ground acceleration (PGA) in the Marmara region of northwestern Turkey has been developed. The data base consists of 751 horizontal components of peak ground acceleration recorded from 78 earthquakes, including the 1999 Izmit (M w = 7.4) and the 1999 Duzce (M w = 7.2) earthquakes. All the raw records are of the main earthquakes and their aftershocks.

Studia Geophysica et Geodaetica, 2011

The city of Adapazarı -located in the Marmara Region of northwest Turkey -is situated on a deep s... more The city of Adapazarı -located in the Marmara Region of northwest Turkey -is situated on a deep sedimentary basin and was the city most heavily damaged by the strong ground motion of the 17 August 1999 Kocaeli earthquake (moment magnitude M w = 7.4). This study determines site amplifications of the attenuation relationships for shallow earthquakes in the Adapazarı basin by using the previous ground motion prediction equations (GMPEs) and the traditional spectral ratio method. The site amplifications are determined empirically by averaging the residuals between the observed and predicted peak ground acceleration (PGA) and spectral acceleration (SA) values for various periods. Residuals are significantly correlated with the known characteristics of geological units. A new attenuation model has also been developed for 5% damped spectral acceleration to determine the dependence of strong ground motions on frequency.

Journal of Asian Earth Sciences, 2013

The numerical simulations of recent tsunami caused by 11 March 2011 off-shore Pacific coast of To... more The numerical simulations of recent tsunami caused by 11 March 2011 off-shore Pacific coast of Tohoku-Oki earthquake (M w 9.0) using diverse co-seismic source models have been performed. Co-seismic source models proposed by various observational agencies and scholars are further used to elucidate the effects of uniform and non-uniform slip models on tsunami generation and propagation stages. Non-linear shallow water equations are solved with a finite difference scheme, using a computational grid with different cell sizes over GEBCO30 bathymetry data. Overall results obtained and reported by various tsunami simulation models are compared together with the available real-time kinematic global positioning system (RTK-GPS) buoys, cabled deep ocean-bottom pressure gauges (OBPG), and Deep-ocean Assessment and Reporting of Tsunami (DART) buoys. The purpose of this study is to provide a brief overview of major differences between point-source and finite-fault methodologies on generation and simulation of tsunamis. Tests of the assumptions of uniform and non-uniform slip models designate that the average uniform slip models may be used for the tsunami simulations off-shore, and far from the source region. Nevertheless, the heterogeneities of the slip distribution within the fault plane are substantial for the wave amplitude in the near field which should be investigated further.

EGU General Assembly Conference Abstracts, Apr 1, 2016

The aim of this study is the simulation and visualization of the initial and maximum tsunami wave... more The aim of this study is the simulation and visualization of the initial and maximum tsunami wave heights in 2D and 3D along the Mediterranean coasts inferred from the five largest earthquakes in history in this region. The earthquakes considered in the study are 21 July 365 Crete, 8 August 1303 Crete, 3 May 1481 Rhodes, 28 December Messina and 21 May 2003 Algeria. All these earthquakes spawned tsunamis and inflicted damage in coastal regions. The study was conducted to explain which could be the potential Tsunami consequences caused by similar earthquakes occurring in the region in the future. The methodology used for the calculation of tsunami wave heights from the earthquakes includes the determination of earthquake parameters, modeling of the initial wave height, simulation of the wave propagation and calculation of the maximum wave heights near coastal areas. The parameters of the earthquakes are based on previously published fault mechanism solutions and known tectonic features of the regions. Static dislocation algorithm for the initial wave height is used from the parameters of focal mechanism solutions. The study was conducted also to understand the reliability of the previously published focal mechanism solutions for the earthquakes by using the principal stress axis in the regions. The 2D and 3D visualized models of tsunamis from the earthquakes include isometric grid representing the sea surface for the purpose of a better understanding of the initial tsunami mechanism compared to 1D visualizations. In many studies, the earthquake locations, tectonic features of the regions, initial heights and tsunami simulations are shown on maps as bird’s eye in 1D visualization. However these kinds of features are related in depths and bathymetric features. For that reason, our approaches will contribute to have better understanding where the uplift- subsidence of initial heights and crests-troughs of simulated wave heights and thus provide a better insight of the tsunami features. The results of the simulations show the endangered coastal areas from the historically largest earthquakes in Mediterranean Region. Furthermore, these results may enable to construct early warning systems and may help to reduce the tsunami risk along the Mediterranean coasts.

9th Congress of the Balkan Geophysical Society, 2017

Summary The crustal compensation rate can be estimated from the differences gravimetric Moho and ... more Summary The crustal compensation rate can be estimated from the differences gravimetric Moho and isostatic Moho with respect to gravimetric Moho, and allow the establishment of the relationship between isostatic compensation and seismicity in the central Anatolian region. The compensation rates range between 92% and 108%. What is surprising about the most of events are aligned in the zones that encompass seismic activity with the rates between 99% and 101% that are almost fully compensated. It is understood that the pattern of seismicity is also dependence of rheological structure of crustal blocks. The areas where compansation rate less than 100% and greater than 100% correspond to undercompensation and overcompensation, respectively. The results in undercompensation provide aseismic zones where preseismic locking is high and a major role for accommodating the stress evaluation of crustal blocks, and may then be related to preseismic activity. The crustal thickening obtained from gravity inversion in the eastern part of the central Anatolian region suggests overcompensated crust and the buoyant forces that result from subsidence, controlled by the density contrast between crust and lithospheric mantle. The overcompensation areas are almost aseismic, and indicates isostatic readjustment.

In this study, The numerical simulations of November 13, 2016 Kaikoura, New Zealand eaerthquake (... more In this study, The numerical simulations of November 13, 2016 Kaikoura, New Zealand eaerthquake (M w : 7.8) have been performed. The earthquake occurred at a depth of 15 km at the transition between the Alpine fault in the South Island and the Kermadec-Tonga subduction zone. The approximation of non-linear long wave equations is performed and adopted to simulate tsunami propagations with an initial displacement of the ocean bottom deformation due to faulting. Co-seismic source models proposed by United States Geological Survey (USGS) are further used to represent the effects of various slip models on tsunami prediction along the coastal regions of New Zealand. The maximum value of the initial heights are calculated as 1.18 and -0.2 meters for uplift and subsidence areas from uni-form point source models. However, these maximum values are 1.01 and -0.1 meters from finite-fault source models. We have also compared our simulated tsunami waveforms with the observed tide gauge records. T...

Journal of Asian Earth Sciences, 2019

In this study, the regional components of global model EGM08 Bouguer anomalies obtained by low pa... more In this study, the regional components of global model EGM08 Bouguer anomalies obtained by low pass filtering were inverted to map the geometries of Moho and Lithosphere-Asthenosphere Boundary (LAB) of the central Anatolian region. It was determined the Moho and LAB depths in the region to be 35.8-41.2 km and 67-91 km, respectively. The results from rheological modeling indicate mechanical decoupling of the crust and uppermost lithospheric mantle in eastern part and coupling in the western part of the study area. We also compare the rheological stratification with the focal depth distribution of earthquakes to examine the possible discrepancies between the brittle-ductile transition zone and the maximum depths of earthquakes along the selected profiles. The spatial variations of effective elastic thicknesses (EET) of the lithosphere have been estimated from the strength of the crust and lithospheric mantle by implying deformation gradient at Moho and LAB. The EET values vary in the range of 19-24.3 km. Although the EET values are relatively high in the eastern part of the region, lower EET values are directly underlain by thinned lithosphere of northwestern and southwestern part of central Anatolian region. We also analyze the crustal rheologies obtained from the lithospheric strength by delineating the pattern of crustal seismic activities.

2273-2285The 27 February 2010 Maule (Chile) tsunami was numerically modeled using the SWAN (Simul... more 2273-2285The 27 February 2010 Maule (Chile) tsunami was numerically modeled using the SWAN (Simulating WAves Near-Shore) code which solves the non-linear long wave equations of fluid flow by a finite difference algorithm. The computational area is divided into two computational domains with a grid of 2 arc min and 0.5 arc min. Bathymetry data for the domains are interpolated from the General Bathymetry Chart of the Ocean (GEBCO) 30 arc-seconds grid data. Results from uniform and non-uniform slip models are compared with available tide gauges and Deep-ocean Assessment and Reporting of Tsunami (DART) buoy records

A new attenuation relation for peak ground acceleration (PGA) in the Marmara region of northweste... more A new attenuation relation for peak ground acceleration (PGA) in the Marmara region of northwestern Turkey has been developed. The data base consists of 751 horizontal components of peak ground acceleration recorded from 78 earthquakes, including the 1999 Izmit (M w = 7.4) and the 1999 Duzce (M w = 7.2) earthquakes. All the raw records are of the main earthquakes and their aftershocks.

Studia Geophysica et Geodaetica, 2011

The city of Adapazarı -located in the Marmara Region of northwest Turkey -is situated on a deep s... more The city of Adapazarı -located in the Marmara Region of northwest Turkey -is situated on a deep sedimentary basin and was the city most heavily damaged by the strong ground motion of the 17 August 1999 Kocaeli earthquake (moment magnitude M w = 7.4). This study determines site amplifications of the attenuation relationships for shallow earthquakes in the Adapazarı basin by using the previous ground motion prediction equations (GMPEs) and the traditional spectral ratio method. The site amplifications are determined empirically by averaging the residuals between the observed and predicted peak ground acceleration (PGA) and spectral acceleration (SA) values for various periods. Residuals are significantly correlated with the known characteristics of geological units. A new attenuation model has also been developed for 5% damped spectral acceleration to determine the dependence of strong ground motions on frequency.

Journal of Asian Earth Sciences, 2013

The numerical simulations of recent tsunami caused by 11 March 2011 off-shore Pacific coast of To... more The numerical simulations of recent tsunami caused by 11 March 2011 off-shore Pacific coast of Tohoku-Oki earthquake (M w 9.0) using diverse co-seismic source models have been performed. Co-seismic source models proposed by various observational agencies and scholars are further used to elucidate the effects of uniform and non-uniform slip models on tsunami generation and propagation stages. Non-linear shallow water equations are solved with a finite difference scheme, using a computational grid with different cell sizes over GEBCO30 bathymetry data. Overall results obtained and reported by various tsunami simulation models are compared together with the available real-time kinematic global positioning system (RTK-GPS) buoys, cabled deep ocean-bottom pressure gauges (OBPG), and Deep-ocean Assessment and Reporting of Tsunami (DART) buoys. The purpose of this study is to provide a brief overview of major differences between point-source and finite-fault methodologies on generation and simulation of tsunamis. Tests of the assumptions of uniform and non-uniform slip models designate that the average uniform slip models may be used for the tsunami simulations off-shore, and far from the source region. Nevertheless, the heterogeneities of the slip distribution within the fault plane are substantial for the wave amplitude in the near field which should be investigated further.