Ergin Ulutaş - Academia.edu (original) (raw)

Papers by Ergin Ulutaş

4th Congress of the Balkan Geophysical Society, 2005

O19 - 01 SEISMOLOGY & EARTHQUAKES EMPIRICAL ATTENUATION RELATIONSHIP OF PGA BASED ON 17 AUGUS... more O19 - 01 SEISMOLOGY & EARTHQUAKES EMPIRICAL ATTENUATION RELATIONSHIP OF PGA BASED ON 17 AUGUST 1999 KOCAELI AND 12 NOVEMBER 1999 DUZCE EARTHQUAKES DATA Ergin Ulutas T. Serkan Irmak I.Talih Guven Berna Tunc Taciser Cetinol Deniz Caka Nuray Alpaslan Suleyman Tunc Metin Asci Şerif Baris M. Firat Ozer Kocaeli University Earth and Space Sciences Research Center Turkey Summary Using a database of 390 strong ground motion recordings from 29 earthquakes (Mw>4.5) empirical PGA (peak ground acceleration) attenuation relations have been derived for the peak horizontal components of records. The records are of the main and aftershocks of 17 August 1999

Proceedings, Nov 5, 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.

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.

An attenuation relation for peak ground acceleration (PGA) in Eastern Marmara region (39.50-42.00... more An attenuation relation for peak ground acceleration (PGA) in Eastern Marmara region (39.50-42.00N, 28.00-31.50E) which is the Northern part of Turkey has been developed. The data base consist of 221 horizontal components of peak ground acceleration from 22 earthquakes (M >= 4.0), including the 17 Agust 1999 Kocaeli earthquake (M_w = 7.4)and 12 Novamber 1999 Duzce earthquake (M_w = 7.2). These data were found to be adequately represented by the functional relationship Log A=0.505171+(0.537579*M)-log(R+0.008347*100.5* M)-(0.00242*R) where A represents the peak values scaled from the two horizontal components of each recording., M is the moment magnitude and R is the epicentral distance. This functional relationship has been found by using multiple regression analyses. The peak ground horizontal acceleration attenuation relationship for region has been deduced with data from Kandilli Observatory Earthquake Research Institute of Bogaziçi University and Earthquake Research Department...

Samoa tsunami provided an unexpected exercise for the NOAA's tsunami forecast system, undergoing ... more Samoa tsunami provided an unexpected exercise for the NOAA's tsunami forecast system, undergoing operational testing at U.S. Tsunami Warning Centers (TWCs). Both TWCs and staff of the Pacific Marine Environmental Laboratory exercised the forecast system to provide tsunami prediction for the Pacific U.S. coastal communities where forecast models have already been developed. The forecast model from a tsunameterconstrained tsunami source, giving the U.S. coastlines more than three and half hours of lead time to respond to the approaching tsunami waves. Even with this unusual and complex earthquake source, the forecast provided required accuracy for important emergency management decisions. During the event, a high-resolution inundation model was quickly developed to compute the tsunami inundation in Samoa Islands-particularly in Tutuila Island. This allowed for the first test of the real-time inundation forecast capability of the system. In addition, the model inundation estimates provided valuable guidance for disaster recovery activities and for the post-tsunami survey guidance. The results illustrate recent improvements and new capabilities of the tsunami forecast system. The problems and lessons learned for both far-field and local tsunami forecast will be discussed.

This study determined soil amplification and predominant period along with the effect of local ge... more This study determined soil amplification and predominant period along with the effect of local geology in Düzce Basin. The data sets provided by different seismic networks recorded the main occurrences and aftershocks of the 12 November 1999 Düzce and 17 August 1999 Kocaeli earthquakes were used. Site amplifications at different periods were determined for 31 strong ground motion records of five stations located in the Düzce Basin. The previous ground motion prediction equations (GMPEs), H/V (Horizontal/Vertical) spectral acceleration ratio (HVSAR) and soil-to-rock Response Spectral Acceleration Ratio (RSAR) methods were used to determine soil amplification and predominant period. It was determined that the local geological conditions affect site amplifications at stations. The site amplification values ranged from 1.33 to 2.23 for the soil medium by averaging the residuals between the observed and predicted peak ground accelerations (PGAs). The HVSAR method resulted in amplification and predominant period values of the stations from 2.7 to 10 and from 0.4 to 0.7 s respectively. The RSAR method yielded amplification values from 1.5 to 14 s and predominant period values from 0.5 to 0.8 s for the stations. The thickness, lithological variations and low physical geotechnical properties of alluvial deposits were responsible for the site amplifications and predominant periods.

The finite-fault slip models of the 2012 Queen Charlotte and 2015 Chile earthquakes are estimated... more The finite-fault slip models of the 2012 Queen Charlotte and 2015 Chile earthquakes are estimated from a back-projection method that uses teleseismic Pwaveforms to integrate the direct P-phase with reflected phases from structural discontinuities near the source. Non-uniform rupture models of the fault plane, which are obtained from the finite fault modeling, are used in order to describe the vertical displacement on seabed. In general, the vertical displacement of water surface was considered to be the same as ocean bottom displacement, and it is assumed to be responsible for the initial water surface deformation gives rise to occurrence of tsunami waves. In this study, it was calculated by using the elastic dislocation algorithm. The results of numerical tsunami simulations are compared with tide gauges and Deep-ocean Assessment and Reporting of Tsunami (DART) buoy records. De-tiding, de-trending, low-pass and high-pass filters were applied to detect tsunami waves in deep ocean se...

This study was undertaken with reference to the J apan earthquake of 11 March 2011. The aim of th... more This study was undertaken with reference to the J apan earthquake of 11 March 2011. The aim of the study is to simulate the wave propagation of the tsunami of this earthquake, by comparing with the available deep ocean pressure se nsors (DART) and tide gauge records. Nonlinear shallow water equations are solved with a finite di fference scheme, using a computational grid with different cell sizes over GEBCO30 bathymetry data. Co-seismic source models proposed by different organizations and researchers were carried out to e xplain the tsunami propagation. The source models were used to model the deformation on sea bottom which is translated directly to the water surface. The approach is based on the dislocation algorithm for a finite rectangular fault and empirical scalin g laws for earthquake sources. Based on the various s ource models, arrival times and maximum wave heights are presented here followed by the analysis of the results. The assumption of the average uniform slip model...

Pure and Applied Geophysics, 2019

The July 20, 2017 Bodrum-Kos Earthquake caused tsunami wave motions and damage in the south of Bo... more The July 20, 2017 Bodrum-Kos Earthquake caused tsunami wave motions and damage in the south of Bodrum Peninsula, Turkey, and on Kos Island, Greece. Immediately after the earthquake, we conducted several post-tsunami field surveys including interviews in coastal zones impacted by the tsunami, i.e., the coastlines of Bodrum Peninsula, Karaada Islet and Akyaka Town in Gökova Bay, Turkey, and eastern Kos Island, Greece. We present observations and measurements to document the variation of the tsunami effects along the coast. The largest tsunami runup was about 1.9 m and observed at the mouth of a small dry streambed at Gumbet Bay, Bodrum. No significant water motions were reported at the northern and western coasts of Bodrum Peninsula. The tsunami runup distribution along the coast of eastern Kos was overall regular, with runup not exceeding 1 m except in the Port of Kos where a 1.5 m tsunami runup was measured.

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

Coastal Engineering Proceedings, 2018

A magnitude (Mw) 6.6 earthquake occurred on July 20, 2017 (22:31 UTC) in between Bodrum, Turkey a... more A magnitude (Mw) 6.6 earthquake occurred on July 20, 2017 (22:31 UTC) in between Bodrum, Turkey and Kos Island, Greece. Field surveys are conducted in the region (Yalciner et al., 2017) including southern and northern coastlines of Bodrum peninsula, Karaada, Akyaka town and Kos Island. A tide gauge located in Bodrum main port recorded the tsunami. The main objectives of these field surveys are to document tsunami effects along the coast, to obtain the available data on the wave height and inundation extent, and to understand and explain the tsunami source in details. In addition, questionnaires were conducted during the field survey in order to understand evacuation behavior and have clearly shown that the disaster education and public awareness are still low in the region. Numerical modeling studies are carried out in order to investigate the tsunami generation mechanism by comparing model and survey results. It is seen that the source of the earthquake is at the south of Karaada-B...

Natural Hazards and Earth System Science, 2012

This study analyzes the response of the Global Disasters Alerts and Coordination System (GDACS) i... more This study analyzes the response of the Global Disasters Alerts and Coordination System (GDACS) in relation to a case study: the Kepulaunan Mentawai earthquake and related tsunami, which occurred on 25 October 2010. The GDACS, developed by the European Commission Joint Research Center, combines existing web-based disaster information management systems with the aim to alert the international community in case of major disasters. The tsunami simulation system is an integral part of the GDACS. In more detail, the study aims to assess the tsunami hazard on the Mentawai and Sumatra coasts: the tsunami heights and arrival times have been estimated employing three propagation models based on the long wave theory. The analysis was performed in three stages: (1) pre-calculated simulations by using the tsunami scenario database for that region, used by the GDACS system to estimate the alert level; (2) near-realtime simulated tsunami forecasts, automatically performed by the GDACS system whenever a new earthquake is detected by the seismological data providers; and (3) post-event tsunami calculations using GCMT (Global Centroid Moment Tensor) fault mechanism solutions proposed by US Geological Survey (USGS) for this event. The GDACS system estimates the alert level based on the first type of calculations and on that basis sends alert messages to its users; the second type of calculations is available within 30-40 min after the notification of the event but does not change the estimated alert level. The third type of calculations is performed to improve the initial estimations and to have a better understanding of the extent of the possible damage. The automatic alert level for the earthquake was given between Green and Orange Alert, which, in the logic of GDACS, means no need or moderate need of international humanitarian assistance; however, the earthquake generated 3 to 9 m tsunami run-up along southwestern coasts of the Pagai Islands where 431 people died. The post-event calculations indicated medium-high humanitarian impacts.

akademikpersonel.kocaeli.edu.tr

... For the rapid TEW and web applications, the sinusoidal shape is normally assumed for automati... more ... For the rapid TEW and web applications, the sinusoidal shape is normally assumed for automatic calculations in absence of information on the ... be modeled when the earthquake parameters (Strike, dip, rake) available right after an earthquake by using the JRC-SWAN manually. ...

Arabian Journal of Geosciences, 2020

The paper deals with the analysis of the propagation, heights, and arrival times of a tsunami tha... more The paper deals with the analysis of the propagation, heights, and arrival times of a tsunami that may occur on the coastal areas of Cyprus and Eastern Mediterranean in the case of an earthquake in southern Cyprus. Following a review of the seismic risk and historical earthquakes which occurred in southern Cyprus, it was concluded that this region may be subject to high vulnerability if a tsunami occurs. A study was conducted on the numerical modelling of a possible tsunami generated by movement along the fault of the 1222 Paphos earthquake. The region where the earthquake occurred can be attributed to the Cyprian Arc in the southwest of Cyprus. This arc is one of the most active seismic zones in the Mediterranean, which has led to the occurrence of earthquakes from submerged seismogenic sources. A methodology is used to simulate tsunami wave propagation for the Eastern Mediterranean coastal areas which requires the initial wave due to fault parameters as well as the bathymetry data. The GEBCO30 bathymetry data are used which have a grid spacing of 0.30 arc min. The fault parameters are deduced from the maximum stress directions and source geometry of the region from the moment tensor solutions derived from analyzing of earthquake waveforms. The numerical tsunami propagation model was performed by using SWAN code. The simulated highest tsunami heights were 4.02 m in Kouklia (Cyprus); 2.85 m in Paphos Ktima (Cyprus); 2.58 in Episkopi (Cyprus); 2.06 in Peyia (Cyprus); 1.76 in Yennadhi, Rhodes (Greece); 1.53 in Burg Migheizil (Egypt); 1.46 m in Tarabulus (Lebanon); 1.39 m in Bur Said (Egypt); 1.28 in Al-Burj (Egypt); and 0.60 in Muğla-Aksaz (Turkey). The results of the model outline the extent of the tsunami waves of damaging size, but destructive event in the region.

Journal of Asian Earth Sciences, 2019

Abstract In this study, the regional components of global model EGM08 Bouguer anomalies obtained ... more Abstract 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.

Istanbul 2012 - International Geophysical Conference and Oil & Gas Exhibition, 2012