Tamer Duman - Academia.edu (original) (raw)

Papers by Tamer Duman

Bulletin of Earthquake Engineering, Apr 9, 2017

Over the years, several local and regional seismic hazard studies have been conducted for the est... more Over the years, several local and regional seismic hazard studies have been conducted for the estimation of the seismic hazard in Turkey using different statistical processing tools for instrumental and historical earthquake data and modeling the geologic and tectonic characteristics of the region. Recently developed techniques, increased knowledge and improved databases brought the necessity to review the national active fault database and the compiled earthquake catalogue for the development of a national earthquake hazard map. A national earthquake strategy and action plan were conceived and accordingly with the collaboration of the several institutions and expert researchers, the Revision of Turkish Seismic Hazard Map Project (UDAP-Ç-13-06) was initiated, and finalized at the end of 2014. The scope of the project was confined to the revision of current national seismic hazard map, using the state of the art technologies and knowledge of the active fault, earthquake database, and ground motion prediction equations. The following two seismic source zonation models are developed for the probabilistic earthquake hazard analysis: (1) Area source model, (2) Fault and spatial smoothing seismic source model (FSBCK). In this study, we focus on the development and the characterization of the Fault Source model, the background spatially smoothed seismicity model and intrinsic uncertainty on the earthquake occurrence-rates-estimation. Finally, PSHA results obtained from the fault and spatial smoothed seismic source model are presented for 43, 72, 475 and 2475 years return periods (corresponding to 69, 50, 10, and 2% probability of exceedance in 50 years) for PGA and 5% damped spectral accelerations at 0.2 and 1.0 s.

Geomorphology, Dec 1, 2005

Sometimes regional meteorological anomalies trigger different types of mass movements. In May 199... more Sometimes regional meteorological anomalies trigger different types of mass movements. In May 1998, the western Black Sea region of Turkey experienced such a meteorological anomaly. Numerous residential and agricultural areas and engineering lifelines were buried under the flood waters. Besides the reactivation of many previously delineated landslides, thousands of small-scale landslides (mostly the earthflow type) occurred all over the region. The earthflows were mainly developed in flyschtype units, which have already presented high landslide concentrations. In this study, three different catchments-namely Agustu, Egerci, and Kelemen-were selected because they have the most landslide-prone geological units of the region. The purposes of the present study are to put forward the spatial distributions of the shallow earthflows triggered, to describe the possible factors conditioning the earthflows, and to produce the shallow earthflow susceptibility maps of the three catchments. The unique condition units (UCU) were employed during the production of susceptibility maps and during statistical analyses. The unique condition units numbered 4052 for the Agustu catchment, 13,241 for the Egerci catchment and 12,314 for the Kelemen catchment. The earthflow intensity is the highest in the Agustu catchment (0.038 flow/UCU) and lowest in the Egerci catchment (0.0035 flow/UCU). Logistic regression analyses were also employed. However, during the analyses, some difficulties were encountered. To overcome the difficulties, a series of sensitivity analyses were performed based on some decision rules introduced in the present study. Considering the decision rules, the proper ratios of UCU free from earthflow (0) / UCU including the earthflow (1) for the Agustu, Egerci and Kelemen catchments were obtained as 3, 6, and 5, respectively. Also, a chart for the proper ratio selection was developed. The regression equations from the selected ratios were then applied to the entire catchment and the earthflow susceptibility maps were produced. The landslide susceptibility maps revealed that 15% of the Agustu catchment, 8% of the Egerci catchment, and 7% of the Kelemen catchment have very high earthflow

Engineering Geology, Sep 1, 2005

Landslides are common natural hazards in the seismically active North Anatolian Fault Zone of Tur... more Landslides are common natural hazards in the seismically active North Anatolian Fault Zone of Turkey. Although seismic activity, heavy rainfall, channel incisions, and anthropogenic effects are commonly the main triggers of landslides, on March 17, 2005, a catastrophic large ...

Engineering Geology, Feb 1, 2009

ABSTRACT

Bulletin of the Geological Society of Greece, 2017

The Acıpayam Fault is an active fault segment which is located on the central part of Fethiye Bur... more The Acıpayam Fault is an active fault segment which is located on the central part of Fethiye Burdur Fault Zone in SW Turkey. According to the Active Fault Map of Turkey published by MTA (Turkey), it is described as a Quaternary fault. Acıpayam Fault extends from Acıpayam at northeast to Akköprü Dam at southwest. The general strike of fault is N 35°E, approximately 60 km long and it’s a normal fault with minor sinistral strike-slip component. The fault is composed of three fault section, which are named as Örenköy, Olukbaşı and Yolçatı, seperated from each other by step-over zones. In this study, active tectonic features of Acıpayam fault are investigated and paleoismological trench surveys are perfomed at the Örenköy fault section. Two cross trenches were excavated along the fault. The samples collected from the trenches were dated using the 14C dating method. Örenköy trenches were photographed using the Paleoseismological Three Dimensional Virtual Photography Method, which is a ne...

International Journal of Applied Earth Observation and Geoinformation, 2012

The main purpose of the present study is to evaluate the potential use of Terra ASTER data-the L3... more The main purpose of the present study is to evaluate the potential use of Terra ASTER data-the L3A DEM and its derivatives in landslide susceptibility mapping. For the purpose, an appropriate application site from the Western Black Sea region of Turkey-the Kelemen catchment area was selected. During the analyses, a two-stage comparative evaluation was carried out. In the first stage, the differences between the DEMs obtained from Terra ASTER L3A data and the conventional topographic data; and their first and second derivatives were investigated. Subsequently, different susceptibility maps were produced by using the DEMs and the topographic attributes obtained from both source of data in addition to the spectral information acquired from satellite sensor. According to the results of the comparative evaluations, a strong correlation between Terra ASTER L3A DEM and the conventional topographic data was obtained. However, depending on the increment of the degree of the derivative, an evident decrease in the spatial correlations was observed. On the contrary, the final model performance, prediction capacity, and the spatial performance statistics for the landslide susceptibility maps produced by using both source of data were found as very high and close to each other.

Geomorphology, Feb 1, 2008

Considering damage to man-made structures by natural hazards in Turkey, landslides are the second... more Considering damage to man-made structures by natural hazards in Turkey, landslides are the second most important hazard after earthquakes. For this reason, a large-scale study titled Turkish Landslide Inventory Project, has been carried out since 1998. During this project, some special, susceptibility, hazard and risk assessments have been performed. In this study, a landslide susceptibility map of a part of tectonic Kelkit Valley in the north of central Turkey was produced, employing binary logistic regression analyses. To achieve the most appropriate results some sensitivity analyses were also carried out. For this purpose, four different data sets were constructed considering conditioning factors used and sampling strategies applied for the training data sets in this study. As a consequence of the analyses, the most proper outcomes were obtained by using the data set in which continuous topographical parameters and lithological dummy variables were implemented together and 50% of training data set was taken from seed cells at random. Correct classification percentage and Root Mean Square Error (RMSE) values for the validation data for that case were estimated as 84.16% and 0.36, respectively. This prediction capability shows that the landslide susceptibility map produced in this research paper can be used for the planning of protective and mitigation measures in the region.

AGUFM, Dec 1, 2005

... System, TURKEY. Authors: Yildirim, C.; Dor, O.; Rockwell, T.; Emre, O.; Ben-Zion, Y.; Sisk, M... more ... System, TURKEY. Authors: Yildirim, C.; Dor, O.; Rockwell, T.; Emre, O.; Ben-Zion, Y.; Sisk, M.; Duman, T. Affiliation ... Trousdale Ave. 90089, Los Angeles, CA 90089 United States ; ), AC(San Diego State University, Dept. Geological ...

AGUFM, Dec 1, 2001

Prior to the August 17 1999 Mw 7.4 Izmit earthquake, nobody had reported a convincing recurrence ... more Prior to the August 17 1999 Mw 7.4 Izmit earthquake, nobody had reported a convincing recurrence interval of the North Anatolian fault (NAF). Because of sparse geological data and documentation available for the historical earthquakes, a recurrence interval of ~450 years was used for long-term earthquake probability forecasting (Stein et al., 1997). To reveal the average recurrence interval of the

EAEJA, Apr 1, 2003

Fault segmentation plays an important role to evaluate the magnitude and cascade of the future ea... more Fault segmentation plays an important role to evaluate the magnitude and cascade of the future earthquakes on a long active fault. Correlation between behavioral segments and rupture process of the 1999 Izmit and Duzce earthquakes provide the size and jog characteristics of the segments of the North Anatolian Fault. From this point of view, we have been carrying out very

AGU Fall Meeting Abstracts, Dec 1, 2001

The Duzce fault is located along the eastern end of the northern strand of the North Anatolian Fa... more The Duzce fault is located along the eastern end of the northern strand of the North Anatolian Fault zone in NW Anatolia. A 43-km-long surface rupture, reaching 5.4 m right lateral displacement, was formed during the November 12 1999 Mw 7.2 Duzce earthquake, which occurred three months after the Mw 7.4 Izmit earthquake. Despite of the clear geomorphic imprints of accumulated offsets, there are no historical documents available for the paleoseismicity of the Duzce fault. We thus performed trench surveys at two sites, Cakirhaciibrahim and Beykoy, along the fault. The Cakirhaciibrahim site is located on the center of the Duzce fault, and shows extentional en echelon ruptures associated with the 1999 earthquake. The maximum amount of right lateral slip, and northern-side-up vertical separation at the site are 3.60 m and 0.70m, respectively. One of the three trenches crosses the pure right lateral trace, whereas the others cuts traces that vertical component is dominant. The stratigraphy in the trenches mainly consists of floodplain fine sediments (intercalated by one paleosol) and underlying Holocene alluvial gravels. Two faulting events including the 1999 earthquake were identified in these trenches. At Beykoy site, a trench was excavated across the western end of the Dagdibi subsegments of the 1999 shock, and three trenches were excavated in the transpressional thrust zone between the Aydinpinar and Dagdibi subsegments. At the trench site on the main rupture zone, an oblique slip of 1.50 m right lateral and 0.90 m vertical displacements were measured after the main shock. In the trench, Holocene fluvial gravels in the upthrown northern block juxtapose thick floodplain fine sediments intercalating with a few paleosols in the downthrown southern block. Identifying the same fluvial gravels on the bottom of the trench in the downthrown block, we have measured at least 4.3 m of the accumulated vertical offset of the gravel unit. Based on the fault structures and abrupt downward increases in the displacements, we found the evidence for three faulting events including the 1999 shock. In the thrust zone, the trenches exposed that the gravel units thrusts over the floodplain sediments. Total vertical offset of the gravel units is more than 2 m. Because measured vertical separation at the Duzce shock is 0.4-0.5 m and we only found one paleofaulting event, we could mention that magnitude of the penultimate event was larger than the 1999 event. The dating results from Cakirhaciibrahim trench indicate that the penultimate event occurred sometime between about 200 yr B.P. and 300 yr B.P., possibly correlates with historical 1719 or 1754 earthquake. Together with the recent paleoseismological results on the 1999 Izmit rupture zone, we may argue that the 1719 earthquake had the similar triggering process that 1999 both Izmit and Duzce showed. >http://staff.aist.go.jp/s-toda/NAF2001/duzce.html

Maden tetkik ve arama dergisi, 2019

Geodinamica Acta, Jul 14, 2016

The Bekten Fault is 20-km long N55°E trending and oblique-slip fault in the dextral strike-slip f... more The Bekten Fault is 20-km long N55°E trending and oblique-slip fault in the dextral strike-slip fault zone. The fault is extending sub-parallel between Yenice-Gönen and Sarıköy faults, which forms the southern branch of North Anatolian Fault Zone in Southern Marmara Region. Tectonomorphological structures indicative of the recent fault displacements such as elongated ridges and offset creeks observed along the fault. In this study, we investigated palaeoseismic activities of the Bekten Fault by trenching surveys, which were carried out over a topographic saddle. The trench exposed the fault and the trench stratigraphy revealed repeated earthquake surface rupture events which resulted in displacements of late Pleistocene and Holocene deposits. According to radiocarbon ages obtained from samples taken from the event horizons in the stratigraphy, it was determined that at least three earthquakes resulting in surface rupture generated from the Bekten Fault within last~1300 years. Based on the palaeoseismological data, the Bekten Fault displays non-characteristic earthquake behaviour and has not produced any earthquake associated with surface rupture for about the last 400 years. Additionally, the data will provide information for the role of small fault segments play except for the major structures in strike-slip fault systems.

Geophysical Journal International, May 1, 2008

The east and west rupture directions of the 1943 and 1944 earthquakes on the North Anatolian Faul... more The east and west rupture directions of the 1943 and 1944 earthquakes on the North Anatolian Fault (NAF) are hypothesized to represent, respectively, long term preferred propagation directions on the corresponding sections of the NAF. Fault sections with preferred rupture direction are expected to have an asymmetric damage structure with respect to the slipping zone. To test the above hypothesis, we study geological and geomorphologic manifestations of structural asymmetry with respect to the active trace of the NAF along the 1943 and 1944 sections. The following fault zone elements are mapped: gouge fabric in the cm scale, fault core structure in a metre scale, and secondary faults and fault rocks in tens of metres scale. Mapping results at three sites on the 1943 rupture and one site on the 1944 rupture are consistent with accumulation of more rock damage on the south side of the 1943 section and on the north side of the 1944 section. Erosion patterns adjacent to the fault that are not correlated with the distribution of intrinsic and extrinsic erosion-controlling variables (e.g. rock type) are interpreted as morphologic responses to the damage content of rocks and its impact on rock erodibility. The valleys of 11 rivers are parallel to the studied fault sections. About 75 per cent of the total river valleys length along the 1943 rupture is on the south side of the fault, and about 89 per cent of the total river valleys length along the 1944 rupture is on the north side of the fault. Morphometric analysis of watersheds in two correlative terrains displaced along the 1944 rupture section shows that stream erosion is considerably more intense in the terrain north of the fault, with drainage density values almost double in the north compare to the south. Badland topography at two sites along the 1943 rupture section is substantially more developed at the ∼100 m scale on the south side of fault. Our observations along the 1943-1944 rupture sections, including various types of signals that span a large range of scales, are systematically compatible with an opposite sense of damage asymmetry between the two fault sections. These observations are consistent with opposite preferred direction of ruptures for the two sections, similar to the propagation directions of the two recent earthquakes. If those rupture directions are dictated by the velocity structure at depth, we infer that the south side of the 1943 rupture has faster seismic velocity at seismogenic depth than the north side, and that the sense of velocity contrast is reversed along the 1944 rupture zone.

Seismological Research Letters, Jul 1, 2003