Geophysical Engineering

Researches aimed at enriching the number of available documentary sources on earthquakes have an important role in seismology. To this end, this paper documents the history of prominent earthquakes associated with the NW-SE trending Sultandag-Aksehir Fault and Aksehir-

Some earthquakes in the Eastern Mediterranean are tsunamigenic, and some of their tsunamis affected the coastal area of the Gulf of Fethiye, SW Turkey. Recent trenching surveys on the low-lying coastal areas of Dalaman delta beach across the Rhodes Pass revealed three probable tsunami impacts as a result of the historical earthquakes of 1303, 1481, and 1741. Yet there have been relatively few studies of the processes associated with tsunami sediment transport, their deposition, and nature in geological record. In addition to the interpretation of sedimentary features, accurate palaeo-environmental assessments might be possible by distinctive biogeochemical researches on marine-sourced organic matters, geochemical properties, quantitative amounts of marine biomarkers, and deterministic ratios. The identification of major lipid biomarkers (fatty acids and sterols) in the samples recovered from the sidewalls of the studied trench, for example, indicated biogenic contributions due to th...

The most earthquake-prone areas in the eastern central Aegean Sea are the Izmir Bay, the Karaburun peninsula and the island of Chios. The level of seismic activity and tsunami potential are influenced by the presence of normal faults around the region. There have been about 20 moderate-size earthquakes from 496 BC to 1949 AD. Among these earthquakes, the ones on the dates

During two distinct earthquakes occurred on March 7, 1867 and October 6, 1944, tsunami waves were also observed at some localities around the Gulf of Edremit, NE Aegean Sea. The first event (M w = 6.8) mostly affected the city of Mitilini of Lesvos Island while the Gulf of Edremit-Ayvacık earthquake (M S = 6.8) largely affected the northern and eastern coastal areas of the Gulf of Edremit. In 1944 earthquake, numerous surface cracks and water gushes were reported. The coastal neighborhoods of the town of Ayvalık in the east were flooded by tsunami waves. At the WSW extend of the main fault observed on land, which is parallel to the present-day slip vectors, some normal-oblique faults were observed close and subparallel to the northern coast. On the basis of historical documents, reports, interviews, geological setting, field observations and marine seismic reflection data, the 1944 earthquake was not triggered by one of the main fault segments but by a secondary fault or fault group which was described in this study. Depending on the distribution of tensional and compressional forces in the region, which rotates clockwise under the control of the middle strand of the North Anatolian fault, secondary fault groups become important. The moment tensor parameters of such small-size events have been determined and have obtained consistent results with the faults proposed in this study.

Published in Special Volume: "The 1999 Izmit and Duzce Earthquakes: Preliminary Results" Eds. A.Barka, O.Kozaci, S.Akyuz, and E.Altunel), ITU, Istanbul, 2000. ... THE 1999 EARTHQUAKE SEQUENCE ALONG THE NORTH ANATOLIAN TRANSFORM AT THE JUNCTURE ...

hendislig i Bö lü mü , Ç anakkale, Turkey 2 I _ stanbul Ü niversitesi, Jeoloji Mü hendislig i Bö lü mü , I _ stanbul, Turkey 3 Tü rkiye Petrolleri Anonim Ortaklıg ı, Ankara, Turkey 4 I _ stanbul Ü niversitesi, Jeofizik Mü hendislig i Bö lü mü , I _ stanbul, Turkey Eastern Marmara region consists of three different morphotectonic units: Thrace-Kocaeli Peneplain (TKP) and Ç amdag-Akçakoca Highland (Ç AH) in the north, and Armutlu-Almack Highland in the south of the North Anatolian Fault Zone (NAFZ). The geologic-morphologic data and seismic profiles from the Sakarya River offshore indicate that the boundary between the TKP in the west and Ç AH in the east is a previously unrecognized major NNE-SSW-trending strike-slip fault zone with reverse component. The fault zone is a distinct morphotectonic corridor herein named the Adapazar-Karasu corridor (AKC) that runs along the Sakarya River Valley and extends to its submarine canyon along the southern margin of the Black Sea in the north. It formed as a transfer fault zone between the TKP and Ç AH during the Late Miocene; the former has been experiencing extensional forces and the latter compressional forces since then. East-West-trending segments of the NAFZ cuts the NE-SW-trending AKC and their activity has resulted in the formation of a distinct fault-bounded morphology, which is characterized by alternating E-W highlands and lowlands in the AKC. Furthermore, this activity has resulted in the downward motion of an ancient delta and submarine canyon of the Sakarya River in the northern block of the NAFZ below sea level so that the waters of the Black Sea invaded them. The NE-SW-trending faults in the AKC were reactivated with the development of the NAFZ in the Late Pliocene, which then caused block motions and microseismic activities throughout the AKC.

We discuss the subsurface structure of the Karadere-Duzce branch of the North Anatolian Fault based on analysis of a large seismic data set recorded by a local PASSCAL network in the 6 months following the M w = 7.4 1999 Izmit earthquake. Seismograms observed at stations located in the immediate vicinity of the rupture zone show motion amplification and long-period oscillations in both P-and S-wave trains that do not exist in nearby off-fault stations. Examination of thousands of waveforms reveals that these characteristics are commonly generated by events that are well outside the fault zone. The anomalous features in fault-zone seismograms produced by events not necessarily in the fault may be referred to generally as fault-zone-related site effects. The oscillatory shear wave trains after the direct S arrival in these seismograms are analysed as trapped waves propagating in a low-velocity fault-zone layer. The time difference between the S arrival and trapped waves group does not grow systematically with increasing source-receiver separation along the fault. These observations imply that the trapping of seismic energy in the Karadere-Duzce rupture zone is generated by a shallow fault-zone layer. Traveltime analysis and synthetic waveform modelling indicate that the depth of the trapping structure is approximately 3-4 km. The synthetic waveform modelling indicates further that the shallow trapping structure has effective waveguide properties consisting of thickness of the order of 100 m, a velocity decrease relative to the surrounding rock of approximately 50 per cent and an S-wave quality factor of 10-15. The results are supported by large 2-D and 3-D parameter space studies and are compatible with recent analyses of trapped waves in a number of other faults and rupture zones. The inferred shallow trapping structure is likely to be a common structural element of fault zones and may correspond to the top part of a flower-type structure. The motion amplification associated with fault-zone-related site effects increases the seismic shaking hazard near fault-zone structures. The effect may be significant since the volume of sources capable of generating motion amplification in shallow trapping structures is large.

The b-value of the Gutenberg-Richter's frequency-magnitude relation and the p-value of the modified Omori law, which describes the decay rate of aftershock activity, were investigated for more than 500 aftershocks in the Aksehir-Afyon graben (AAG) following the 15 December 2000 Sultandagi-Aksehir and the 3 February 2002 Ç ay-Eber and Ç obanlar earthquakes. We used the Kandilli Observatory's catalog, which contains records of aftershocks with magnitudes ‡2.5. For the Ç obanlar earthquake, the estimated b-values for three aftershock sequences are in the range 0.34 £ b £ 2.85, with the exception of the one that occurred during the first hour (4.77), while the obtained p-values are in the range 0.44 £ p £ 1.77. The aftershocks of the Sultandagi earthquake have a high p-value, indicating fast decay of the aftershock activity. A regular increase of b can be observed, with b < 1.0 after 0.208 days for the Ç ay-Eber earthquake. A systematic and similar increase and decrease pattern exists for the band p-values of the Ç obanlar earthquakes during the first 5 days.

We analyzed statistical properties of earthquakes in western Anatolia as well as the North Anatolian Fault Zone (NAFZ) in terms of spatio-temporal variations of fractal dimensions, p- and b-values. During statistically homogeneous periods characterized by closer fractal dimension values, we propose that occurrence of relatively larger shocks (M &gt;= 5.0) is unlikely. Decreases in seismic activity in such intervals result in spatial b-value distributions that are primarily stable. Fractal dimensions decrease with time in proportion to increasing seismicity. Conversely, no spatiotemporal patterns were observed for p-value changes. In order to evaluate failure probabilities and simulate earthquake occurrence in the western NAFZ, we applied a modified version of the renormalization group method. Assuming an increase in small earthquakes is indicative of larger shocks, we apply the mentioned model to micro-seismic (M&lt;= 3.0) activity, and test our results using San Andreas Fault Zone ...

The ancient city of Patara (Fethiye, Turkey) is one of the places which may possibly have been hit by historical tsunamis. The marsh-filled depositional sedimentary basins behind the sand dunes and low-lying coastal areas along the Patara beach may hide the fingerprints of historical tsunami impacts. An engine core was recovered from the marsh area in the margin of a lagoon to provide biogeochemical evidences for the possible paleotsunami deposits in the study area. The core has been described lithologically and then scanned by multi-sensor core logger. Fatty acid biomarkers can be used to assess the degree of marineterrestrial mixture and their distributions indicate if most of the organic matters in the samples are marinesourced. For discrimination of marine and freshwater sub-environments; we have determined mono-and polyunsaturated fatty acids and high-branched isoprenoids using standard chromatographic techniques (GC/MS-SIM). On the basis of knowledge on sedimentary and paleo-environment conditions, and on the micropaleontological and biochemical data obtained from our analyses, the results indicate some influxes of marine water in a freshwater environment. Whether they can represent possible tsunami deposits or not, however, is not easy to answer.

From a global perspective, the universality of gender-related societal issues is particularly significant. Although gender inequality is considered a sociological problem, the large number of female victims in disasters warrants an assessment of disaster management sciences. In this article, related concepts are discussed based on their relevance sociologically and in disaster management to develop a common terminology and examine this complex topic, which is rooted in different social profiles and anthropological heterogeneity throughout the world. A brief history is discussed, and significant examples are provided from different disasters in Turkey to illustrate why a woman-oriented approach should be adopted when evaluating concepts of gender inequality. Observations of disasters have shown that it is important to apply international standards (humanitarian charter and minimum disaster response standards), especially

The most earthquake-prone areas in the eastern central Aegean Sea are the Izmir Bay, the Karaburun peninsula and the island of Chios. The level of seismic activity and tsunami potential are influenced by the presence of normal faults around the region. There have been about 20 moderate-size earthquakes from 496 BC to 1949 AD. Among these earthquakes, the ones on the dates