Intra-basinal water movements induced by faulting: the August 17, 1999, Gölcük (İzmit Bay) earthquake (Mw=7.4)

doi:10.1016/S0025-3227(00)00090-6

Marine Geology

Volume 170, Issues 3–4, 15 November 2000, Pages 263-270

https://doi.org/10.1016/S0025-3227(00)00090-6 Get rights and content

Abstract

A strong earthquake (M_w=7.4) occurred near the town of Gölcük, İzmit Bay, Western Turkey, at 00:01 GMT on August 17, 1999. İzmit Bay is a E–W trending pull-apart basin with a surface area of about 300 km² along the North Anatolian Fault Zone (NAF), in the eastern extension of the Sea of Marmara. The earthquake was caused by a westerly movement of the Anatolian plate along NAF and was accompanied by isolated, chaotic water movements along the northern and southern shores of the bay. At localities along the shoreline a sudden drop in sea level, and a subsequent rise was prominent. The mode of observed sea-level movements rules out the occurrence of a basin-wide tsunami, sensu stricto. Instead, the water movements are attributed to localized sudden dip–slip movements of fault blocks in this pull-apart basin.

Introduction

Large waves constitute the subject of many myths in open seas and oceans. Tsunami (harbor wave in Japanese) is a synonym for large waves accompanying major seismic events in oceans or seas. Tsunamis are frequently generated in the Pacific Ocean from large subduction zone earthquakes (Geist, 1998), but limited to neither the Pacific basin nor seismic events as demonstrated by the 1883 eruption of the Volcano Krakatoa in Indian Ocean, and the Storegga Slides in the northern Atlantic Ocean (Harbitz, 1992). Occurrence of large waves has also been reported in the history of semi-closed basins such as the Mediterranean, the Aegean Sea and the Sea of Marmara (Ambraseys, 1962); however, details are well established for only some of these events. For instance, while the July 9, 1956, Amorgos Basin (south Aegean Sea) tsunami is well understood (Perissoratis and Papadopoulos, 1999), details are sketchy about tsunami reported to have occurred during the 1509 earthquake in the Sea of Marmara, when the Sultan of the Ottoman Empire temporarily abandoned the capital city of Istanbul located on this sea. Waves were said to be higher than 6 m.

The town of Gölcük is located in the İzmit Bay region in northwestern Anatolia (Fig. 1, inset). It is known to have a long earthquake history extending through Ottaman, Seljuk and Byzantium times (Ambraseys and Finkel, 1991). It was recently struck by an earthquake with a magnitude of 7.4 (M_w) at 00:01 GMT on August 17, 1999. The earthquake had epicentral coordinates of 40°36′N and 29°48′E on the North Anatolian Fault and a strike–slip faulting mechanism is suggested (e.g. Kandilli Observatory and Earthquake Research Institute (KOERI); the National Earthquake Information Center (NEIC) and the Harvard (HRV) Seismological Station). It caused substantial loss of life and extensive property damage, killing more than 16,000 people and damaging about 50,000 buildings.

Chaotic water movements were reported to have occurred synchronous with the earthquake along the shoreline of the İzmit Bay, and a fault-related mechanism was indicated (Öztürk, 1999). Widespread water movements, on a large scale, have also been reported (Altınok et al., 1999), but have not been substantiated adequately. In this paper, observed water movements, vis-à-vis tsunamis, are described and a source mechanism is proposed in relationship to the seismo-tectonic events that occurred during the Gölcük earthquake of August 17, 1999.

Section snippets

Morphology and structure

İzmit Bay is a 49 km long east-westerly prolongation of the Sea of Marmara into the continental Anatolia and has an area of about 300 km² (Fig. 1a). It is narrowest between Gölcük and the east of Yarımca (Körfez), having a width of about 1800 m. The widest portion is between the towns of Hereke and Karamürsel, where it is almost 9800 m wide. It is deepest (204 m) west of Gölcük along the southern shore, which is characterized by sharply inclined bathymetry. The bathymetry gradually flattens towards

Water movements

Significant water movements were observed synchronous with the August 17, 1999, Gölcük earthquake. In Tütünçiflik, on the northern shore, boat owners preparing for a fishing trip felt a sudden withdrawal of water at the time of the earthquake, as though their boat hit the sea bed. Seamen described a sea-level drop of 3–5 m and a shoreline withdrawal of 10 m. Shortly after, they noted a steady sea-level rise of about 20 cm over the normal level that was likened to boiling milk in a heated pot.

Discussion and conclusions

During the earthquake, the sea-level movements and waves were not widespread, but localized and chaotic. Wave heights were variable, with the highest wave reported to be about 4 m. Sea-level movements were restricted to sections of the coastline affected by coseismic ground subsidence along the southern coast and sites along the northern coast opposite from the areas of subsidence. Sea-level movements had a different character on the northern shore than the southern. Sea-level movements were

Acknowledgements

Partial support by the Istanbul University and the Turkish Marine Foundation (TUDAV) to the senior author is gratefully acknowledged. Dr B. Öztürk is thanked for his assistance in the determination of phyto-zoobenthos species, and Dr J.R. Hein for his encouragement and organizational contribution, which made this work possible.

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Sedimentary earthquake records in the İzmit Gulf, Sea of Marmara, Turkey
2012, Sedimentary Geology
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The data further suggest that the 5–7 cm-thick sediment below the base of the THU-1 corresponding to 21 a. was eroded by the turbidity current. Onshore studies carried out after the earthquake indicate that the event was followed by a tsunami with 1 to 2.5-m high runup and coastal landslides (Öztürk et al., 2000; Altınok et al., 2001, 2011). Water column oscillations associated with the mass-flow could have caused first erosion at the seafloor, and then deposition of THU-1.
Sedimentary earthquake records of the last 2400 a, including that of the devastating 17 August 1999 İzmit earthquake (Mw = 7.4), were studied in cores from the 210 m-deep central Karamürsel Basin of the İzmit Gulf in the eastern Sea of Marmara, using laser grain-size, physical properties, stable O and C isotopes and XRF Core Scanner analyses, and dated by radionuclide and radiocarbon methods. The earthquake records are represented by turbidite–homogenite mass-flow units (THU) that commonly contain a basal coarse layer, a middle laminated silt layer and an overlying homogeneous mud layer. The coarse basal part has a sharp and sometimes scoured lower boundary, and includes multiple coarse (sand/silt) layers or laminae showing normal size grading. Multiple coarse layers and occasional bi-directional cross-bedding suggest deposition from a bed-load during water column oscillations, or seiche effect. The grain-size characteristics of the overlaying laminated silt and the homogeneous mud units indicate deposition from weak oscillating currents and homogeneous suspension, respectively. High Mn value just below the base of THUs suggests diagenetic enrichment at oxic/anoxic redox boundary before the mass-flow event. Sharp decrease in Mn with very low values within the THUs suggests transient redox conditions following the mass-flow. Variable geochemical compositions of the basal coarse layers indicate different sediment sources for different THUs. Eight sedimentary earthquake records observed in the last 2400 a in the İzmit Gulf can be confidently correlated with the historical earthquakes of 1999, 1509 AD (Ms = 7.2), 1296 AD (I = VII), 865 AD (I = VIII), 740 AD (I = VIII), 268 AD (I = VIII), 358 AD (I = IX), and 427 BC. This gives an earthquake recurrence time of ca. 300 a, with the interval between consecutive events ranging from 90 to 695 a.
Clay mineral distribution in last Glacial-Holocene sediment cores from the eastern Marmara Sea (çinarcik Basin-Izmit Gulf Transition), NW-Turkey: Multisources and transport paths in a two-way flow system
2012, Quaternary International
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Such seasonal changes are also known from the İzmit Gulf (Oğuz and Sur, 1986; Algan et al., 1999). There exist a large number of studies on the geological evolution and sedimentary history of the greater Çınarcık Basin and İzmit Gulf areas, suggesting a close relation to the tectonic activities along the North Anatolian Fault Zone and sea-level changes in the Marmara Sea and its neighbouring regions (Şengör et al., 1985; Smith et al., 1995; Wong et al., 1995; Görür et al., 1997; Parke et al., 1999; Okay et al., 2000; Öztürk et al., 2000; Gökaşan et al., 2001; Le Pichon et al., 2001; Aksu et al., 2002; İmren et al., 2001; Alpar and Yaltırak, 2002; Hiscott and Aksu, 2002; Yaltırak, 2002; Çağatay et al., 2003; Demirbağ et al., 2003; Gökaşan et al., 2003; Armijo et al., 2005; McHugh et al., 2006; Beck et al., 2007; Dolu et al., 2007; Kuşçu, 2009; Okyar et al., 2008; Dolu et al., 2007). The Çınarcık Basin started to develop in early Pliocene as result of a dextral strike-slip movement at a releasing fault junction of the westward-propagating North Anatolian Fault (Fig. 1).
The regional variations in grain size, XRD-bulk and clay mineral distribution in 97 sediment samples from 6 gravity cores obtained from 20 to 300 m water depths have been investigated to reveal source and transportation patterns as well as the effects of climatic and sea-level changes during the last 25,000 ¹⁴C BP in the eastern Marmara Sea (EMS), NW Turkey. The major proportions of sediments in the EMS consist of silt (20–83%) and clay (17–90%), whereas sand and gravel abundances rarely exceed 10%. Of the bulk minerals, 10-Å micas (23–55%) and feldspars (17–55%) dominate over quartz (10–21%) and calcite (10–26%). Smectites (23–62%), illite (18–36%), chlorites (6–21%), kaolinite (2–20%) and 14S–14C mixed layer minerals (0–27%) constitute the principal clay mineral assemblages. Both bulk and clay mineral assemblages in the EMS are similar to those found in the İzmit Gulf, on the southern Marmara shelf, at the Marmara–Aegean approaches and the southern Black Sea. This would suggest that there is no distinct source for mineral assemblages of the study area outside the Marmara Basin. The concentrations of clay fractions and clay mineral assemblages tend to increase or decrease with depth in the cores, but this is limited to some intervals and not to entire sections in the cores. This distribution pattern therefore represents rather local sources of provenance and surrounding fluvial drainage basins together with dilution and distribution effects by current transport processes, rather than the expected paleoclimatic features and sedimentary input by inflowing Black Sea and Aegean Sea water masses throughout the last Glacial to Holocene.
Controversy over the great flood hypotheses in the Black Sea in light of geological, paleontological, and archaeological evidence
2007, Quaternary International
Legends describing a Great Flood are found in the narratives of several world religions, and the biblical account of Noah's Flood is the surviving heir to several versions of the ancient Mesopotamian Flood Myth. Recently, the story of the biblical deluge was connected to the Black Sea, together with the suggestion that the story's pre-Mesopotamian origins might be found in the Pontic basin [Ryan, W.B.F., Pitman, III, W.C., 1998. Noah's Flood: The New Scientific Discoveries About the Event That Changed History. Simon and Schuster, New York]. Based on the significance of this flood epic in the Judeo-Christian tradition, popular interest surged following publication of the idea.
Currently, two Great Flood scenarios have been proposed for the Black Sea: (1) an Early Holocene event caused by catastrophic Mediterranean inflow at 7.2 ky BP (initial hypothesis of [Ryan et al., 1997. An abrupt drowning of the Black Sea shelf. Marine Geology 138, 119–126]) or 8.4 ky BP (modified hypothesis of [Ryan et al., 2003. Catastrophic flooding of the Black Sea. Annual Review of Earth and Planetary Science 31, 525–554.); and (2) a Late Pleistocene event brought on by Caspian influx between 16 and 13 ky BP [Chepalyga, A.L., 2003. Late glacial Great Flood in the Black Sea and Caspian Sea. GSA Annual Meeting and Exposition, 2–5 November 2003, Seattle, USA, p. 460]. Both hypotheses claim that the massive inundations of the Black Sea basin and ensuing large-scale environmental changes had a profound impact on prehistoric human societies of the surrounding areas, and both propose that the event formed the basis for the biblical Great Flood legend.
This paper attempts to determine whether the preponderance of existing evidence sustains support for these Great Floods in the evolution of the Black Sea. Based upon established geological and paleontological data, it finds that the Late Pleistocene inundation was intense and substantial whereas the Early Holocene sea-level rise was not. Between 16 and 13 ky BP, the Late Neoeuxinian lake (the Late Pleistocene water body in the Pontic basin pre-dating the Black Sea) increased rapidly from ∼−14 to −50 m (below the present level of the Black Sea), then rose gradually to ∼−20 m by about 11 ky BP. At 11–10 ky BP (the Younger Dryas), it dropped to ∼−50 m. When the Black Sea re-connected with the Sea of Marmara at about 9.5 ky BP, inflowing Mediterranean water increased the Black Sea level very gradually up to ∼−20 m, and in so doing, it raised the salinity of the basin and brought in the first wave of Mediterranean immigrants. These data indicate no major drawdown of the Black Sea after the Younger Dryas, and they do not provide evidence for any catastrophic flooding of the Black Sea in the Early Holocene.
In addition, available archaeological and paleoenvironmental evidence from the Pontic region reveal no recognizable changes in population dynamics between 14 and 6 ky BP that could be linked to an inundation of large magnitude [Dolukhanov, P., Shilik, K., 2006. Environment, sea-level changes, and human migrations in the northern Pontic area during late Pleistocene and Holocene times. In: Yanko-Hombach, V., Gilbert, A.S., Panin, N., Dolukhanov, P.M. (Eds.), The Black Sea Flood Question: Changes in Coastline, Climate, and Human Settlement. Springer, Dordrecht, pp. 297–318; Stanko, V.N., 2006. Fluctuations in the level of the Black Sea and Mesolithic settlement of the northern Pontic area. In: Yanko-Hombach, V., Gilbert, A.S., Panin, N., Dolukhanov, P.M. (Eds.), The Black Sea Flood Question: Changes in Coastline, Climate, and Human Settlement. Springer, Dordrecht, pp. 371–385]. More specifically, Mesolithic and early Neolithic archaeological data in southeastern Europe and Ukraine give no indications of shifts in human subsistence or other behavior at the time of the proposed catastrophic flood in the Early Holocene [Anthony, D., 2006. Pontic-Caspian Mesolithic and Early Neolithic societies at the time of the Black Sea Flood: A small audience and small effects. In: Yanko-Hombach, V., Gilbert, A.S., Panin, N., Dolukhanov, P.M. (Eds.), The Black Sea Flood Question: Changes in Coastline, Climate, and Human Settlement. Springer, Dordrecht, pp. 345–370; Dergachev and Dolukhanov, 2006. The Neolithization of the North Pontic area and the Balkans in the context of the Black Sea Floods. In: Yanko-Hombach, V., Gilbert, A.S., Panin, N., Dolukhanov, P.M. (Eds.), The Black Sea Flood Question: Changes in Coastline, Climate, and Human Settlement. Springer, Dordrecht, pp. 489–514].
Modes, rates and geomorphological consequences of active tectonics in the Marmara Region, NW Turkey-A critical overview based on seismotectonic field observations
2007, Quaternary International
The Marmara region is a tectonically active belt in northwestern Turkey, where field evidence of the collusion, escape and strike-slip tectonics is manifested. The effect of tectonics on the modification of coastal and morphological features of NW Turkey is, although extensive, relatively unknown and rarely appreciated.
Active tectonics in the region has normal and reverse forms of dip-slip (namely uplift and subsidence) and strike-slip, as is plainly demonstrated by the 1999 Marmara earthquake sequence along the North Anatolian Fault (NAF). These tectonic effects are presently related to the geometry of the NAF, the mode of lateral movement along it, and proximity to the fault. The 1999 earthquakes provided data indicating that over a return period of about 250 years, seismotectonic strike-slip movements recur up to 5 m and dip-slip movements up to 2.6 m, suggesting the rate of tectonics along the NAF in the Marmara region is on the order of 20 mm/a for strike-slip and 10 mm/a for dip-slip movements. These rates are sufficiently large to form during the late Quaternary prominent features of the landscape in the Marmara region.
Seafloor gas seeps and sediment failures triggered by the August 17, 1999 earthquake in the Eastern part of the Gulf of İzmit, Sea of Marmara, NW Turkey
2005, Marine Geology
On August 17, 1999, a major earthquake (M_w=7.4) occurred, affecting a large area in northwestern Turkey. A 150-km-long section of the North Anatolian Fault ruptured from the entrance of the Gulf of İzmit to Gölyaka in the east during the earthquake. We utilized high-resolution shallow seismic data acquired during a post-earthquake cruise to find evidence of gas seeps, gas-charged sediments, and sediment failure in the Eastern (İzmit) Basin of the Gulf of İzmit. The data showed anomalies that suggest the presence of increased gas in the gulf after the earthquake. Five major zones of offshore mass movement were found in the study area. Comparison of data collected before and after the earthquake indicates that the apparent amount of gas increased after the earthquake and the mass movement has a causative relationship to the August 17, 1999 earthquake. Therefore, we conclude that the seismic event, presence of increased gas, and the offshore mass movements in the study area are interrelated.
Abrupt environmental changes within a late Holocene lacustrine sequence south of the Marmara Sea (Lake Manyas, N-W Turkey): Possible links with seismic events
2002, Marine Geology
A coring campaign in Lake Manyas (Kuş Gölü) on the southern coast of the Sea of Marmara (Turkey) has provided insights into basin infilling processes during the upper 11 metres of the sedimentary record. Combined sedimentary features between 5 and 4 m depth have been explained by a seismite. A brittle mixed layer (uniquely rich in seeds and ostracod valves) was widely detected at 4 m downcore. This has been interpreted as being the result of a seiche either through a salt inundation linked to a tsunami in the Sea of Marmara (the large-scale scenario) or a local hydrothermal fluid discharge (the small-scale scenario). Ostracod valves, which are usually not preserved in Lake Manyas sediment, are either incorporated here as tsunami debris (providing a spatially averaged snapshot of the regional assemblage) or are locally preserved following a temporary geochemical/hydrochemical change of the water of unknown duration (but probably several decades). The brittle mixed layer overlies cracks resulting from the direct effects of the seismic shock wave on slightly compacted sediment. At around 964 cm depth palynological and particle-size analyses indicate a change from backswamp to open lacustrine conditions. The end of the backswamp has been correlated with a decrease in the level of the Sea of Marmara from 4000 to 3000–2800 yr ago (uncal.), caused by regional tectonic movements. An age–depth model is presented based on two AMS radiocarbon dates, on the palynological detection of the end of the Beyşehir Occupation Phase (130 cm above the event) and on maximal sedimentation accumulation rates obtained by radionuclide analyses. The entire study sequence covers the last 4300 yr. The paper examines the possibility of an Early Byzantine age for the seismic event. This may have been the historical event at AD 460 that destroyed Cyzicus (the ancient Erdek, 20 km north of the lake) and various villages in the interior and was felt widely in the then-known world. Other possibilities include various local and regional events in that same period: the Early Byzantine Tectonic Paroxysm and the large earthquake in AD 447 that affected the entire Sea of Marmara region.

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Letter SectionIntra-basinal water movements induced by faulting: the August 17, 1999, Gölcük (İzmit Bay) earthquake (Mw=7.4)

Abstract

Introduction

Section snippets

Morphology and structure

Water movements

Discussion and conclusions

Acknowledgements

Mar. Geol.

Mar. Geol.

Tsunami generation of the Kocaeli Earthquake (August 17th, 1999) in the İzmit Bay: coastal observations,bathymetry and seismic data

Turkish J. Mar. Sci.

Data for the investigation of the seismic-sea waves in the Eastern Mediterranean

Bull. Seism. Soc. Am.

Strike–slip fault geometry in Turkey and its influence on earthquake activity

Tectonics

İzmit körfezi Kuvaterner deniz dibi çökellerinin stratigrafik ve yapisal özellikleri ile kalınlıklarının daǧılımı

TJK Bülteni

Letter Section
Intra-basinal water movements induced by faulting: the August 17, 1999, Gölcük (İzmit Bay) earthquake (M_w=7.4)