Magnetotelluric imaging of the fault rupture area of the 1999 İzmit (Turkey) earthquake

Tank, Sabri Bülent; Honkura, Yoshimori; Ogawa, Yasuo; Matsushima, Masaki; Oshiman, Naoto; Tunçer, Mustafa; Çelik, Cengiz; Tolak, E.; Işıkara, A. M.

doi:10.1016/j.pepi.2004.08.033

Cited by 79 publications

(75 citation statements)

References 30 publications

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“…Ritter et al 2003Ritter et al , 2005Unsworth & Bedrosian 2004;Tank et al 2005;Thiel et al 2009;Becken et al 2011;Desissa et al 2013). The geometry and the overall conductance of FZCs depend on local geological, hydrogeological conditions and the geodynamic (tectonic) setting of a fault (see Unsworth & Bedrosian 2004;Ritter et al 2005, and references therein.).…”

Section: Discussion O F T H E 2 -D E L E C T R I C a L C O Nmentioning

confidence: 99%

Crustal metamorphic fluid flux beneath the Dead Sea Basin: constraints from 2-D and 3-D magnetotelluric modelling

et al. 2016

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S U M M A R YWe report on a study to explore the deep electrical conductivity structure of the Dead Sea Basin (DSB) using magnetotelluric (MT) data collected along a transect across the DSB where the left lateral strike-slip Dead Sea transform (DST) fault splits into two fault strands forming one of the largest pull-apart basins of the world. A very pronounced feature of our 2-D inversion model is a deep, subvertical conductive zone beneath the DSB. The conductor extends through the entire crust and is sandwiched between highly resistive structures associated with Precambrian rocks of the basin flanks. The high electrical conductivity could be attributed to fluids released by dehydration of the uppermost mantle beneath the DSB, possibly in combination with fluids released by mid-to low-grade metamorphism in the lower crust and generation of hydrous minerals in the middle crust through retrograde metamorphism. Similar high conductivity zones associated with fluids have been reported from other large fault systems. The presence of fluids and hydrous minerals in the middle and lower crust could explain the required low friction coefficient of the DST along the eastern boundary of the DSB and the high subsidence rate of basin sediments. 3-D inversion models confirm the existence of a subvertical high conductivity structure underneath the DSB but its expression is far less pronounced. Instead, the 3-D inversion model suggests a deepening of the conductive DSB sediments off-profile towards the south, reaching a maximum depth of approximately 12 km, which is consistent with other geophysical observations. At shallower levels, the 3-D inversion model reveals salt diapirism as an upwelling of highly resistive structures, localized underneath the Al-Lisan Peninsula. The 3-D model furthermore contains an E-W elongated conductive structure to the northeast of the DSB. More MT data with better spatial coverage are required, however, to fully constrain the robustness of the above-mentioned off-profile features.

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Section: Discussion O F T H E 2 -D E L E C T R I C a L C O Nmentioning

confidence: 99%

Crustal metamorphic fluid flux beneath the Dead Sea Basin: constraints from 2-D and 3-D magnetotelluric modelling

et al. 2016

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“…Some earlier studies performed in the area Oshiman et al, 2002;Tank et al, 2003Tank et al, , 2005Kaya et al, 2009) attempted to resolve the resistivity structure at mid-crustal depths. In particular, they tried to get information about the electrical properties of the seismogenic zone.…”

Section: Resultsmentioning

confidence: 99%

“…Tank et al (2003) then imaged the western part of the epicentral region of theİzmit earthquake, in order to study the electrical resistivity structure with respect to the characteristic seismic behavior. Tank et al (2005) added long-period data to the wide-band dataset of Honkura et al (2000) and proposed a deep (surface-50 km) electrical-conductivity model for the eastern Marmara region. Kaya et al (2009) performed a comparison between the eastern and western parts of the Düzce Fault (Fig.…”

Section: Audio Frequency Magnetotellurics (Amt) Data Collectionmentioning

confidence: 99%

Fault zone conductors in Northwest Turkey inferred from audio frequency magnetotellurics

Tank

2012

Earth Planet Sp

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A comparison of the electrical properties of the two main branches of the North Anatolian Fault is made based on audio-frequency magnetotelluric (AMT) surveys carried out along three typical pro les across the North Anatolian Fault Zone (NAFZ). These two branches are (i) the active northern branch (Izmit-Adapazar Fault (IAF)) where the 17 August, 1999, Izmit earthquake took place, and (ii) the less active southern branch (IznikMekece Fault (IMF)). In this paper, we focus on the shallow depths (surface-1.5 km) in search for conductors near the fault zone for the purpose of comparing these two branches with each other, as well as other strike-slip faults. Phase tensor analyses and Groom-Bailey decompositions were applied to check the dimensionality of the AMT data. Following the tensor analyses and decompositions, two-dimensional inversions were carried out to yield models based on the transverse electric (TE), and transverse magnetic (TM), modes. These models suggest that the North Anatolian Fault exhibits signs of fault zone conductors (FZC) regardless of being active or less active.

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“…Many recent MT studies have revealed that fault zones are either conductive or fall at the boundaries between conductive and resistive zones [e.g., Mackie et al, 1997a;Unsworth et al, 2000;Becken et al, 2005;Tank et al, 2005]. A common explanation is the presence of fluids in fractured rock on the fault.…”

Section: Discussionmentioning

confidence: 99%

“…To our knowledge, this is the closest any resistivity monitoring experiment has been to a moderate or large earthquake. While Tank et al [2005] were conducting an MT survey across the North Anatolian fault zone at the time of the 1999 M7.4 Izmit earthquake, they did not report any coseismic changes of resistivity. They were also able to find a single resistivity model that was consistent with soundings recorded both before and after the earthquake, suggesting any such changes must have been small.…”

Section: Introductionmentioning

confidence: 99%

Electrical resistivity changes not observed with the 28 September 2004 M6.0 Parkfield earthquake on the San Andreas fault, California

Park¹,

Larsen²,

Lee³

2007

J. Geophys. Res.

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[1] An 18 a long experiment to capture changes in electrical resistivity prior to, during, and after a M6 earthquake on the San Andreas fault at Parkfield, California, culminated with an event of that magnitude on 28 September 2004. Resistivity was monitored with a telluric array, giving precisions in measured parameters of 0.2% or less. No coseismic resistivity changes greater than 5% could have occurred or they would have been detected by the array, and any precursory changes would have been much smaller because maximum possible precursory strains were 4000 times smaller than the coseismic strain. Given that the earthquake ruptured directly beneath the telluric array, this experiment places a bound on the amount resistivity might change at the hypocentral location; changes measured with instruments farther from earthquakes can only be smaller. It is still possible that a measurable change with a larger earthquake or other fault geometries are capable of generating larger signals, but our results show clearly that future experiments should be designed with precisions of much better than 0.1% if they are to be successful.

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Magnetotelluric imaging of the fault rupture area of the 1999 İzmit (Turkey) earthquake

Cited by 79 publications

References 30 publications

Crustal metamorphic fluid flux beneath the Dead Sea Basin: constraints from 2-D and 3-D magnetotelluric modelling

Crustal metamorphic fluid flux beneath the Dead Sea Basin: constraints from 2-D and 3-D magnetotelluric modelling

Fault zone conductors in Northwest Turkey inferred from audio frequency magnetotellurics

Electrical resistivity changes not observed with the 28 September 2004 M6.0 Parkfield earthquake on the San Andreas fault, California

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