Crustal thickness variations and isostatic disequilibrium across the North Anatolian Fault, western Turkey

A.W. Frederiksen, D. A. Thompson, S. Rost, D. G. Cornwell, L. Gulen, G. A. Houseman, M. Kahraman, S. A. Altuncu Poyraz, U. M. Teoman, N. Turkelli, M. Utkucu

Research output: Contribution to journalArticle

8 Citations (Scopus)
10 Downloads (Pure)

Abstract

We use teleseismic recordings from a dense array of seismometers straddling both strands of the North Anatolian Fault Zone to determine crustal thickness, P/S velocity ratio and sedimentary layer thickness. To do this, we implement a new grid search inversion scheme based on the use of transfer functions, removing the need for deconvolution for source normalization and therefore eliminating common problems associated with crustal-scale receiver function analysis. We achieve a good fit to the data except at several stations located in Quaternary sedimentary basins, where our two-layer crustal model is likely to be inaccurate. We find two zones of thick sedimentary material: one north of the northern fault branch, and one straddling the southern branch. The crustal thickness increases sharply north of the northern strand of the North Anatolian Fault Zone (NAFZ), where the fault nearly coincides with the trace of the Intra-Pontide Suture; the velocity ratio changes across the southern fault strand, indicating a change in basement composition. We interpret these changes to indicate that both strands of the NAFZ follow preexisting geological boundaries rather than being ideally aligned with the stress field. The thick crust north of the northern NAFZ strand is associated with low topography and so is inconsistent with simple models of isostatic equilibrium, requiring a contribution from mantle density variations, such as possible loading from underthrust Black Sea oceanic lithosphere.
Original languageEnglish
Pages (from-to)751-757
Number of pages7
JournalGeophysical Research Letters
Volume42
Issue number3
Early online date9 Feb 2015
DOIs
Publication statusPublished - 16 Feb 2015

Fingerprint

North Anatolian Fault
Turkey
crustal thickness
disequilibrium
strands
fault zone
Black Sea
oceanic lithosphere
deconvolution
seismograph
transfer function
sedimentary basin
stress field
seismographs
basements
lithosphere
transfer functions
stress distribution
topography
crust

Keywords

  • Turkey
  • North Anatolian fault
  • Moho
  • crustal thickness
  • vp/vs

Cite this

Crustal thickness variations and isostatic disequilibrium across the North Anatolian Fault, western Turkey. / Frederiksen, A.W.; Thompson, D. A.; Rost, S.; Cornwell, D. G.; Gulen, L.; Houseman, G. A.; Kahraman, M.; Altuncu Poyraz, S. A.; Teoman, U. M.; Turkelli, N.; Utkucu, M.

In: Geophysical Research Letters, Vol. 42, No. 3, 16.02.2015, p. 751-757.

Research output: Contribution to journalArticle

Frederiksen, AW, Thompson, DA, Rost, S, Cornwell, DG, Gulen, L, Houseman, GA, Kahraman, M, Altuncu Poyraz, SA, Teoman, UM, Turkelli, N & Utkucu, M 2015, 'Crustal thickness variations and isostatic disequilibrium across the North Anatolian Fault, western Turkey', Geophysical Research Letters, vol. 42, no. 3, pp. 751-757. https://doi.org/10.1002/2014GL062401
Frederiksen, A.W. ; Thompson, D. A. ; Rost, S. ; Cornwell, D. G. ; Gulen, L. ; Houseman, G. A. ; Kahraman, M. ; Altuncu Poyraz, S. A. ; Teoman, U. M. ; Turkelli, N. ; Utkucu, M. / Crustal thickness variations and isostatic disequilibrium across the North Anatolian Fault, western Turkey. In: Geophysical Research Letters. 2015 ; Vol. 42, No. 3. pp. 751-757.
@article{c815f068322645bab7d2d8d3a5919329,
title = "Crustal thickness variations and isostatic disequilibrium across the North Anatolian Fault, western Turkey",
abstract = "We use teleseismic recordings from a dense array of seismometers straddling both strands of the North Anatolian Fault Zone to determine crustal thickness, P/S velocity ratio and sedimentary layer thickness. To do this, we implement a new grid search inversion scheme based on the use of transfer functions, removing the need for deconvolution for source normalization and therefore eliminating common problems associated with crustal-scale receiver function analysis. We achieve a good fit to the data except at several stations located in Quaternary sedimentary basins, where our two-layer crustal model is likely to be inaccurate. We find two zones of thick sedimentary material: one north of the northern fault branch, and one straddling the southern branch. The crustal thickness increases sharply north of the northern strand of the North Anatolian Fault Zone (NAFZ), where the fault nearly coincides with the trace of the Intra-Pontide Suture; the velocity ratio changes across the southern fault strand, indicating a change in basement composition. We interpret these changes to indicate that both strands of the NAFZ follow preexisting geological boundaries rather than being ideally aligned with the stress field. The thick crust north of the northern NAFZ strand is associated with low topography and so is inconsistent with simple models of isostatic equilibrium, requiring a contribution from mantle density variations, such as possible loading from underthrust Black Sea oceanic lithosphere.",
keywords = "Turkey, North Anatolian fault, Moho, crustal thickness, vp/vs",
author = "A.W. Frederiksen and Thompson, {D. A.} and S. Rost and Cornwell, {D. G.} and L. Gulen and Houseman, {G. A.} and M. Kahraman and {Altuncu Poyraz}, {S. A.} and Teoman, {U. M.} and N. Turkelli and M. Utkucu",
note = "Funded by •NERC. Grant Number: NE/I028017/1 •Boğazi{\cc}i University Research Fund (BAP-project 6922) •Sakarya University Research Fund (BAP-project 2012-01-14-006)",
year = "2015",
month = "2",
day = "16",
doi = "10.1002/2014GL062401",
language = "English",
volume = "42",
pages = "751--757",
journal = "Geophysical Research Letters",
issn = "0094-8276",
publisher = "AMER GEOPHYSICAL UNION",
number = "3",

}

TY - JOUR

T1 - Crustal thickness variations and isostatic disequilibrium across the North Anatolian Fault, western Turkey

AU - Frederiksen, A.W.

AU - Thompson, D. A.

AU - Rost, S.

AU - Cornwell, D. G.

AU - Gulen, L.

AU - Houseman, G. A.

AU - Kahraman, M.

AU - Altuncu Poyraz, S. A.

AU - Teoman, U. M.

AU - Turkelli, N.

AU - Utkucu, M.

N1 - Funded by •NERC. Grant Number: NE/I028017/1 •Boğaziçi University Research Fund (BAP-project 6922) •Sakarya University Research Fund (BAP-project 2012-01-14-006)

PY - 2015/2/16

Y1 - 2015/2/16

N2 - We use teleseismic recordings from a dense array of seismometers straddling both strands of the North Anatolian Fault Zone to determine crustal thickness, P/S velocity ratio and sedimentary layer thickness. To do this, we implement a new grid search inversion scheme based on the use of transfer functions, removing the need for deconvolution for source normalization and therefore eliminating common problems associated with crustal-scale receiver function analysis. We achieve a good fit to the data except at several stations located in Quaternary sedimentary basins, where our two-layer crustal model is likely to be inaccurate. We find two zones of thick sedimentary material: one north of the northern fault branch, and one straddling the southern branch. The crustal thickness increases sharply north of the northern strand of the North Anatolian Fault Zone (NAFZ), where the fault nearly coincides with the trace of the Intra-Pontide Suture; the velocity ratio changes across the southern fault strand, indicating a change in basement composition. We interpret these changes to indicate that both strands of the NAFZ follow preexisting geological boundaries rather than being ideally aligned with the stress field. The thick crust north of the northern NAFZ strand is associated with low topography and so is inconsistent with simple models of isostatic equilibrium, requiring a contribution from mantle density variations, such as possible loading from underthrust Black Sea oceanic lithosphere.

AB - We use teleseismic recordings from a dense array of seismometers straddling both strands of the North Anatolian Fault Zone to determine crustal thickness, P/S velocity ratio and sedimentary layer thickness. To do this, we implement a new grid search inversion scheme based on the use of transfer functions, removing the need for deconvolution for source normalization and therefore eliminating common problems associated with crustal-scale receiver function analysis. We achieve a good fit to the data except at several stations located in Quaternary sedimentary basins, where our two-layer crustal model is likely to be inaccurate. We find two zones of thick sedimentary material: one north of the northern fault branch, and one straddling the southern branch. The crustal thickness increases sharply north of the northern strand of the North Anatolian Fault Zone (NAFZ), where the fault nearly coincides with the trace of the Intra-Pontide Suture; the velocity ratio changes across the southern fault strand, indicating a change in basement composition. We interpret these changes to indicate that both strands of the NAFZ follow preexisting geological boundaries rather than being ideally aligned with the stress field. The thick crust north of the northern NAFZ strand is associated with low topography and so is inconsistent with simple models of isostatic equilibrium, requiring a contribution from mantle density variations, such as possible loading from underthrust Black Sea oceanic lithosphere.

KW - Turkey

KW - North Anatolian fault

KW - Moho

KW - crustal thickness

KW - vp/vs

U2 - 10.1002/2014GL062401

DO - 10.1002/2014GL062401

M3 - Article

VL - 42

SP - 751

EP - 757

JO - Geophysical Research Letters

JF - Geophysical Research Letters

SN - 0094-8276

IS - 3

ER -