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SUMMARY:Lithospheric structure\, anisotropy and seismicity of the active N
 orth Anatolian Fault\, Turkey - Dave Cornwell - University of Aberdeen
DTSTART:20191106T160000Z
DTEND:20191106T170000Z
UID:TALK131296@talks.cam.ac.uk
CONTACT:Jenny Jenkins
DESCRIPTION:The collective seismological results from the Dense Array for 
 Northern Anatolia (DANA) will be presented in this talk. DANA was part of 
 the multi-disciplinary Faultlab project\, designed to collect passive seis
 mological data across the seismically-active North Anatolian Fault in nort
 hern Turkey to image the fault structure in the lower crust and upper mant
 le. The North Anatolian Fault Zone (NAFZ) is a major continental strike-sl
 ip fault system that extends ~1200 km across Turkey. Our study region samp
 les the NAFZ near the epicentres of two large earthquakes that occurred in
  1999 at Izmit (M7.5) and Düzce (M7.2) and where estimates of present-day
  slip rate are 20-25 mm/yr. Using recordings of teleseismic earthquakes fr
 om a rectangular seismometer array spanning the NAFZ with 66 stations at a
  nominal inter-station spacing of 7 km and 7 additional stations further a
 field\, we build a detailed 3-D image of structure and anisotropy using re
 ceiver functions\, tomography and shear wave splitting and illuminate majo
 r changes in the architecture and properties of the upper crust\, lower cr
 ust and upper mantle\, both across and along the two branches of the NAFZ\
 , at length scales of less than 20 km. Recent work with the DANA dataset h
 as improved the earthquake catalogue and applied harmonic analysis of rece
 iver functions with local and teleseismic shear wave splitting constrain z
 ones of anisotropy in the crust and mantle. We show that the northern NAFZ
  branch depth extent varies from the mid-crust to the upper mantle and it 
 is likely to be less than 10 km wide. A high velocity lower crust and a re
 gion of crustal underthrusting appear to add strength to a heterogeneous c
 rust and play a role in dictating the variation in faulting style and post
 -seismic deformation. Sharp changes in lithospheric mantle velocity and an
 isotropy are constrained as the NAFZ is crossed\, whereas crustal structur
 e and anisotropy vary considerably both parallel and perpendicular to the 
 faulting. We use our observations to test current models of the localisati
 on of strike-slip deformation and develop new ideas to explain how narrow 
 fault zones develop in heterogeneous lithosphere.\n \nReferences:\nhttps:/
 /agupubs.onlinelibrary.wiley.com/doi/abs/10.1002/2017JB015386\nhttps://agu
 pubs.onlinelibrary.wiley.com/doi/full/10.1002/2017GL072726\nhttps://www.sc
 iencedirect.com/science/article/pii/S0012821X15005348\nhttps://www.science
 direct.com/science/article/pii/S0040195115003522
LOCATION:Marine/Wolfson Building lecture hall\, Bullard Labs.
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