Shear wave velocity structure of the Izmit Bay area (Turkey) estimated from active-passive array surface wave and single-station microtremor methods

SUMMARY To provide quantitative information on the shear wave velocity structure of the Izmit Bay area, we conduct active–passive array surface wave and single-station microtremor measurements at 60 sites. We process these array measurements to produce combined Rayleigh wave dispersion curves that span a broad-frequency range (0.5–20 Hz). We also make use of horizontal-to-vertical spectral ratio (HVSR) curves obtained from the single-station microtremor measurements to benefit from their close relation to the ellipticity of Rayleigh waves. Using the dispersion curve sensitivity to the absolute velocities and the shape of the HVSR curve sensitivity to the velocity contrasts of the velocity-depth model, we have applied a combined inversion technique to derive better constrained shear velocity models at each site. The derived shear velocity models are used to provide a Vs30 site classification map and information on the sediment-bedrock structure for the Izmit Bay area. The Vs30 map shows that the entire shoreline regions including artificial infill areas of the Izmit Bay have Vs30 values less than 200 m s−1, locally as low as 80 m s−1. The older sediment areas of the Izmit basin have Vs30 values ranging between 250 and 350 m s−1. The highest Vs30 values are associated with rock sites reaching about 950–1300 m s−1. We also present a high correlation between the Vs30 values and the phase velocity of Rayleigh wave corresponding to the 40 m wavelength (C40). The important implication of this correlation is that Vs30 may be estimated from C40 without inverting the dispersion curve. The inferred sediment-bedrock interface along a cross-section shows an antisymmetric V shaped basin with a sedimentary cover thickness reaching about 1200 m at the deepest part of the Izmit basin. This deepest part coincides in the map view where the North Anatolian fault zone crosses the basin in the east–west direction. The sedimentary cover thickness is found to be 750 m in the Golcuk–Derince basin.

[1]  T. Ohmachi,et al.  Ground Motion Characteristics Estimated from Spectral Ratio between Horizontal and Verticcl Components of Mietremors. , 1997 .

[2]  Cécile Cornou,et al.  Assessing the reliability of the modified three-component spatial autocorrelation technique , 2007 .

[3]  Cécile Cornou,et al.  Deriving Wavefield Characteristics and Shear-Velocity Profiles from Two- Dimensional Small-Aperture Arrays Analysis of Ambient Vibrations in a Small-Size Alluvial Basin, Colfiorito, Italy , 2006 .

[4]  Claude Rangin,et al.  THE NORTH ANATOLIAN FAULT: A NEW LOOK , 2005 .

[5]  K. Campbell,et al.  NGA Ground Motion Model for the Geometric Mean Horizontal Component of PGA, PGV, PGD and 5% Damped Linear Elastic Response Spectra for Periods Ranging from 0.01 to 10 s , 2008 .

[6]  Gilberto Saccorotti,et al.  Shallow-velocity models at the Kilauea Volcano, Hawaii, determined from array analyses of tremor wavefields , 2003 .

[7]  M. Erdik,et al.  Site Effects in Avcilar, West of Istanbul, Turkey, from Strong- and Weak-Motion Data , 2002 .

[8]  J. Henstridge.  A signal processing method for circular arrays , 1979 .

[9]  K. Irikura,et al.  S-Wave Velocity Structure of the Taichung Basin, Taiwan, Estimated from Array and Single-Station Records of Microtremors , 2004 .

[10]  Mark D. Petersen,et al.  A Time-Dependent Probabilistic Seismic-Hazard Model for California , 2000 .

[11]  Mustafa Erdik,et al.  Site-Specific Issues for Strong Ground Motions during the Kocaeli, Turkey, Earthquake of 17 August 1999, as Inferred from Array Observations of Microtremors and Aftershocks , 2002 .

[12]  M. Asten,et al.  Initial results from spatially averaged coherency, frequency-wavenumber, and horizontal to vertical spectrum ratio microtremor survey methods for site hazard study at Launceston, Tasmania , 2009 .

[13]  Jianghai Xia,et al.  Combined Use of Active and Passive Surface Waves , 2005 .

[14]  William A. Bryant,et al.  A Site-Conditions Map for California Based on Geology and Shear-Wave Velocity , 2000 .

[15]  Pierre-Yves Bard,et al.  Numerical and Theoretical Investigations on the Possibilities and Limitations of Nakamura's Technique , 1994 .

[16]  Gerard T. Schuster,et al.  Simulation of 3D elastic wave propagation in the Salt Lake Basin , 1995, Bulletin of The Seismological Society of America (BSSA).

[17]  J. Capon.  High-resolution frequency-wavenumber spectrum analysis , 1969 .

[18]  W. B. Joyner,et al.  Strong Motion from Surface Waves in Deep Sedimentary Basins , 2000 .

[19]  Brian L. N. Kennett,et al.  Automatic Phase-Detection and Identification by Full Use of a Single Three-Component Broadband Seismogram , 2000 .

[20]  M. Matsushima,et al.  Magnetotelluric imaging of the fault rupture area of the 1999 Izmit (Turkey) earthquake , 2005 .

[21]  Dario Albarello,et al.  Statistical Analysis of Noise Horizontal-to-Vertical Spectral Ratios (HVSR) , 2005 .

[22]  Walter H. F. Smith,et al.  New, improved version of generic mapping tools released , 1998 .

[23]  Richard D. Miller,et al.  Multichannel analysis of surface waves , 1999 .

[24]  Peter Bormann,et al.  ASSESSMENT OF THE NATURAL FREQUENCY OF THE SEDIMENTARY COVER IN THE COLOGNE AREA (GERMANY) USING NOISE MEASUREMENTS , 2001 .

[25]  S. Sawada,et al.  Bedrock structure in Adapazari, Turkey—a possible cause of severe damage by the 1999 Kociaeli earthquake , 2002 .

[26]  Mitsuo Nogoshi,et al.  On the Propagation Characteristics of Microtremor , 1970 .

[27]  Kim B. Olsen,et al.  Site Amplification in the Los Angeles Basin from Three-Dimensional Modeling of Ground Motion , 2000 .

[28]  R. T. Lacoss,et al.  ESTIMATION OF SEISMIC NOISE STRUCTURE USING ARRAYS , 1969 .

[29]  Edward H. Field,et al.  Accounting for Site Effects in Probabilistic Seismic Hazard Analyses of Southern California: Overview of the SCEC Phase III Report , 2000 .

[30]  Y Nakamura,et al.  A METHOD FOR DYNAMIC CHARACTERISTICS ESTIMATION OF SUBSURFACE USING MICROTREMOR ON THE GROUND SURFACE , 1989 .

[31]  Dino Bindi,et al.  Suitability of Short-Period Sensors for Retrieving Reliable H/V Peaks for Frequencies Less Than 1 Hz , 2008 .

[32]  Cécile Cornou,et al.  Analysis of dense array noise measurements using the modified spatial auto-correlation method (SPAC): application to the Grenoble area , 2001 .

[33]  Stefano Parolai,et al.  Joint inversion of H/V ratios and dispersion curves from seismic noise: Estimating the S‐wave velocity of bedrock , 2005 .

[34]  E. Bozdağ,et al.  Estimation of site amplifications from shear-wave velocity profiles in Yeşilyurt and Avcılar, Istanbul, by frequency–wavenumber analysis of microtremors , 2005 .

[35]  M. Ergin,et al.  Site amplification at Avcılar, Istanbul , 2004 .

[36]  M. Martini,et al.  Shallow velocity structure of Stromboli volcano, Italy, derived from small-aperture array measurements of Strombolian tremor , 1998, Bulletin of the Seismological Society of America.

[37]  Stefano Parolai,et al.  Joint inversion of phase velocity dispersion and H/V ratio curves from seismic noise recordings using a genetic algorithm, considering higher modes , 2005 .

[38]  Donat Fäh,et al.  A theoretical investigation of average H/V ratios , 2001 .

[39]  Matthias Ohrnberger,et al.  Array performances for ambient vibrations on a shallow structure and consequences over Vs inversion , 2008 .

[40]  S. Sawada,et al.  Modeling of 3D Subsurface Structure and Numerical Simulation of Strong Ground Motion in the Adapazari Basin during the 1999 Kocaeli Earthquake, Turkey , 2005 .

[41]  Frank Scherbaum,et al.  Determination of shallow shear wave velocity profiles in the Cologne, Germany area using ambient vibrations , 2003 .

[42]  Francisco J. Chávez-García,et al.  Site effect evaluation using spectral ratios with only one station , 1993, Bulletin of the Seismological Society of America.

[43]  Paul R. Lintz,et al.  Plane waves at small arrays , 1973 .

[44]  Keiiti Aki,et al.  Space and Time Spectra of Stationary Stochastic Waves, with Special Reference to Microtremors , 1957 .

[45]  Toshimi Satoh,et al.  Estimation of S-Wave Velocity Structures in and around the Sendai Basin, Japan, Using Array Records of Microtremors , 2001 .

[46]  M. I. Seht,et al.  Microtremor measurements used to map thickness of soft sediments , 1999 .

[47]  Katsuaki Konno,et al.  AN ESTIMATING METHOD FOR THE AVERAGE S-WAVE VELOCITY OF GROUND FROM THE PHASE VELOCITY OF RAYLEIGH WAVE , 2000 .

[48]  I. Cho,et al.  Beyond the SPAC Method: Exploiting the Wealth of Circular-Array Methods for Microtremor Exploration , 2007 .

[49]  Arthur Frankel,et al.  Three-dimensional simulations of ground motions in the San Bernardino Valley, California, for hypothetical earthquakes on the San Andreas fault , 1993, Bulletin of the Seismological Society of America.

[50]  Michael W. Asten,et al.  Array estimators and the use of microseisms for reconnaissance of sedimentary basins. , 1984 .

[51]  Kohji Tokimatsu,et al.  S-Wave Velocity Profiling by Joint Inversion of Microtremor Dispersion Curve and Horizontal-to-Vertical (H/V) Spectrum , 2005 .

[52]  I. Cho,et al.  New Circular-Array Microtremor Techniques to Infer Love-Wave Phase Velocities , 2009 .