Migration imaging and forward modeling of microseismic noise sources near southern Italy

[1] This study combines migration and forward source modeling techniques to examine the existence and location of persistent seismic noise near southern Italy. Our results demonstrate that noise source modeling is both feasible and recommended in validating the “ambient source” assumption prior to noise-based velocity analyses. Persistent noise sources near the Gargano promontory and the Tyrrhenian Sea coast are strongly suggested by the observed cross-correlations. The presence of a single point source or a cluster of point sources could both produce coherent Rayleigh wave energy in southern Italy. While the nature of the noise sources is still uncertain, baroclinic estimates and dynamic topography models favor an explanation that encompasses atmosphere-ocean coupling and heightened wave interaction off the Adriatic coast. Our records indicate that these noise sources can maintain their average location for up to 7 months despite seasonal and, possibly, daily variations.

[1]  R. Snieder.  Extracting the Green's function from the correlation of coda waves: a derivation based on stationary phase. , 2004, Physical review. E, Statistical, nonlinear, and soft matter physics.

[2]  A. Paul,et al.  Long-Range Correlations in the Diffuse Seismic Coda , 2003, Science.

[3]  B. Gutenberg.  Observations and Theory of Microseisms , 1951 .

[4]  Peter Gerstoft,et al.  A year of microseisms in southern California , 2007 .

[5]  D. L. Anderson,et al.  Preliminary reference earth model , 1981 .

[6]  Toshiro Tanimoto,et al.  Cause of continuous oscillations of the Earth , 1999 .

[7]  Peter Gerstoft,et al.  Surface wave tomography from microseisms in Southern California , 2005 .

[8]  Robert B. Herrmann,et al.  Imaging the Upper Crust of the Korean Peninsula by Surface-Wave Tomography , 2007 .

[9]  Fukao,et al.  Earth's background free oscillations , 1998, Science.

[10]  S. Webb.  The Earth’s ‘hum’ is driven by ocean waves over the continental shelves , 2007, Nature.

[11]  Peter Gerstoft,et al.  Extracting time‐domain Green's function estimates from ambient seismic noise , 2005 .

[12]  Peter Gerstoft,et al.  P‐waves from cross‐correlation of seismic noise , 2005 .

[13]  Jon F. Claerbout,et al.  Synthesis of a layered medium from its acoustic transmission response , 1968 .

[14]  M. Longuet-Higgins.  A theory of the origin of microseisms , 1950, Philosophical Transactions of the Royal Society of London. Series A, Mathematical and Physical Sciences.

[15]  R. Weaver,et al.  On the emergence of the Green's function in the correlations of a diffuse field: pulse-echo using thermal phonons. , 2001, Ultrasonics.

[16]  Amir Khan,et al.  Rayleigh‐wave group‐velocity of the Icelandic crust from correlation of ambient seismic noise , 2007 .

[17]  Pierre-Marie Poulain,et al.  Drifter observations of surface circulation in the Adriatic Sea between December 1994 and March 1996 , 1999 .

[18]  Anatoli L. Levshin,et al.  Ambient noise Rayleigh wave tomography across Europe , 2007 .

[19]  Arthur L. Lerner-Lam,et al.  Probing the sources of ambient seismic noise near the coasts of southern Italy , 2007 .

[20]  Aniello Russo,et al.  The Adriatic Sea General Circulation. Part II: Baroclinic Circulation Structure , 1997 .

[21]  B. Kennett.  The effects of attenuation on seismograms , 1975 .

[22]  Barbara Romanowicz,et al.  A study of the relation between ocean storms and the Earth's hum , 2006 .

[23]  Michel Campillo,et al.  High-Resolution Surface-Wave Tomography from Ambient Seismic Noise , 2005, Science.

[24]  Kazunari Nawa,et al.  Incessant excitation of the Earth’s free oscillations , 1998 .

[25]  Michael H. Ritzwoller,et al.  Source location of the 26 sec microseism from cross‐correlations of ambient seismic noise , 2006 .

[26]  Richard L. Weaver,et al.  On the emergence of the Green's function in the correlations of a diffuse field: pulse-echo using thermal phonons. , 2001, Ultrasonics.

[27]  Michel Campillo,et al.  A study of the seismic noise from its long-range correlation properties , 2006 .

[28]  Maarten V. de Hoop,et al.  Surface-wave array tomography in SE Tibet from ambient seismic noise and two-station analysis: I - Phase velocity maps , 2006 .

[29]  G. Ekström.  Time domain analysis of Earth's long‐period background seismic radiation , 2001 .

[30]  Stefano Zecchetto,et al.  Sea Surface Winds over the Mediterranean Basin from Satellite Data (2000–04): Meso- and Local-Scale Features on Annual and Seasonal Time Scales , 2007 .

[31]  Frank L. Vernon,et al.  Strong directivity of ocean‐generated seismic noise , 2004 .

[32]  Morgan P. Moschetti,et al.  Surface wave tomography of the western United States from ambient seismic noise: Rayleigh wave group velocity maps , 2007 .

[33]  Stephen Bannister,et al.  Ambient noise Rayleigh wave tomography of New Zealand , 2007 .

[34]  Kees Wapenaar,et al.  Relations between reflection and transmission responses of three-dimensional inhomogeneous media , 2004 .

[35]  A. Pascual,et al.  A Mean Dynamic Topography of the Mediterranean Sea computed from altimetric data, in-situ measurements and a general circulation model , 2007 .

[36]  Yingjie Yang,et al.  Processing seismic ambient noise data to obtain reliable broad-band surface wave dispersion measurements , 2007 .

[37]  J. Claerbout,et al.  Acoustic daylight imaging via spectral factorization: helioseismology and reservoir monitoring , 1999 .

[38]  Morgan P. Moschetti,et al.  Surface wave tomography of the western United States from ambient seismic noise: Rayleigh and Love wave phase velocity maps , 2008 .

[39]  G. Kunetz,et al.  Sur certaines propriétés d'une onde acoustique plane de compression dans un milieu stratifié , 1962 .

[40]  M. Steckler,et al.  Modeling of sequence geometry north of Gargano Peninsula by changing sediment pathways in the Adriatic Sea , 2007 .

[41]  Michael H. Ritzwoller,et al.  Characteristics of ambient seismic noise as a source for surface wave tomography , 2008 .