Burtin_et_al_2010 - Geophysical Journal International...

Info icon This preview shows pages 1–2. Sign up to view the full content.

View Full Document Right Arrow Icon
Geophys. J. Int. (2010) 182, 1161–1173 doi: 10.1111/j.1365-246X.2010.04701.x GJI Geodynamics and tectonics Location of river-induced seismic signal from noise correlation functions A. Burtin, 1 J. Vergne, 2 L. Rivera 2 and P. Dubernet 1 1 Laboratoire de G´eologie, ´ Ecole Normale Sup´erieure de Paris, CNRS UMR 8538, Paris, France. E-mail: [email protected] 2 Institut de Physique du Globe de Strasbourg (CNRS/UDS), Strasbourg, France Accepted 2010 June 14. Received 2010 June 11; in original form 2009 July 28 S U M M A R Y We extend the use of noise correlation functions (NCFs) to locate stream segments of the trans-Himalayan Trisuli River that are responsible for the large high-frequency seismic noise observed at Hi-CLIMB stations. Cross-correlations of continuous seismic records at several pairs of stations indicate that some seismic sources are coherent only during the monsoon period. To locate these sources, we perform a migration of a selection of NCF envelopes filtered at frequencies ranging from 2 to 6 Hz. We produce a set of coherence maps at each frequency and for various apparent velocities to determine the regions which best explain the observed NCFs. The highest coherences are always located along restricted portions of the Trisuli River and are generally obtained for an apparent velocity of 3 ± 0 . 3 km s 1 . We also carry out a set of synthetic tests based on a full forward modelling approach for different distribution of sources. These simulations indicate that (1) the observed NCFs are dominated by Rayleigh surface waves and/or S waves, (2) cannot result from the coherence of P waves and (3) the recorded sources are effectively located along the Trisuli River. These tests also reveal some artefacts induced by the linear geometry of the Hi-CLIMB network. We take these artefacts into account and determine that the sources of seismic noise are mostly concentrated along the steepest portion of the Trisuli River with a maximum at the front of the High Range. We associate the river sources to the impacts of sediment particles on the channel bed and their distributions are in good agreement with incision rates along the river. Therefore, this study reveals the ability of locating zones of high river sediment transport and bedrock erosion based on the analysis of seismic noise recorded outside the stream. Key words: Interferometry; Geomorphology; Tectonics and landscape evolution; Asia. 1 I N T RO D U C T I O N The revolution brought by the digital acquisition of seismologi- cal data has increased the interest of studying continuous seis- mic recordings which has led in turn to an expansion in the ex- ploration and comprehension of seismic noise. Ambient noise af- fects the entire frequency band of interest in seismology. At very low frequencies (0.002–0.01 Hz), the seismic ‘hum’ of the Earth has a complex origin which includes interactions between atmo- sphere, ocean and seafloor (e.g. Rhie & Romanowicz 2004, 2006).
Image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Image of page 2
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern