Ambient seismic noise, once regarded as a nuisance, is now a core part of the seismological toolkit. Tomographic images are constructed from surface waves within small arrays and on the continental scale. Reflected waves are recovered from cross- and autocorrelations of the ambient field at local and teleseismic distances. Temporal variations of wave velocities and impedance structure are observed in the very shallow subsurface and at significant depth and led to the discovery of dynamic processes in the subsurface with relevance for earthquake triggering and relaxation, volcano and landslide dynamics as well as for the production from hydrocarbon reservoirs and geothermal fields. Established techniques are now routinely applied but new types of applications and continuing developments of new processing strategies constantly extend the capabilities of the noise based techniques. In addition, there are many unknowns related to the distributed and temporally variable sources of ambient vibrations. This variability affects the stability of seismic ‘noise correlation’ signals which leads to uncertainties in the seismic images and complicated time-lapse observations.

In this session, we focus on open questions and methodological advances in seismic interferometry and ambient noise based seismology. We invite (A) contributions on new methodological approaches in seismic interferometry and noise processing (B) studies of time variations of elastic material properties and (C) investigations of the sources of the ambient seismic noise.

This extends to evaluations of the accuracy of noise-based measurements for use in tomography or time-dependent imaging. It includes theoretical advances, such as the use of deconvolution or those exploring the role of source distribution or scattering, as well as methodological improvements and alternative processing techniques aimed at enhancing the quality of the correlations. Understanding the noise generation processes (microseisms, hum, microbaroms, etc) and causes of temporal variations of the noise field and the medium properties (dynamic and static stress changes, hydrology, etc.), and their effects on noise correlations is of fundamental interest in this context.

Invited speaker: Lise Retailleau (Stanford, USA)