Contact Information

Division of Biogeoscience
Division of Geology and Geochemistry
Division of Urban Geograpahy and Regional Studies
Study Office

P.O. Box 64
(Gustaf Hällströmin katu 2a)
FI-00014 University of Helsinki

Department Office
Institute of Seismology

P.O. Box 68
(Gustaf Hällströmin katu 2b)
FI-00014 University of Helsinki

phone +358 294 1911 (university exchange)
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Send us email (firstname.lastname@helsinki.fi)

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Laboratories and Facilities

Coordinates

Gregor Hillers, PhD
Associate Professor in Seismology
Exactum D420
+358 2 941 51627
+358 50-3118206

ORCID

0000-0003-2341-1892

Summary

Changes in the physical properties of the Earth occur on a vast range of time scales. These scales range from the millions of years associated with the organization of the tectonic plates to the seconds it takes for an earthquake rupture to propagate. Within this spectrum, I am mostly interested in dynamic processes and tectonic phenomena that are tangible for human experience.

As a seismologist, I decipher signatures of time dependent rock properties that can be studied using seismic waves. I study waves excited by earthquakes as well as the ambient seismic wavefield or background noise. I try to measure the response or behavior of rocks to various loading mechanisms. This means I estimate how the seismic velocities of crustal rocks or fault zone rocks change in response to pressure or stress changes. Loading mechanisms can include atmospheric processes (how do pressure, temperature, and precipitation affect rock properties?), tidal forces (what are the effects of the gravitational tug of sun and moon?), tectonic deformation (can we measure the load change from one earthquake on another earthquake fault?), and anthropogenic or engineering activity (how do rocks behave in response to fluid injection, impoundment, excavation, ground water depletion?). The fun challenge is to learn from the responses associated with each event to better understand earthquakes or other modes of deformation along fault zones.

Research Interests

Fault zone seismology
Fault zone dynamics
Array seismology
Ambient noise surface wave imaging
Passive monitoring

Publications

Hillers, G. and M. Campillo (2018), Fault Zone Imaging from Correlations of Aftershock Waveforms, Pure Appl. Geophys., doi:10.1007/s00024-018-1836-7 pdf

Roux, P., D. Bindi, T. Boxberger, A. Colombi, F. Cotton, I. Douste-Bacque, S. Garambois, P. Gueguen, G. Hillers, D. Hollis, T. Lecocq, and I. Pondaven (2018), Toward Seismic Metamaterials: The METAFORET Project, Seism. Res. Lett., doi:10.1785/0220170196

Hillers, G., P. Roux, M. Campillo, and Y. Ben-Zion (2016), Focal spot imaging based on zero lag cross-correlation amplitude fields: Application to dense array data at the San Jacinto fault zone, J. Geophys. Res. Solid Earth, 121, 8048-8067, doi:10.1002/2016JB013014

Roux, P., L. Moreau, A. Lecointre, G. Hillers, M. Campillo, Y. Ben-Zion, D. Zigone, and F. Vernon (2016), A methodological approach toward high-resolution seismic imaging of the San Jacinto Fault Zone using ambient-noise recordings at a spatially dense array, Geophys. J. Int., 206, 980–992, doi:10.1093/gji/ggw193,

Hillers, G. and M. Campillo (2016), Fault zone reverberations from cross-correlations of earthquake waveforms and seismic noise, Geophys. J. Int., 204, 1503–1517, doi:10.1093/gji/ggv515

Hillers, G., S. Husen, A. Obermann, T. Planès, E. Larose, and M. Campillo (2015), Noise-based monitoring and imaging of aseismic transient deformation induced by the 2006 Basel reservoir stimulation, Geophysics, 80, 51–68, doi:10.1190/GEO2014-0455.1

Hillers, G., Y. Ben-Zion, M. Campillo, and D. Zigone (2015), Seasonal variations of seismic velocities in the San Jacinto Fault area observed with ambient seismic noise, Geophys. J. Int., 202, 920–932, doi:10.1093/gji/ggv151

Hillers, G., L. Retailleau, M. Campillo, A. Inbal, J.-P. Ampuero, and T. Nishimura (2015), In-situ observations of velocity changes in response to tidal deformation from analysis of the high-frequency ambient wavefield, J. Geophys. Res., 120, 210–225, doi:10.1002/2014JB011318

Colombi, A., J. Chaput, F. Brenguier, G. Hillers, P. Roux, and M. Campillo (2014), On the temporal stability of the coda of ambient noise correlations, C. R. Geoscience, 346, 307–316, doi:10.1016/j.crte.2014.10.002

Landès, M., A. Le Pichon, N. M. Shapiro, G. Hillers, and M. Campillo (2014), Explaining global patterns of microbarom observations with wave action models, Geophys. J. Int., 199, 1328–1337

Hillers, G., M. Campillo, Y. Ben-Zion, and P. Roux (2014), Seismic fault zone trapped noise, J. Geophys. Res., 119, 5786–5799, doi:10.1002/2014JB011217

Hillers, G., M. Campillo, and K.-F. Ma (2014), Seismic velocity variations at TCDP are controlled by MJO driven precipitation pattern and high fluid discharge properties, Earth Planet. Sci. Lett., 391, 121–127, doi:10.1016/j.epsl.2014.01.040

Hillers, G., Y. Ben-Zion, M. Landès, and M. Campillo (2013), Interaction of microseisms with crustal heterogeneity: A case study from the San Jacinto fault zone area, Geochem. Geophys. Geosyst., 14, doi:10.1002/ggge.20140

Hillers, G., M. Campillo, Y.-Y. Lin, K.-F. Ma, and P. Roux (2012), Anatomy of the high-frequency ambient seismic wave field at the TCDP borehole, Taiwan, J. Geophys. Res., 117, doi:10.1029/2011JB008999

Hillers, G., N. Graham, M. Campillo, S. Kedar, M. Landès and N. Shapiro (2012), Global oceanic microseism sources as seen by seismic arrays and predicted by wave action models, Geochem. Geophys. Geosyst., 13, doi:10.1029/2011GC003875

Hillers, G. and Y. Ben-Zion (2011), Seasonal variations of observed noise amplitudes at 2 – 18 Hz in southern California, Geophys. J. Int., 184, 860–868, doi: 10.1111/j.1365-246X.2010.04886.x

Hillers, G., J. M. Carlson, and R. J. Archuleta (2009), Seismicity in a model governed by competing frictional weakening and healing mechanisms, Geophys. J. Int., 178, 1363–1383, doi: 10.1111/j.1365-246X.2009.04217.x

Hillers, G. and S. G. Wesnousky (2008), Scaling Relations of Strike Slip Earthquakes With Different Slip Rate Dependent Properties at Depth, Bull. Seism. Soc. Am., 98(3), 1085–1101, doi: 0.1785/0120070200

Hillers, G., P. M. Mai, Y. Ben-Zion, and J.-P. Ampuero (2007), Statistical properties of seismicity of fault zones at different evolutionary stages, Geophys. J. Int., 169, 515–533, doi: 10.1111/j.1365-246X.2006.03275.x

Hillers, G., Y. Ben-Zion, and P. M. Mai (2006), Seismicity on a fault controlled by rate- and state-dependent friction with spatial variations of the critical slip distance, J. Geophys. Res., 111, B01403, doi:10.1029/2005JB003859

Hillers, G. and S. A. Miller (2007), Dilatancy controlled spatio-temporal slip evolution of a sealed fault with spatial variations of the pore pressure, Geophys. J. Int., 168, 431–445, doi: 10.1111/j.1365-246X.2006.03167.x

Hillers, G. and S. A. Miller (2006), Stability regimes of dilatant, fluid infiltrated fault plane in a 3-D elastic solid, J. Geophys. Res., 111, B08304, doi:10.1029/2005JB003872

Mai, P. M., J. Ripperger, J.-P. Ampuero, and G. Hillers (2006), Frontiers in Source Modeling for Near-Source Ground-Motion Prediction, Third International Symposium on the Effects of Surface Geology on Seismic Motion, Grenoble, edited by P.-Y. Bard, E. Chaljub, C. Cornou, F. Cotton, P. Guegen, 97–114

Employment

2017 - present: Associate Professor, Institut of Seismology, University of Helsinki, Helsinki, Finland
2012 - 2017: DFG Heisenberg Fellow, Institut des Sciences de la Terre, Université Grenoble Alpes, Grenoble, France
2010 - 2012: Postdoctoral Researcher, Institut des Sciences de la Terre, Université Grenoble Alpes, Grenoble, France
2008 - 2010: Postdoctoral Researcher, Seismological Laboratory, Caltech, Pasadena, USA
2006 - 2008: Postdoctoral Researcher, University of California Santa Barbara, Santa Barbara, USA

Education

PhD Geophysics, ETH Zürich, Switzerland, 2005
Diploma in Geophysics, Ruhr-Universität Bochum, Germany, 2001