Gregor Hillers

Gregor Hillers, PhD

Associate Professor in Seismology
Exactum D420
gregor.hillers[at]helsinki.fi
+358 50 31 18 206   (mobile number)
+358 29 41 51 627   (landline > mobile device)

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
 

Zigone, D., Y. Ben-Zion, M. Lehujeur, M. Campillo, G. Hillers and F. L. Vernon (2019), Imaging subsurface structures in the San Jacinto fault zone with high-frequency noise recorded by dense linear arrays, Geophys. J. Int., 217, 879–893, doi: 10.1093/gji/ggz069 pdf

Mao, S., M. Campillo, R.D.van der Hilst, F. Brenguier, L. Stehly and G. Hillers (2019), High temporal resolution monitoring of small variations in crustal strain by dense seismic arrays., Geophys. Res. Lett., 46, 128–137, doi: 10.1029/2018GL079944 pdf

Taylor, G., S. Rost, G. A. Houseman, and G. Hillers (2019), Near-surface structure of the North Anatolian Fault zone from Rayleigh and Love wave tomography using ambient seismic noise, Solid Earth, 10, 363–378, doi: 10.5194/se-10-363-2019 pdf

Inbal, A., T. Cristea-Platon, J.-P. Ampuero, G. Hillers, D. Agnew and S. E. Hough (2018), Sources of long-range anthropogenic noise in southern California and implications for tectonic tremor detection, Bull. Seism. Soc. Am., 108(6), 3511–3527, doi: 10.1785/0120180130 pdf

Hillers, G. and M. Campillo (2018), Fault Zone Imaging from Correlations of Aftershock Waveforms, Pure Appl. Geophys., 175, 2643–2667, 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., 89, 582–593, doi: 10.1785/0220170196 pdf

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 pdf

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 pdf

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 pdf

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 pdf

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 pdf

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 pdf

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 pdf

Landes, 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, doi: 10.1093/gji/ggu324 pdf

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 pdf

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 pdf

Hillers, G., Y. Ben-Zion, M. Landes, 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 pdf

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 pdf

Hillers, G., N. Graham, M. Campillo, S. Kedar, M. Landes 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 pdf

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 pdf

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 pdf

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 pdf

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 pdf

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 pdf

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 pdf

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 pdf

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, Institute 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