Gregor Hillers, PhD
Professor in Seismology
Exactum D420
gregor.hillers[at]helsinki.fi
+358 50 31 18 206
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
Reviewed Articles
Taylor, G., Hillers, G., and T. A. T. Vuorinen (2021), Using array-derived rotational motion to obtain local wave propagation properties from earthquakes induced by the 2018 geothermal stimulation in Finland, Geophys. Res. Lett., 48, e2020GL090403, doi: 10.1029/2020GL090403, pdf, AGU-2020_13-min_presentation
Veikkolainen, T., J. Kortström, T. Vuorinen, I. Salmenperä, T. Luhta, P. Mäntyniemi, G. Hillers, and T. Tiira (2021), The Finnish National Seismic Network: Toward Fully Automated Analysis of Low-Magnitude Seismic Events, Seismol. Res. Lett., doi: 10.1785/0220200352 pdf
Lecocq, T., S. P. Hicks, K. Van Noten, K. van Wijk, P. Koelemeijer, R. S. M. De Plaen, F. Massin, G. Hillers, R. E. Anthony, M.-T. Apoloner, M. Arroyo-Solórzano, J. D. Assink, P. Büyükakpınar, A. Cannata, F. Cannavo, S. Carrasco, C. Caudron, E. J. Chaves, D. G. Cornwell, D. Craig, O. F. C. den Ouden, J. Diaz, S. Donner, C. P. Evangelidis, L. Evers, B. Fauville, G. A. Fernandez, D. Giannopoulos, S. J. Gibbons, T. Girona, B. Grecu, M. Grunberg, G. Hetényi, A. Horleston, A. Inza, J. C. E. Irving, M. Jamalreyhani, A. Kafka, M. R. Koymans, C. R. Labedz, E. Larose, N. J. Lindsey, M. McKinnon, T. Megies, M. S. Miller, W. Minarik, L. Moresi, V. H. Márquez-Ramı́rez, M. Möllhoff, I. M. Nesbitt, S. Niyogi, J. Ojeda, A. Oth, S. Proud, J. Pulli, L. Retailleau, A. E. Rintamäki, C. Satriano, M. K. Savage, S. ShaniKadmiel, R. Sleeman, E. Sokos, K. Stammler, A. E. Stott, S. Subedi, M. B. Sørensen, T. Taira, M. Tapia, F. Turhan, B. van der Pluijm, M. Vanstone, J. Vergne, T. A. T. Vuorinen, T. Warren, J. Wassermann, and H. Xiao (2020), Global quieting of high-frequency seismic noise due to COVID-19 pandemic lockdown measures, Science, doi:10.1126/science.abd2438 article HelsinginSanomatArticleFIN GlobalPressCoverage
Moreau, L., P. Boué, A. Serripierri, J. Weiss, D. Hollis, I. Pondaven, B. Vial, S. Garambois, E. Larose, A. Helmstetter, L. Stehly, G. Hillers, and O. Gilbert (2020), Sea ice thickness and elastic properties from the analysis of multimodal guided wave propagation measured with a passive seismic array, J. Geophys. Res.: Oceans, 125, e2019JC015709, doi: 10.1029/2019JC015709 pdf
Hillers, G., T. A. T. Vuorinen, M. R. Uski, J. T. Kortström, P. B. Mäntyniemi, T. Tiira, P. E. Malin, and T. Saarno (2020), The 2018 Geothermal Reservoir Stimulation in Espoo/Helsinki, Southern Finland: Seismic Network Anatomy and Data Features, Seismol. Res. Lett., 91 (2A), 770–786, doi: 10.1785/0220190253 pdf PressReleaseENG PressReleaseFIN HelsinginSanomatArticleFIN
Qiu, H., G. Hillers, and Y. Ben-Zion (2020), Temporal changes of seismic velocities in the San Jacinto Fault zone associated with the 2016 Mw 5.2 Borrego Springs earthquake, Geophys. J. Int., 220, 1536–1554, doi: 10.1093/gji/ggz538 pdf
Taylor, G. and G. Hillers (2020), Estimating temporal changes in seismic velocity using a Markov chain Monte Carlo approach, Geophys. J. Int., 220, 1791–1803, doi: 10.1093/gji/ggz535 pdf code
Hillers, G., M. Campillo, F. Brenguier, L. Moreau, D. C. Agnew, and Y. Ben-Zion (2019), Seismic velocity change patterns along the San Jacinto fault zone following the 2010 M 7.2 El Mayor-Cucapah and M 5.4 Collins Valley earthquakes, J. Geophy. Res. Solid Earth, 124, 7171–7192, doi:10.1029/2018JB017143 pdf
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
Book chapters
Obermann, A. and G. Hillers (2019), Seismic time-lapse interferometry across scales, in Advances in Geophysics, edited by C. Schmelzbach, Vol. 60, chapter 2, 65–143 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
Data sets
Hillers, G., T. A. T. Vuorinen, E. J. Arola, V. E. Katajisto, M. P. Koskenniemi, B. M. McKevitt, S. Rezaei, L. A. Rinne, I. E. Salmenperä, P. J. Seipäjärvi, L. S. O. Väkevä, A. I. Voutilainen, K. Arhe, A. K. Juntunen, J. Keskinen, P. Lindblom, K. Oinonen, and T. Tiira (2019), A 100 3-component sensor deployment to monitor the 2018 EGS stimulation in Espoo/Helsinki, southern Finland, Dataset. GFZ Data Services, doi:10.5880/GIPP.201802.1 link
Employment
since 04 / 2021: Professor, Institute of Seismology, University of Helsinki, Helsinki, Finland
2017 - 2021: Tenure Track 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