Abstract
Weak seismic vibrations—tectonic tremor—can be used to delineate some plate boundary faults. Tremor on the deep San Andreas Fault, located at the boundary between the Pacific and North American plates, is thought to be a passive indicator of slow fault slip. San Andreas Fault tremor migrates at up to 30 m s−1, but the processes regulating tremor migration are unclear. Here I use a 12-year catalogue of more than 850,000 low-frequency earthquakes to systematically analyse the high-speed migration of tremor along the San Andreas Fault. I find that tremor migrates most effectively through regions of greatest tremor production and does not propagate through regions with gaps in tremor production. I interpret the rapid tremor migration as a self-regulating cascade of seismic ruptures along the fault, which implies that tremor may be an active, rather than passive participant in the slip propagation. I also identify an isolated group of tremor sources that are offset eastwards beneath the San Andreas Fault, possibly indicative of the interface between the Monterey Microplate, a hypothesized remnant of the subducted Farallon Plate, and the North American Plate. These observations illustrate a possible link between the central San Andreas Fault and tremor-producing subduction zones.
This is a preview of subscription content, access via your institution
Access options
Subscribe to this journal
Receive 12 print issues and online access
$259.00 per year
only $21.58 per issue
Rent or buy this article
Prices vary by article type
from$1.95
to$39.95
Prices may be subject to local taxes which are calculated during checkout
Similar content being viewed by others
References
Beroza, G. C. & Ide, S. Slow earthquakes and nonvolcanic tremor. Annu. Rev. Earth Planet. Sci. 39, 271–296 (2011).
Shelly, D. R., Beroza, G. C. & Ide, S. Non-volcanic tremor and low frequency earthquake swarms. Nature 446, 305–307 (2007).
Obara, K. Nonvolcanic deep tremor associated with subduction in southwest Japan. Science 296, 1679–1681 (2002).
Dragert, H., Wang, K. & Rogers, G. Geodetic and seismic signatures of episodic tremor and slip in the northern Cascadia subduction zone. Earth Planets Space 56, 1143–1150 (2004).
Shelly, D. R., Beroza, G. C. & Ide, S. Complex evolution of transient slip derived from precise tremor locations in western Shikoku, Japan. Geochem. Geophys. Geosyst. 8, Q10014 (2007).
Ghosh, A. et al. Rapid, continuous streaking of tremor in Cascadia. Geochem. Geophys. Geosyst. 11, Q12010 (2010).
Shelly, D. R. Migrating tremors illuminate complex deformation beneath the seismogenic San Andreas fault. Nature 463, 648–652 (2010).
Houston, H., Delbridge, B. G., Wech, A. G. & Creager, K. C. Rapid tremor reversals in Cascadia generated by a weakened plate interface. Nature Geosci. 4, 404–409 (2011).
Ando, R., Nakata, R. & Hori, T. A slip pulse model with fault heterogeneity for low-frequency earthquakes and tremor along plate interfaces. Geophys. Res. Lett. 37, L10310 (2010).
Ando, R., Takeda, N. & Yamashita, T. Propagation dynamics of seismic and aseismic slip governed by fault heterogeneity and Newtonian rheology. J. Geophys. Res. 117, B11308 (2012).
Rubin, A. M. Designer friction laws for bimodal slow slip propagation speeds. Geochem. Geophys. Geosyst. 12, Q04007 (2011).
Obara, K., Matsuzawa, T., Tanaka, S. & Maeda, T. Depth-dependent mode of tremor migration beneath Kii Peninsula, Nankai subduction zone. Geophys. Res. Lett. 39, L10308 (2012).
Ide, S. Striations, duration, migration and tidal response in deep tremor. Nature 466, 356–359 (2010).
Nadeau, R. M. & Dolenc, D. Nonvolcanic tremors deep beneath the San Andreas Fault. Science 307, 389 (2005).
Shelly, D. R. & Hardebeck, J. L. Precise tremor source locations and amplitude variations along the lower-crustal central San Andreas Fault. Geophys. Res. Lett. 37, L14301 (2010).
Thomas, A. M., Bürgmann, R., Shelly, D. R., Beeler, N. M. & Rudolph, M. L. Tidal triggering of low frequency earthquakes near Parkfield, California: Implications for fault mechanics within the brittle-ductile transition. J. Geophys. Res. 117, B05301 (2012).
Rubin, A. M. & Armbruster, J. G. Imaging slow slip fronts in Cascadia with high precision cross-station tremor locations. Geochem. Geophys. Geosyst. 14, 5371–5392 (2013).
Kao, H., Wang, K., Dragert, H., Kao, J. Y. & Rogers, G. Estimating seismic moment magnitude (Mw) of tremor bursts in northern Cascadia: Implications for the “seismic efficiency” of episodic tremor and slip. Geophys. Res. Lett. 37, L19306 (2010).
Samuelson, J., Elsworth, D. & Marone, C. Shear-induced dilatancy of fluid-saturated faults: Experiment and theory. J. Geophys. Res. 114, B12404 (2009).
Segall, P., Rubin, A. M., Bradley, A. M. & Rice, J. R. Dilatant strengthening as a mechanism for slow slip events. J. Geophys. Res. 115, B12305 (2010).
Yamashita, T. & Suzuki, T. Dynamic modeling of slow slip coupled with tremor. J. Geophys. Res. 116, B05201 (2011).
Yamashita, T. Generation of slow slip coupled with tremor due to fluid flow along a fault. Geophys. J. Int. 193, 375–393 (2013).
Segall, P. & Rice, J. R. Dilatancy, compaction, and slip instability of a fluid infiltrated fault. J. Geophys. Res. 100, 22155–22171 (1995).
Shelly, D. R., Beroza, G. C., Ide, S. & Nakamula, S. Low-frequency earthquakes in Shikoku, Japan and their relationship to episodic tremor and slip. Nature 442, 188–191 (2006).
Audet, P., Bostock, M. G., Christensen, N. I. & Peacock, S. M. Seismic evidence for overpressured subducted oceanic crust and megathrust fault sealing. Nature 457, 76–78 (2009).
Thomas, A. M., Nadeau, R. M. & Burgmann, R. Tremor-tide correlations and near-lithostatic pore pressure on the deep San Andreas fault. Nature 462, 1048–1051 (2009).
Beeler, N. M., Thomas, A., Bürgmann, R. & Shelly, D. Inferring fault rheology from low-frequency earthquakes on the San Andreas. J. Geophys. Res. 118, 5976–5990 (2013).
Ghosh, A., Vidale, J. E., Sweet, J. R., Creager, K. C. & Wech, A. G. Tremor patches in Cascadia revealed by seismic array analysis. Geophys. Res. Lett. 36, L17316 (2009).
Rice, J. R. in Fault Mechanics and Transport Properties of Rocks (eds Evans, B. & Wong, T-f.) 475–503 (Academic Press, 1992); http://go.nature.com/3Uia78
Ingebritsen, S. E. & Manning, C. E. Permeability of the continental crust: Dynamic variations inferred from seismicity and metamorphism. Geofluids 10, 193–205 (2010).
Ingebritsen, S. E. & Manning, C. E. Geological implications of a permeability-depth curve for the continental crust. Geology 27, 1107–1110 (1999).
Shelly, D. R. & Johnson, K. M. Tremor reveals stress shadowing, deep postseismic creep, and depth-dependent slip recurrence on the lower-crustal San Andreas fault near Parkfield. Geophys. Res. Lett. 38, L13312 (2011).
Wesnousky, S. G. Predicting the endpoints of earthquake ruptures. Nature 444, 358–360 (2006).
Shelly, D. R. Periodic, chaotic, and doubled recurrence intervals on the deep San Andreas Fault. Science 328, 1385–1388 (2010).
Pikser, J. E., Forsyth, D. W. & Hirth, G. Along-strike translation of a fossil slab. Earth Planet. Sci. Lett. 331, 315–321 (2012).
Wang, Y. et al. Fossil Slabs attached to unsubducted fragments of the Farallon Plate. Proc. Natl Acad. Sci. USA 110, 5342–5346 (2013).
Bohannon, R. G. & Parsons, T. Tectonic implications of post-30 Ma Pacific and North American relative plate motions. Geol. Soc. Am. Bull. 107, 937–959 (1995).
Kirby, S. H., Wang, K. & Brocher, T. M. A large mantle water source for the northern San Andreas fault system: A ghost of subduction past. Earth Planets Space 66, 1–18 (2014).
Waldhauser, F. & Schaff, D. P. Large-scale relocation of two decades of Northern California seismicity using cross-correlation and double-difference methods. J. Geophys. Res. 113, B08311 (2008).
Acknowledgements
I am very grateful for feedback and reviews from G. McLaskey, O. Kaven, D. Hill, J. Hardebeck, A. Thomas, D. Trugman and N. Beeler, all of which helped to improve the manuscript. The HRSN borehole seismic network, which was used to detect LFEs examined in this study, is operated by UC Berkeley. Data were obtained through the Northern California Earthquake Data Center (NCEDC).
Author information
Authors and Affiliations
Corresponding author
Ethics declarations
Competing interests
The author declares no competing financial interests.
Supplementary information
Supplementary Information
Supplementary Information (PDF 484 kb)
Rights and permissions
About this article
Cite this article
Shelly, D. Complexity of the deep San Andreas Fault zone defined by cascading tremor. Nature Geosci 8, 145–151 (2015). https://doi.org/10.1038/ngeo2335
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1038/ngeo2335
This article is cited by
-
Cascading rupture of patches of high seismic energy release controls the growth process of episodic tremor and slip events
Earth, Planets and Space (2021)
-
Geological constraints on the mechanisms of slow earthquakes
Nature Reviews Earth & Environment (2021)
-
Similarity of fast and slow earthquakes illuminated by machine learning
Nature Geoscience (2019)
-
Strength of tremor patches along deep transition zone of a megathrust
Scientific Reports (2018)
-
The Parkfield tremors reveal slow and fast ruptures on the same asperity
Nature (2016)