Evidence for temporal clustering of large earthquakes in the wellington region from computer models of seismicity

  • Russell Robinson GNS Science, Lower Hutt, New Zealand
  • Rafael Benites GNS Science, Lower Hutt, New Zealand
  • Russ Van Dissen GNS Science, Lower Hutt, New Zealand


Temporal clustering of large earthquakes in the Wellington region, New Zealand, has been investigated with a computer model that generates long synthetic seismicity catalogues. The model includes the elastic interactions between faults. Faults included in the model, besides the subduction thrust between the Australian and Pacific plates, are segments of the four major strike-slip faults that overlie the plate interface (Wairarapa, Wellington, Ohariu, and Wairau faults). Parameters of the model are adjusted to reproduce the geologically ohserved slip rates of the strike-slip faults. The seismic slip rate of the subduction thrust, which is unknown, is taken as 25% of the maximum predicted by the plate tectonic convergence rate, and its position fixed according to recent geodetic results. For comparison, the model was rerun with the elastic interactions suppressed, corresponding to the usual approach in the calculation of seismic hazard where each fault is considered in isolation. Considering earthquakes of magnitude 7.2 or more ("characteristic" events in the sense that they rupture most of a fault plane). the number of short (0-3 years) inter-event times is much higher with interactions than for the corresponding case without interactions (46% vs. 2% or all inter-event times). This reduces to 9% vs. 2% if the subduction thrust is removed from the models. Paleoseismic studies of the past seismic behaviour of the subduction thrust are clearly needed if the degree of clustering is to be tightly constrained. Although some other aspects of our model can he improved in future, we think that the probability of significant short-term clustering of large events, normally neglected in hazard studies, is very high. This has important implications for the engineering, insurance and emergency response communities.


Ben-Zion. Y. and J.R. Rice, (1993). Earthquake failure sequences along a cellular fault zone in a threedimensional elastic solid containing asperity and nonasperity regions. J. Geophys. Res., 98, 14. 109-14, 131.

Darby, D.J., J. Bcavan, and R. Williams, (1996). Coupling of the Hikurangi subduction interface beneath the Wellington region of New Zealand as inferred from GPS measurements. Eos Trans. AGU, 77(22). Western Pacific Geophysics Meet. Suppl. Wl4. Also recent unpublished results.

Dowrick, D.J., (1991). A revision of attenuation relationships for Modified Mercalli intensity in New Zealand earthquakes. Bull. N.Z. Nat. Soc. Earthquake Eng., 24. 210-224. DOI: https://doi.org/10.5459/bnzsee.24.3.210-224

Kagan, Y.Y., and D.D. Jackson, (1991). Long-term earthquake clustering. Geophys. J. Int., 104, 117-133. DOI: https://doi.org/10.1111/j.1365-246X.1991.tb02498.x

Okada, Y., (1992). Internal deformation due to shear and tensile faults in a half-space. Bull. Seismol. Soc. Am., 82, 1018-1040.

Reasenberg, P. A., and R.W. Simpson, (1992). Response of regional seismicity to the static stress change produced by the Loma Prieta earthquake. Science, 255, 1687-1690. DOI: https://doi.org/10.1126/science.255.5052.1687

Robinson. R., (1986). Scismicity, structure, and tectonics of the Wellington region, New Zealand. Geophys. J. Roy. Astron. Soc., 87, 379-409. DOI: https://doi.org/10.1111/j.1365-246X.1986.tb06629.x

Robinson, R., and R. Benites. (1995). Synthetic seismicity models of multiple interacting faults. J. Geophys. Res., 100. 18229-18238. DOI: https://doi.org/10.1029/95JB01569

Robinson, R., and R. Benites, (1996). Synthetic seismicity models for the Wellington region, New Zealand: Implications for the temporal distribution of large events. J. Geophys. Res., 101, 27,833-27,845. DOI: https://doi.org/10.1029/96JB02533

Simpson, R.W., and P. A. Reasenberg, (1994). Earthquake-induced static-stress changes on central California faults. In: The Loma Prieta, California, Earthquake of October 17, 1989 - Tectonic Processes and Models, edited by R.W. Simpson. U.S. Geol. Surv. Prof. Pap. 1550-F, F55-F89.

Stirling, M.W.. S.G. Wesnousky, and K. Shimazaki, (1996). Fault trace complexity, and the shape of the magnitude-frequency distribution for strike-slip faults: A global survey. Geophys. J. Int., 124, 833-868. DOI: https://doi.org/10.1111/j.1365-246X.1996.tb05641.x

Van Dissen, R.J, and K.R. Berryman, (1996). Surface rupture earthquakes over the last ca. 1000 years in the Wellington region, New Zealand, and implications for ground shaking hazard. J. Geophys. Res., 101, 5,999-6,019. Also recent unpublished results.

Walcott. R.I., (1978). Geodetic strains and large earthquakes in the axial tectonic belt of North Island, New Zealand. J. Geophys. Res., 83, 4419-4429. DOI: https://doi.org/10.1029/JB083iB09p04419

Walcott, R.I., (1984). The kinematics of the plate boundary zone through New Zealand: a comparison of short- and long-term deformations. Geophys. J. R. Astron. Soc., 79, 613-633. DOI: https://doi.org/10.1111/j.1365-246X.1984.tb02244.x

Ward, S.N., (1992). An application of synthetic seismicity calculations in earthquake statistics: The Middle America Trench. J. Geophys. Res., 97, 6675-6682. DOI: https://doi.org/10.1029/92JB00236

Ward, S.N., (1996). A synthetic seismicity model for southern California: Cycles, probabilities, and hazard. J. Geophys. Res., 101, 22,393-22,418. DOI: https://doi.org/10.1029/96JB02116

How to Cite
Robinson, R., Benites, R., & Van Dissen, R. (1998). Evidence for temporal clustering of large earthquakes in the wellington region from computer models of seismicity . Bulletin of the New Zealand Society for Earthquake Engineering, 31(1), 24-32. https://doi.org/10.5459/bnzsee.31.1.24-32

Most read articles by the same author(s)