The Mw 7.6 Dusky Sound earthquake of 2009
Preliminary report
DOI:
https://doi.org/10.5459/bnzsee.43.1.24-40Abstract
The Mw 7.6 Dusky Sound earthquake of July 15th, 2009, was the largest magnitude earthquake in New Zealand since the devastating 1931 Hawke’s Bay event (Ms 7.8). The earthquake was sufficiently large to generate at least a 2.3 m wave at Passage Point. Despite its large magnitude, this event resulted in relatively minimal damage when compared to worldwide events of a similar size. This can be explained as a fortunate combination of the sparse population of the area and the specific physical characteristics of the earthquake. Centroid Moment Tensor (CMT) solutions define the rupture surface as a low-angle plane and finite fault inversions confirm the slip occurred on the interface between the eastward-subducting Australian plate and overriding Pacific plate, initiating at about 30 km depth and rupturing upward and southwestward to about 15 km depth. The oceanward rupture directivity likely contributed to the lower intensity of measured ground motion than might be expected for such a large, shallow event. The amount of radiated seismic energy from the earthquake was relatively small, and far fewer landslides were triggered from this event than from the 2003 Mw 7.2 Fiordland event.
References
Bowman, D. D. & King, G. C. P., (1995). “Accelerating seismicity and stress accumulation before large earthquakes,” Geophysical Research Letters, 28, 4039-4032. DOI: https://doi.org/10.1029/2001GL013022
Bowman, D. D., Ouillon, G., Sammis, C. G., Sornette, A. & Sornette, D., (1998) “An observational test of the critical earthquake concept”. Journal of Geophysical Research, 103, 24359-24372. DOI: https://doi.org/10.1029/98JB00792
Choy, G.L., McGarr, A., Kirby, S.H. and Boatwright, J., (2006). “An overview of the global variability in radiated energy and apparent stress”. Geophysical Monograph, 170: 43-57.
Christensen, D.H. and Ruff, L.J., (1983). “Outer-rise earthquakes and seismic coupling.” Geophysical Research Letters, 10(8): 697-700. DOI: https://doi.org/10.1029/GL010i008p00697
DeMets, C., Gordon, R.G., Argus, D.F. and Stein, S., (1994). “Effect of recent revisions to the geomagnetic reversal time scale on estimates of current plate motions”. Geophysical Research Letters, 21(20): 2191-2194. DOI: https://doi.org/10.1029/94GL02118
Doser, D.I., Webb, T.H. and Maunder, D.E., (1999). “Source parameters of large historical (1918-1962) earthquakes, South Island, New Zealand.” Geophysical Journal International, 139(3): 769-794. DOI: https://doi.org/10.1046/j.1365-246x.1999.00986.x
Dowrick, D.J., Hancox, G.T., Perrin, N.D., Dellow, G.D., (2008). “The Modified Mercalli Intensity Scale – Revisions arising from New Zealand experience”. Bulletin of the New Zealand Society for Earthquake Engineering, Vol. 41, No. 3, September 2008, pp 193–205.
Dreger, D. & Helmerberger, D. V., (1993). “Determination of source parameters at regional distances with single station or sparse network data”. Journal of Geophysical Research, 98, 8107-8125. DOI: https://doi.org/10.1029/93JB00023
Dreger, D. S., (2003). “TDMT_INV: Time Domain Seismic Moment Tensor INVersion” International Handbook of Earthquake and Engineering Seismology, 81B, 1627. DOI: https://doi.org/10.1016/S0074-6142(03)80290-5
Eberhart-Phillips, D. and Reyners, M., (2001). “A complex, young subduction zone imaged by three-dimensional seismic velocity, Fiordland, New Zealand.” Geophysical Journal International, 146(3): 731-746. DOI: https://doi.org/10.1046/j.0956-540x.2001.01485.x
Guerrieri, L., Vittori, E., (2007). “Intensity Scale ESI (Environmental Seismic Intensity Scale)” 2007. Memorie Descriptive Della Carta Geologica d‟Italia, 74, Servizio Geologico d‟Italia – Dipartimento Difesa del Suolo, APAT, Rome, Italy.
Hancox, G.T., Cox, S.C., Turnbull, I.M., Crozier, M.J., (2003). “Reconnaissance studies of landslides and other ground damage caused by the Mw7.2 Fiordland earthquake of 22 August 2003”. Institute of Geological & Nuclear Sciences science report 2003/30, 32 p.
Hancox, G.T., Perrin, N.D., (2009). “Green Lake Landslide and other giant and very large postglacial landslides in Fiordland, New Zealand”. Quaternary Science Reviews: Special Issue “Natural hazards, extreme events, and mountain Topography”, Volume 28, Issues 11–12, June 2009, pp 1020–1036. DOI: https://doi.org/10.1016/j.quascirev.2008.08.017
Jaume, S. C. & Sykes, L. R., (1999). “Evolving toward a critical point : A review of accelerating seismic moment/energy release prior to large and great earthquakes”. Pure and Applied Geophysics, 155, 279-305. DOI: https://doi.org/10.1007/s000240050266
Jonsson, S., Zebker, H., Segall, P. & Amelung, F., (2002). “Fault slip distribution of the Hector Mine earthquake estimated from satellite radar and GPS measurements”, Bulletin of the Seismological Society of America, 92, 1377-1389. DOI: https://doi.org/10.1785/0120000922
King, G. C. P. & Cocco, M., (2001). “Fault interaction by elastic stress changes: New clues from earthquake sequences” Advances in Geophysics, 44, 1-38. DOI: https://doi.org/10.1016/S0065-2687(00)80006-0
Massonnet, D. & Feigl, K., (1998). “Radar interferometry and its application to changes in the Earth surface”, Reviews of Geophysics, 36, 441-500. DOI: https://doi.org/10.1029/97RG03139
McVerry, G. H., Zhao, J. X., Abrahamson, N. A. & Sommerville, P. G., (2006). “New Zealand acceleration response spectrum attenuation relations for crustal subduction zone earthquakes” Bulletin of the New Zealand Society for Earthquake Engineering, 39 (1): 1-58. DOI: https://doi.org/10.5459/bnzsee.39.1.1-58
Pasyanos, M. E., Dreger, D. S. & Romanowicz, B., (1996). “Towards real-time determaination of regional moment tensors”, Bulletin of the Seismological Society of America, 86, 1255-1269.
Prasetya, G., Beavan, J., Wang, X., Reyners, M., Power, M., Wilson, K. and Lokovich, B., “Evaluation of the July 15, 2009 Fiordland, New Zealand tsunami in the source region”, submitted to Pure & Applied Geophysics.
Reyners, M., McGinty, P., Cox, S., Turnbull, I., O‟Neill, T., Gledhill, K., Hancox, G., Beavan, J., Matheson, D., McVerry, G., Cousins, J., Zhao, J., Cowan, H., Caldwell, G., Bennie, S. and the GeoNet team, (2003). “The MW 7.2 Fiordland earthquake of August 21, 2003: background and preliminary results”. Bulletin of the New Zealand Society for Earthquake Engineering, 36(4).
Ristau, J., (2008). “Implementation of routine regional moment tensor analysis in New Zealand”. Seismological Research Letters, 79, 400-415. DOI: https://doi.org/10.1785/gssrl.79.3.400
Robinson, R., Zhou, S., Johnston, S. & Vere-Jones, D., (2005). “Precursory accelerating seismic moment release (AMR) in a synthetic seismicity catalog: A preliminary study”. Geophysical Research Letters, 32, L07309. DOI: https://doi.org/10.1029/2005GL022576
Rosen, P., Hensley, P., Joughin, I., Li, F., Madsen, S., Rodriguez, E. & Goldstein, R., (2000). “Synthetic aperture radar interferometry”, Proceedings of the IEEE, 88, 333-382. DOI: https://doi.org/10.1109/5.838084
Stein, R. S., (1999). “The role of stress transfer in earthquake occurrence”. Nature, 402, 6762, 605-609. DOI: https://doi.org/10.1038/45144
Van Dissen, R., Cousins, J., Robinson, R., Reyners, M., (1994). “The Fiordland earthquake of 10 August 1993”. Bulletin of the New Zealand Society for Earthquake Engineering 27: 147-154.
Wdowinski, S., Bock, Y., Zhang, J., Fang, P. and Genrich, J., (1997). “Southern California Permanent GPS Geodetic Array: Spatial filtering of daily positions for estimating coseismic and postseismic displacements induced by the 1992 Landers earthquake”, Journal of Geophysical Research, 102, 18,057-18,070. DOI: https://doi.org/10.1029/97JB01378
Wegmüller, U. & Werner, C., (1997). “Gamma SAR processor and interferometry software”, Third ERS Symposium on Space at the service of our Environment, Florence, Italy.
