Spatial distribution of ground shaking in characteristic earthquakes on the Wellington and Alpine faults, New Zealand, estimated from a distributed-source model

Abstract

A distributed-source model, recently developed by the authors, was used to study the spatial distribution of Modified Mercalli (MM) intensities and peak ground accelerations (PGA) in characteristic earthquakes, of Mw7.5 and 8.1 respectively, on the 75 km long Wellington fault and the 413 km long Alpine fault. In each event the predicted intensities reach MM10 and the PGAs reach 0.8g near the fault trace over much of its length, varying along it depending on the location of asperities. PGAs are related to MM intensity using a quadratic expression derived using New Zealand data. Comparisons are made between the PGA patterns estimated indirectly from the distributed-source MM intensity model and those estimated directly from a PGA model, which defines site-source distance as the shortest distance from the site to the fault. There are many similarities and some differences, the latter being attributable largely to the different methods of measuring site-to-source distances. Finally selected seismic risk issues for people and the built environment, including lifelines, are considered for Alpine fault earthquakes.

References

Cousins J., Spence, R. and So, E. (2008), “Estimated casualties in New Zealand earthquakes”. Proceedings Australian Earthquake Engineering Conference, AAES 2008, November 21-23, Ballarat, Victoria, Australia.

Davenport, P.N. (2003), “Instrumental measures of earthquake intensity in New Zealand”. Pacific Conference on Earthquake Engineering, Christchurch.

Dowrick, D.J. (1994), “Damage and intensities in the magnitude 7.8 1929 Murchison, New Zealand, earthquake”. Bulletin of the New Zealand National Society for Earthquake Engineering 27(3): 190-204.

Dowrick, D.J. and Rhoades, D.A. (1993), “Damage costs for commercial and industrial property as a function of intensity in the 1987 Edgecumbe earthquake”. Earthquake Engineering and Structural Dynamics 22: 869-884. DOI: https://doi.org/10.1002/eqe.4290221004

Dowrick, D.J. and Rhoades, D.A. (1999), “Attenuation of Modified Mercalli intensity in New Zealand earthquakes”. Bulletin of the New Zealand National Society for Earthquake Engineering 32(2): 22-89.

Dowrick, D.J. and Rhoades, D.A. (2005a), “Revised models for attenuation of Modified Mercalli intensity in New Zealand earthquakes”. Bulletin of the New Zealand Society for Earthquake Engineering 38(4): 185-214.

Dowrick, D.J. and Rhoades, D.A. (2005b), “Risk of casualties in New Zealand earthquakes”. Bulletin of the New Zealand Society for Earthquake Engineering 38(2): 53-72.

Dowrick, D.J. and Rhoades, D.A. (2010), “A distributed-source approach to modelling the spatial distribution of MM intensities resulting from large crustal New Zealand earthquakes”. Bulletin of the New Zealand Society for Earthquake Engineering 43(2): 85-109.

Dowrick, D.J., Rhoades, D.A. and Davenport, P.N. (2003), “Damage ratios for domestic property in the magnitude 7.2 1968 Inangahua, New Zealand, earthquake”. Bulletin of the New Zealand Society for Earthquake Engineering 36(1): 25-46.

Dowrick, D.J., Hancox, G.T., Perrin, N.D. and Dellow, G.D. (2008), “The Modified Mercalli intensity scale: Revisions arising from New Zealand experience”. Bulletin of the New Zealand Society for Earthquake Engineering 41(3): 193-205.

McVerry, G.H., Zhao, J.X., Abrahamson, N.A., and Somerville, P.G. (2006), “New Zealand acceleration response spectrum attenuation relations for crustal and subduction zone earthquakes”. Bulletin of the New Zealand Society for Earthquake Engineering 39(1): 1-58.

NZS 1170.5 (2004), Structural Design Actions Part 5: Earthquake Actions. Standards New Zealand, Wellington.

Smith, W.D. (2002), “A model for MM intensities near large earthquakes”. Bulletin of the New Zealand Society for Earthquake Engineering 35(2): 96-107.

Somerville, P.G., Irakura, K., Graves, R., Sawada, S., Wald, D., Abrahamson, N., Iwasaki, Y., Kagawa, T., Smith, N. and Kowada, A. (1999), “Characterizing earthquake slip models for the prediction of strong ground motion”. Seismological Research Letters 70: 59-80. DOI: https://doi.org/10.1785/gssrl.70.1.59

Stirling, M.W.: Earthquake Hazards Team (2007), “Updating the national seismic hazard model for New Zealand”. Paper 072, Proceedings of the 8th Pacific Conference on Earthquake Engineering, Singapore.

Sutherland, R. and 18 others (2007), “Do great earthquakes occur on the Alpine Fault in Central South Island, New Zealand?” In: A Continental Plate Boundary: Tectonics at South Island, New Zealand. Geophysical Monograph Series No 175: 235-251. DOI: https://doi.org/10.1029/175GM12

Published
2011-03-31
How to Cite
Dowrick, D. J., & Rhoades, D. A. (2011). Spatial distribution of ground shaking in characteristic earthquakes on the Wellington and Alpine faults, New Zealand, estimated from a distributed-source model. Bulletin of the New Zealand Society for Earthquake Engineering, 44(1), 1-18. https://doi.org/10.5459/bnzsee.44.1.1-18
Section
Articles