Fault parameters and tsunami excitation of the May 23, 1989, MacQuarie Ridge Earthquake

Satake, Kenji; Kanamori, Hiroo

doi:10.1029/gl017i007p00997

Cited by 27 publications

(17 citation statements)

References 10 publications

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“…There are also no obvious outliers in the position time series. One possible source of unusual motion at this site could be postseismic effects of the great Macquarie Ridge earthquake of 1989 [ Ekstrom and Romanowicz , 1990; Satake and Kanamori , 1990]. We have generated several models using the code of Pollitz [1997] and a variety of mantle viscosity structures.…”

Section: Discussionmentioning

confidence: 99%

Motion and rigidity of the Pacific Plate and implications for plate boundary deformation

et al. 2002

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[1] Using up to 11 years of data from a global network of Global Positioning System (GPS) stations, including 12 stations well distributed across the Pacific Plate, we derive present-day Euler vectors for the Pacific Plate more precisely than has previously been possible from space geodetic data. After rejecting on statistical grounds the velocity of one station on each of the Pacific and North American plates, we find that the quality of fit of the horizontal velocities of 11 Pacific Plate (PA) stations to the best fitting PA Euler vector is similar to the fit of 11 Australian Plate (AU) velocities to the AU Euler vector and $20% better than the fit of nine North American Plate (NA) velocities to the NA Euler vector. The velocities of stations on the Pacific and Australian Plates each fit a rigid plate model with an RMS residual of 0.4 mm/yr, while the North American velocities fit a rigid plate model with an RMS velocity of 0.6 mm/yr. Our best fitting PA/AU relative Euler vector is located $170 km southeast of the NUVEL-1A pole but is not significantly different at the 95% confidence level. It is also close (<70 km in position and <3% in rate) to a pole derived from transform faults identified from satellite altimetry, suggesting that the vector has not changed significantly over the past 3 Myr. Our relative Euler vector is also consistent with all known geological and geodetic evidence concerning the AU/PA plate boundary through New Zealand. The GPS sites offshore of southern California are presently moving 4-5 ± 1 mm/yr relative to predicted Pacific velocity, with their residual velocities in approximately the opposite direction to PA/NA relative motion. Likewise, the easternmost sites in South Island, New Zealand, are moving $3 ± 1 mm/yr relative to predicted Pacific velocity, with the residuals in approximately the opposite direction to PA/AU relative motion. These velocity residuals are in the same sense as predicted by elastic strain accumulation on known plate boundary faults but are of a significantly higher magnitude in both southern California and New Zealand, implying that the plate boundary zones in both regions are wider than previously believed.

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Section: Discussionmentioning

confidence: 99%

Motion and rigidity of the Pacific Plate and implications for plate boundary deformation

et al. 2002

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“…The strike varies from 29" to 57". However, except for Satake & Kanamori (1990), the other studies indicate a strike between 29" and 40", with the body wave studies giving the strike close to 31" and the long-period surface wave studies, values around 38".…”

Section: The Main Shockmentioning

confidence: 91%

“…The main shock has been the subject of several studies and the results are briefly discussed below. The studies fall into two groups: the broad-band body wave studies (Braumiller & Nabelek 1990; Ekstrom & Romanowicz 1990;Satake & Kanamori 1990;Tichelaar & Ruff 1990) and long-period surface wave studies (Ekstrom & Romanowicz 1990;Satake & Kanamori 1990;Anderson & Zhang 1991). In addition, the Harvard CMT solution was published by Dziewonski et af.…”

Section: The Main Shockmentioning

confidence: 99%

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The Macquarie Ridge earthquake of 1989

Das¹

1993

Geophysical Journal International

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S U M M A R YA study of the seismicity on the central portion of the Macquarie Ridge before and after the 1989 May 23 Macquarie Ridge earthquake (Mw = 8.2) and the solution of the inverse problem to obtain the moment release time history during the earthquake are presented. The aftershock study shows that there were remarkably few and small aftershocks on the main fault. The aftershocks were distributed along a 220 km portion of the India/Australia-Pacific plate boundary and indicate that the motion was bilateral on a vertical fault. In addition, the earthquake reactivated a 175 km section of a fault to its west which had been dormant since at least 1964 and 44 per cent of the aftershocks occurred on this feature. Moreover, the largest aftershocks in the five month period following the event occurred not on the main fault plane but on the reactivated one. Based on available bathymetry, gravity and magnetic anomaly data from the region, this reactivated feature is interpreted as being an old oceanic fracture zone and hence a pre-existing zone of weakness. The aftershock distribution and their focal mechanisms are interpreted in terms of the tectonics of the region and suggest that a triangular piece of crust to the west of the Macquarie Ridge is being 'squeezed' to the north and west. The centroid-moment tensor solution was obtained using both GDSN and GEOSCOPE data simultaneously. It shows that the motion was primarily strike-slip on a vertical fault with a moment of Mo= 1.5 x lo2' N m and a centroid depth of 19.5 km. The moment release distribution and time history were obtained by inversion of broad-band body waves recorded digitally by the GDSN and GEOSCOPE networks. The rupture is found to be bilateral with the propagation first starting towards the north-east and a few seconds later towards the south-west. The moment release was low in the hypocentral area with the higher areas of moment located towards the north-east and south-west of this. The average rupture speed was approximately the shear wave speed. No simple relation between the moment release pattern and the distribution of aftershocks on the fault plane was found. Instead, the aftershock distribution is seen to be dominated by the intersection of the reactivated fault and the main fault plane with most aftershocks occurring to the north of this intersection.

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“…Dziewonski et al 1990). The estimates of the fault length range from about 100 to 200 km (Braunmiller & Nab61ek 1990;Satake & Kanamori 1990;Das 1993;Das & Kostrov 1994). Braunmiller & Nab6lek (1990) and Das (1993) favoured bilateral rupture propagation, while Satake & Kanamori ( 1990) ing rupture.…”

Section: The 1989 May 23 Macquarie Ridge Earthquakementioning

confidence: 99%

Detecting slow, long-duration slip of large earthquakes using very long-period orbital surface waves

Nábělek

1996

Geophysical Journal International

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S U M M A R YIn this paper, we present a simple yet effective technique for measuring the source time-delay spectrum from very long-period world-circling surface waves without relying on assumed earth models or calculation of synthetic seismograms. By using autocorrelation and self-convolution functions derived from whole seismograms of large earthquakes recorded at a seismic station it is possible to isolate the source effects and precisely (5 5 s) determine the source delay spectrum at periods as long as 600 s.Measurements at such long periods are necessary for detecting slow precursory slip and slow creep after the main 'fast' seismic phase of large earthquakes. We apply this technique to five recent large earthquakes: the 1989 Macquarie Ridge ( M , 8.2), the 1992 Nicaragua ( M , 7.6), the 1993 Mariana Islands ( M , 7.8), and the 1994 deep events in Fiji ( M , 7.6) and Bolivia ( M , 8.3).Our results are largely in agreement with the results obtained by other investigators. The Mariana Islands, Fiji, and Bolivia earthquakes had a normal rupture duration. The Nicaragua earthquake exhibits a source time-delay spectrum with the delay increasing from 31 s at the 100 s period to 50 s at the 600 s period, indicating an unusually slow rupture process. The Macquarie Ridge earthquake is anomalous by the discrepancy between the Love-wave and Rayleighwave estimates. Love waves, in the period band of 150 to 600 s, show a normal, flat source-delay spectrum with a delay of about 28 s. The Rayleigh-wave spectrum agrees with the Love-wave spectrum for periods smaller than 200 s and greater than 400 s; however, it shows a significantly shorter source delay (about 15 s) in the 250 to 350 s period range. The unusual nature of the Macquarie Ridge earthquake's surface wave spectrum was pointed out by Ihmli, Harabaglia & Jordan (1993) who also provided an explanation in terms of a slow, precursory moment release. This explanation is not consistent with the flat Love-wave spectrum determined here.

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Fault parameters and tsunami excitation of the May 23, 1989, MacQuarie Ridge Earthquake

Cited by 27 publications

References 10 publications

Motion and rigidity of the Pacific Plate and implications for plate boundary deformation

Motion and rigidity of the Pacific Plate and implications for plate boundary deformation

The Macquarie Ridge earthquake of 1989

Detecting slow, long-duration slip of large earthquakes using very long-period orbital surface waves

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