New Macroseismic Intensity Assessment Method for New Zealand Web Questionnaires

Tatiana Goded, Nick Horspool, Silvia Canessa

Penerbit : Seismological Research Letters

Tahun : 2018

This article presents the implementation of an expert-based method to calculate community intensities (community modified Mercalli intensity [CMMI]) for New Zealand earthquakes, using GeoNet’s “Felt Classic” (2004–2016) online felt reports. The method has been implemented and tested for about 43,000 felt reports from nine recent moderate-to-large (Mw 5.7–7.8) New Zealand earthquakes, including the damaging 4 September 2010 Mw 7.1 Darfield, 22 February 2011 Mw 6.2 Christchurch, and 14 November 2016 Mw 7.8 Kaikoura earthquakes. Results from this method (matrix method) have been compared for the 14 February 2016 Mw 5.7 Christchurch earthquake using three independent approaches: (1) postal traditional method, (2) community intensities from New Zealand’s latest ground-motion intensity conversion equation (GMICE), and (3) community intensities from a recent GMICE using California data. Results show a good consistency in community intensities between the matrix, postal traditional, and California GMICE methods. However, CMMI derived using the New Zealand GMICE shows a tendency to overestimate the intensities by about 2–3 intensity levels in comparison with the CMMI and traditional MMI, showing the need to review the current New Zealand GMICE.

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