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Session: ShakeMap-related Research, Development, Operations, Applications and Uses

Type: Oral

Room: 202A/B

Date: 4/19/2023

Presentation Time: 02:15 PM Pacific

Presenting Author: Anna E. Kaiser

Description

GNS Science is developing new tools to rapidly deliver near-real time ground shaking maps (ShakeMapNZ) for New Zealand. Maps will be available through the GeoNet website, a Shaking Layer data website, and an API. This project is a collaboration between GeoNet, New Zealand’s geohazards monitoring agency, and the Rapid Characterisation of Earthquake and Tsunami (R-CET) science programme.

ShakeMapNZ uses the USGS ShakeMap software to combine observed strong motion data with ground motion model predictions, resulting in spatial estimates of ground shaking for each intensity type e.g. PGA, PGV, MMI, Sa(T). The New Zealand system is optimised with region-specific data, ground motion model weightings, and default tectonic classifications. In the first instance, maps are automatically generated and updated based on basic earthquake parameters (M and hypocentre) determined by GeoNet’s 24/7 monitoring center. First maps are available within 10 – 20 mins and have provided robust representations of shaking for small to moderate sized events (up to M6) observed to date.

Large earthquakes such as the 2016 Mw 7.8 Kaikōura earthquake pose additional challenges for automatic shakemap generation, which is based on point source models. For example, a large extended source, rupture complexity and/or potential disruption to strong motion stations may lead to large inaccuracies in initial shaking intensities, particularly in the near-source region. In recognition of this challenge, we have designed an applicationvto allow seismologists to dynamically update ShakeMapNZ during an earthquake response. Advanced earthquake information such as finite fault rupture, Mww, focal mechanism, tectonic classification, felt reports or additional strong motion data can be integrated efficiently into shaking maps when available. To further this goal, the R-CET programme had also been developing new rapid source chracterisation tools, including real-time Finite-fault Rupture Detection (FinDer) and regional w-phase solutions. These tool outputs are being tested and optimised to improve the accuracy of shaking maps with promising results.