Characteristics of two tsunamis generated by successive <i>M</i><sub>w</sub> 7.4 and <i>M</i><sub>w</sub> 8.1 earthquakes in the Kermadec Islands on 4 March 2021

Abstract. On 4 March 2021, two tsunamigenic earthquakes (Mw 7.4 and Mw 8.1) occurred successively within 2 h in the Kermadec Islands, offshore New Zealand. We examined sea level records at tide gauges located ?100 to ?2000 km from epicenters, conducted Fourier wavelet analyses as well numerical modeling of both tsunamis. indicated that energy first tsunami is mainly distributed over period range 5–17 min, whereas it 8–32 min for second tsunami. Wavelet plots showed oscillations continued even after arrival As epicenters are close each other (?55 km), we reconstructed source spectrum by using empirical Green's function. The main spectral peaks 25.6, 16.0, 9.8 min. results similar those calculated tsunami-to-background ratio method also consistent with models.