A Numerical Investigation of Boumerdes-Zemmouri (Algeria) Earthquake and Tsunami

On May 21, 2003 Boumerdes-Zemmouri (Algeria) earthquake generated a small tsunami, which was recorded at several locations around the coast of Balearic Islands, Spain. Recent field studies (Meghraoui, et al., 2004) and teleseismic wave analysis (Yiga, 2003) indicated that the earthquake magnitude is stronger than that suggested by the Harvard CMT solution. Moreover, the seafloor displacement is also not uniform along the rupture line. In this paper, we perform a numerical investigation to evaluate the accuracy of various suggested fault plane mechanisms. The numerical model is based on the shallow-water equations and numerical results are compared with the measured wave heights at San Antonio and Ibiza, Spain. The sensitivity of fault plane parameters is also examined. Our simulations show that the fault plane mechanism proposed by Meghraoui, et al. gives much better tsunami wave height predictions than that of Harvard CMT solution, although some discrepancies still exist. Using an inversion method with the tide gage measurements at San Antonio, we further improve the fault plane model, which is further validated with the data taken at Ibiza. Our new fault plane model suggests a stronger earthquake with larger seafloor uplifts.