摘要：A magnitude 7.5 earthquake occurred on 28 September 2018 at 10:02:43UTCnear the city of Palu on the Indonesian island of Sulawesi. It was ashallow, strike-slip earthquake with a rupture extending to a length of about150km and reaching the surface. Moreover, this earthquake was identified asone of very few events having a super-shear rupture speed. Clear and long-lasting infrasound signatures related to this event wereobserved by four infrasound arrays of the International Monitoring System ofthe Comprehensive Nuclear-Test-Ban Treaty Organization as well as by onenational infrasound station in Singapore. Although these infrasound stationsSING (Singapore), I39PW (Palau), I07AU (Australia), I40PG (Papua New Guinea)and I30JP (Japan) are located at large distances of between 1800 and 4500kmfrom the earthquake's epicentral region, the observed infrasound signalsassociated with this event were intense, including both seismic and acousticarrivals. A detailed study of the event-related infrasound observations and thepotential infrasound generation mechanisms is presented, coveringrange-dependent infrasound transmission loss and propagation modeling andcharacterization of the atmospheric background conditions, as well asidentification of the regions of seismoacoustic activity by applying a back-projection method from the infrasound receivers to potential source regions.This back projection of infrasonic arrivals allows one to estimate that the maininfrasound source region for the Sulawesi earthquake is related to theextended rupture zone and the nearby topography. This estimation and acomparison to other super-shear as well as large regional earthquakesidentify no clear connection between the earthquake's super-shear natureand the strong infrasound emission.
