Seismic Location of the 4 August 2020 Beirut Port Chemical Explosion

On 4 August 2020 Lebanon’s capital, Beirut, was rocked by a sequence of colocated fires and chemical explosions that left hundreds of people dead, thousands injured and homeless, demolished the city’s seaport, and heavily damaged the surrounding neighborhoods and businesses. The event was well recorded by many regional seismic stations in and around the eastern Mediterranean Sea. Using a network of 58 stations, 105 regional seismic phases, and a Bayesian methodology places the event at 1.8 km south of the ground-truth location, the seaport warehouse. Achieving this accuracy is significant, considering very limited local seismic data were available to use in this study. The location bias is attributed, in large part, to a small but statistically significant difference in the Moho velocity for sea paths compared with continental paths. The depth to the Moho is generally consistent with the iasp91 model. Concurrent to the port explosion is a series of unrelated small explosions, 11 s apart, attributed to a seismic survey that was being carried out at the time in the eastern Mediterranean Sea using air guns.

Lora RTT Ranging Characterization and Indoor Positioning System

In recent years, indoor positioning systems (IPS) are increasingly very important for a smart factory, and the Lora positioning system based on round-trip time (RTT) has been developed. This paper introduces the ranging characterization, RTT measurement, and position estimation method. In particular, a particle filter localization method-aided Lora pseudorange fitting correction is designed to solve the problem of indoor positioning; the cumulative distribution function (CDF) criteria are used to measure the quality of the estimated location in comparison to the ground truth location; when the positioning error on the x -axis threshold is 0.2 m and 0.6 m, the CDF with pseudorange correction is 61% and 99%, which are higher than the 32% and 85% without pseudorange correction. When the positioning error on the y -axis threshold is 0.2 m and 0.6 m, the CDF with pseudorange correction is 71% and 99.9%, which are higher than the 52% and 94.8% without pseudorange correction.