A massive explosion in the city of Beirut, Lebanon, killed more than 100 people and flattened nearby buildings, sended shock waves to more than 250 kilometers across the ground. Eyewitness accounts described widespread shacking of buildings in a radius of 50 kilometers, and trembling of the ground felt still 250 kilometers away from the explosion center.

According to first estimates by geologists, the blast was equivalent to a magnitude between 3.5 - 4.5 earthquake comparable to the energy released by a detonation of 1.000 to 3.000 tons of TNT.

The explosion was not registered by the seismological stations in Hungary, but the Piszkés-tető (PSZI) infrasound stations detected the shock wave followed the explosion.

At the bottom of the following figure are the four registers of PSZI, and at the top, the detections are colored according to both apparent velocity and azimuth. In the case of a direct wave, at a distance of almost 2100 km between the Piszkés roof and Beirut - at a speed of 340 m / s - the journey time is about 1 hour 42 minutes, so the arrival is expected to be around 16:50 (UTC). Seen from PSZI, Beirut is located at an azimuth of about 134 °.
As expected, detections appeared from 134 ° +/- 4 ° at that time, shown in green at the top of the figure.

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