Jordan Seismological Observatory reports a 4.5M seismic measurement from the Beirut blast. That’s mind-boggling for a conventional, surface-level explosion.
This is so large that it bears waiting for measurements from other seismic monitors.
For instance, @ctbto_alerts’ IMS should be able to contribute to our understanding of this event.
Another data point from the European-Mediterranean Seismological Centre, which reports 3.5M. emsc-csem.org/Earthquake/ear… 
(Obligatory reminder that the moment magnitude scale is logarithmic so the difference in scale between 3.5M and 4.5M generally corresponds to a 10x seismograph difference and a 30x difference in energy release.)
The CTBTO (@ctbto_alerts) has primary/auxiliary monitoring stations in the vicinity (Israel/Jordan closest).
Appending for completeness: USGS measured M3.3 in Beirut yesterday and has a helpful page explaining methods. earthquake.usgs.gov/earthquakes/ev…
