This would be detectable a long ways away from the source. Acoustic energy like this attenuates slowly. In marine seismic exploration for oil and gas we use air

This would be detectable a long ways away from the source. Acoustic energy like this attenuates slowly. In marine seismic exploration for oil and gas we use airgun source arrays that develop about 1000-2000 psi. You can watch your hydrophone array and see other crews operating tens of miles away and in the past, before source separation techniques allowed processing of data from surveys where simultaneous acquisition was occurring in close proximity, crews worked together to avoid having their data step on the other party's data so they operated withing time windows to minimize interference. Nowadays with very precise clocks and event timing down to the gnat's ass fraction of a second it is less necessary since records can be correlated between source sensors and remote receivers with extreme accuracy. An event that registers as a 3.9 earthquake on a land seismometer far from the source tells you nothing about the energy near the source. That wave traveled thru the water column and into the sediments on the seafloor then into the crust beneath before being recorded at distant stations. It suffered attenuation at each interface due to Snell's Law. Some is transmitted, the rest is reflected across each impedance boundary. The true measure of the energy of this event comes from the near-field hydrophones. I bet they don't release that data. With that you could determine how loud it was at the source. Water doesn't attenuate acoustic signals very well though they do reflect at internal temperature and salinity interfaces. Navies take advantage of this lack of attenuation in their subsea communication strategies which allow communication over huge distances through subsurface water layers. Interesting stuff. This event will show up on seismic records from hydrophones as a broadband signal with a large bubble pulse and multiple collapse peaks. The initial blast creates a huge bubble that collapses back in on itself and re-forms and collapses several times reverberating. It is huge and will affect marine life many miles from the test location. It would be interesting to see a decibel graph of the energy and power spectrum. Even though modern seismic surveys are timed to avoid important seasons for known marine life there is no way to minimize the impact this will have on marine life that is currently nearby and "out of season" or out of the public eye. I mentioned to a fellow geophysicist that submarine echo sounders were likely the cause of marine mammal beachings and this person, a PhD in Geophysics, told me that I was wrong because he had studied the issue for the industry and the energy from those tests was too low, the wrong bandwidth, etc. He said he would buy me lunch and show me the data to back that up. I'm glad I have had the means to purchase my own lunch since that offer was made.