Personally I really don't think that 500 kg is enough to cause a 2.3 seismic event.
However just the sheer knowledge getting out is definitely going to be catastrophic for Russia if they were to have used a nuclear device and even a small nuclear device.
I'm not saying they used one of the big ones I'm saying they just used a small tactical one and most likely a remote operated vehicle to place it in a position where it would damage both these pipelines at once.
And it's four pipelines so. There's big huge problems going down and of course the initial claims are going to be understated and claim conventional munitions.
However the unfortunate fact of such a large Richter scale event? And Richter scale events are clearly measurable. And exponential.
320 kg of explosive will equal 1.5 Richter scale measurement.
That means if we extrapolate that data 10 * 10 * 10 * 10 * 10 * 10 * 10.... You end up with a massive amount of energy release.
And it really doesn't matter how much was used it was so excessive that it puts out its own message.
I have too little knowledge about this, but haven't heard anyone with expertise mentioning this.
If it was Russia, then they did send a powerful message. They could destroy all sorts of infrastructure in international waters and cause a complete meltdown of the global economy with Europe going down the most. In the worst case, we'd end with 10$ per day or roughly the mid 1950s again, but without a war hardened generation and no social or cultural cohesion.
On top comes the motive for Russia that it is a massive land power connecting various global regions. Irrespective of who the perpetrator was, the explosions will give them a massive advantage over projects in open waters like pipelines, communication cables, oil drilling, or even shipping. All of that will have to be reinforced with no end in sight. Costs will quadruple to protect everything sufficiently against such attacks.
Look up Richter scale...
Do some simple math. It's crazy...
Yeah there's no way 500 kg of explosive was used. It was way more.
This Wikipedia table would imply otherwise. Where did you come up with your figures?