8 minutes ago, Ixidor said:

I think you only pick one rock within range 1.

1 hour ago, Aircraft Terrier said:

To clarify, any individual seismic only blows up 1 asteroid, not all within range, so a single charge cannot set off a chain reaction of multiple explosions.

Have we seen the rules card for it somewhere?. Hmmm.

Quote

"Other devices, like Seismic Charges, let you make use of obstacles on the board to damage enemy ships. Not only does one of these Seismic Charges cause an obstacle at range 0–1 to be removed when it detonates, it also showers ships within range 0–1 of that obstacle in debris, causing damage."

...Doesn't sound promising that it's an area hit. Like you say, it's probably just 'choose one' - but then that does mean multiple charges are more viable if you're not going to waste all the rocks in an area in one go.

6 minutes ago, Magnus Grendel said:

Have we seen the rules card for it somewhere?. Hmmm.

I can't find the standalone image for it anymore, but the device rules were part of early leaks, and seismics read:
At the end of the Activation Phase this device detonates. When this device detonates, choose 1 obstacle at range 0-1. Each ship at range 0-1 of the obstacle suffers 1 (damage) damage. Then remove that obstacle.