Providing a larger version of that page for others to be able to read the text.
The next page of the comic explained it, but I'm not sure how readily available that next page is for people online.
In short, after Genosha's destruction, Lorna remained in its ruins with the final moments of millions of dead Genoshans playing in and around her constantly until she was dug out of the ruins. It's magnetic patterns of those final moments. Given her powers, she's able to read, retain, broadcast and boost those signals. Of course, we didn't get to see what Lorna personally living through those moments was like until later in Austen's run.
Then we have how she developed afterward as a result, culminating in Uncanny X-Men #442-443, but pages not in this post due to image limit.
Collectively, this is why Genosha is so important for Lorna. The genocide wasn't just some flash in the pan inconvenience, trauma of the week kind of thing. It soaked into the very core of her and tormented her relentlessly. It was a deep wound that she suffered through greatly as she worked toward her own brand of recovery out of it - and recovery takes many forms. Since recovery doesn't mean going back to the way things were before as if the trauma never happened. As we see in who Magneto became in his recovery after the Holocaust. Something too many writers fail (whether by accident or choice) to understand.
And just as the genocide and Lorna's development afterward are important for the character, so too was the activity and development she had on Genosha
before the genocide. Those moments were the foundation for just how devastating the genocide was for her.