Anyone in #archaeology out there who has used, or knows about seismic detection of buried buildings?

The challenge: there's a church, St. Ann's, in Bethesda, north Wales, that was buried under slate waste in the mid-19th century. It's since been a topic of fascination because there are no reliable depictions of it, though there is one graffito that could be it.

The depth of burial is not great, probably 15-20m. I guess the haphazard, flat slate surfaces making up the waste could be a problem?