[C210N]

I have not seen any "key" that states 10.0 km equates to "undetermined". Do you know that for a fact, or is it assumption?

Seems to me, "undetermined" could just as easily be denoted as "*" or "N/A" or "unknown". Why not 100km? Why not 0km?

[stars & stripes forever]

https://www.usgs.gov/faqs/why-do-so-many-earthquakes-occur-a-depth-10km?qt-news_science_products=0#qt-news_science_products

[thinden]

bttt