This is a layman's question. While looking for something I read in the news today, I stumbled upon the Haean region in South Korea (38°17'15.96"N, 128° 7'57.18"E) in Google Earth.
To me it looks either like a caldera or like a meteor impact site. Does anyone know from available facts whether one or the other is true? Wikipedia doesn't say anything about it. Is there any way to tell from the geometric features alone, or does it require taking soil samples from the site?
Interestingly there are some more crater-like features in South Korea (e.g. 37°49'5.12"N, 127° 3'12.53"E, almost perfect circular shape). Can this be considered a result of the proximity of the pacific ring of fire, or is it just too far away?