Picture 1 is signal of something that is ~240 km away (if it's an earthquake). 2 is signal of a non-seismic/non-explosive source (nearby machine oscillating at ~15-ish Hz). 3 is noise/no signal at all. 4 is local signal of non-seismic/non-explosive source.
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Dec 4, 2025 18:27Interesting. Was looking at this data and it sounds like in layman’s terms this equipment does not indicate that significant shaking happened 23 kilometers away at the time of USGS “quake”? It, in fact, is picking up some type of shaking from much farther away?
Correct! Though we can't say more without additional recordings, and it's always possible that what we're looking at is two separate, small non-earthquake sources much closer to the seismometer (this is what makes very small earthquakes hard to analyze).
