They got too close to the edge?
:How far do earthquake waves travel?
We can use the fact that P and S waves travel at different speeds to locate earthquakes. Assume a seismometer are is far enough from the earthquake that the waves travel roughly horizontally, which is about 50 to 500 km for shallow earthquakes."
Far traveling waves seem to be occurring about once a week lately. The one today all the plots are very similar waves.
And the really odd part is the USGS map does not show them even when you view it as one day all quakes.
https://earthquake.usgs.gov/earthquakes/map/#{%22autoUpdate%22%3A[%22autoUpdate%22]%2C%22basemap%22%3A%22grayscale%22%2C%22feed%22%3A%221day_all%22%2C%22listFormat%22%3A%22default%22%2C%22mapposition%22%3A[[7.710991655433217%2C215.859375]%2C[60.23981116999893%2C300.234375]]%2C%22overlays%22%3A[%22plates%22]%2C%22restrictListToMap%22%3A[%22restrictListToMap%22]%2C%22search%22%3Anull%2C%22sort%22%3A%22newest%22%2C%22timezone%22%3A%22utc%22%2C%22viewModes%22%3A[%22list%22%2C%22map%22]%2C%22event%22%3A%22se60070423%22}
https://earthquake.usgs.gov/monitoring/operations/heliplot.php