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  1. Last night in Lima, Perú, we felt an earthquake of 4.5 however the earthquake did not appear on the USGS list... Any reason why?

1. Last night in Lima, Perú, we felt an earthquake of 4.5 however the earthquake did not appear on the USGS list... Any reason why?

To feel a quake but not have it on the list is a little disappointing. However, there are actually a few reasons why the earthquake you felt, or for that matter an earthquake with a magnitude greater than 4.0 may not appear in the 'Global' list of earthquakes.

First of all, for regional earthquake monitoring, there are usually going to be better localized resources than our more globally-oriented data. For example, the USGS has a set of criteria involving such things as number of stations reporting a quake, and quality of the data (as measured, in some instances, by the people who localized the quake in their own country ), etc. which are applied to all quakes before they make it onto the USGS catalog/list.

Another reason why the earthquake did not appear on the 'Global' list could be that the reporting stations do not have a "fast" way of reporting to other sources, or they want to be sure before they report it? For example I got a similar question from a person in Chile last week and upon investigation I did learn that the nearest station (LCO I think it was) sends us their data on tape, once each TWO months.

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