What makes an earthquake "significant"?


What makes an earthquake "significant"?

Events in this list and shown in red on our real-time earthquake map and list are considered “significant events’, and they are determined by a combination of magnitude, number of Did You Feel It responses, and PAGER alert level.

Here is the equation:

mag_significance = magnitude * 100 * (magnitude / 6.5);
pager_significance = (red) ? 2000 : (orange) ? 1000 : (yellow) ? 500 : 0;
dyfi_significance = min(num_responses, 1000) * max_cdi / 10;

significance = max(mag_significance, pager_significance) + dyfi_significance;

Any event with a significance > 600 is considered a significant event and appears on the list.