Petra,

A strong quiet period hit central Alaska beginning October 15 and lasting until October
21. During this time there were no earthquakes of
M>3 in the Alaska catalog (see link below). Activity began to pick up on October 21 and was quite strong on October 22 and 23 in the region. Generally about 3 or more events occur of M>3 in the region on a given day, so this quiet may be considered significant as a possible precursor to the strong earthquake that followed.

A second set of observations involves the unusual earthquakes that began in the U.S. around Oct. 19 - a Ml 3.3 in Oklahoma, the first recorded in that region in months, and the strong swarm of more than 50 events of M>2 that
also began on about Oct. 19 in the Alpine Junction area of Wyoming and was at it's maximum on Oct. 22-23 including an event of Ml 4.2. At the same time several light, but unusual earthquakes were occurring in southeastern Canada including a Ml 3.2 near Miramichi on the Maine Border. Add to that the very unusual earthquake swarm in the greater Manchester U.K area which aso began on October 19 but which maximized with an event of 3.5 on Oct. 21 (Manchester is located 60 degrees from the Alaska earthquake), and we see a pattern of unusual earthquakes at specific distances where triggering is expected from Alaska occurring beginning on 18 October and maximizing in most areas the day before the Alaska earthquake occurred. This is a typical precursory pattern before strong shocks in Alaska and has been commented on in this forum by Don and others in the past.

Observations of this type may have allowed you to be much more precise in your timing and location.

• Alaska Earthquakes