Yesterday I read this fascinating article about the likelihood of a major earthquake and tsunami striking the Pacific Northwest of the United States. There's a major subduction zone along the coast, and although earthquakes there are rare, they are quite severe when they happen. The last earthquake in this area most likely occurred in the year 1700, so before any literate cultures were there. In determining the date of this earthquake — along with using scientific methods — "a seismologist at the University of Washington, together with nine colleagues, collected and analyzed Native American reports of earthquakes and saltwater floods. Some of those reports contained enough information to estimate a date range for the events they described. On average, the midpoint of that range was 1701."
(1) How could one estimate a precise year for an earthquake by relying on oral histories? What exactly is the methodology?
(2) Are there other examples of linking myths and oral histories that describe catastrophic events to very real natural disasters? I ask this with regard to both ancient societies whose myths are written down and modern ones that have passed down their traditions and stories orally.
Specifically referring to the Cascadia Earthquake of 1700 I think that the oral history was used more as a means to confirm evidence that scientists had already found regarding that event. I live in the PNW and ever since I was at Camp Merriwether as a boy scout I have been fascinated with the Cascadia Subduction Zone. Reading further into it, I believe that the evidence they had found was mainly around multiple drowned out areas from the resulting tsunami. They conducted studies around these areas finding that the sediment was consistent with a seismic event as well as a tsunami. Furthermore, they used the trees from these areas to determine exactly what year this event happened. Now while the natives living in the area may not have had a literary system in which to record these events by date, there was another civilization was affected by the tsunami that did have a literary system at the time. The Japanese. Using the Japanese records from a Tsunami that occurred in January of 1700 scientists concluded that there had been some type of seismic event in the Pacific Ocean to cause this. This is where the reports of the Native Americans comes in. Using their oral history combined with the tree rings and the records from the Japanese, they concluded that the event occurred on January 26th 1700. While the Native American history may not have had specific dates, it was a large piece that helped solve this puzzle.