Vancouver Island Nature Tours

With the recent huge earthquake in Japan, I immediately thought of my personal exposure to a similar event here. I live in the Tsunami Hazard Zone in Port Alberni. Of course, almost everyone in Port Alberni and most people on Vancouver Island are aware of the tsunami that hit the west coast of the island on Good Friday 1964. The communities most damaged were Zeballos, Tahsis and Port Alberni, the latter, being a big community sustained the most damage. The 1964 event was very serious. But there was an even more serious Tsunami that happened around 9:00 PM, 26 January 1700. Of course this was before any European contact with the people living in this area then. So how do we know about this event and exactly when it was? Well first there is the oral history of the local tribes around here. The tsunami hit the village of the people living in at Pacheena Bay, the end of the West Coast Trail. According to the story, first there was an enormous amount of shaking, so violent that people couldn’t stand. It woke everyone up. Then a huge wave wiped out the village. Everyone but one person was killed by being swept out to sea. Only one person survived, Anacla aq sop. The current chief of the Huu-ay-aht, Spencer Peters is descended from her. Then there are written records along a 500-mile stretch of the eastern Japanese coastline of a tsunami, but no earthquake on January 26, 1700. The waves were about 1-5meters in height. Because of the lack of local earth movement, the earthquake must have come from across the ocean. Another reason we know about this, are several ghost forests along the coasts of Washington and Oregon. Scientists realised that these dead trees along the very edge of salt marshes were there because land had subsided in a large earthquake. Through dendrochronology they were able to closely ascertain the date of the event. Finally there is the geological evidence from up and down the west side of North America of a sand and gravel layer that could only have been laid down by a tsunami. Scientists have looked in tidal marches and estuaries from California to northern Vancouver Island and found this layer. One of the places it was found was in Port Alberni in the Somass Estuary. Being largely undeveloped, it is much easier to find evidence for these events here than higher on the floodplain where logging and construction have taken place. Using sedimentation rates, scientists have been able to determine the approximate date of the event, 1700. So, all this independent evidence points to the same time period.

Both the 1964 and the 1700 tsunamis are recorded in the sediments of the Somass river estuary. The former, being smaller, laid down a smaller layer of sand and gravel. The older and larger tsunami laid down a much larger layer, scary large. This tsunami was estimated to be 9.0 on the Richter scale and just off this coast in the Columbia Subduction Zone. Through extrapolation someone has determined the height of the wave from the earlier earthquake. They used this to draw a map of the likely inundation that would occur in the event of a similar huge earthquake. I sure hope everyone in town knows where the edge of it is.

On a more personal note, I have a niece, her husband, and her baby in Japan at the moment. They are OK so far. But I’m sure that they are being affected through brown-outs, pending food shortages, and possible radioactive contamination if a nuclear reactor fails. My thoughts are with them.

I have also taken guests from Japan on tours on two occasions. My thoughts are with them and their relatives.