Seldovia beach erosion and glacial rebound

Observation: Over the past two winters our beach has transformed. All the material from one end of the beach got pushed to the other end. In moving this material old pieces of what was probably above water many years ago are now exposed. Rocks that have never been seen before are now 4' tall in places. Big cobble rocks are all that's left where sand used to be. At the other end of the beach a large rock out cropping is almost buried while another is gone completely from being covered up. Could this be from isostatic rebound from the 64 earthquake? Could the rising land have come up and caught the current now and changed how it enters and affects Seldovia Bay.

**LEO says* One measure of coastal and sea change is the NOAA Sea Level Trend Map which shows data from global tide buoys. Only buoys which have been in place for over 30 years are included. The tide buoy for Seldovia (and much of southern Alaska) show that sea level in Seldovia (1964 to 2014) has dropped at a rate of 10.24 mm/year. That adds up to a rate of 3.36 feet every 100 years. The reason for the drop in sea level is glacial rebound - the rise of the land relative to the sea, as a result of the weight from glacial ice melt being transferred from the land to the ocean. The rate of rebound is increasing in many areas due to the rapid melting of glaciers. See New York Times article As Alaska Glaciers Melt, It’s Land That’s Rising. Sea also USGS resources on the topic of glacier change. Whether sea level change is related to the beach change reported by Michael Opheim in Seldovia, is unknown. LEO Network is looking for help on this question. Members please feel free to contact us using the 'Comment' feature at your "For Members" page. This looks like a good opportunity for a time lapse camera. Learn more hear about the LEO Network Community Camera Project. M. Brubaker

National Ocean Service Consultation Nic Kinsman writes: "Great summary in the LEO consult on our NOAA Sea Level Trend Viewer! I would also recommend looking at the Seldovia tide station Also, the trends on our map are based on long-term tide stations, as opposed to buoys. The tide stations allow us to monitor changes in the average ocean level relative to fixed points on land -- this is what provides us with a complete understanding of what we call the Relative Sea Level Trend (a combination of the absolute change in the average ocean surface combined with the motion of the land). You can see where the Seldovia tide station is located on the map here. If you want to get a better understanding of just the motion of the land, we can look at continuously operating GPS stations. There has been one operating in Seldovia since ~2002 as part of the Plate Boundary Observatory. You can see a great plot of how the land in Seldovia is moving at the above link and also here. The upward motion of the crust here is likely a combined result of multiple factors, including isostatic rebound due to glacial ice loss, residual post-seismic adjustments from the 1964 earthquake (and other seismic activity), and more regional tectonic trends/motion. For more detailed information about land motion in this region a recommended expert to talk to would be Dr. Jeff Freymueller at UAF's Geophysical Institute: http://gps.alaska.edu/jeff/ Dr. Freymueller actually has a whole project on Sea Level Trends in Kachemak Bay