by Alejandro Sandell-Gandara
Adam Johnson describes how archeologists are observing tsunami surges as a way to predict the impact of rising sea levels on archeological sites. In 2011 the 9.0 magnitude Tohoku earthquake created a tsunami that caused damage to Japan and communities across the pacific. The costal archaeological sites at Pu’uhonua o Honaunau National Historical Park on Hawai’i were affected by the tsunami.
The Pu’uhonua archaeological site in the coast of Kona is significant due to its ceremonial complex. On the site there is the Hale o Keawe temple which served as a royal mausoleum. The site is located on the coast line and surrounded by a stone wall to the east and south. The site has been excavated by several archeologists and determined to be originally related to chief Ehu-kai-milano in the 1500s. In the 1600s, Umi-a-Liloa built the stone wall around the site. An analysis and excavation of the bedrock shoreline shows evidence of activities such as dyeing of fishnets, processing seaweed, and pounding fish bait.
Tsunamis, hurricanes, and high surf caused damage to this site. The first documented tsunami occurred in 1819; a two-meter-high wave caused by a submarine fault in Chile struck the archeological site from the northwest, filled the royal fishponds with stones and sand, and broke down the northern part of the stone wall. Since 1900, twenty-four tsunamis have been recorded in Hawai’i with eleven causing significant damage.
In 1992, hurricane Iniki struck Hawai’i and caused 143 mph winds and water levels thirty feet above normal. The hurricane damaged the archaeological site by destroying structures and removing surface sand and sediments.
The damage caused by rising sea levels, hurricanes, and tsunamis can be analyzed and used to predict the effects of climate change. The destruction caused by these natural disasters confirm that climate change would cause major damage to archeological sites in coastal areas.
Adam Johnson, Lisa Marrack & Sara Dolan (2015) Threats to Coastal Archaeological Sites and the Effects of Future Climate Change: Impacts of the 2011 Tsunami and an Assessment of Future Sea-Level Rise at Hōnaunau, Hawai’i, The Journal of Island and Coastal Archaeology, 10:2, 232-252, DOI: 10.1080/15564894.2014.980472