Sedimentary record of recent tsunamis in the Huelva Estuary (southwestern Spain)

Abstract

The coast of the Gulf of Cadiz has been repeatedly struck by tsunamis during the late Holocene and the historic period. Historical documents record at least seven catastrophic tsunamis affecting this coast while others have been detected by oceanic instruments. Nevertheless, very few studies have documented the sedimentary record of these tsunamis in the low-energy coastal environments of the Gulf of Cadiz. The Huelva Estuary is located at the central sector of the Gulf of Cadiz and is a mesotidal estuary fed by the Tinto and Odiel rivers. The mean tidal range of the Huelva Estuary is ca 2m and the mean significant wave height is ca 0.5m. The outer part of the estuary is characterized by extensive sand-rich sedimentary bodies of marine origin, whereas the central and inner parts are infilled by muddy, tidally deposited sediment bodies. Recorded within these estuarine sediment bodies are five, laterally continuous shelly units. These units display many of the typical characteristics of tsunami deposits; each typically comprises an erosional base followed by a fining-upwards sequence that begins with the shell accumulation and ends with bioturbated muddy sand. The results of 14C ages and recent radionuclides accumulation rates in this study illustrate that these five tsunami deposits correspond with known events that occurred in AD 1755, 1531, 949 (1033?), 881, and 395 (381?), all of which are documented in historical sources.