DOI: 10.17603/ds2-0sek-4434
title: Runup Survey
title: in Tsunami Runup Survey Data from the 2015 Taan Fjord Landslide Event

description: On 17 October 2015, a mountainside collapse at the terminus of Tyndall Glacier in southeast Alaska generated a landslide-triggered mega-tsunami. The landslide sent approximately 7.6 × 10^7 m³ of rock and glacial sediment into Taan Fjord, abruptly displacing the water. The ensuing tsunami reached a peak runup of ~193 m on a steep slope directly across from the landslide, ranking among the highest tsunami runups ever documented. The wave inundated over 20 km² of terrain around Taan Fjord and Icy Bay, stripping forests and depositing sediment up to hundreds of meters inland. In summer 2016, a comprehensive field campaign surveyed the event, recording precise tsunami runup elevations, flow depths, and inundation distances at dozens of sites throughout the fjord and adjacent coastlines. Here we present the resulting datasets: a georeferenced catalogue of tsunami runup measurements, high-resolution topography and bathymetry data, and an extensive collection of field photographs. These data provide an quantitative record of a mega-tsunami’s onshore effects, intended as a benchmark dataset for landslide-tsunami modeling and hazard assessment. The Taan Fjord tsunami dataset will facilitate rigorous testing of landslide tsunami generation and propagation models and improve our understanding of the geomorphic consequences of large impulsive wave events in coastal and glacial fjord settings.
description: In 2016, a  team conducted three dedicated field surveys (in April, June, and August) to measure the Taan Fjord tsunami’s impacts systematically. The field response was challenging due to the remoteness and scale of the area affected. Access to Icy Bay was achieved by boat (from Yakutat), with additional support from a small airplane and helicopter for personnel and equipment transport. Travel within Taan Fjord itself required small vessels – inflatable boats, skiffs, and packrafts – to reach steep shorelines and narrow inlets. Despite logistical difficulties (including dense vegetation, steep unstable terrain, and wildlife), the team successfully surveyed essentially all tsunami-affected shorelines throughout Taan Fjord and outer Icy Bay. These surveys focused on identifying tsunami high-water marks and runup indicators, such as trim lines on hillslopes, mud or silt splatter on rocks and tree trunks, snapped or bent trees, debris wedged in branches, and deposits of driftwood or sediment. At each significant marker, the team measured the elevation and geographic coordinates of the point, documented the observation with notes and photographs, and recorded the type of evidence. Particular effort was made in the initial April 2016 survey to capture ephemeral low-elevation indicators before spring growth and rain could obscure them. This early “reconnaissance” survey, with a small 4-person crew, focused on easily accessible low runup sites and served to assess field conditions. The main survey in June 2016 involved a larger interdisciplinary team and aimed to perform a comprehensive tsunami runup survey across Taan Fjord and adjacent coastlines. Finally, a follow-up survey in August 2016 targeted a few remaining unsurveyed areas and gaps from the earlier efforts (due to time or weather constraints). By the end of the summer, the field team had collected a near-complete set of runup measurements and observations, spanning from the inner fjord near the landslide scar all the way to the outer limits of discernible tsunami effects in Icy Bay.