The landslide flowed into Taan Fjord, triggering a localised tsunami that was detected 155 km away, according to the Lamont-Doherty press release. The tsunami moved boulders up to 16 feet (5 m) in diameter where it was largest (Figure 3). 2018. Koppes, M. and B. Hallet. 2018. The 2015 landslide and tsunami in Taan Fiord, Alaska. Part of the debris traversed the width of the fjord and re-emerged onto land, depositing coherent hummocks with preserved source stratigraphy on an alluvial fan and adjacent moraines on the far side of the fjord. In October 2015, a massive landslide slid into Taan Fjord and created a tsunami in excess of 600 feet. On October 17, 2015, 180 million tons of rock slid into Taan Fiord, an arm of Icy Bay, generating a tsunami that stripped forest from 8 square miles (20 square km) of Wrangell St.-Elias National Park and Preserve and reached as high as 633 feet (193 m) above the … In the case of Taan Fjord, the result was a massive tsunami," said Dr Dan Shugar, assistant professor of Geoscience at the University of Washington Tacoma and co-author of the report. The 2015 landslide and tsunami reshaped the landscape at the terminus of Tyndall Glacier. A small portion of the landslide traveled across the fjord bottom and slid back up above the waterline on the far side of the fjord, forming 30-70 feet-high (10-20 m) debris hillocks. A structure built here or in analogous locations would likely fare better even than more exposed locations that are significantly farther from the tsunami source. Precursory deformation began decades before failure, and the event left a distinct sedimentary record, showing that geologic evidence can help understand past occurrences of similar events, and might provide forewarning. Die daraus resultierende Welle war bis zu 193 Meter hoch . 180 Millionen Tonnen Gestein donnerten damals in einen Fjord. After the failure in 2015, a portion of the slide block remained on the slope, still covered by jumbled, but still largely upright alder forest (Dufresne et al. New methodology for computing tsunami generation by subaerial landslides: Application to the 2015 Tyndall Glacier landslide Alaska. The landslide is enormous – Stark and Ekstrom estimate from the seismic data that it had a mass of about 180 million tonnes, which would give a volume in the order of 72 million cubic metres. A recent string of massive landslides in Alaska and around the world bears the fingerprint of climate change. The tsunami travelled ca. Mt. Because this is a recently deglaciated fjord with steep slopes and crossed by a major fault, one possibility was a landslide-generated tsunami. In contrast, one small island that used to support supra-tidal vegetation was scoured down such that now it is only a shoal emerging at low tide (location marked on Figure 5). The 2015 tsunami was the largest to occur in this narrow window of time, but it likely wasn’t the only tsunami. Areas near stream deltas or other sediment sources might be buried by transported sediment. Malaspina Glacier. Dufresne, A., M. Geertsema, D. H. Shugar, M. Koppes, B. Higman, P. J.Haeussler, C. Stark, J. G. Venditti, D. Bonno, C. Larsen, S. P. S.Gulick, N. McCall, M. Walton, M. G. Loso, and M. J. Willis. As it moved down the fjord, the wave stripped vegetation to varying heights that gradually diminished down-fjord. 50 m on the opposite shore of the fjord. Current velocity validation using natural indicators of previous tsunami flow, or using direct observations of tsunamis, are badly needed. “Earlier, we … Geologic effects and records of tsunamis. Tsunamis are water waves generated by a sudden force (Bourgeois 2009), typically through either rapid displacement of the seafloor (during earthquakes or from submarine landslides), or through displacement and impact (by mountain landslides entering water, glacial ice collapses, or meteorite impacts). 2012. The October 17th, 2015 Taan Fiord landslide and tsunami generated a runup of 193 m, nearly an order of magnitude greater than most previously surveyed tsunamis. The colors on the tsunami indicate the height, with the reds indicating tsunami crest elevations of 40 m (130 ft) above the tide and the dark blues showing tsunami trough depressions of 20 m (65 ft) below the tide level. Like all tsunami waves, it would also be prone to breaking in shallow water. When they retreat, whether due to changing climate or to regular glacial cycles, they remove that support, allowing slopes to sag and fractures to expand, making them vulnerable to failure. 2018). In Alaska, four giant tsunamis have been triggered by subaerial landslides in the past century: in Lituya Bay in 1938 and 1958 (Miller 1960); in Grewingk Lake in 1967 (Wiles and Calkin 1992); and in Taan Fiord in 2015 (Higman et al. It is possible to anticipate areas of potential hazard for vessels using tsunami models. Worldwide glacial retreat and thinning, it states, exposes unstable slopes and increases the likelihood of major landslides, triggering high-runup tsunamis. Researchers employed a variety of instruments to conduct a ground-based tsunami runup survey, including a laser rangefinder, a total station, and two differential Real Time Kinematic (RTK) GPS systems. Sedimentology and geomorphology of a large tsunamigenic landslide, Taan Fiord, Alaska, Submarine deposition of a subaerial Landslide in Taan Fiord, Alaska, Previous Chapter: Modern Changes in Kennicott Glacier: Implications for Residents, Visitors, and the Other 3,120 Glaciers in Wrangell-St. Elias National Park and Preserve. Sedimentology and geomorphology of a large tsunamigenic landslide, Taan Fjord, Alaska. While at the site in 2016, they collected lidar and imagery for Structure from Motion (SfM) over Taan Fiord and parts of Icy Bay. Climate Change. Field work was carried out in the summer of 2016, and by the time this paper was written, almost all of the supraglacial debris was advected into the fjord and half the subaerial hummocks were buried by glacial advance; this rapid change illustrates how highly active sedimentary processes in high-altitude glacial settings can skew any landslide-frequency analyses, and emphasizes the need for timely field investigations of these natural hazards. (US Government Printing Office Washington, DC). Ekström, G. and C. P. Stark. We are able to image the landslide and postlandslide deposits, on and beneath the fjord bottom, up to 6 km away from where it entered the water. Fortunately, the debris from that event didn't reach the water, avoiding a tsunami. The glacier is named after the Tlingit native word for "Sea Lion". Ultra-rapid landscape response and sediment yield following glacier retreat Icy Bay, southern Alaska. The wave affected the … The fjord was exposed by the recent retreat of Tyndall Glacier. Months later, teams of scientists visited the site to document both the landslide and tsunami. The quick detection of this event, the existence of high quality pre-event topographic data, … Deposits were more typically 12-20 inches (30-50 cm) thick over areas as far as 6 miles (10 km) from the source. 180 Millionen Tonnen Gestein donnerten damals in einen Fjord. Multibeam sonar and sub-bottom profiling show blocky deposits capped by more homogenous layered deposits filling the fjord bottom (Haeussler et al. They crash ashore more like a wind wave, rising to their peak elevations within a few minutes at most. The October 17th, 2015 Taan Fiord landslide and tsunami generated a runup of 193 m, nearly an order of magnitude greater than most previously surveyed tsunamis. Journal of Sedimentology 364: 302-318. Geomorphology 78: 207–221. Though landslides like this can happen at any time, these events are becoming more frequent—driven by climate change-induced glacial retreat and permafrost thaw. They happen quickly and pose a threat to anything and everything in their path. The resulting landslide generated a megatsunami in Taan Fjord. Photo: Ground Truth Trekking (CC BY-NC 3.0) As Glaciers Melt, Will Deadly Landslides Increase? In 2015 rutsche dort innerhalb von wenigen Minuten nach einem kleinem Erdbeben eine riesige Erdmasse ins Icy Bay (St. Elias Wrangell Mountain National Park) ab. Tsunami-inducing landslides are rare but have occurred in Alaska and elsewhere. Taan Fjord is on the east side of Icy Bay, about 14 miles (22 km) north-northeast of Point Riou. Haeussler, P. J., S. P. S. Gulick, N. McCall, M. Walton, R. Reece, C. Larsen, D. H. Shugar, M. Geertsema, J. G. Venditti, and K. Labay. The 2015 Taan Fjord tsunami was generated by a 99 million cubic yards (76 million cubic meters) landslide that occurred following retreat of the Tyndall Glacier. Giant waves in lituya bay, Alaska. The Taan Fiord event provides warning that Icy Bay may see similar, potentially more deadly events in the future. Reconstruction of a debris-slide-initiated flood in the southern Kenai Mountains Alaska. Ground Truth Trekking, licensed under CC BY 3.0. At least two sites (see Figure 1) along the fjord have fresh landslide deposits extending into the ocean, and a ridge opposite the 2015 slide is laced with fissures that may produce future failures. The person in the photo is standing about 190 m above the fjord level, just below the limit of inundation (near the point marked with 193 m runup in Fig. Recent papers take a detailed look at the events leading up to and during one of the most massive landslide and tsunamis ever recorded. English: Tsunami impacts near the landslide. Tree trunks that remained standing after the tsunami were scoured by strong sediment-laden currents that sometimes severely abraded the upstream side of trees, leaving them peppered with small rocks (Figure 3). Approximately 90% of the landslide entered the fjord, generating a tsunami. Coastal Features, Glaciers, Alaska. In some areas where there was abundant loose sediment, deposits of everything from boulders to sand were so thick that they raised ground elevations by over 16 feet (5 m). “In Taan Fiord (Icy Bay, Alaska), a landslide that began moving slowly decades ago suddenly failed in October 2015. On October 17th, 2015, the largest landslide in North America in decades occurred in Taan Fjord, an arm of southeast Alaska's Icy Bay. Smaller vessels might experience some of the same hazards as can be found in tidal rapids—strong eddy-lines and whirlpools that can capsize and sink boats. Photo: Ground Truth Alaska (CC BY-NC 3.0) Responding to this May’s warning, Chugach National Forest officials advised the public to avoid the famously scenic Harriman Fiord, a staple for recreation and tourism activity that provides revenue across south-central Alaska. Scientific Reports 8: 12993. Am 17. Bourgeois, J. In the last century, 10 of the 14 highest tsunamis in the world were in glaciated mountains and four were in Alaska parks, which include vast tracts of glaciated terrain (Table 1). Even where the wave is not breaking, tsunamis can generate strong currents. Am 17. To date, most post-tsunami surveys are from earthquake-generated tsunamis and the geomorphic signatures of landslide tsunamis or their potential for preservation are largely uncharacterized. Check out this article and video. Rapid retreat of glacial ice from Taan Fiord, Alaska over the last 50 years, combined with the presence of local faulting, likely contributed to the massive October 17th, 2015 landslide near the head of the fjord that induced a tsunami with maximum runup of 193 m (Dufresne et al., 2018; Higman et al., 2018). English: Changes in Taan Fiord. 2017. 2018. Natur Forscher rekonstruieren Mega-Tsunami, der sich 2015 in Alaska ereignete. Erosion rates during rapid deglaciation in Icy Bay Alaska. 2017. doi:10.7289/V5PN93H7 A small volume of the total slide mass remains within the source area and is topped by striated blocks (> 10 m across) and standing trees that were transported down the slope in intact positions during the landslide. Initial observations of the 11 June 2012 rock/ice avalanche, Lituya mountain, Alaska. “The resulting tsunami reached elevations of … Geomorphology 5: 535–546. Most of the research on tsunami impacts has focused on longer-period regional tsunamis—especially subduction zone earthquake tsunamis that produce some of the longest period waves. The colors on the tsunami indicate the speed, with the reds indicating tsunami flow speeds of 30 m/s (~65 mph). It had almost no human impacts—nobody was near enough to be harmed, and the only damage to infrastructure was rocks scattered on a beach used for landing bush planes—good fortune that may not characterize similar events in the future. While most of the Taan landslide debris entered the fjord, in other cases, the percentages of debris deposited in water bodies may be minimal to non-existent. These results could then be compared to areas of infrastructure development, popular tourist destinations, and ship course data (e.g., from Automatic Identification System (AIS) ship-tracking systems) to identify areas of particular vulnerability. Ships carried in such currents would be vulnerable to collisions that could rupture the hull, or they might be carried broadside into shoals where they could be rolled over. 2017). This landslide-generated tsunami had a maximum height of over 600 feet. Tyndall Glacier retreated at an increasing pace through the late 20th century until it stabilized in 1991, at approximately the location of the current terminus. Sie schickte eine Tsunamiwelle, die 193 m hoch an den gegenüberliegenden Talhängen aufprallte. Die Flutwelle scheint gewaltige Ausmaße gehabt zu haben. An 800 foot (250 m) diameter hill that was surrounded but not overtopped by the tsunami had runups of over 160 feet (50 m) where the tsunami directly impacted it, but less than 65 feet (20 m) on the lee side (Figure 5). The Journal of Geology 1: 3. Der Tsunami wälzte sich bis in die eigentliche Bucht und rasierte auf seinem Weg das mit Tannen bestandene Ufer kahl. Piles of earth and rock following the 2015 Taan Fjord landslide and tsunami. Flow indicators from satellite imagery suggest that the maximum tsunami runup immediately adjacent to … The resulting tsunami reached elevations as high as 193 m, one of the highest tsunami runups ever documented worldwide. The impact of the slide with the water generated one of the tallest tsunami waves in historical times. Journal of Geophysical Research, Earth Surface DOI: 10.1029/2018JF004608. Visit our keyboard shortcuts docs for details, Next Chapter: Catastrophic Glacier Collapse and Debris Flow at Flat Creek, Previous Chapter: Geohazards in Alaska’s National Parks. 2018. At the mouth of the fjord, 10 miles (16 km) from the landslide, the wave reached 50 feet (15 m), and dragged icebergs through moraine hills. The event was detected within hours through automated seismological techniques, which also estimated the mass and direction of the slide - all of which were later confirmed by remote sensing. Using a variety of Digital Elevation Modeling (DEM) and imagery sources, the research team was able to estimate the landslide volume, document movement leading up to the event, and map the deposit thickness. The 2015 landslide and tsunami reshaped the landscape at the terminus of Tyndall Glacier. Taan Fjord Landslide and Tsunami. Much of the landslide material was deposited on the Tyndall Glacier and into the fjord. The tsunami was triggered by a landslide on October 17, 2015, at the head of the fjord. F2. 2013. Coe, J. VIDEO: Camp Bay, height Also, while modeled tsunami runup has been widely validated, currents produced by tsunami flows are rarely directly documented, and tsunami models differ substantially in the results they produce (Lynett et al. 1960. However, no such preparation was conducted and it’s urgent that we learn from the 2015 event and take steps to assess and mitigate hazards in Icy Bay and elsewhere before another event happens. Tsunamis generated by subaerial landslides are often confined to a few tens of kilometers around the landslide, both because shorter-period waves disperse energy more quickly and because they commonly are triggered in relatively confined bays and lakes. 2006. Oktober 2015 landete ein Erdrutsch von rund 180 Millionen Tonnen Gestein auf der Zehe des Tyndall Glacier und im Wasser des Taan Fjords. Slope failure at the terminus of Tyndall Glacier on 17 October 2015 sent 180 million tons of rock into Taan Fiord, Alaska. Higman, B., M. Geertsema, D. Shugar, P. Lynett, and A. Dufresne. National Geophysical Data Center, NOAA. To date, most post-tsunami surveys are from earthquake-generated tsunamis and the geomorphic signatures of landslide tsunamis or their potential for preservation are largely uncharacterized. The landslide triggered an enormous local tsunami. Initial estimates of the maximum tsunami run up were as high as 150 m using the Alaska IfSAR-derived DEM. Klaus Taschwer . Inverse and forward modeling can provide the framework of a detailed understanding of the geologic and hazards implications of similar events. Russel, I. C. 1893. A wave of such extreme amplitude and short wavelength would be likely to break even at fjord depths of hundreds of feet. More recently, a 2015 landslide near Alaska’s Taan Glacier produced a 633 feet (193 meter) wave in Taan Fjord that smashed into the opposite wall of the glacial valley. Additionally, glacial retreat is exposing new bodies of water that may be vulnerable to tsunamis. 2018). The Taan Fiord tsunami was preceded by a century of rapid glacial retreat (Koppes and Hallet 2006), decades of ground cracking and creep (Meigs et al. Days later, high-resolution satellite imagery revealed the landslide and tsunami impacts, and tide gage data from more than 90 miles (~150 km) away at Yakutat showed small fluctuations in water level (4 inches or ~0.1 m) resulting from the tsunami. Die Folge war ein Tsunami mit knapp 200 Meter Höhe. However, most of the slide mass sped across the shoreline and terminus of Tyndall Glacier and entered Taan Fiord. In Grönland löste ein Erdrutsch an der Westküste im Jahr 2017 eine über 90 Meter hohe Welle aus , die einen Großteil eines nahe gelegenen Fischerdorfes zerstörte und vier Menschen tötete. 2019. Signs of active displacement are clearly visible in remote-sensed data extending back to the mid-1990s. In Alaska stürzten 2015 am Taan Fjord enorme Gesteinsmassen ins Meer. Tyndall Glacier, Taan Fjord Mega-Tsunami. Scientific Reports 8(1): 12993. doi:10.1038/s41598-018-30475-w Submarine deposition of a subaerial landslide in Taan Fjord, Alaska. In the case of the massive landslide that fell into Taan Fjord, Alaska, the answer was no—and yes. The location shown here is near the mid-length of Taan Fiord, where the survey team set up their primary base camp. Sedimentology and geomorphology of a large tsunamigenic landslide, Taan Fiord, Alaska. Much of the landslide material was deposited on the Tyndall Glacier and into the fjord. Changes like this can render existing nautical charts unreliable and might mean that they need to be updated with new bathymetric surveys before large ships can return to waters impacted by similarly large landslides.

taan fjord tsunami

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