Lituya bay megatsunami simulation dating

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lituya bay megatsunami simulation dating

Lituya Bay Landslide Impact Generated Mega-Tsunami 50 th Anniversary . Radiocarbon dates on high moraines suggest retreat of glaciers only in the last .. with numerical simulations of Lituya Bay outside the immediate impact area. 5 . The Lituya Bay earthquake occurred at July 9 at with a moment magnitude of Local date, July 10, () . Subsequent mathematical modeling at the Los Alamos National Laboratory (Mader, , Mader. 60 years ago: The earthquake and Lituya Bay megatsunami . generator to blast simulated rockslides into at scale model of Gilbert Inlet. the bottom of Gilbert Inlet to measure and date the layers of sediment.

I know the glacier is hidden by the point when you're in Anchorage Cove, but I know what I saw that night, too. The glacier had risen in the air and moved forward so it was in sight. It must have risen several hundred feet. I don't mean it was just hanging in the air.

lituya bay megatsunami simulation dating

It seems to be solid, but it was jumping and shaking like crazy. Big chunks of ice were falling off the face of it and down into the water. That was six miles away and they still looked like big chunks.

They came off the glacier like a big load of rocks spilling out of a dump truck. That went on for a little while—it's hard to tell just how long—and then suddenly the glacier dropped back out of sight and there was a big wall of water going over the point.

The wave started for us right after that and I was too busy to tell what else was happening up there.

lituya bay megatsunami simulation dating

One example is the log of Jean Francois de Galaup who discovered the bay in Neither water drainage from a lake, nor landslide, nor the force of the earthquake itself led to the megatsunami, although all of these may have contributed. Instead, the megatsunami was caused by a massive and sudden impulsive impact when about 40 million cubic yards of rock several hundred meters above the bay was fractured from the side of the bay, by the earthquake, and fell "practically as a monolithic unit" down the almost vertical slope and into the bay.

lituya bay megatsunami simulation dating

The study concluded that: At the head of the bay is a mountain bordering Gilbert Inlet that, because it confined the rapidly moving water, was stripped of vegetation to a height of 1, feet meters Figure 4, also see the red dot in Figure 1. Lituya Bay is a perfect subject for exploration with Google Earth, for a number of reasons including the fact that the outline of the land-stripping event is still clearly visible along the shore of the bay and in Figure 1 on this page.

To more clearly show the stripped areas, Figure 5 is a historical aerial photograph taken shortly after the tsunami in Lituya Bay historical photo sourcesummershowing stripped areas Red dot: In the Lituya Bay Wikipedia articlewe read, "On July 9,an earthquake caused a landslide in the Crillon Inlet at the head of the bay".

But according to the linked Lituya Bay megatsunami article and the article it sourcesthe landslide took place in Gilbert Inlet, on the opposite side. In the Lituya Bay Wikipedia articlewe also read, "The wave possessed sufficient power to snap off all the trees up to 1, feet m high around the bay. Moving on in the same article, we read, "Based on Swanson's description of the length of time it took the wave to reach his boat after overtopping Cenotaph Island near the bay's entrance But the wave didn't "overtop" Cenotaph Island, it denuded the island up to about half its height on the eastern shore and less on the west, as clearly shown in my image in Figure 3 and the historical photo of Figure 5, on this page.

Apparently to remind Lituya Bay visitors how dangerous the place is, on June 11th this year, a huge landslide on nearby Lituya Mountain registered seismically as a magnitude Early Exploration The above account only begins to describe Lituya Bay from a historical perspective.

But the original monument has disappeared, possibly washed away during the megatsunami, reminding us all that nature is in charge. Sailor Warnings To any sailors reading this article who might consider visiting Lituya Bay, I have this advice — read the Coast Pilot chart before attempting to enter Lituya Bay key Coast Pilot quote: Specifically, pay attention to the strong currents at the entrance and the fact that the current direction is not aligned with the physical entrance, which creates a risk that a boat may be swept diagonally onto rocks regardless of the current direction.

Also, on an ebb tide, when the wind and swell come from the southwest as they often do, waves break across and outside the entrance because of opposing wind and current and see below. The three criteria we tried to ful- extended and generalized by a number of authors.

In this frame- fill in order to reconstruct the slide geometry where: This model is useful for the generation and evolution of tsunamis trig- 4.

Lituya Bay, Alaska earthquake and megatsunami - Wikipedia

In order to reproduce the main features of the slide impact, H. Fritz This section describes the system of partial differential equa- and collaborators designed a pneumatic landslide generator. They tions modelling landslide generated tsunamis based on layered intend to model the transition from rigid to granular slide motion. PDE describing the coupled two-layer system writes as: Then, the way those subscript 2 to the lower layer composed of the fluidized material.

H x, y indicates the depth of non erodi- 5. Those tween the two layers, and is defined as: Here the same strategy is used to cor- possible to the real event, a sensitivity analysis has been performed. With this strategy, spurious waves reflection in the coast are 2 the ratio of densities between the water and the mean density avoided and a more realistic simulation of the flooded areas is ob- of the slide, r, and, 3 the friction between layers mfhave been tained.

Moreover, transitions between sub and supercritical flows, retained as varying parameters for this sensitivity analysis. The val- that appears continuously in simulations as the one presented here, ues for these three parameters have been moved over the following which further complicate matters, are also suitably treated.

Coastline becomes a moving boundary, computed by closest to the optimal m, the numerical scheme. Consequently, no Creek, specific stabilization model technique is either required.

lituya bay megatsunami simulation dating

SF W are discretized is presented. The re- Finally the optimal parameters found were: The three- Setting the three parameters to the values given above, simu- step method will be denoted as follows: The resulting scheme is exactly well-balanced for the station- i the runup in Gilbert Inlet reached Next section describes in some detail the numerical experi- 5. Landslide initial conditions have been described in Section??. In this section model results correponding to A high efficient GPU based implementation of the numerical that simulation are presented, first studying the main characteristics scheme presented before has been developed in order to be able of the giant wave generated in Gibert Inlet and then describing its to compute high accuracy simulations in reasonable computational evolution through the main stem of Lituya Bay.

The wave is 6 J. Furthermore, the runup is extended Runup ex- tension and trimline coincide quite accurately in this sector Figure?? There is a large runup extension over the Lituya Glacier from 7. Finally it can be observed a good concordance between trimline and runup on the t: While the maximum runup on the east side of Gilbert head is reached, the southern propagating part of the initial wave, with more than m high, moves in a south-west direction, hitting the 7.

In the meanwhile, part of the trimline around the east part of the north shore due to the higher water reaching the maximum runup area over Gilbert head retreats slopes. Good concordance between trimline and runup in the north back down and part flows over the Gilbert head, inundating the shoreline of La Chausse Spit is also found. Both waves swept both shorelines in their path.

1958 Lituya Bay, Alaska earthquake and megatsunami

In the north In this case, inundation extension includes vicinity areas of Fish shoreline the runup reaches between m height??. In order to achieve a better agreement be- the south shoreline the runup reaches between m height. About the east third of the south shores. Moreover, the numerical model 25 seconds later, a second wave with approximately 32 m height provides mean runup heights around m while mean trimline hits the east coast Figure??. There is a good agreement both in The Paps shores as in t: After hitting Cenotaph Island, the wave is splitted in two parts, one advancing in the shallow channel north of the island and other one traveling through the deeper channel south of the island.

Waves higher than 25 m hit the north shoreline area in front of Cenotaph 7. In the south shoreline in tween runup and trimline is not so accurate. As already mention, it would be east of the Paps. At 5 m 50 s the wave reaches La One of the items to be checked in the sensitivity analysis presented Chausse Spit, passing over it to the sea and partially reflecting a in Section?? There- wave inside the bay.