Wednesday, July 15, 2009

#39 - Lituya Bay

Besides the fine fishing, the other reason to visit the Lituya Bay is the tsunami. Today we will pull and re-bait our traps and tour the Bay looking for signs of the tsunami. Both crab traps were empty except for a starfish having an affair with the bait can.

Lituya Bay is kinda shaped like a fish, just one of the reasons it's a hot fishing spot.

Please have these love affairs underwater, not out in the open.

So besides halibut, there is also giant prawns in the deep recesses of the Bay.

Bob is so excited by the prawns he quickly re-baits and is ready to reset the prawn traps in record time.

We motor east to the Cascade Glacier at the head of the Bay.

The same topography that leads to the heavy tidal currents at the entrance also created the highest wave from a tsunami ever recorded anywhere in the world. An earthquake caused a landslide in the Gilbert Inlet at the head of the bay on July 9, 1958, generating a massive mega-tsunami measuring 1,720 feet high. The wave stripped trees and soil from the opposite headland and consumed the entire bay. There were three fishing boats anchored near the entrance of Lituya Bay on the day the giant waves occurred. One boat sank and the two people on board lost their lives. The other two boats were able to ride the waves. When the wave reached the open sea it dissipated quickly.

The giant wave run-up of 1720 feet at the head of the Bay and the subsequent huge wave along the main body of Lituya Bay were caused primarily by an enormous rockfall into Gilbert Inlet at the head of Lituya Bay, triggered by an earthquake. The large mass of rock impacted the bottom of the inlet with great force. The displaced water and the folding of sediments broke and uplifted 1300 feet of ice along the entire front of the Lituya Glacier and the impact resulted in water splashing action that reached the 1720 foot elevation on the other side of the inlet.

Artist's view of 1958 earthquake triggered rock slide into Gilbert Inlet
Heller,V, Hager, W,: Impulse product parameter in landslide generated
impulse waves, J. Waterw. Port C-ASCE 2010.
Today, you can easily see the height of the wave by noticing the tree line: new growth versus old growth.

Further down the Bay the wave dissipated in height.

Photo of Lituya Bay the day after the wave.  This and below photos were
captured by USFS Officer Miller.  
Denuded peninsula forming west wall of Gilbert Inlet and rock slide
that filled most of the Inlet. 
View looking northeast across Lituya Bay towards Gilbert Inlet.
A recent geologic study has determined that slides and tsunamis have been rather frequent in Lituya Bay. Approximately every 30 years since about 1860 a slide, and possibly a tsunami, has occurred. This pattern stopped after the 1958 slide, so many believe another slide, and tsunami are overdue. So with those facts in hand, we decided to anchor on the east side of Centotaph Island last night, the anchorage of one of the surviving boats form the 1958 slide.

But today's cruise sort of explains why a recent slide may not cause another tsunami. The head of Lituya Bay has filled in with slide material. There is no water or ice to displace anymore, and thus no tsunami. Thankyou Dr. Benson, nice work.

Gilbert Inlet is no more. The area that caused the 1958 tsunami no longer has water or ice, just slide material.

After careful study, Dr. Benson has updated this Lituya Bay chart to reflect the filled in inlets at the head of the Bay.

All this study makes a researcher thirsty, but researchers don't like warm beer, even here in Alaska. Let's collect some glacier ice to fill the cooler and chill our beverage.

Wild Blue holding position at the head of Lituya Bay.

More research is needed so an expedition party is organized and managed by Ground Captain Gerard. Four crew take the tender ashore for the assault of the Cascade Glacier, or it's waterfall. It's a rough 2-hour, uphill trek but the expedition succeeds and photographs record their findings.

Expedition party hikes to the face of the Cascade Glacier. Let's hope a chunk doesn't decide to detach.

A roaring waterfall greets the team and they celebrate their accomplishment.

Gerard takes it all near the face of Cascade Glacier.

At last it's dinner time. Let's see what should we have with our halibut. How about fresh prawns? We cook them for just four minutes only as per the Karen Almas recipe. What an awesome sweet flavor!

Just 4 minutes cooking time only, and seasoned with Pappy's per Williebird's request.

There's way more than we can eat in one sitting, so we sit down twice!

The complete Lituya Bay epicurean experience: fresh LB BBQ halibut, wild rice, peas and fresh LB prawns. Awesome!

Well this is our anchorage for tonight on the east side of Centotaph Island. It has a nice view of the glacier and is perfect. We'll explore Centotaph Island tomorrow. Good night.

1 comment:

  1. Interesting idea re: why there haven't been any giant waves in Lituya since '58, even though we're supposedly long overdue for one by the historical record. The satellite photos of Lituya on Google Maps support that the inlets have been filled beyond what the charts show. On the other hand, Don Miller's USGS study of the '58 wave suggested that the areas prone to landslides in Lituya Bay extend beyond just the inlets; see
    My amateur guess would be there's still the possibility of future waves, but its much reduced from what it was before '58.
    Great photos, thanks again for sharing them!