Alaskan Geology and The 1964 Earthquake

Prince William Sound glacier

When speaking of Alaska as a physical place, as a raw and textured landscape replete with massive ranges, volcanoes, and mountain-studded coastline, it’s important to remember that it lies along the Ring of Fire at the boundary of the Pacific and North American tectonic plates. If not for that fact, Alaska would be an entirely different sort of place. It would certainly be less dangerous, and maybe therefore less alluring. Mountain climbers would not flock here to tackle the continent’s highest peaks. Few would find reason to hop a ferry up its vast shores from town to town, exploring the tall fingers of coast on Prince William Sound or the glaciated bays along the Gulf of Alaska. Possibly, the fish would find its rivers less hospitable, and so too would the fishermen. In short, a different breed of wanderers, if any at all, would find themselves dreaming of the inimitable beauty of the Far North and seeking adventure here.

So, because Alaska has turned out to be the sort of place it is, we’d like to delve for a moment into the geologic drama that has shaped it and ultimately brought us here.

Bush plane in Denali

Alaska is essentially an immense mosaic. The accretion of its myriad pieces was and still is driven by plate tectonics, wherein the Pacific plate, like a vast and insistent conveyor belt, thrusts into the North American plate, compressing and folding the lands together to form a slew of valleys and ranges from the Brooks to the Alaskan and Chugach, to name a few. These pieces–once islands, chunks of ocean floor, bits broken off from other lands, and volcanic excretions–came together over the course of hundreds of millions of years of slow collision.


It’s that process that drew Denali, North America’s tallest peak at 20,320 feet, skyward and continues to do so by a millimeter per year. Because it is composed mainly of granite unlike its older sedimentary neighbors (once submerged in ocean waters,) it’s much more resistant to weathering, giving it that striking 18,000-foot relief from base to summit–greater than Everest, K2, or Aconcogua. The Denali region is also rife with volcanic rock, as seen in the variegated slopes of Polychrome Pass.

Denali National Park

Outside of old stones in Denali and elsewhere in the interior, though, Alaska’s volcanism is still very active. Many volcanoes have erupted this year. Volcanoes exist almost exclusively on the coast as a result of subduction, which creates heated magma chambers at the plate’s edge. These same tectonic forces are responsible for earthquakes. Most are small and go unnoticed, but they’re occasionally devastating, like the infamous temblor of half a century ago.

Cordova harbor

At 5:36 PM on March 27, 1964–the evening of Good Friday–a magnitude 9.2 earthquake struck near Valdez, violently shaking all the coastal towns along Prince William Sound and the Kenai Peninsula on up to Anchorage. Everyone in Alaska, and parts of Canada and Washington, felt the earth’s convulsions over an astounding four continuous minutes–minutes, maybe, in which many folks had been contemplating the long, momentous death of one man on a cross. Those four minutes would prove momentous for the south-central Alaskan coast as well, and much was changed so that the shape of things here is now reckoned from them.

The consequences are still evident almost 50 years later, as we saw in several places we visited. Cordova’s Million Dollar Bridge was built in the early 1900s to haul copper on the railway and then converted in the 50s to a highway for visitors to the Childs and Miles glaciers, which flow into the Copper River from the Chugach mountains. It was destroyed in the upheaval and left broken for the next 40 years. Even now, sections of plank remain on the reconstructed portions, and the bridge is somewhat cockeyed where it was torn. Even the terminal face of Child’s glacier, visible from the bridge, is still largely masked by the earthen debris deposited on its southwestern flank.


Orca Adventure Lodge, where we stayed in Cordova, was renovated from an old dorm for workers at the now-defunct Orca Cannery, which once harvested the abundant Razor Clams on the shore. The quake raised the seabed around Cordova six to eight feet, lifting clam beds out of the intertidal zone and crashing the clam industry there. Remnants of the old docks now stand isolated and rotting in the water, an old piece of machinery abandoned on an island of beams. Orcas, once frequent visitors, for the most part stopped entering Orca Inlet, now too shallow for their comfort.

Cordova dock

This sort of thing happened in many other nearby towns. Valdez, which we saw from our ferry back to Whittier, was originally four miles farther east, but it suffered enough damage to warrant relocation, and the native village of Chenega was destroyed entirely, a third of its population lost. A significant section of the Seward Highway on the Turnagain Arm, which we drove to visit Seward and Homer on the Kenai Peninsula, sunk below the high water mark in the tremor and had to be rebuilt in the following years. I don’t know the details of Seward’s damage beyond the expected wrecked buildings, but in Homer the popular Spit sank some eight feet, shrinking to a thin spur. The vegetation there died, leaving the gravel and sand surface that you see today.

Homer Spit

The Great Alaskan Earthquake killed 131 people, most from subsequent tsunamis, and destroyed several villages. It remains the second largest recorded temblor in history, and like all of the strongest ones it was a megathrust earthquake. These occur at plate boundaries, in this case the convergence of the Pacific and North American plates. What happens, essentially, is that the dense Pacific plate subducts beneath those surrounding it in the Ring of Fire. At the Alaskan coast, that means a slow build up of immense pressure as the Pacific compresses into Alaska some six centimeters a year. When that tension finally releases, the earth’s crust shifts and the denser Pacific plate crashes down below. Most of the time, these are subtle shifts, like an animal settling into sleep. But in 1964, the pent-up pressure was so huge that its release was catastrophic, a massive beast disturbed into paroxysmal wakefulness.

Childs Glacier


The Kenai Peninsula

Resurrection Bay

South of Anchorage, the 200-mile-long tooth of the Kenai Peninsula cuts the Cook Inlet from the Gulf of Alaska in a variegated swath of subarctic terrain. The northernmost crown of the Ring of Fire, the Kenai, they say, is Alaska in miniature. It bears each of the state’s ecosystems aside from Arctic tundra–boreal forest, coastal rainforest and wetlands, sea ice in the fjords, and no shortage of soaring mountains–and it consequently made for an ideal five-day tour with our friend Mike Webster who kindly flew up to meet us.

Mike left Santa Fe, Phoenix-bound, the same day we did more than a month earlier, so it was good to see our friend again, and a little surreal now that we were all together in Alaska, exploring a small part of this state as we so often explored northern New Mexico, camping and hiking and generally being outside amidst all the natural beauty. We reunited at the airport, stocked up on grocery essentials and some Midnight Sun Kodiak Brown and headed south to Seward at the north tip of Ressurection Bay.

Lost Lake

The Seward Highway is a national scenic byway and a worthy destination in itself. Glaciated peaks thrust skyward from the water along the fjord-like Turnagain Arm of the Cook Inlet. Dozens of waterfalls litter the shore, and you can trace the thin ribbons of water up to high snowfields where they originate. Mike was snapping iPhone photos at every bend in the road that opened to new vistas. But as he noted, you can’t quite capture the majesty of this place, merely hint at some portion of it. Sometimes a cloud hides the neck of a mountain and you look higher to be astonished by its true height peaking above.

Exit Glacier

We grabbed a spot in the Primrose Campground 17 miles out from town. The mosquitos were few, but flies swarmed in their place with unexpected fury. Somehow Paige and Mike didn’t seem bothered, but I couldn’t stand still without being attacked. The next site over was a clearer, more open space where the flies were less abundant and the ground flatter, so we moved, carrying Mike’s already-setup tent. Having decided to do the long hike to Lost Lake and back, which began from our campsite, we paid for two nights and headed toward Seward to check out Exit Glacier and the town.

Exit Glacier

Like most glaciers of the world, Exit Glacier was once much larger. As we passed into Kenai Fjords National Park to see it, signs indicated where its terminal face had once been more than a century earlier, and we could track its insistent retreat to the slope partway up the foot of the mountain from which it flows. The hike to the face was quick and easy. Where it stopped, water trickled out in a little cloudy rivulet with the sound of further retreat on a warm day.



Mile 0 of the Iditarod Trail, Seward is a small town of about 2,600 named after William H. Seward, Lincoln’s Secretary of State who was responsible for negotiating Alaska’s purchase from Russia. We walked the few blocks of pleasant main drag down to the water for a little wading and relaxing on the shores of Resurrection Bay, where we almost lost Mike. He’d gone back to the car for a jacket. Paige and I, ready to head back to camp for dinner, thought we’d intercept him as he walked back. It is, after all, a rather small town with approximately one main three-block street. But he’d come back down a street that was not quite as main as the one we simultaneously walked up, and we kept missing each other for the next 20 minutes, the maximum length of time you can lose someone in Seward who isn’t climbing Mount Marathon.




Because computer and internet time is pretty limited for us here in Alaska, I’m forced to make the rest of the Kenai visit brief, but I’ll be sure to include a lot of pictures to make up for it. The next morning we went out for a tiring but excellent 15-mile hike. It started out very buggy in the trees for many miles, past an abandoned miner’s cabin, but once we emerged into the tundra, the morning fog had lifted to reveal gorgeous views of the mountains around us. We found Lost Lake, hungry for lunch, and spent a good amount of time lounging and even napping on the shore. It was an idyllic place, the kind that makes you forget about any other worries beyond the bare moment.



We spent the next two nights in Homer at a hillside campsite overlooking Kachemak Bay and the snow mantled peaks across it. We hung out a bit on the Spit, grabbed a pizza and walked around the shops there. All the kayak tours seemed to be booked through the weekend, so we just decided to take it easy in Homer, which amounted to: a guided beach walk at the nature center, the nature center itself, skipping stones at the water’s edge on the Homer Spit, cruising Skyline Drive (a scenic road above town, bordered by hills rife with fireweed, with expansive views over the bay,) burritos at Cosmic Kitchen (breakfast, lunch, and Mexican,) and a little fireside beer tasting.



Homer Spit


Five days is too short a time to spend with such an excellent and admirable friend as Mike, and it ended all too soon, as things are wont to do. On the last day, we drove back to Anchorage, walked around the Saturday Market, and got lunch at our favorite Anchorage establishment, the Glacier Brewhouse, before dropping Mike off at the airport. It was sad to see him go, not knowing this time when exactly we’d next meet, that sadness made more acute with the knowledge that our time all together in Santa Fe is gone. But we know it won’t be long, and the memories we’ve made will only be bolstered by those we have ahead of us, as good friends. Meanwhile, the adventure continues. And we’ll drink to that.