Written by Ed Zalisko
Anchorage is located on the coastline of South-Central Alaska, where part of the Pacific plate is sinking under the state. The tremendous energy of plate tectonic motion is promoting volcanic activities to the west, in the Aleutian Islands, and contributed to the 9.2 earthquake that rocked Anchorage and the region in 1964. It was the second strongest earthquake in recorded Earth history. And it is a region packed with glaciers, mountains, whales, bears, and moose.
So my wife Amy and I decided this would be a great place to take three short field courses on earthquakes, tsunamis, glaciers, and the ecology of the region. The trip would involve two all-day boat trips to see whales, dolphins, seals, sea otters, bears, birds, and more than 30 glaciers up close, where you have to dodge the floating chunks of ice that recently calved into the sea.
We arrived in Anchorage in mid-June and settled in for 12 days of adventure. The field courses were offered by three science faculty members out of the University of Alaska, at Anchorage. They were each well-known and respected scientists who were to be our teachers. They would take us to the “good places” they know well!
South-Central Alaska is cold enough, and wet enough, to produce hundreds of glaciers within the local region. Other parts of Alaska are even colder, but don’t get the precipitation for glacier production. We were looking forward to seeing the glaciers up-close. And we were not disappointed.
Matanuska Glacier is about 25 miles long and within an hour’s drive north of Anchorage. About 15 faculty members were in our group when we started up the path at the lowest point on the glacier. The surface was covered with fine gravel that had accumulated along the way, and at first we couldn’t tell we were on ice. Dr. Kris Crossen was our guide and teacher. She explained that glaciers flow slowly, like rivers, downhill. They plow and grind up the region and leave large deposits when they retreat. In Illinois, the glaciers left huge amounts of this fine sediment (called loess) that has contributed to the rich soils of our region. We could see 20-30 feet thick loess deposits along the braided streams just downhill of the glacier. Dr. Crossen brought a gallon of water with her, which she used to clean off a patch of the glacier where we were standing. Sure enough, our path and the piles around us were actually ice, covered in a thin coat of gravel that helped us get traction as we walked.
As we prepared to move on to clear ice, we each strapped special grippers to our shoes and took ski poles to help keep us upright. Our destination ahead consisted of large columns of ice several hundred feet tall that surrounded a small pond of water that was cupped on the glacial surface. It was one of the most beautiful places we had ever seen. Fans of the movie Frozen would not be disappointed.
The next day, we made our way about 50 miles southeast to Whittier, where we boarded a small boat that would take us to see glaciers in Prince William Sound. This is the region devastated by the 1989 oil spill near Valdez. Our trip would take us to regions little affected by the spill, where we saw 2 Killer Whales, hundreds of sea otters (nearly the size of a human), glaciers of all shapes and sizes, and seals perched on floating chunks of ice the size of cars. Some glaciers continue to advance while others are in retreat. Today, more glaciers are retreating than advancing.
The ecology class took us South to the Kenai Peninsula, where there is a debate about moose populations. Some scientists think that the number of moose in a region is primarily the result of the number of bear and wolf predators (mostly on young moose). One of our instructors, an expert on moose diets, suggested that the availability of food is a more important determining factor. In large regions where fire occurred several years earlier, moose find plenty of food amongst the regrowing vegetation, and moose populations increase. As we sat near the Kenai River for lunch, smoke from a large fire blocked much of the sun.
The following day we took another boat ride to see wildlife again along the Kenai Peninsula, in the waters of Kenai Fjords National Park. It was an overcast, calm day, just ripe for wildlife watching. We saw more than 20 humpback whales from as close as is allowed with some rubbing against shoreline rocks (as seals swam circles around them). The boat cruised close to a cliff, where horned and crested puffins were darting between the water and shore. As we moved from one humpback to another, about 20 Dahl’s porpoises leaped out of the water at the front of our boat. These small porpoises are considered to be the fastest marine mammals known and most of us on the boat squealed with delight as they charged back and forth beneath us.
But the highlight of this boat trip was the chance to see 2 fin whales, gently resting near the surface. Fin whales are the second largest whales on Earth reaching 70 to 80 feet in length. They are usually spotted in this region just a few days a year, as they take one breath and dive back into deep water. Our captain was overjoyed and surprised by what we saw in this shallow water near the coastline. She assured us we were very, very lucky.
The last field course addressed the geology of the region and began with a study of the devastating 1964 earthquake. We spent several hours in a classroom understanding the movement of the plates, volcanic activity in the region, and the need for a warning system to alert people of a coming tsunami. Then we went to see the 1964 earthquake damage.
Underlying some parts of Anchorage is a thick layer of sediment called Bootlegger Cove Clay. The shaking of an earthquake causes the clay to act more like a liquid. Things once above the clay start to sink in during shaking. During the 1964 quake, about 75 homes were destroyed as large regions sunk and landslides moved buildings downhill to the water. We were going to tour the area now designated Earthquake Park, where much of this destruction occurred and the region has not been rebuilt.
About 2:30 PM on this first day of our Earthquake course, Dr. Crossen took us to the Anchorage shoreline. She handed us some Bootlegger Cove Clay she just dug up from the area where we were standing. We passed the clay around to better understand how it can become more like a liquid in an earthquake. As we stood along the shoreline of Earthquake Park, Ed stood steady to feel the properties of the clay below his feet. And then the quake hit. Shifting back and forth, from left to right foot in a rocking motion, Ed thought he was somehow standing on a loose board or rock. Looking around, he saw a long piece of metal swaying wildly back and forth. Amy was stooped down to look at the clay when she started swaying, feeling motion sick, like being on a boat.
“Guys, I think we just had an Earthquake.”
When it stopped, Ed looked at his watch, and said “Guys, I think we just had an Earthquake. It is 2:32 PM.” Pulling out his iPhone with Internet access, he started to confirm the event. “Give them 10 minutes”, said Dr. Crossen. The National Tsunami and Earthquake Center located in Palmer, just north of Anchorage, will issue an immediate report. They did. The final intensity, confirmed and revised slightly by the US Geological Survey, was a 5.8 magnitude earthquake. A quake, the first day of the earthquake class! And one of the largest earthquakes to hit the region in the previous 13 years!
We were all delighted and safe. The 1964 earthquake was more than 1000 times greater, and had lasted for nearly 6 minutes. Our earthquake (on 24 June 2015) lasted only about 15 seconds. For reference in Illinois, the earthquake that struck the South-Central Illinois region on 18 April 2008 was a magnitude 5.4.
For the next few days, we asked around to see if others felt the quake. People in buildings noticed lights flickering and some clanking or rattling of building parts. But others who were moving in cars were less likely to detect the earthquake motion. You had to be sitting still and we were.
Two days later, we had a special 2.5-hour tour of the National Tsunami and Earthquake Center in Palmer. The United States has just 2 centers to monitor the Pacific and North American Regions. This center is responsible for all of North America and parts of the Caribbean. (The other center is in Hawaii and is responsible for most of the Pacific.) Their main goal is to quickly characterize all earthquakes within 5 minutes so that they can send out warnings to regions that might be affected by a resulting tsunami. As the director told us, if you are within a region of the earthquake, and near a shoreline, you should just run to high ground. Our center will not be able to provide a tsunami warning quick enough to help. The center is able to forecast tsunamis generated from distant earthquakes, such as the 9.0 quake that devastated Fukushima, Japan in March of 2011. The Palmer center is responsible for determining the sizes, times, and locations of the tsunamis and played a critical role in the tsunami produced by the Fukushima quake. Such warnings can help to save thousands of lives.
Smart phones now have the ability to detect emergency announcements such as tsunami and tornado warnings. The alerts are sent to phones within an impacted region. When the director told us about this system, many members of our group checked our phones to confirm that our Emergency Alert Notifications were turned on! As long as our phones are charged and with us and we have cell phone access, we should receive warnings wherever we travel.
The Director asked us if we wanted to see the data received at their center regarding “our” 24 June earthquake. He pulled up the different types of data and explained how they calculated the location and strength of the quake. From direct experience to data analysis at the national center, we learned much about Alaskan earthquakes that have helped to shape this spectacular region.