'Black swans' of science: Alaska's big earthquake and Exxon Valdez oil spill

Fifty years ago, North America's most powerful recorded earthquake struck Alaska. With an epicenter in Prince William Sound, the magnitude-9.2 earthquake demolished communities in the state's most populous region, created numerous killer tsunami waves, and resulted in 131 deaths, including some as far away as California. The catastrophic quake is today considered a scientific "black swan," an extremely rare, unpredictable and disastrous event. Twenty-five years later, also in Prince William Sound, came another "black swan," a disaster that officials had assured would not happen except possibly once in a century: the Exxon Valdez oil spill.

Aside from the common geographic locations and the human, environmental and financial tolls that both events took -- and the massive rebuilding and cleanup efforts that followed -- the earthquake and the spill share similar legacies, said keynote speakers at a science conference that kicked off its 13th annual meeting on Monday in Anchorage.

The 1964 Alaska earthquake struck "at a pivotal time in the history of earth science," Peter Haeussler, a U.S. Geological Survey geologist who heads that agency's Alaska earthquake hazards program, said in his address at the Alaska Marine Science Symposium.

When it happened, scientists did not understand why, Haeussler said. There were no seismic fault lines visible at the earth's surface, he said, yet the ground in Southcentral Alaska moved substantial distances -- up, down and sideways.

Then George Plafker, one of three USGS scientists sent to the scene to investigate, came up with an explanation: The Alaska quake confirmed the then-new theory of plate tectonics. Plafker, still working for the USGS, and his colleagues found that the quake resulted when the oceanic crust of the earth slipped beneath the continental crust.

"As a result of this work, people kind of had the lights turned on," Haeussler said. The movements of those geologic plates explained not only major earthquakes in the modern era but also ancient quakes that left their mark on the landscape long before there were written records, he said.

"All of the giant earthquakes are now understood in the shadow of the earthquake in 1964," he said.

Some of the huge waves resulting from the earthquake were generated by earth movements at sea and rolling across the ocean in a matter of hours. Others, more localized, were caused by earthquake-triggered landslides and came very quickly, he said. The Alaska earthquake gave scientists material to understand both types of tsunamis, he said.

The 1989 Exxon Valdez spill, in contrast to the earthquake, was a human-caused disaster, though one that experts had assured would not happen, said Robert Spies, former chief scientist for the federal-state council overseeing a government trust fund created with a civil settlement paid by Exxon.

The Exxon Valdez remains the largest oil tanker spill in U.S. waters. In the immediate aftermath, Spies said, scientists' focus was on the toll of dead animals and damaged fish runs -- up to 1,200 miles of coastline was hit by oil, including salmon-spawning sites; 2,000 sea otters and 200 to 300 harbor seals killed; 150,000 to 250,000 birds killed. The scope of damages was regularly contested by Exxon, Spies said.

But later, after Exxon settled civil claims with the state and federal governments and the Exxon Valdez Oil Spill Trustee Council was formed, the fierceness of Exxon's objections lessened somewhat, Spies said. Over time, scientists realized that their focus needed to be on the long-term state of the ecosystem that remained, he said.

Lingering effects of the spill turned out to be more widespread, though sometimes more subtle, than previously understood, he said.

While long-term studies are now considered crucial to understanding oil-spill effects, that was not always an easy sell to politicians, Spies said. Frank Murkowski, elected governor after serving two decades in the U.S. Senate, dismantled the long-term Gulf of Alaska ecosystem monitoring program established by the Exxon Valdez Oil Spill Trustee Council. The head of the monitoring program was fired, Spies said. "Governor Murkowski was not a friend of long-term monitoring," he said.

One lesson learned from the spill is that assurances of cleanup are "wishful thinking," Spies said. That is especially true in challenging areas like the Chukchi Sea in the Arctic, where Shell and other companies are seeking to develop oil leases, he said.

The Exxon Valdez spill was caused by human error and complacency, he said. "It's my personal opinion that the margin for human error is much smaller in the Arctic," he said.

Contact Yereth Rosen at yereth(at)alaskadispatch.com