Cook Inlet Earthquake – Alaska – December 31, 1901

Earthquakes are frequent in Alaska but less frequent in magnitudes over 7. This 1901, magnitude 7.1, earthquake was related to a volcano nearby that erupted frequently. The earthquake caused widespread destruction and triggered a tsunami but, because there were so few people living in the area in 1901, there was no record of casualties.

On the morning of December 31, 1901, a 7.1 magnitude earthquake shook Cook Inlet in Alaska. The quake was accompanied or followed soon after by several tsunamis, all of them created by the Augustine stratovolcano on the Island of Augustine in Cook Inlet. It, like other stratovolcanoes, has a symmetrical, cone-shaped appearance and over the past two centuries it has erupted more frequently than any other of the many volcanoes in this southern part of Alaska where most of the state’s people live.

It was active in 1812, 1883, 1902, 1935, 1963, 1971, 1976, and 1986. As recently as 2006, the volcano was very active again, sending plumes of smoke and ash 30,000 feet into the air. It is hard to separate the earthquakes of Cook Inlet from the volcanic eruptions on Augustine Island. Both are so frequent that it is likely that they are interrelated. Between 1899 and 1903, the period within which the 1901 occurred, there were five earthquakes in and around Cook Inlet, each one of magnitude greater than 7, a rare thing even for Alaska.

The tsunamis that Augustine produced in 1883, a well-documented event, rose as high as sixty feet in inlets like the one at Port Graham, fifty miles from Augustine on the east side of Cook Inlet. Elsewhere on the inlet, at Homer and Anchor Point seventy-five miles northeast of Augustine, deposits from earlier tsunamis were later identified at elevations of twenty-four feet above sea level. A description of the 1883 event indicated that the summit was destroyed, leaving a jagged crater at the top of the mountain. The tsunamis that accompanied the eruption completely destroyed the boats that were moored at English Bay and Port Graham and they also deluged the homes that were close to the ocean.

Smoke and ash flows covered the whole area. These features were repeated again and again in the eruptions of subsequent years. Cook Inlet had become famous a hundred years earlier as the site where Captain Cook attempted to claim this part of the world for Britain. In 1778 Captain Cook sent a boat ashore on what is now Turnagain Arm with one of his lieutenants who was instructed to bury an earthen bottle with a parchment inside it on which he wrote a formal ownership claim for England of all the land drained by the waters of Cook Inlet. The bottle has never been found and this may explain why Alaska became the property of Russia until it was purchased by the United States in 1866.

During this age of exploration, the latter part of the eighteenth century, it was common for captains to make a formal act of possession when they found lands that no other country had already claimed. When Cook left England in 1776 he knew the Spanish were planning another voyage to the Northwest Coast, so he made his first claim north of where he thought the Spanish might have reached. He succeeded in getting closer to places such as Cook Inlet and Prince William Sound than any other explorer of that time. The Russians had only reached the western coastal areas of Alaska.

Cook met with Russian explorers and they shared charts. Quite apart from discovering new lands there was another purpose behind Britain’s desire to explore the northernmost part of the Pacific Ocean. Different European nations wanted to find an ocean passage to Asia via northern Canada. Both before Cook’s time and after it different explorers had tried to find such a sea passage but none of them were any more successful than Cook. We know today that theirs was an impossible task, even in summertime, with the kinds of ships they had in the eighteenth century. Now, in the light of global warming and the increasing volume of ice that is seen to be disappearing from the Arctic Ocean, it might be a very different story if people on wooden sailing ships were to try again.

Apart from the competition among Europeans to be the first to find new lands to claim, there was very little about southern Alaska in 1901 that interested either the U.S. or Europe. The contrast between 1901 and today is as great as one could find anywhere in the world. Air travel and oil have transformed life for everyone in Alaska. A brief summary of Augustine’s eruption in 1976, an event that was carefully monitored simply because, by that time, major commercial and industrial enterprises were active in southern Alaska and they needed to know the extent to which they might be harmed by Augustine’s eruptions. Advance warnings of impending action came in the form of swarms of earthquakes deep down within the mountain. This was followed by six major explosive eruptions.

Ash was repeatedly blasted skyward to heights of 40,000 feet, then fell back to cover an area of more than 100,000 square miles. In between the explosive episodes, ash and gas avalanches swept down gullies in the mountain’s sides, often at speeds of 100 mph, to end up in Cook Inlet. The internal temperatures in these flows reached 1,000 degrees Fahrenheit. The destructive effects of the ash were felt in many places. It stripped the wax from skis, irritated eyes, especially those with contact lens, and endangered turbines, forcing industries to stop and clean their machines.

In the late 1980s before Alaska’s Volcano Observatory was installed, Anchorage was being used as a refueling stop for flights between the U.S. or Europe and Asian cities. The great circle route, the shortest path between two points, happens to pass through Anchorage so more and more airlines used this city as a convenient stopover. On December 15, 1989, a Boeing 747 en route from Amsterdam, carrying 231 passengers and a crew of thirteen, began its descent into Anchorage. Another 747 had followed the same descent path only twenty minutes earlier and had landed safely. The plane from Amsterdam however ran into a cloud of ash 150 miles downwind while still at an altitude of 22,000 feet.

The volcano had erupted about ninety minutes earlier. As the pilot attempted to climb out of the ash, some particles that were melted by the heat of the engines began to solidify, forming a glassy coating on the turbine blades, thus restricting air intake. All four engines shut down. For the next eight minutes the plane glided steeply, losing 12,000 feet of altitude before the pilot was able to restart the engines. He managed to get the plane back to Anchorage and land it safely. All four engines and the electrical circuits had to be replaced and all the fine ash removed. Total cost of these repairs was $80 million. Shortly after this incident, new efforts were launched by the installation and constant monitoring of the Alaska Volcano Observatory to make sure, as far as was humanly possible, that an event of this kind would not happen again. There are monitoring stations now all along the volcanic arc, with special additional sites close to the main airport.

When volcanoes erupt explosively, high-speed flows of pyroclastic ash and landslides can devastate areas ten or more miles away, and huge mudflows of volcanic ash and debris can inundate valleys more than fifty miles downstream. Around island volcanoes, like Augustine in Cook Inlet, pyroclastic flows and landslides can generate tsunamis that threaten nearby coastal communities. Explosive eruptions can also produce large earthquakes. In 1912, at Katmai, fourteen quakes of magnitude 6 to 7 rocked the region, and countless smaller shocks occurred. However, the greatest hazard posed by eruptions of most Alaskan volcanoes is ash. Minor amounts can create health problems, close roads and airports, disrupt utilities, and contaminate water supplies for hundreds of miles downwind. Since it is now possible, through observation of the frequency and strength of earthquakes immediately prior to an eruption, to predict to within a few hours when the eruption will occur, people will not again be taken by surprise.

To cope with the difficulty of seeing the Augustine Volcano during an eruption, seismometers were installed. These instruments can sense earthquakes caused by magma and other fluids moving beneath and within the volcano. The challenge of safe air travel is one, and perhaps the easier of the two revolutionary developments that have changed the face of Alaska in the second half of the twentieth century. The other challenge is oil. The cold northern shores of Alaska do not look like a place that once was a warm tropical environment, full of rich vegetation, but that is exactly what it once was, hundreds of millions of years ago. Oil and gas are being extracted from this area and moved by pipeline to the south coast of Alaska for onward transportation by ship.

The permafrost terrain through which the oil has to be taken is a constant challenge to the engineering skills of those involved. Equally challenging is the problem of remediation when accidents occur. The Arctic environment is fragile and the low temperatures of water ensure that pollutants remain in place for long periods of time. The oil and gas reserves for the whole petroleum province, with a concentration in and around Prudhoe Bay amounting to seventy billion barrels of oil and forty trillion cubic feet of gas, is one of the largest in the United States and represents about one-fourth of the nation’s production of oil.

There is a continuous flow of oil tankers, day and night, transporting oil to southern places and they have to approach land through narrow channels. As they move in and out they have to contend with unexpected masses of ice released from eruptions on volcanoes like Augustine and scattered over the neighboring ocean. In 1989, the oil tanker Exxon Valdez ran aground on Bligh Island in Prince William Sound, spilling ten million gallons of oil. More than 5,000 kilometers of Alaska’s coastline was contaminated and all kinds of marine life were decimated. While mistakes were made in the course of navigating the ship though the Sound, the initial source of the problem was the rerouting of the ship to avoid a sudden mass of ice that had covered the normal route.

In 1912, Alaska was very sparsely populated, and there were few airplanes. Now, nearly three-quarters of a million people live in the state, and aircraft carrying more than 15,000 passengers and millions of dollars in cargo pass near Alaska’s more than forty historically active volcanoes each day. The heavy ash fall produced by another eruption like the one that happened at Katmai in 1912 would bring the state’s economy to a standstill and kill or injure hundreds. Clinics would be overwhelmed by people with eye, throat, and lung damage. Building ventilation systems would have to be closed to outside air. Ash entering computers, bankcard machines, and other electronic equipment would cause them to break down. Automobile, snowmobile, and boat engines would also be damaged.

Airports, including Anchorage, which handles the largest amount of air cargo of any airport in the United States and is a refueling stop for many trans-Pacific flights, would be closed until runways could be cleared of ash. To avoid the ash cloud, aircraft would have to be diverted around most of Alaska, Canada, and the Northern United States, seriously disrupting national and international commerce.

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