great wave hokusai

Three hundred and fifteen years ago tonight, on January 26, 1700, at about 9:00 PM local time, one of the most severe earthquakes in recent geological history raked the part of North America that is now known as the Pacific Northwest. This incredibly violent quake was about the same magnitude as the temblor that would destroy Lisbon 55 years later, and considerably stronger than the San Francisco earthquake of 1906. The quake opened great fissures in the ground and knocked down trees like matchsticks. Although the region’s human population of Native Americans didn’t keep written records that were precisely dated, oral traditions passed down for generations after the earthquake make clear that it was gigantic and terribly destructive, and lived long in the collective memories of Pacific Coast peoples.

Destructive as the earthquake was in North America, though, it also had an impact across the Pacific Ocean in Japan. The monster earthquake triggered an even more terrifying tsunami that moved along the great ocean like a ripple in a bathtub. In the village of Tsugaruishi, on the northwestern coast of the main island of Honshu, a wall of high water swept away houses and was blamed for starting a fire in the town of Kuwagasaki. Damage and flooding occurred in many other Japanese coastal towns and was mentioned in official reports sent to the shogun’s capital at Edo, as well as private family sources. The 1700 tsunami did kill a few people and cause property damage, but it certainly wasn’t an epic disaster that would sear its way indelibly into the history books–which is why virtually no one in the modern world knew about it until recently.

ghost forest

“Ghost forests” like this one on the coasts of Oregon and Washington have proven very useful in examining the history of previous environmental catastrophes like the Cascadia earthquake.

Indeed, this earthquake, which geologists have named the Cascadia earthquake, is something of a sleeper in world environmental history. Of course the science of geology was not well developed in 1700 and no systematic records of earth tremors were kept the way they have been for the last century or so. Basically, the only earthquakes that got into the historical record had to be big enough and noticeable enough to get a lot of people writing about them in records that survived, which usually meant they had to cause a lot of death and destruction in a popular area. Records of natural disasters kept by non-Western societies, especially those with oral traditions, are especially unlikely to pop up on the radar screen of world history. In the case of the 1700 quake and tsunami, the quake happened in a sparsely populated area, in a society with an oral tradition and no written records; the related tsunami occurred in Japan, a society with many written records, but which was closed off from the rest of the world by deliberate design for the next 150 years. Thus, as big as this quake was, it has generally not “made the scoreboard” of world historical events until recently.

That began to change in the first decade of the present century when American and Japanese geologists, studying various physical environmental clues about the past, realized they were on to something big. Some of the stumps of trees snapped off by the quake were occasionally visible at low tide on the Oregon coast, at the fascinating but little-known site known as the “Neskowin Ghost Forest.” Damaged trees at this site go back thousands of years, suggesting various other violent cataclysms in the distant past, but some trees seem to have been broken in 1700. (Trees can usually lead to precise dates because of dendrochronology, the counting of the rings). When geologic experts began mining historical records in Japan for occurrences on the coast at that time, they eventually found the records of the tsunami waves from the small Japanese towns. The key fact was that none of the Japanese records mention a local earthquake preceding the flooding and fire events of January 1700.

With these two sets of clues–one physical, the other historical–the true picture of what happened that night more than 300 years ago came together. The violent quake that destroyed and submerged trees on the coast of Oregon caused a tsunami that washed up in Japan a few hours later; because the time of the arrival of some of the waves on shore was recorded precisely in a few of the Japanese records, and the speed of propagation of waves can be calculated mathematically, the experts could even tell the likely time of day of the earthquake: about 9:00 in the evening. It’s extremely rare for an event like this, so far back in the past, can be assigned not only an exact date but an exact time.

japanese coast

Japan at the time of the Cascadia earthquake/tsunami was a quiet, relatively peaceful nation of mountains and coastal villages, such as seen in this period watercolor.

The great Cascadia earthquake of 1700 is interesting for its own sake, but it becomes rather ominous when one understands what it portends for the future. Many of us have heard of geologists’ predictions about the strength and timing of future earthquakes, especially in relation to heavily-populated areas of California; the great future quake that may destroy L.A. or San Francisco is spoken of as “The Big One.” Here in the Pacific Northwest we’re waiting for our own “Big One,” usually called the “Pacific Rim Quake.” It will likely happen exactly the same way the Cascadia quake did, emanating from friction between two tectonic plates rubbing together under the Northwest. Our earthquakes in Oregon are less common than those in California, and because of that the danger is greater. Large buildings in the northwest generally haven’t been built to be earthquake-resistant until fairly recently, at least not in the way buildings in California have been. The destruction and loss of life that could result from the Pacific Rim Quake could be staggering.

When will it happen? There’s no way to be sure, of course, but the obvious implications illustrate why studying environmental history matters. The 1700 earthquake spawned a tsunami that did little damage in Japan, but no one can be sure the next time we’ll be so lucky. This episode from the past shows us that a massive tremor on the Oregon coast could have disastrous consequences not just in the local area, but all the way across the Pacific. Historians’ business is explaining the past, but sometimes the past can give us a glimpse of the future–and sometimes it’s frightening.

For this article I drew heavily from the USGS report “The Orphan Tsunami of 1700” by Brian Atwater, Musumi Rokkaku-Satoko, Satake Kenji and others. That report (which is in the public domain) is available here. The header image at the top of this page is a famous print by the 19th century Japanese artist Hokusai. The photo of coastal trees is (I believe) a U.S. government photo in the public domain.