Comment by jandrewrogers
Comment by jandrewrogers 3 hours ago
I think you underestimate the frequency, strength, and geographic distribution of strong earthquakes in the US. There is nothing comparable in Europe. You have to engineer for the strongest earthquake, not the average one, and on the US west coast that is M8-9+ depending on the specific location. The construction techniques in Japan and US are very similar because both have similarly extreme earthquakes.
The entire western third of the US is has several M7+ earthquakes per century, with a M6 every couple years, and the occasional M8-9+. The 1964 Anchorage earthquake was stronger (M9.2) than the 2011 Japanese earthquake that caused the great tsunami.
In the eastern US, there is a giant seismic zone that had multiple M8+ earthquakes in the 19th century. These were so powerful they changed the path of the mighty Mississippi River. People forget about it because it hasn’t had a large earthquake in over a century.
A lot of R&D is done on new construction techniques for extreme earthquake risks. The challenge with reinforced concrete is the absurd amount of reinforcement and steel you need to make it survive an earthquake that strong, which makes construction slow and expensive. The state-of-the-art doesn’t use reinforced concrete at all, even in skyscrapers; they use specially designed welded steel plates and fill the empty spaces with poured concrete.
The US has an anomalously high exposure to natural disasters as an accident of geography. For example, people often forget just how many active volcanoes there are in the US, including multiple super-volcanoes. While I live in an area well-known for its M9+ earthquake and tsunami risk, I can see three active volcanoes from my kitchen window.