A new study published in the journal Tectonics reveals new details about how the Seattle fault zone may have developed more than 50 million years ago. According to the study, a rock layer called "Siletzia" was pushed in part up and over ancient North America and in part down and under it, and a tear between the two eventually became the "proto-Seattle fault." "Siletzia verged onto the continent 50 million years ago, and the Seattle fault is a fault that creates earthquakes in the modern day, in the modern tectonic environment," said Megan Anderson, lead author on the study and an earthquake geologist with the Washington Department of Natural Resources. The "Seattle fault" is a zone of faults stretching east to west, putting more than 4 million people at risk of earthquakes in Washington state. READ MORE: https://www.king5.com/article/tech/science/environment/new-study-shows-potential-origins-seattle-fault-zone/281-9489a74c-aa78-4725-938d-cc201745313f