In the middle of the Northern line (if you’re taking the day train), you may be able to see some of the first hills poking out of the alluvial floodplain.
Underneath, is a fault-line between the Eurasian Plate, which goes from around here all the way over Asia and Europe to Iceland(!!!), and the Sunda Plate, which encompasses most of Southeast Asia across to the Philippines to the East, and the deep-sea trenches off the coast of Indonesia to the South and West.
Fortunately, we’re on the least seismically active fault-line, but the Sunda plate is still moving at approximately 1 centimetre per year to the east relative to the realestate to the the North. Given that this rail line is over a century old, lets hope the steel has bent and stretched a meter or so over the years.
Approximately a millenia ago, the Singhanavati Kingdom – an ancient but progressive Lanna society on the River Kok in the far north suffered a huge earthquake, leading to the fall of its great city of Yonok. Literally, it fell, and was submerged by the waters of what is now Chiang Saen Lake. The survivors of this earthquake are among those who set up Chiangmai on higher ground.
Although earthquakes are rare in Thailand, the 5 active faultiness in the North have become more active since the huge 2004 Indian Ocean Earthquake. The last noteable earthquake in Northern Thailand was in 2014, when an earthquake measuring 6.3 hit near Chiang Rai.