By Carly Faber, researcher, UiT
Carly is a rock detective who hunts for evidence of ancient earthquakes around the world. She completed her PhD in Tromsø and a postdoc at McGill University in Montreal. In this article, Carly provides some background about earthquakes, and then goes on to tell us how she identifies ancient earthquakes in rocks. This tool is also applied to landslides. Next time you are hiking in the Norwegian mountains, you may just be stepping on signs of an old earthquake or landslide!
Like landslides, earthquakes are dangerous natural phenomenon that cause loss of human life and costly damage to infrastructure. And like coastal landslides, earthquakes can cause tsunamis, which compound the seriousness of their effects. Earthquakes can also trigger landslides and rockfalls when they happen in mountainous areas. Humans have been recording earthquakes for nearly 4000 years, and the deadliest earthquake in recorded history occurred in 1556 in Shaanxi, China where it is estimated that around 830 000 people died. The magnitude was around 8. The highest ever recorded magnitude for an earthquake was 9.5 for the 1960 Valdivia earthquake in Chile (Kanamori, 2006). There are several methods to measure earthquakes, and the most common scale used to estimate the magnitude of an earthquake today is the moment magnitude scale (MMS). The MMS measures shaking during an earthquake. The MMS replaces the outdated Richter scale, which cannot adequately measure earthquakes over magnitude 8. The MMS is a log scale, which means that at magnitude 9.5, the Valdivia earthquake shook around 32 times more than the magnitude 8 earthquake at Shaanxi. Norway’s most significant earthquake happened in 1904, in the Oslofjord area. It had a magnitude 5.4, and while there were no casualties, damage was caused to buildings. Continue reading Earthquakes: the landslides of the deep