7 February 2018
Taroko Gorge: the potential effects of the M=6.4 Hualien earthquake yesterday
The M=6.4 earthquake near to Hualien in Taiwan yesterday is known to have caused some building collapses in the city. Rescue operations are ongoing; hopefully the impacts will not be too severe. The epicentre of the earthquake was very close to the mouth of the Li Wu River to the north of Hualien. This is the USGS Shakemap data for the earthquake:-
The course of the Li Wu river is the alignment of the Central Cross Island Highway, the most important road linking the east and west coasts of Taiwan. The west end of this road was profoundly damaged during the 1999 Chi Chi Earthquake, and indeed the northern branch on the western side of the Central Mountains has not reopened. On the east side of the island the highway runs along the base of Taroko Gorge through a National Park, truly one of the great natural wonders of the world. This area is very special to me as I spent a large part of the early stages of my academic career undertaking fieldwork in Taroko Gorge – it is an area that I know well and love.
The effects of this earthquake will be fascinating as the Central Cross Island Highway is very prone to landslides and rockfalls. The Taroko Gorge section has been carved into the base of what are usually described as marble cliffs, although in reality the geology is a mixture of marble and schist in many places. This is an area that suffers landslides on a regular basis; its performance during significant shaking has always been a concern.
To date I have found one image of the impact of the earthquake, via Twitter, which suggests multiple small detachments:
In recent years a huge amount of effort has been put into making this road more resilient to rockfalls. If it has come through this earthquake relatively unscathed (and reports suggest that it is open, although we await confirmation of this) then it will be a major triumph for the engineers. The image above shows however that it was very fortunate that the earthquake occurred late at night, when there were no tourists, and little traffic, on the road.