Early warning and rockfalls in the 3 April 2024 Hualien earthquake – GWC Mag

The Landslide Blog is written by Dave Petley, who is widely recognized as a world leader in the study and management of landslides.

Yesterday, very interesting dashcam footage emerged of rockfalls triggered by the 3 April 2024 Mw=7.4 Hualien earthquake. The footage is dramatic in itself, but also serves to highlight the value of earthquake early warning systems.

The most amazing video is the one below, which was posted to Twitter. This video includes two sets of footage:-

The footage is from one of the mountain roads, it is not clear which one. The video captures the earthquake early warning going off at 2 seconds into the video. The driver wisely stops in a rockfall shelter. The rockfalls start at 13 seconds into the video, so the warning period was about 11 seconds

The early warning gives the driver enough time to save themselves. However, this was possible because they had a plan – to stop under a protective structure – and that structure was available. The car in front did not seek protection; it is not clear why. It ended up in a very perilous situation.

Of course, the other point to note is the horrendous situation on the uncovered sections of the road once the rockfalls started. This was a living hell.

The second set of footage in the above video also shows the early warning alarm being triggered, the driver seeking shelter and massive rockfall activity. Here, it is clear that even within the shelter there is significant risk of harm.

There are two further videos in the tweet below, from another location, but showing a similar outcome:-

And finally, there is this one:-

The videos are summarised in a news report posted to Youtube by Taiwan News Formosa TV:-

But this segment also carries another piece of footage at the end, which was a video of the mountains captured by a passenger in a plane that was flying overhead. This is a still from that footage:-

The Hualien earthquake has provided fresh insight into landslide processes in steep mountain areas during large earthquakes.

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