Thread by @JudithGeology

This made me gasp.

Of course I knew that rock falls pose a hazard in earthquakes, but I've never seen anything like this.

But wait - that huge rock was there *before* the earthquake.



#TurkeySyriaEarthquake

1/

This photo from Google Earth from 2008 shows the big rock, but uncracked. Did it crack in the earthquake? Maybe, I don't know.

2/

lh5.googleusercontent.com/p/AF1QipPPHvsy…

The location is close to the fault that slipped, and there must have been many rock falls both in the earthquake and in the past - perhaps in past earthquakes!

3/

Some of the landslides in the Feb 6 earthquakes are huge.

This drone footage illustrates how a landslide can completely obliterate a road - critical infrastructure needed to supply aid.

4/

In the preceding video you can see that water has started to collect behind the landslide. Landslide dams pose a flood risk: as water starts to percolate through the loose material, the "dam" can fail suddenly, leading to flooding downstream.

5/

Earthquake-triggered landsliding may be a "secondary" hazard of earthquakes, but can be widespread & devastating. Here you can see before (bottom) and after (top) satellite images from the 2008 M7.9 Wenchuan earthquake, China. (Red = vegetation)

6/

earthobservatory.nasa.gov/images/8788/si…

Here is water that collected behind one of those dams, putting already damaged areas at risk of flooding.

Areas below had to be evacuated, and the dams blasted.

(2008 Wenchuan earthquake, China)

7/

earthobservatory.nasa.gov/images/8765/la…

My apologies for double-posting; I initially had not realized that the rock in the first video pre-dated the earthquake and did not want to perpetuate that impression.

Thanks to @PulsarWX for sharing these videos with me.

8/end