Following the post above, where earthquakes can trigger landslides, landslides can trigger earthquakes. Let's say that warming of ocean water destabilizes frozen methane and causes a submarine landslide on an escarpment above a thrust fault...and 3.3 km x 3.3 km x 100 m thick sediments slide from the hanging-wall to the footwall of a thrust fault. With density of 2 g/cc, and a fault area of 10 km x 15 km, because water with a density of 1 gg/cc replaces the slide volume, the vertical load is decreased on average over the fault by 0.67 bars. It is the vertical load that hold low-angle thrust faults together, and thus the fault would be weakened, and earthquake advanced by (for a slip rate of 1 mm/yr and 1 m slip earthquake, and stress drop of 100 bars) 6.7 years. If a series of strong El Ninos raised the water table in fractures on a mountain, the rock would be weakened, and a slide of rock of the same dimensions might occur. This time, the load removed from the fault is (for granite) 2.65 times as large, and the thrust earthquake might be advanced by almost 18 years. John...any errors in this? I suppose rigidity of the hanging-wall could distribute the unloading over a wider area, but I think it more likely that the part of the fault right under the slide would be unloaded stronger than discussed above. I almost clicked "submit" and I realized I overstated the bars by a factor of 10, so I just increased the size of the slide and hopefully have it correct this time.
Something to think about next time you fuel your Hummer.
Chris