[rz2k]

Doesn't any earthquake, regardless of fault type increase the immediate risk of a submarine landslide?

There are many steep canyons on the Pacific coast, and here is just one example of mass casualties from a tsunami resulting from a submarine landslide triggered by a strike-slip fault earthquake:

Caltech, 2018[1]: "Contrary to Previous Belief, Strike-Slip Faults Can Generate Large Tsunamis"

[1] https://www.caltech.edu/about/news/contrary-to-previous-beli...

[cossatot]

Yes, the probability of tsunamogenic landslides do increase during earthquakes, but it's still quite unlikely for an event of this magnitude tens of km from the continental slope; this is why a properly-calibrated tiered system would be better.

The reason that the Palu event is so notable is precisely because it's uncommon. It's also a very different system: the causative fault is running along the axis of a shallow bay that is only a few km across, so even if the landslide did occur, rapid movement of the steep, shallow coastlines would surely have generated a smaller tsunami. It's a geographical and tectonic situation in which at least a minor tsunami is expected a priori conditional upon an earthquake, so a warning system would account for that in principle. (In practice there isn't time enough to mobilize because the tsunami hits while the ground is still shaking). The bay at Palu is like a somewhat larger Tomales bay--an earthquake right there is going to make some waves. Very different situation than one far off shore.

[dragonwriter]

> Yes, the probability of tsunamogenic landslides do increase during earthquakes, but it's still quite unlikely for an event of this magnitude tens of km from the continental slope; this is why a properly-calibrated tiered system would be better

There is a tiered system, its calibrated based on a combination of magnitude and warning time for the initial alerts (updated notices are based on other measurements and observations, but if gathering and analyzing observations before an initial warning doesn't leave time to act on it, it doesn't matter how accurate the warning is.)

[gosub100]

Those can even happen in bodies of fresh water. There's evidence of one at Lake Tahoe discovered by robot submersibles.