panxi said:
When you said location is one of the key element, what does it mean? How does the location of earthquake epicenter affect the tsunami occurence?
Astro answered that in the text you quoted from him, did you not read it all ?
Astronuc said:
Earthquakes on land (away from coast) will not cause tsunamis. Earthquakes near the coast or underwater may cause tsunamis if a lot of a water is displaced.
That's the basic importance as to whether a quake will produce a tsunami or not.
After that, ( as has been stated) it is the type of rupture.
Thrust earthquakes
will produce tsunamis. The size of the tsunami is then related to the size of the rupture,
that is, the length and offset on the fault.
Strike-slip ruptures underwater are not likely to produce tsunamis as there is no or little vertical offset.
The problem is, faults are rarely pure thrust or strike-slip. Most times even the best thrust fault event will have some strike-slip motion and even the best strike-slip fault event is likely to have a little thrust movement.
And there is every variation imagineable between those two extremes.
Here's a fault I visited recently in the NE of the South Island of New Zealand. This is one of a number of faults that were both on-land ( mostly) and some were coastal that the combined rupturing produced a Mw7.8 event in November 2016.
This fault is partially on-land and runs offshore. It's mapped length is around 3km
The greatest offset observed is 2m vertical and 6m horizontal. It uplifted some 10km of coastline that once used to be submerged at high tide but now is well above high water level.
my photos
looking along a long section of the rupture
View is NW, uplifted side is seaward side. Around 1 - 1.5 metres beside me
further NW along (~100m) the fault and at the largest vertical offset, ~ 2m
Sadly the dumping of rock from the various landslips has almost covered the fault
Google Earth aerial view
This uplift produced a small tsunami along the coast of around 1m
Dave
