If there is already a high tide, nine more feet would be disaster.
Looks like roughly halfway between high and low tide.
http://www.tide-forecast.com/locations/Port-Moresby-Papua-New-Guinea/tides/latest
A lot of it really depends on how much water is in the wave.
Nine feet is a lot, but if it’s nine feet high, and a mile thick moving at 30mph, then that would be a calamity.
A lot of the damage caused by the 2004 Indian Ocean tsunami was by a wave with only a foot or so in height at landfall, but it kept coming, and coming, ... and pushing objects into other objects, creating sharp edge debris, etc., and then to pull all that crap back when the wave receded.
Throw in the undermining structures not built to withstand rushing waters, and you get the picture with even a larger wave.