Combining the best features of both systems is achieved by using similar "Sonobuoys" with Pressure to SONAR transponders that direct the radio beacon to shore rather than to a satellite that forwards the data to a centralized processing center. This system will require more Sonobuoys, as its protection is localized, but it will be more attractive to the many conflicting factions around the Indian Ocean.
This "Distributed Tsunami Warning System" is more flexible, and less prone to tampering by an enemy nation.
Now the placement of the Sonobuoys will be more critical because of the propagation velocity of a tsunami which is 300 miles per hour. To get a 15-minute warning, the sonobuoy must be 75 miles out to sea from the deep-water mark. If you are on the beach when the alarm sounds you have 15 minutes to find high ground more than 30 feet above beach level.
My system gives you that high ground in the form of a tsunami-proof hotel with special features that enable it to protect the patrons on the beach where it is located.