The "max gain" which is the maximum absolute value of the reciprocal Green's Function of a city vulnerable to tsunami damage is used to evaluate the efficiency of the location for tsunami detecting instruments. The max gain is the correlation between the water elevation variations at the observatory and the vulnerable coastal city. After vulnerable cities are determined, the max gain diagram can be used to determine the most favorable location for observation.

To verify the applicability of the methodology of a tsunami monitoring system, the Marine Cable Hosted Observatory (MA CHO) project in Taiwan is analyzed in detail. Four vulnerable cities, Tou-cheng, Chi-long, Su-ao, and Hua-lien, are chosen first. It is found that from the hydro dynamic point of view the Ryukyu Is land Arc is more important than the Yaeyama Ridge. The max gain distribution is found to be useful for optimizing the tsunami monitoring sys tem in that some modification on the node locations is predicted to significantly improve the efficiency of the tsunami sensors without changing the route or the cost.