Earthquakes and Antipodes

Strange coincidence? – quakes in Haiti and Chile, then in Taiwan shortly thereafter.  Ever been inside a building with a spherical dome roof? If you are, let’s say, on one edge of the building, you can talk without raising your voice to someone on the opposite edge. The hemispherical surface focuses the soundwaves. The earth is not a perfect sphere, but slightly irregular and oblate. There are multiple focal points.