Strange sonic rumble perplexes Costa Rica

Early Monday morning, an unknown hum reverberated across Costa Rica, leaving citizens and experts throughly confused. According to OVSICORI, the Costa Rica Volcanologist and Seismologist Organization, there was no tectonic activity at the time. What were some other suspects for this brontide, or aural cryptid?… » 1/12/12 12:15pm 1/12/12 12:15pm