Capítulo 21: Snap!

SCP-1638 designates a roughly circular forested area approximately five kilometers in diameter located in [REDACTED] County, California. Flora in the area consists mostly of Monterey pines (Pinus radiate) and Blue Gum (Eucalyptus globulus) trees. The area also maintains a population of Monarch butterflies (Danaus plexippus) which occur in numbers ██ percent higher than in similar environments; hereinafter referred to as SCP-1638-1. SCP-1638-1 do not display normal migratory behavior and remain within the area year-round, but display no individual anomalous behavior outside of a Harpo event. Individually, none of the flora, fauna or inorganic features of the area displays any anomalous behavior or biology. However, taken collectively, the combined surface geometry of all these elements within SCP-1638 displays a powerful anechoic effect - such that the ambient sound level within the area is generally no higher than five decibels. SCP-1638 is capable of dynamically controlling most natural surface geometries (including leaves, forest ground detritus, and invertebrate fauna) such that sound energy is either absorbed or destructively canceled by either another source or its own echoes. Any sound exceeding 85 decibels at its source which is sustained for longer than 10 seconds within SCP-1638 will trigger a Harpo event. During such an event, SCP-1638-1 within a kilometer radius of the source of the sound will display swarming behavior and congregate in an area around the disturbance. Once a critical mass of SCP-1638-1 is reached (at least 50,000), instances of SCP-1638-1 will collectively position their wings such that an amplified version of SCP-1638's normal anomalous effect occurs. Sound levels during such an event approach are as low as -14 decibels, even when sound is generated by PA speakers.