十万个为什么·科学阅读30篇（4）

27 / 30

为什么冰川在崩解前会发出低频轰鸣声？

Before large ice chunks break off glaciers, microfractures spread rapidly through stressed ice layers deep below the surface.
These fractures generate seismic waves below 20 Hz—inaudible to humans but detectable by geophones and infrasound arrays.
Water trapped in crevasses expands and contracts under pressure, amplifying resonance in ice-air cavities.
Scientists record these rumbles hours before visible calving, using them as early warning signals.
The sound frequency correlates with ice thickness and internal strain rates measured via GPS and satellite radar.
Ice behaves like a brittle solid under tension but flows plastically over years—creating complex stress-release acoustics.
Rumble intensity spikes when meltwater lubricates the glacier bed, accelerating basal sliding and fracture propagation.
This phenomenon helps distinguish natural calving from iceberg detachment triggered by warming ocean currents.
Monitoring infrasound improves safety for nearby research stations and coastal communities.
It also reveals how climate-driven melt alters glacier dynamics faster than surface observation alone can show.