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Earth's Crust Cracks: Norway Earthquake Explains the Rumble
1 May
Summary
- Earthquakes cause rocks to crack, releasing energy that can melt stone.
- A 3.6 magnitude earthquake near Oslo was felt by many residents.
- Seismic waves from earthquakes generate heat and audible sound.
A moderate earthquake with a magnitude of 3.6 occurred near Oslo on April 26, providing a rare experience for many residents in eastern Norway. The event was characterized by a distinct, long-lasting rumble, which scientists attribute to rocks cracking deep within the Earth's crust due to immense pressures. This fracturing releases a significant amount of energy.
This released energy can generate intense heat, with the potential to melt rocks into glass-like materials in extreme cases, though it is unclear if Sunday's earthquake was strong enough for this. The energy also propagates as seismic waves, causing the ground to shake and producing audible sound. These sound waves travel through the air, vibrating eardrums and being perceived as a rumble.
When earthquakes occur close to the surface, higher frequency sounds within the human hearing range can be produced, often described as underground growls or roars. If the earthquake originates deeper or is further away, lower frequency sounds are generated, which may be felt as vibrations but are inaudible to humans. This explains why seismic waves can be detected across long distances even when the sound is not heard.
