microseísmos

Microseisms are small, continuous seismic vibrations that occur naturally across the Earth's surface. They are a fundamental part of the ambient seismic noise, meaning they are always present, although their amplitude can vary. These tremors are typically too small to be felt by humans and are only detectable by sensitive seismograph instruments.

The primary cause of microseisms is widely believed to be the interaction of ocean waves with the seafloor. As large ocean waves move, they exert pressure on the seabed. When waves of similar height and frequency travel in opposite directions, their pressure fluctuations can interfere constructively, generating seismic waves that propagate into the Earth's crust. Other contributing factors may include atmospheric pressure variations and surf activity.

Microseisms exhibit a characteristic frequency range, usually between 0.05 and 0.5 Hertz. Their amplitude is generally in the order of nanometers to micrometers. Studies of microseismic patterns can provide valuable information about ocean wave conditions, particularly in remote or unmonitored oceanic regions. They also present a challenge for seismologists when studying smaller, more distant earthquakes, as the microseismic background noise can mask weaker seismic signals. Understanding and filtering out microseisms is therefore an important aspect of seismic data analysis.