What is another word for micro seisms?
Pronunciation: [mˈa͡ɪkɹə͡ʊ sˈa͡ɪzəmz] (IPA) 
Micro seisms are tiny seismic vibrations that occur naturally in the earth's surface. Synonyms for micro seisms include microearthquakes, tremors, vibrations, and ground motions. Microearthquakes are extremely small earthquakes that are typically too weak to be felt, but can be detected by sensitive seismographs. Tremors and vibrations also refer to slight movements of the earth's surface, but can also be used to describe physical movements in the body. Ground motions refer specifically to the movement of the earth's surface caused by seismic activity. Regardless of the term used, micro seisms can provide valuable information to scientists studying the geology and seismic activity of a particular region.
