Thread by @IRIS_EPO

Watch the waves from the M6.4 #PuertoRicoEarthquake roll across the USArray Transportable Array seismic network (usarray.org )!

This animation, called a Ground Motion Visualization (GMV), shows the motion of the ground as detected on USArray seismometers - each dot is a seismic station and when the ground moves up it turns red and when it moves down it turns blue - the vertical motion.

Waves generated by an #earthquake travel around and through the earth, but they get smaller (attenuate) as they move away from the earthquake location, just like ripples in a pond.

Once the earthquake waves are far enough away from the location where the #earthquake occurred they can no longer be felt by people, BUT they can still be detected by sensitive seismic instruments.

That's what this animation is showing - the very, very small waves from the M6.4 earthquake traveling both through the earth and across earth's surface - too small to feel, but not too small to measure.

The scale is along the bottom. It is in micrometers (microns). For reference, the diameter of a human hair is ~50-75 microns. No one in the US would have felt shaking from this event!

Some of the instruments look like they are experiencing shaking before the seismic waves arrive. This is due to the setting of the animation and the calibration of the individual seismic instrument.

This animation is created using a US based seismic deployment called USArray. There are lots of seismic instruments in Canada, they just aren't used in this particular visualization.

To see more GMV's visits ds.iris.edu/spud/gmv/17971…