This is an earthquake recorded at 20150221111409NZDT in Kapiti, New Zealand. geonet.org.nz knows it as 2015p137639.
The left sound channel shows horizontal acceleration. The right: vertical. The video shows the vertical and horizontal axes correctly.
At around 2 seconds you'll see, hear, and perhaps feel, a peak in vertical, higher frequency movement. This is the primary or P wave.
After around 4 more seconds the secondary or S wave arrives. This has lower frequencies and has more horizontal component.
The time between the P and S waves is proportional to the distance from the earthquake.
This earthquake was at a distance of about 32km. Divided by 4 seconds this gives a rough factor of 8km per second of difference between P and S wave arrival times.
Here's Wikipedia on seismic waves.
P wave
S wave