(Georgia Institute of Technology, 2011)
Peng, Zhigang
Below is the image and sound of the seismic recording at station HVSC (more than 1.5 g vertical acceleration) for the 2011/02/21 Mw6.3 New Zealand earthquake. This vertical seismogram is recorded by strong motion sensors only about 1 km distance from the epicenter. From the sound below, you can hear not only the mainshock like a train running towards you, but also many small pops that are early aftershocks immediately afterward. The data can be downloaded from the Center for Engineering Strong Motion Data website.