Fig. 2From: Remotely triggered seismicity in north China following the 2008 Mw 7.9 Wenchuan earthquake(a) Seismicity within 30 days and 120 km of station NKY near Beijing. The solid line shows the cumulative number of events, and the solid circles mark the 4 events occurred during the passage of the surface waves. The horizontal dashed line marks the magnitude threshold of 1.5. The corresponding β statistic with m ≥ 1.5 is 0.35. (b) The high-pass-filtered envelope functions at station NKY (solid line) and nearby station DHC (gray line; shifted up by 1.25 in log10 amplitude) within 1 hour of the P wave arrival of the Wenchuan earthquake (vertical dashed line). The horizontal gray and black dashed line marks the median and 9 times the median absolute deviation (MAD), which is used a threshold to pick seismic events. The open and solid circles mark the hand-picked events before and after the P arrival. The corresponding β statistic computed events within 6 hour and 1 hour before the P arrival 2.6 and 1.4, respectively. (c) The top three traces: the broadband three component (transverse, radial and vertical) seismograms recorded at station NKY. The middle three traces: 5 Hz high-pass-filtered seismograms showing small local earthquakes during the passage of surface waves. The corresponding local magnitudes of these events are also marked. The bottom two traces: zoom-in plots of the vertical seismograms showing the P and S waves of the two triggered earthquakes recorded at station NKY and a nearby station DHC with a distance of 22.4 km.Back to article page