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Fig. 2 | Earth, Planets and Space

Fig. 2

From: Remotely triggered seismicity in north China following the 2008 Mw 7.9 Wenchuan earthquake

Fig. 2

(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.

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