Figure 5
The influences of active tectonic blocks and epicenter distances on the relative amplitudes of pre-seismic changes. (a) Illustration of the relative amplitudes of the anomalous changes before the MDEQ, MYEQ, and DLHEQ observed by the Zuoshu groundwater level, Gonghe groundwater temperature, Xining gaseous radon, and Yushu groundwater temperature (expressed with red, blue, purple, and black). The right axis labels the relative amplitude, while the left axis indicates the distance to the epicenter of each mainshock, with the time of the anomaly displayed by the horizontal axis. Meanwhile, the situations for the relationship between the detection earthquake and each observation station are listed with numbers 1–3. Situation 1: The station and earthquake are on the same active tectonic block, situation 2: on the adjacent blocks, and situation 3: others. (b) Statistics of relative amplitude changing with epicenter distance. The grey shows the area with epicenter distances less than 250 km, in which the situation for each observation station is labeled. (c) Variation of relative amplitudes with the situations of 1–3. The red pentagrams represent the average amplitude in each situation.
