Sounding curves at three representative sites for sensitivity test with and without the C2 conductor. (a) Site K222. (b) Site 227. (c) Site 214. See Figure 7 for their locations. Blue, red, green, and black symbols with error bars (only where error bars are larger than the symbols) represent xx, xy, yx, and yy components, respectively. Those with solid lines and broken lines represent model responses with and without the C2 conductor, respectively.