Fig. 4From: Continuity, segmentation and faulting type of active fault zones of the 2016 Kumamoto earthquake inferred from analyses of a gravity gradient tensorFirst horizontal derivative (HD) distribution of the Bouguer anomaly shown in Fig. 3. A structural boundary is recognized as higher values. The continuous black lines show active faults (Nakata and Imaizumi 2002) and the broken black lines show the extended fault line of the Futagawa fault zone (HERP 2013a)Back to article page