Fig. 1

Topographic maps for Nepal and the Kathmandu Valley (a and b). c is a close-up map around the valley center and airport (dark green area). The large black box and red lines with triangles in a represent a wide area around the valley and MFT, respectively. The light green line labeled X and Y indicates where the cross sections in Fig. 6 are taken. The thick lines in blue indicate the Bagmati River in all maps, while thin lines in medium blue indicate other major rivers in a or tributaries of the river in b and c. The Kathmandu Valley and its internal sediments are surrounded by the basin boundary (brown) and sedimentary boundary (black) of Shrestha et al. (1998) in b. In b and c, the sites for microtremor observations, stations of strong motion seismometers, and locations of boring survey results are plotted with red, magenta, and orange circles, respectively. The violet dots are points of gravity observation, and a seismic reflection survey is conducted along the very thick lines in light green