Fig. 6

Morphology and combination features of liquefied sand volcanoes induced by the Songyuan M5.7 earthquake. a An isolated sand volcano, approximately 12 m in diameter with a crater of approximately 1.3 m in diameter (photo was taken from site A in Fig. 5); b Sand volcanoes distributed in group with craters of 0.7–1.0 m in diameter, concentric ring terraces formed by multistage sand volcano eruptions, gully developed in the crater margin and runoff on the surface of sand volcano deposition (photo was taken from site B in Fig. 5); c Small-scale linear sand volcano distributed in groups with a thickness of 2 cm (photo was taken from site D in Fig. 5); d Hill-shaped isolated sand volcano with no crater, 3.1 m long, 1.6 m wide, and 0.45 m high, with the direction of long axis close to N-S (photo was taken from site E in Fig. 5)