Abstract: Icequakes on Laohugou Glacier No.12 were observed by operating a portable digital seismometer for 9 days in Oct. 2015. Lots of seismic signals relating to glacier dynamic characteristics were found. On the basis of signal frequency and duration time, two types of seismic event can be divided. Short-period icequakes have time duration less than 0.1 s, the frequency domains are among 20-100 Hz and the numbers are up to 6 600 per day. The majority of seismic events are short-period icequakes. Long-period icequakes have time duration from several minutes to several hours, the frequency domains are among 0.1-10 Hz and the numbers are up to 296 during the observation. Comparing the time distribution of short-period icequakes with local air temperature, it is found that once temperature drops, the numbers of short-period icequake increase rapidly. And once temperature rises, the numbers of short-period icequake decrease. The time distributions of short-period icequakes have a diurnal cycle. It is inferred that once air temperature decreases, temperature of glacier ice decreases and as a result, the fracture at the surface of glacier under tensile thermal stress was happened. Using Maxwell Model to calculate glacier stress change, the diurnal cycle of short-period icequakes can be explained.

Key words: glacier, icequake, Laohugou Glacier No.12, diurnal cycle, fracture, Maxwell Model