The Hunga-Tonga-Hunga-Ha’apai volcano in Tonga erupted violently on January 15,2022.After 8 hours and 39 minutes,an infrasound array in Kunming at a distance of 10151 km away from the volcano recorded a sequence of s...The Hunga-Tonga-Hunga-Ha’apai volcano in Tonga erupted violently on January 15,2022.After 8 hours and 39 minutes,an infrasound array in Kunming at a distance of 10151 km away from the volcano recorded a sequence of strong infrasonic waves.The average period of the first four infrasonic waves is 443 s with propagation speed of 321 m/s.The azimuth angle of this event has been estimated by applying the progressive multi-channel correlation(PMCC)method to process the received signals.During continuous monitoring,the infrasonic waves propagating along and opposite to the direction towards the Kunming array around the earth are recorded respectively.展开更多
Observation results of abnormal acoustic-gravity waves before a Beijing earthquake （ML =3.0） are presented. During this period, abnormalities of earth surface tilt variations were also recorded. The cross-correlatio...Observation results of abnormal acoustic-gravity waves before a Beijing earthquake （ML =3.0） are presented. During this period, abnormalities of earth surface tilt variations were also recorded. The cross-correlations between the both values are high, which reach maximal values of 0.5 in the area close to the epicenter. The correlations decrease with increasing distances from the epicenter. It was proposed that generation of the anomalous waves may be associated with the pressure and wind perturbations in the air flow caused by slowly shaking mountains during slow surface motion preceding the earthquake in Beijing. Based on the wind velocity data taken from a 350 m meteorological tower in Beijing, the propagation of ducted acoustic-gravity waves in a two-layer model of the atmosphere was numerically simulated. It is shown that characteristic periods, amplitudes and velocities of the simulated phases which were assumed from non-stationary air flow relative to mountains are approximate to the observed phases. A consistency between the simulated results and observation data indicates that a slow surface motion may be a possible source of the anomalous acoustic-gravity waves observed prior to the earthquake.展开更多
基金supported by the National Natural Science Foundation of China(11774372,11874389)。
文摘The Hunga-Tonga-Hunga-Ha’apai volcano in Tonga erupted violently on January 15,2022.After 8 hours and 39 minutes,an infrasound array in Kunming at a distance of 10151 km away from the volcano recorded a sequence of strong infrasonic waves.The average period of the first four infrasonic waves is 443 s with propagation speed of 321 m/s.The azimuth angle of this event has been estimated by applying the progressive multi-channel correlation(PMCC)method to process the received signals.During continuous monitoring,the infrasonic waves propagating along and opposite to the direction towards the Kunming array around the earth are recorded respectively.
基金supported by the National Natural Science Foundation of China(11174320,11304352)
文摘Observation results of abnormal acoustic-gravity waves before a Beijing earthquake （ML =3.0） are presented. During this period, abnormalities of earth surface tilt variations were also recorded. The cross-correlations between the both values are high, which reach maximal values of 0.5 in the area close to the epicenter. The correlations decrease with increasing distances from the epicenter. It was proposed that generation of the anomalous waves may be associated with the pressure and wind perturbations in the air flow caused by slowly shaking mountains during slow surface motion preceding the earthquake in Beijing. Based on the wind velocity data taken from a 350 m meteorological tower in Beijing, the propagation of ducted acoustic-gravity waves in a two-layer model of the atmosphere was numerically simulated. It is shown that characteristic periods, amplitudes and velocities of the simulated phases which were assumed from non-stationary air flow relative to mountains are approximate to the observed phases. A consistency between the simulated results and observation data indicates that a slow surface motion may be a possible source of the anomalous acoustic-gravity waves observed prior to the earthquake.
