昆明地震台数字仪记录汶川及周边地震波形特征

Waveform features of the earthquakes in Wenchuan and adjacent area recorded by digital instruments in Kunming Seismic Station

2008年5月12日14时28分,四川汶川发生M_S8.0地震,之后,发生了诸多震级大小不同的余震,昆明地震台记录余震震级一般为4.2级以上,如:汶川、北川、青川乃至甘肃的武都区、陕西的宁强县等余震,至昆明地震台的距离从5.5°—8.7°左右。汶川地震主震难分,震相特点不突出,各种震相不易分辨。经过几个余震分析之后发现,主震之后的余震波形特征则较为明显,利用这些特征,在之后大震速报的分析中算出的发震时刻和中国地震台网大震速报公布的发震时刻非常接近。这些特征与往常分析地震图时分过的在相同距离范围内,近震波形出现的规律有些不同。此外,若发生近震时,在初动不清的情况下,这样的震中距范围内,需区分它是汶川余震还是其他地方的地震。

At 14：28 of May 12, 2008, Sichuan Wenchuan MsS. 0 earthquake happened, and then, there were many aftershocks of different magnitude. Kunming seismic station can record the aftershocks of magnitude 4.2 or more generally, such as in： Wenchuan, Beichuan, Qing-chuan Wudu and even the areas of Gansu, Ningqiang County in Shaanxi, which with the epicentral distances to Kunming Seismic Station from 5.5 degrees to 8.7 degrees. The main shock of Wenchuan earthquake was different, did not highlight the characteristics of seismic phases, and was difficult to distinguish the various phases. Based on the analysis of some aftershocks, it is found that the wave characteristics of aftershocks are more obvious. Using these features, the moment and original time of earthquakes calculated by Kunming Seismic Station are much similar to those published in the earthquake quick report of National Seismic Network. These features are different from those of the near-by earthquakes in the same distance scope that used to be studied. Furthermore, the features would help us to distinguish a aftershock of Wenchuan earthquake from the earthquake occurring at other place, as well as the earthquake is in this epicentral distance range, despite the first arrive phases of the earthquake is not clear.