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Initialization and development of anthropogenic seismic processes induced by artificial surface reservoirs

Anthropogenic seismicity explores the phenomenon of seismicity induced or triggered by human industrial activity. Thus, induced seismicity release seismic energy introduced by human activities, into the rock formation; while triggered seismicity are those events, where tectonic energy release is triggered by human activity. This is a special situation when the seismicity is shown to be associated with water reservoirs. Among all earthquakes accompanied by human activities, this type of seismicity causes the strongest earthquakes. The largest earthquakes triggered by water impoundment have exceeded a magnitude of 6. Occurrence of a damaging 6.3 magnitude earthquake at Koyna Dam, India, took place in December 1967. The role of reservoir exploitation in triggering magnitude 7.9 earthquake in China 2008 is still under debate. In Vietnam the strongest case of a reservoir triggered seismic event of magnitude 4.9 took place in Hoa Binh Province, Northern Vietnam, in 1989. In contrast to the natural seismic activity, which is practically static, anthropogenic seismicity varies with time and there are dependencies between the seismicity and human development activities. The anthropogenic seismic activity also depends on the tectonics of the area and the natural seismic processes existing there before humans came there with development. Unfortunately, very often a complete seismic survey begins when noticeable earthquakes appears, which occurs after the seismic processes have reached a maximum. In Vietnam, such measurements had started before the reservoir in Lai Chau was filled up. It will allow exploration of the natural seismicity, which exists in the area of the future dam, and then determine the development of anthropogenic seismic activity associated with the impoundment of water in the reservoir. Measurements are conducted with a dense seismic network consisting of 10 seismic stations located within 20 km from the reservoir. This area is characterized by tectonic seismic activity, therefore there is a high probability to collect appropriate material to study the anthropogenic influence on seismic activity. The aim of the project entitled: “Initialization and development of anthropogenic seismic processes induced by artificial surface reservoirs” is to study the anthropogenic seismicity induced by the filling of water reservoirs and the assessment of the risks related to this activity. The project is funded by National Science Centre and leads by Institute of Geophysics PAS (IG PAS). Data acquisition and interpretation is conducted in close cooperation with the Institute of Geophysics Vietnamese Academy of Science and Technology (IGP VAST).

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