Lower Silesia Coal Basin/SW Poland/ is adjacent to highly gas saturated igneous massiv and since the beginning of this century more than 1500 outbursts have occurred in four existing mines, including 1295 in the most hazardous mine Nowa Ruda. Prevailing part of these are carbon dioxide/coal outbursts of ejected masses 50-5000 tonnes/av.200/t and gas volume released from 200 m3 to 800,000 m3 Magnitude of these phenomena is growing with the depth and for present extraction levels/ 375-753 m/ may be expressed by a formula: M = 4.25/H-400/, where M-masses ejected, t and H - depth of extraction, m. Regulations obligatory hitherto call for gas pressure measurements to be made in 3 m long and 42 mm dia. boreholes spaces not more than 25 m along the longwall face and taking sample of drillings for desorption testing._x000D_
Criteria of a hazard are following: pressure higher than 30 kPa /for C02/ or 80 kPa /for CH4/ and desorption more than 1,44 cm3/g. These criteria are not satisfactory because many outbursts occurred in spite of low values of parameters measured and for several times no hazard was evident after very high values were obtained. Moreover, observations show that a huge majority of case outbursts occurred in coal weakened by local geological distortion.