Preliminary investigation of seismic tremors in the general area of the Leyden coal mine gas-storage reservoir, Colorado

Figure 1, Index map of Denver area, Colorado 2 2. Map of Leyden area, Colorado « In pocket 3. Graph showing operating time of each seismometer and of the electric-power generator------------4 4. Frequency response curves for seismometers---------6 5. Oscillogram of Type I seismic tremor 6. Oscillogram of Type II seismic tremor----7.Histograms showing number of the two types of seismic tremors per day, times of natural gas withdrawal from the Leyden coal mine, and times of gas injection into the mine