Distribution of methane and its homologues in low-layer atmosphere over eastern China and seas

Systematic, fixed-point and long observations and sample testing make clear distributions of methane and the homologues in the low-layer air over east ern China and sea areas. Within about 250 km from epicenter of moderate and strong earthquakes, oil-gas areas have methane concentration anomaly and C O2 anomaly in the low-layer atmosphere around the earthquakes, have a tempe rature increase by 1-6 degrees C at the occurrence of moderate and strong e arthquakes and indicate that concentration anomaly of methane family in the low-layer air can be used as an important index for petroleum geochemical exploration.