Multifractal Analysis of Acoustic Emissions during Hydraulic Fracturing Experiments under Uniaxial Loading Conditions: A Niutitang Shale Example

Table 4

Types of time-frequency characteristics of AE signals.

	Low amplitude (0-0.1)	High amplitude (0.1-5)
Low frequency band (0-200 kHz)	Low amplitude in low frequency band (LL)	High amplitude in low frequency band (HL)
High frequency band (200-400 kHz)	Low amplitude in high frequency band (LH)	High amplitude in high frequency band (HH)