Algorithm 1: Preliminary Screening Algorithm
Require: 1: sigfull: original signal; sigfiltered: bandpass filtered signal 2: env: Hilbert envelope of smoothed bandpass signal 3: stdata: sigfull 81–500 Hz Stockwell transform 4: $f_s$: Sampling frequency; $x$: any time; Eol: event of interest 5: threshold: ripple is 30, fastripple is 20
Ensure:
7: $prob=\frac{{\left|stdata\right|}^2}{-{\sum }_{f\in \left[81,500\right]}\log \left[stdata\right]}$	▷ Relative energy, the ratio of the energy occupied by a certain frequency at that moment
8: $S=-\sum _{f\in \left[81,500\right]}\log \left[prob\right]$	▷ Signal energy entropy
9: if $\forall t\in \left[x,x+\frac{f_s}{100}\right]$, sigfull $\ge$0.9$S_{max}$ & sigfiltered $\le$ 10
10:   baseline$\leftarrow$env(t); baselineFiltered$\leftarrow$sigfiltered(t)
11:   thr$\leftarrow$baseline experience accumulation function 95% threshold
12:   thrFilt$\leftarrow$baselineFiltered experience accumulation function 99% threshold
13: end if
14: if $\forall t\in \left[x,x+0.02f_s\right]$, env(t)$\ge$0.99$thr$ & $env{\left(t\right)}_{max}<$threshold
15:   event$\leftarrow$env(t)
16:   number$\leftarrow$The number of times each event crossed thrFilt
17:   if $number\ge$6
18:     Eol$\leftarrow$event
19:   end if
20: end if
21: for $\exists distance\left[Eo{l}_1,Eo{l}_2\right]<10ms$ do
22:   $Eo{l}_1=Eo{l}_1\cup Eo{l}_2$
23: end for