Advanced S-Phase Detector¶
The scanloc package provides the enhanced S-phase detectors, S-AIC and S-AIC-V, as well as the debugger.
Overview¶
The scanloc package includes two S phase pickers: S-AIC and S-AIC-V, enhancing the performance of the picker with respect to the OpenSource S-L2. Both picker apply an AIC algorithm in order to detect S phases after a P pick was maked. Therefore S phases are only detected after a P detection. Using the S-AIC, S picks are determined on the vectorial sum of the horizontal componentes (L2 trace). The S-AIC-V works like the S-AIC but it picks S phases on the vertical component.
The method which was applied to make the pick can be read
In the method column of the arrival table in the Location tab of scolv [19],
In the picker window from the letter within brackets following a phase type,
In the picker window from the hint which appears when hovering over a pick.
The performance of the pickers have been tested by comparison of automatic with manual picks (see the Figure showing the comparison).
Picker configuration¶
Global module parameters: Add the plugin saic to the configuration of scautopick or the global module configuration for making use of the S-AIC or the S-AIC-V:
plugins = ${plugins},saic
Module parameters: Activate one of the S-phase ickers (S-L2, S-AIC, S-AIC-V) by changing the name of the S picker in the module configuration of scautopick. Deactivating killPendingSPickers will allow to pick S phases even if more P phases were detected before:
spicker = "S-AIC" killPendingSPickers = false
Bindings parameters: Configure the S-picker parameters under spicker in global section of the bindings of scautopick e.g. for S-AIC in local earthquake monitoring. For tuning the values based on actual data you may use the graphical debugger:
detecFilter = "RMHP(10)>>ITAPER(30)>>BW(4,4,20)>>STALTA(0.2,20)" timeCorr = 0 spicker.AIC.noiseBegin = -10 spicker.AIC.signalBegin = 0.5 spicker.AIC.filter = "ITAPER(4)>>BW_HP(4,3)" spicker.AIC.detecFilter = "" spicker.AIC.step = 0.5 spicker.AIC.minSNR = 5 spicker.AIC.minCnt = 5
The AIC parameters spicker.AIC. are used for S-AIC and for S-AIC-V. The parameters of the S-phase pickers can be configured in the global section of the bindings profile of scautopick. The meaning of some parameters are shared between the S-phase pickers:
Parameter
Picker type
Description
noiseBegin
S-AIC, S-AIC-V, S-L2
Data window added before the p pick on order to compensate for effects due to the data processing, filtering and to compute the SNR.
signalBegin
S-AIC, S-AIC-V, S-L2
Start of the data processing relative to the reference P pick.
signalEnd
S-AIC, S-AIC-V, S-L2
End of the data processing relative to the reference P pick.
filter
S-AIC, S-L2
Filter applied before forming the L2 trace.
detectFilter
S-AIC, S-AIC-V, S-L2
Filter applied on the L2 trace before AIC analysis.
step
S-AIC, S-AIC-V
Step size in which the time windows are enlarged.
minSNR
S-AIC, S-AIC-V, S-L2
Minimum SNR in order to accept a pick.
minCnt
S-AIC, S-AIC-V
Minimum number the AIC minimum must be found for subsequent time windows.
uncertainty
S-AIC, S-AIC-V
Pick uncertainty. Unused by the picker but part of the output pick element.
Picker tuning: Debugger¶
The debugger GUI allows the graphics-assisted tuning of the S pickers, S-L2, S-AIC, S-AIC-V. In order to make use of the S picker debugging GUI:
Global module parameters: Add the plugin spickdbg to the global configuration of scolv [19] (
scolv.cfg
)plugins = ${plugins}, spickdbg
Global bindings: Configure the initial parameters in the global bindings of the considered stream. You may adopt parameters from the ones used by the spicker for a good inital guess.
The debugger GUI can be started from the picker window of scolv. If there is an existing P pick, the debugger window can be opened with a right click on the P pick. In the dropdown menu the S picker type can be chosen.
A new pop-up window opens where the P pick (red line) and the newly determined S pick (light blue line) are shown and the parameters can be tested.
The example above shows the debugger GUI for a local earthquake:
Top traces: original filtered data.
Bottom trace: Resulting trace e.g. L2.
First red line: the time of the referenced pick. A pick pick should be selected.
Additional phase picks are shown on top of the data.
Light blue line: the S pick which would be made based on the selected parameters. The number next to ‘AIC’ indicates the SNR.
Lower section: Parameters which can be adjusted.
The initial parameters are read from the global binding configuration from the selected stream. Change the parameters to find the optimum values. Click on the Update button to apply them in the GUI. In order to make use of the tested parameters their values must be configured in the bindings parameter of scautopick or the respective alias.
Parameter |
Description |
---|---|
N |
Start of the noise window |
S0 |
Start of the AIC window |
S1 |
End of the AIC window |
AIC0 |
Start of the data processing relative to the reference P pick. |
AIC |
S pick based on the current parameters with number indicating the SNR. |
AIC1 |
End of the data processing when meeting MinSNR and MinCnt. |
Pick |
Pick time at AIC. |