Computes VS magnitudes based on envelopes calculated by scenvelope.
Part of the VS package.
scvsmag is part of a new SeisComp3 implementation of the Virtual Seismologist (VS) Earthquake Early Warning algorithm (Cua, 2005; Cua and Heaton, 2007) released under the 'SED Public License for SeisComP3 Contributions'. For a given origin it estimates single station magnitudes and a network magnitude based on the envelope attenuation relationship and ground motion amplitude ratio derived by Cua (2005). The original VS algorithm applies the Bayesian theorem by defining magnitude as the value that maximizes the product of a likelihood function and a prior probability density function. In the current version of scvsmag only the likelihood function is implemented and no prior information is used at this stage.
Apart from the standard log messages in scvsmag.log, processing log messages are also written to scvsmag-processing-info.log every time the VS Magnitude of an event is re-evaluated. A typical entry is shown below.
1 2013/06/28 10:51:01 [processing/info/VsMagnitude] Start logging for event: sed2012cyqr
2 2013/06/28 10:51:01 [processing/info/VsMagnitude] update number: 0
3 2013/06/28 10:51:01 [processing/info/VsMagnitude] Sensor: CH..BNALP.HH; Wavetype: P-wave; Soil class: rock; Magnitude: 3.47
4 2013/06/28 10:51:01 [processing/info/VsMagnitude] station lat: 46.87; station lon: 8.43; epicentral distance: 32.26;
5 2013/06/28 10:51:01 [processing/info/VsMagnitude] PGA(Z): 3.57e-03; PGV(Z): 6.91e-05; PGD(Z): 1.62e-06
6 2013/06/28 10:51:01 [processing/info/VsMagnitude] PGA(H): 2.67e-03; PGV(H): 3.44e-05; PGD(H): 1.02e-06
7 2013/06/28 10:51:01 [processing/info/VsMagnitude] Sensor: CH..MUO.HH; Wavetype: S-wave; Soil class: rock; Magnitude: 3.83
8 2013/06/28 10:51:01 [processing/info/VsMagnitude] station lat: 46.97; station lon: 8.64; epicentral distance: 22.45;
9 2013/06/28 10:51:01 [processing/info/VsMagnitude] PGA(Z): 8.19e-03; PGV(Z): 2.12e-04; PGD(Z): 6.91e-06
10 2013/06/28 10:51:01 [processing/info/VsMagnitude] PGA(H): 2.18e-02; PGV(H): 5.00e-04; PGD(H): 1.72e-05
11 2013/06/28 10:51:01 [processing/info/VsMagnitude] Sensor: CH..WILA.HH; Wavetype: P-wave; Soil class: rock; Magnitude: 3.50
12 2013/06/28 10:51:01 [processing/info/VsMagnitude] station lat: 47.41; station lon: 8.91; epicentral distance: 41.16;
13 2013/06/28 10:51:01 [processing/info/VsMagnitude] PGA(Z): 4.38e-03; PGV(Z): 6.42e-05; PGD(Z): 1.85e-06
14 2013/06/28 10:51:01 [processing/info/VsMagnitude] PGA(H): 3.35e-03; PGV(H): 6.40e-05; PGD(H): 1.88e-06
15 2013/06/28 10:51:01 [processing/info/VsMagnitude] Sensor: CH..ZUR.HH; Wavetype: S-wave; Soil class: rock; Magnitude: 3.79
16 2013/06/28 10:51:01 [processing/info/VsMagnitude] station lat: 47.37; station lon: 8.51; epicentral distance: 23.99;
17 2013/06/28 10:51:01 [processing/info/VsMagnitude] PGA(Z): 9.17e-02; PGV(Z): 1.03e-03; PGD(Z): 1.64e-05
18 2013/06/28 10:51:01 [processing/info/VsMagnitude] PGA(H): 9.63e-02; PGV(H): 2.12e-03; PGD(H): 5.31e-05
19 2013/06/28 10:51:01 [processing/info/VsMagnitude] VS-mag: 3.69; median single-station-mag: 3.79; lat: 47.15; lon: 8.52; depth : 25.32 km
20 2013/06/28 10:51:01 [processing/info/VsMagnitude] creation time: 2012-02-11T22:45:40.00Z; origin time: 2012-02-11T22:45:26.27Z; t-diff: 13.73; time since origin arrival: 0.864; time since origin creation: 0.873
21 2013/06/28 10:51:01 [processing/info/VsMagnitude] # picked stations: 6; # envelope streams: 79
22 2013/06/28 10:51:01 [processing/info/VsMagnitude] Distance threshold (dt): 44.68 km; # picked stations < dt: 4; # envelope streams < dt: 4
23 2013/06/28 10:51:01 [processing/info/VsMagnitude] Stations not used for VS-mag: CH.HASLI CH.LLS
24 2013/06/28 10:51:01 [processing/info/VsMagnitude] Magnitude check: 0.027; Arrivals check: 0.000
25 2013/06/28 10:51:01 [processing/info/VsMagnitude] likelihood: 0.99
26 2013/06/28 10:51:01 [processing/info/VsMagnitude] End logging for event: sed2012cyqr
The following table comments each line in the above output.
| Line | Description |
|---|---|
| 1 | Start of the log message for the event with the given event ID |
| 2 | Update counter for this event. |
| 3 - 18 | Information about the stations that contribute to a VS magnitude estimate. Each station has four lines with the first line giving the the stream name, the wavetype of the contributing amplitude, the soil type at the site and the single station magnitude. The next line shows the location and epicentral distance of the sensor. On the two following lines peak-ground-acceleration (PGA) -velocity (PGV) and -displacement (PGD) are given in SI units for vertical and the root-mean-square horizontal component. |
| 19 | The VS magnitude, the median of the single station magnitudes, the cordinates of the hypocenter |
| 20 | The creation time of the magnitude, the origin time and the difference between the two ('tdiff'); also given are the time since origin arrival and time since origin creation which is a measure of how long it took to evaluate the first magnitude estimate. |
| 21 | The number of stations contributing to an origin ('# picked stations') and the number of envelope streams available ('# envelope streams'). |
| 22 | Distance threshold from epicenter within which the relative difference between picked stations and envelope streams is evaluated (see line 24). Also shown is the number of picked stations and envelope streams within this distance threshold. |
| 23 | Stations that were used for picking but not for the magnitude estimation. |
| 24 | 'Magnitude check' is the relative difference between the VS magnitude and the median of the single station magnitudes. If it exceeds a certain threshold the magnitude quality value is set to 0.4 otherwise to 1.0. 'Arrivals check' is the relative difference betweeen the number of picked stations and the number of envelope streams contributing to the VS magnitude. If it exceeds a certain threshold the arrivals quality criteria is set to 0.3 otherwise to 1.0. The full decision tree for computing the likelihood and the related thresholds is shown here. |
| 25 | The 'likelihood' is the product of the magnitude and the arrivals quality criteria. If both are 1.0 than the likelihoodis set to 0.99. |
| 26 | End of the log message for the event with the given event ID. |
The envelope messages received by scvsmag can optionally be written to the log-file envelope-logging-info.log by setting:
vsmag.logenvelopes=true
The format of envelope-logging-info.log is self-explanatory, note however that the timestamp of the envelope value marks the start time of the 1 s waveform window over which the envelope value was computed. Depending on the size of your seismic network, envelope-logging-info.log might quickly use a lot of disk space.
Borcherdt, R. D., 1994: Estimates of Site-Dependent Response Spectra for Design (Methodology and Justification), Earthquake Spectra
Note
If scvsmag receives identical picks from different pipelines, the internal buffering fails. The missing picks are automatically retrieved from the database if necessary and if a connection to the database has been established. Alternatively, if picking is done on the same streams in several pipelines they can be distinguished by modifying their respective public IDs.
scvsmag inherits global options.
Type: boolean
Choose whether to use Vs30 base site effect corrections (see also the option 'vsmag.vs30filename'). Default is false.
Type: string
A ascii grid file of Vs30 values conforming to the standard ShakeMap format. Each line contains a comma separated list of longitude, latitude and the VS30 value for one grid point. Longitude and latitude have to got from lower to higher values and longitudes increase faster than latitudes. Default is your-vs30-gridfile.txt.
Type: double
Define a default Vs30 value for points not covered by the grid file given with 'vsmag.vs30filename'. Default is 910.
Type: int
This defines the time-span after an event's origin time during which the VS magnitude is re-evaluated every second. After origin-time + eventExpirationTime the evaluation will stop. Default is 45.
Type: string
Choose whether to time the event expiration time with respect to the origin time ('ot') or the time of the first VS estimates creation time ('ct'). Default is ct.
Type: int
Define the number of seconds following a clipped record that a stream is not used for magnitude estimation. Default is 30.
Type: int
These two parameters define the timewindow around picks in which scvsmag looks for maximum amplitudes. twstarttime defines the time before the pick and twendtime the time after the pick Default is 4.
Type: int
These two parameters define the timewindow around picks in which scvsmag looks for maximum amplitudes. twstarttime defines the time before the pick and twendtime the time after the pick Default is 35.
Type: string
You can choose between 'realtime' and 'playback' mode. In 'realtime' mode VS magnitudes are evaluated based on a realtime timer. In 'playback' mode the timing is determined by incoming envelope values (i.e. the internal timing is always set to the latest envelope arrival. Default is realtime.
Type: int
Time in seconds with respect to the current Time that envelope values are kept in memory. Envelope values with a timestamp that is older than current Time - vsmag.backslots will be deleted/rejected. Default is 6000.
Type: int
Time in seconds in the future with respect to the current Time that envelope values are kept in memory. This feature can be of interest if scenvelope and scvsmag do not run on the same machine. A difference between the internal clocks can generate envelope messages with a timestamp in the future relative to the receiving machine. Default is 65.
Type: double
This defines a cutoff epicentral distance in kilometers; stations further than that won't be used for magnitude computation; a negative value means no cutoff is applied. Default is 200.
Type: boolean
This toggles envelope logging. Note that this will produce very large files and may fill up your disk if left on for too long. Default is false.
show help message.
show version information
Use alternative configuration file. When this option is used the loading of all stages is disabled. Only the given configuration file is parsed and used. To use another name for the configuration create a symbolic link of the application or copy it, eg scautopick -> scautopick2.
Load given plugins.
Run as daemon. This means the application will fork itself and doesn't need to be started with &.
Enable/disable self-shutdown because a master module shutdown. This only works when messaging is enabled and the master module sends a shutdown message (enabled with --start-stop-msg for the master module).
Sets the name of the master-module used for auto-shutdown. This is the application name of the module actually started. If symlinks are used then it is the name of the symlinked application.
Sets the name of the master-username of the messaging used for auto-shutdown. If "shutdown-master-module" is given as well this parameter is ignored.
Verbosity level [0..4]. 0:quiet, 1:error, 2:warning, 3:info, 4:debug
Increase verbosity level (may be repeated, eg. -vv)
Quiet mode: no logging output
Limits the logging to a certain component. This option can be given more than once.
Use syslog logging back end. The output usually goes to /var/lib/messages.
Path to lock file.
Send log output to stdout.
Debug mode: --verbosity=4 --console=1
Use alternative log file.
Overrides configuration parameter connection.username.
Overrides configuration parameter connection.server.
Overrides configuration parameter connection.timeout.
Overrides configuration parameter connection.primaryGroup.
A group to subscribe to. This option can be given more than once.
Overrides configuration parameter connection.encoding.
Sets sending of a start- and a stop message.
Test mode, no messages are sent
List all supported database drivers.
The database connection string, format: service://user:pwd@host/database. "service" is the name of the database driver which can be queried with "--db-driver-list".
The configmodule to use.
Load the inventory from the given database or file, format: [service://]location
Do not use the database at all