scvsmag

Computes VS magnitudes based on envelopes calculated by scenvelope.

Description

scvsmag is a new implementation of the Virtual Seismologist (VS) Earthquake Early Warning algorithm (Cua, 2005; Cua and Heaton, 2007). 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.

Logging

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

Explanation

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.

References

Borcherdt, R. D., 1994: Estimates of Site-Dependent Response Spectra for Design (Methodology and Justification), Earthquake Spectra

Configuration

etc/defaults/global.cfg

etc/defaults/scvsmag.cfg

etc/global.cfg

etc/scvsmag.cfg

~/.seiscomp3/global.cfg

~/.seiscomp3/scvsmag.cfg

scvsmag inherits global options.

vsmag.siteEffect

Type: boolean

Choose whether to use Vs30 base site effect corrections (see also the option 'vsmag.vs30filename'). Default is false.

Command-line

Generic

-h, --help

show help message.

-V, --version

show version information

--config-file arg

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.

--plugins arg

Load given plugins.

-D, --daemon

Run as daemon. This means the application will fork itself and doesn't need to be started with &.

--auto-shutdown arg

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).

--shutdown-master-module arg

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.

--shutdown-master-username arg

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

--verbosity arg

Verbosity level [0..4]. 0:quiet, 1:error, 2:warning, 3:info, 4:debug

-v, --v

Increase verbosity level (may be repeated, eg. -vv)

-q, --quiet

Quiet mode: no logging output

--component arg

Limits the logging to a certain component. This option can be given more than once.

-s, --syslog

Use syslog logging back end. The output usually goes to /var/lib/messages.

-l, --lockfile arg

Path to lock file.

--console arg

Send log output to stdout.

--debug

Debug mode: --verbosity=4 --console=1

--log-file arg

Use alternative log file.

Messaging

-u, --user arg

Overrides configuration parameter connection.username.

-H, --host arg

Overrides configuration parameter connection.server.

-t, --timeout arg

Overrides configuration parameter connection.timeout.

-g, --primary-group arg

Overrides configuration parameter connection.primaryGroup.

-S, --subscribe-group arg

A group to subscribe to. This option can be given more than once.

--encoding arg

Overrides configuration parameter connection.encoding.

--start-stop-msg arg

Sets sending of a start- and a stop message.

--test

Test mode, no messages are sent

Database

--db-driver-list

List all supported database drivers.

-d, --database arg

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".

--config-module arg

The configmodule to use.

--inventory-db arg

Load the inventory database from a given XML file.

--db-disable

Do not use the database at all