Locates seismic events.
scautoloc is the SeisComP program responsible for automatically locating seismic events in near-real time from phase picks considering associated amplitudes. It tries to identify combinations of picks that correspond to a common seismic or non-seismic event. The picks are sent to LOCSAT for locating. If the produced location meets configurable consistency criteria, it is reported as an origin object , i.e. passed on to other programs that take the origins as input. Phase picks and amplitudes are usually created by scautopick but can also be provided by other means.
The procedure of scautoloc to identify and locate seismic events basically consists of the following steps:
scautoloc receives and filters phase picks to generate origins. These phase picks are used by default if
The phase hint is “P”,
And the evaluation mode is “automatic”. The use of manual picks is controlled by
And the evaluation status is not “rejected”, can be overridden by
All other picks are ignored.
Each incoming pick is checked if it is outdated and if the complete set of associated amplitudes is present already. If a station produces picks extremely often, these are considered to be more likely glitches resulting in an increased SNR threshold.
It is first attempted to associate an incoming pick with a known origin. The association is limited to epicentral distances given by autoloc.maxStationDistance. Especially for large events with stable locations based on many picks already associated, this is the preferred way to handle the pick. If the association succeeds, the nucleation process can be bypassed. Under certain circumstances picks are both associated and fed into the nucleator.
If direct association fails, scautoloc tries to make a new origin out of this and other unassociated, previously received picks. This process is called “nucleation”. scautoloc performs a grid search over space and time, which is a rather expensive procedure as it requires lots of resources both in terms of CPU and RAM. Additional nucleation algorithms may become available in future. The spatial grid is a discrete set of generally arbitrary points that sample the area of interest sufficiently densely. The usability of a pick from a station for a grid point is controlled by the grid itself and the station configuration.
In the grid search, each of the grid points is taken as a hypothetical hypocenter for all incoming picks. Each incoming pick is back projected in time for each of the grid points, on the assumption that it is a first-arrival “P” onset. If the pick indeed corresponds to a “P” arrival of a seismic event, and if this event was recorded at a sufficient number of stations, the back projected new pick will cluster with previous picks from the same event. The cluster will be densest around the origin time at the grid point closest to the hypocenter. In principle, the grid could be so dense that the location obtained from the grid search can be used directly. However, as RAM memory as well as CPU speed is limited, this is not possible. Therefore, if a cluster is identified as a potential origin, it does not necessarily mean that all contributing picks actually correspond to “P” arrivals. It may as well be a coincidental match caused by the coarseness of the grid or possible contamination by picked noise. Therefore, the location program LOCSAT is run in order to try a location and test if the set of picks indeed forms a consistent hypocenter. If the pick residual RMS is too large, an improvement is attempted by excluding each of the contributing picks once to test if a reduction in RMS can be achieved. If the new origin meets all requirements, it is accepted as new seismic event location.
The grid points are specified in a text file configured in
The default file shipped with scautoloc defines a grid with global evenly
distributed points at the surface, and depth points confined to regions of
known deep seismicity. It may be modified, but should not comprise too many
grid points (>3000, depending on CPU speed and RAM).
See below for more details about the grid file.
An origin produced or updated through association and/or nucleation may still be contaminated by phases wrongly interpreted as “P” arrivals. scautoloc tries to improve these origins based on e.g. pick SNR and amplitude. In this processing step, it is also attempted to associate phases which slipped through during the first association attempt, e.g. because the initial location was incorrect. If the origin contains a sufficient number of arrivals to assume a reasonably well location result, scautoloc additionally tries to associate picks as secondary phases such as pP. Such secondary phases are only “weakly associated”, i.e. these phases are not used for the location. For the analyst, however, it is useful to have possible “pP” phases predefined.
This process involves final consistency checks of new/updated origins etc. During this procedure, the origins are not modified any more.
In the course of nucleation and association, as well as in the origin refinement and filtering, certain heuristic criteria are applied to compare the “qualities” of concurring origins. These criteria are combined in an internal origin score, which is based on properties of the picks themselves in the context of the respective origin. The configurable criteria which origins must meet to be reported are:
Minimum number of phases per origins:
Station residual residual:
In addition, the amplitudes provide valuable means of comparing origin qualities. Obviously, a pick with a high SNR will less likely be a transient burst of noise than a pick merely exceeding the SNR threshold. A high-SNR pick thus increases the origin score. Similarly, a pick associated to a large absolute amplitude is more likely to correspond to a real seismic onset, especially in case of simultaneous, large-amplitude observations at neighboring stations. A special case arises, when several nearby stations report amplitudes above a certain “XXL threshold”. For details see the section Preliminary origins. The amplitudes used by scautoloc are of type “snr” and “mb”, corresponding to the (relative, unit-less) SNR amplitude and the (absolute) “mb” amplitude, respectively. These two amplitudes are provided by scautopick. In case of a setup in which scautopick is replaced by a different automatic picker, these two amplitudes must nevertheless be provided to scautoloc. Otherwise, the picks are not used. At the moment this is a strict requirement, in the future it may be changed.
The grid configuration file consists of one line per grid point, each grid point specified by 6 columns:
-10.00 105.00 20.0 5.0 180.0 8
The columns are grid point coordinates (latitude, longitude, depth), radius, maximum station distance and minimum pick count, respectively. The above line sets a grid point centered at 10° S / 105° E at the depth of 20 km. It is sensitive to events within 5° of the center. Stations in a distance of up to 180° may be used to nucleate an event. At least 8 picks have to contribute to an origin at this location. The radius should be chosen large enough to allow grid cells to overlap, but not too large. The size also determines the time windows for grouping the picks in the grid search. If the time windows are too long the risk of contamination with wrong picks increases. The maximum station distance allows to restrict to certain stations for the according grid points. E.g. stations from Australia are normally not required to create an event in Europe. If there is doubt, set the value to 180. The minimum pick count specifies how many picks are required for a given grid point to allow the creation of a new origin. The default grid file contains a global grid with even spacing of ~5° with additional points at greater depths where deep-focus events are known to occur.
Station Configuration File¶
The station configuration file contains lines consisting of network code, station code, usage flag (0 or 1) and maximum nucleation distance. Using a flag of 1 indicates the station shall be used by scautoloc. If it shall not be used, 0 must be specified here. The maximum nucleation distance is the distance (in degrees) from the station up to which this station may contribute to a new origin. If this distance is 180°, this station may contribute to new origins world-wide. However, if the distance is only 10°, the range of this station is limited. This is a helpful setting in case of mediocre stations in a region where there are numerous good and reliable stations nearby. The station will then not pose a risk for locations generated outside the maximum nucleation distance. Network and station code may be wildcards (*) for convenience
* * 1 90 GE * 1 180 GE HLG 1 10 TE RGN 0 10
The example above means that all stations from all networks by default can create new events within 90°. The GE stations can create events at any distance, except for the rather noisy station HLG in the network GE, which is restricted to 10°. By setting the 3rd column to 0, TE RGN is ignored.
Usually, scautoloc will not report origins with less than a certain
number of defining phases (specified by
typically 6-8 phases, with 6 being the absolute minimum. However,
in case of potentially dangerous events, it may be desirable to
receive “heads up” alert prior to reaching the minimum phase count,
especially in a tsunami warning context. If very large amplitudes
are registered at a sufficient number of stations, it is possible to
produce preliminary origins (hereafter called XXL events)
based on less than 6 picks.
Prerequisite is that all these picks have extraordinary large amplitudes of type
autoloc.amplTypeAbs and SNR and lie within a
relatively small region. Such picks are hereafter called XXL picks.
A pick is internally tagged as “XXL pick” if its
amplitude exceeds a certain threshold (specified by
autoloc.xxl.minAmplitude) and has a SNR >
For larger SNR picks with
smaller amplitude can reach the XXL tag, because it is justified to
treat a large-SNR pick as XXL pick even if its amplitude is somewhat
below the XXL amplitude threshold. The XXL criterion should be
judged as workaround to identify picks which justify the nucleation
of preliminary origins.
scautoloc produces two kinds of log files in
A normal application log file containing the processing and location history.
An optional pick log.
The pick log contains all received picks with associated amplitudes in a simple text file, one entry per line. This pick log should always be active as it allows pick playback for trouble shooting and optimization of scautoloc. If something did not work as expected, playing back the pick log will provide a useful way to find the source of the problem without the need of processing the raw waveforms again. The application log file contains miscellaneous information in variable format. The format of the entries may change anytime, so no downstream application should ever depend on it. There are some special lines, however. These contain certain keywords that allow convenient filtering of the most important information using grep. These keywords are NEW, UPD and OUT, for a new, updated and output origin, respectively. They can be used like:
grep '\(NEW\---UPD\---OUT\)' ~/.seiscomp/log/scautoloc.log
This will extract all lines containing the above keywords, providing a very simple (and primitive) origin history.
In principle, scautoloc produces a new solution (origin) after each processed pick. This is desirable at an early stage of an event, when every additional information may lead to significant improvements. A consolidated solution, consisting of many (dozens) of picks, on the other hand may not always benefit greatly from additional picks that usually originate from large distances. Updates after each pick are therefore unnecessary. It is possible to control the time interval between subsequent origins reported by scautoloc. The time interval is a linear function of the number of picks:
Δt = aN + b
Setting a = b = 0, then Δt is always zero, meaning there is never a delay in
sending new solutions. This is not desirable. Setting a = 0.5, each pick will
increase the time interval until the next solution will be sent by 0.5s. This
means that scautoloc will wait 10 seconds after an origin with 20 picks is sent.
The values for a and b can be configured by
scautoloc keeps pick objects in memory only for a certain amount of time. This time
span is with respect to pick time and specified in seconds in
The default value is 21600
seconds (6 hours). After this time, unassociated picks expire. Newly arriving
picks older than that (e.g. in the case of high data latencies) are ignored.
Origins will live slightly longer, including the picks associated to them. The time
to buffer origins is configured by
In a setup where many stations have considerable latencies, e.g. dialup
stations, the expiration times should be chosen long enough to accommodate
late picks. On the other hand, the memory usage for large networks may be a
concern as well. scautoloc periodically cleans up its memory from expired
objects. The time interval between subsequent housekeepings is specified in
buffer.cleanupInterval in seconds.
In the test mode, scautoloc connects to a messaging server as usual and receives picks and amplitudes from there, but no results are sent back to the server. Log files are written as usual. This mode can be used to test new parameter settings before implementation in the real-time system. It also provides a simple way to log picks from a real-time system to the pick log.
For running scautoloc continuously in the background as a daemon it must be enabled and started:
seiscomp enable scautoloc seiscomp start scautoloc
scautoloc normally runs as a daemon in the background, continuously reading
picks and amplitudes and processing them in real time. However, scautoloc
may also be operated in offline mode. This is useful for debugging. Offline
mode is activated by adding the command-line parameter
--offline. When operated in offline mode,
scautoloc will not connect to the messaging. Instead, it reads picks from a
SCML file provided with
--ep or from standard input in the pick file
format. The station coordinates are read from the inventory in the database or
from the file either defined in
Example for entries in a pick file
2008-09-25 00:20:16.6 SK LIKS EH __ 4.6 196.953 1.1 A [id] 2008-09-25 00:20:33.5 SJ BEO BH __ 3.0 479.042 0.9 A [id] 2008-09-25 00:21:00.1 CX MNMCX BH __ 21.0 407.358 0.7 A [id] 2008-09-25 00:21:02.7 CX HMBCX BH __ 14.7 495.533 0.5 A [id] 2008-09-24 20:53:59.9 IA KLI BH __ 3.2 143.752 0.6 A [id] 2008-09-25 00:21:04.5 CX PSGCX BH __ 7.1 258.407 0.6 A [id] 2008-09-25 00:21:09.5 CX PB01 BH __ 10.1 139.058 0.6 A [id] 2008-09-25 00:21:24.0 NU ACON SH __ 4.9 152.910 0.6 A [id] 2008-09-25 00:22:09.0 CX PB04 BH __ 9.0 305.960 0.6 A [id] 2008-09-25 00:19:13.1 GE BKNI BH __ 3.3 100.523 0.5 A [id] 2008-09-25 00:23:47.6 RO IAS BH __ 3.1 206.656 0.3 A [id] 2008-09-25 00:09:12.8 GE JAGI BH __ 31.9 1015.304 0.8 A [id] 2008-09-25 00:25:10.7 SJ BEO BH __ 3.4 546.364 1.1 A [id]
where [id] is a placeholder for the real pick id which has been omitted in this example.
In the above example some of the picks are not in right order of time because of data latencies. In offline mode scautoloc will not connect to the database, in consequence the station coordinates cannot be read from the database and thus have to be supplied via a file. The station coordinates file has a simple format with one line per entry, consisting of 5 columns: network code, station code, latitude, longitude, elevation (in meters). Example:
GE APE 37.0689 25.5306 620.0 GE BANI -4.5330 129.9000 0.0 GE BKB -1.2558 116.9155 0.0 GE BKNI 0.3500 101.0333 0.0 GE BOAB 12.4493 -85.6659 381.0 GE CART 37.5868 -1.0012 65.0 GE CEU 35.8987 -5.3731 320.0 GE CISI -7.5557 107.8153 0.0
The location of this file is specified in
autoloc.stationLocations or on the
command line using -\-station-locations
scautopick and scautoloc Interaction¶
The two main programs in the automatic event detection and location processing
chain, scautopick and scautoloc, only work together if the
information needed by scautoloc can be supplied by scautopick and received
by scautoloc through the message group defined by
connection.subscription or through SCML (
-i). This document explains current
implicit dependencies between these two utilities and is meant as a guide
especially for those who plan to modify or replace one or both of these
utilities by own developments.
Both scautopick and scautoloc are subject to ongoing developments. The explanation given below can therefore only be considered a hint, but not a standard.
scautoloc works with seismic phase picks. In addition, certain amplitudes are used as a kind of quality criterion for the pick, allowing picks with a higher absolute amplitude or signal-to-noise ratio to be given priority in the processing over weak low-quality picks. Due to the filtering of picks by phaseHint it is highly recommended to always set the phaseHint attribute with the appropriate phase name in scautopick. There is no restriction regarding the choice of the publicID of the pick.
By configuration, the performance of scautoloc is also controlled by considering certain amplitudes accompanying the picks. Two kinds of amplitudes may be used together
An absolute amplitude like the one used for calculation of the magnitude “mb”.
Relative amplitude like the dimension-less signal-to-noise ratio amplitude “snr”.
Neither amplitude is used for magnitude computation by scautoloc. The default
amplitude types used by scautoloc are of type “mb” and “snr”. These defaults
can be overridden in
autoloc.amplTypeSNR = snr autoloc.amplTypeAbs = mb
If for instance an alternate picker implementation doesn’t produce “mb”-type
absolute amplitude but e.g. “xy”, then
autoloc.amplTypeAbs needs to be set to
“xy” to have them recognized by scautoloc.
Currently there must be an absolute and a relative amplitude for every pick
as configured by
These amplitudes must be computed by scautopick.
scautoloc will always wait until both amplitudes have arrived, which
results in an overall processing delay, corresponding to the usually delayed availability
of amplitudes with respect to the corresponding pick. The default absolute
amplitude “mb”, for instance, takes a hard-coded 30-seconds time interval to
be computed. This length of data thus has to be waited for, plus a little
extra because of the size of the miniSEED records.
An alternate picker implementation could produce a different absolute-amplitude type than “mb”. That amplitude might be based on a different filter pass band and much shorter time window than the default “mb” amplitude, thus allowing a significantly improved processing speed. The choice of amplitude type and time window greatly depends on the network. For a regional or even global network the 30-seconds processing delay won’t play a role, and we need the mb amplitude anyway. Here the delay of solutions produced by scautoloc is mostly controlled by the seismic traveltimes. Not so in case of a local or small-regional network, where the mb-type amplitude is of limited value and where a meaningful absolute amplitude might well be produced with just a second of data and at higher frequencies. Currently this isn’t possible with scautopick but this issue will be addressed in a future version.
scautoloc inherits global options.
locator.* Define parameters of the locator. Only LOCSAT is supported.
The locator profile to use.
For each location, scautoloc performs checks to test if the depth estimate is reliable. If the same location quality (e.g. pick RMS) can be achieved while fixing the depth to the default depth, the latter is used. This is most often the case for shallow events with essentially no depth resolution.
The locator might converge at a depth of 0 or even negative depths. This is usually not desired, as 0 km might be interpreted as indicative of e.g. a quarry blast or another explosive source. In the case of "too shallow" locations the minimum depth will be used.
Note that the minimum depth can also be configured in scolv, possibly to a different value.
buffer.* Control the buffer of objects.
Time to keep picks in the buffer with respect to pick time, not creation time.
Time to keep origins in buffer.
Clean-up interval for removing old/unused objects.
autoloc.* Define parameters for creating and reporting origins.
Maximum travel-time RMS for a location to be reported.
Maximum travel-time residual (unweighted) for a pick at a station to be used.
Minimum number of phases for reporting origins.
Maximum permissible depth for reporting origins.
Maximum secondary azimuthal gap for an origin to be reported by. The secondary gap is the maximum of the sum of 2 station gaps.
Default: 360 degrees, i.e. no restriction based on this parameter.
Maximum epicntral distance to stations for accepting picks.
If the station count for stations at < 105 degrees distance exceeds this number, no picks at > 105 degrees will be used in location. They will be loosely associated, though.
If this string is non-empty, an amplitude obtained from an amplitude object is used by … . If this string is "mb", a period obtained from the amplitude object is also used; if it has some other value, then 1 [units?] is used. If this string is empty, then the amplitude is set to 0.5 * thresholdXXL, and 1 [units?] is used for the period.
If this string is non-empty, it is used to obtain a pick SNR from an amplitude object. If it is empty, the pick SNR is 10.
Location of the grid file for nucleating origins.
Location of the station configuration file for nucleating origins.
The station file to be used when in offline mode. If no file is given the database is used. An example is given in "@DATADIR@/scautoloc/station-locations.conf".
Receive and process manual phase picks.
Receive and process manual origins. Manual picks and arrival weights will be adopted from the manual origin and the processing continues with these. Origins produced this way by adding incoming automatic picks are nevertheless marked as automatic origins. But they may contain manual picks (even pP and S picks).
Add the LOCATION group to connection.subscriptions for receiving manual origins!
This is an experimental feature relevant only for large regional and global networks, where results by analysts can be expected before the end of automatic event processing.
Adopt the depth from manual origins. Otherwise the default depth in locator.defaultDepth is considered.
Restrict pick processing to the given author name(s). Apply comma separation for a list of names. If any author name is given, picks from other authors are ignored.
Compare located origin with the origin at the depth given by locator.defaultDepth. The origin with lower RMS is reported.
Parameter "a" in the equation t = aN + b. t is the time interval between sending updates of an origin. N is the arrival count of the origin.
Parameter "b" in the equation t = aN + b. t is the time interval between sending updates of an origin. N is the arrival count of the origin.
Activate for writing pick log files to "pickLog".
Location of pick log file containing information about received picks. Activate "pickLogEnable" for writing the files.
autoloc.xxl.* Create origins from XXL picks. These origins will receive the status “preliminary”. Use with care! Enabling XXL picks may result in frequent fake solutions.
Picks with exceptionally large amplitudes may be flagged as XXL, allowing (in future) faster, preliminary "heads-up" alerts.
This option enables the feature.
Minimum amplitude for a pick to be flagged as XXL. The value corresponds to the amplitude type configured in autoloc.amplTypeAbs. NOTE that BOTH minAmplitude and minSNR need to be exceeded!
Minimum SNR for a pick to be flagged as XXL. NOTE that BOTH minAmplitude and minSNR need to be exceeded!
Minimum number of XXL picks for forming an origin. Must be >= 4.
Maximum epicentral distance for accepting XXL picks.
Maximum depth for creating origins based on XXL arrivals.
- -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. Example: 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¶
Set 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¶
Set 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 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¶
Limit the logging to a certain component. This option can be given more than once.
- -s, --syslog¶
Use syslog logging backend. The output usually goes to /var/lib/messages.
- -l, --lockfile arg¶
Path to lock file.
- --console arg¶
Send log output to stdout.
Execute in debug mode. Equivalent to --verbosity=4 --console=1 .
- --log-file arg¶
Use alternative log file.
- -S, --subscribe-group arg¶
A group to subscribe to. This option can be given more than once.
- --start-stop-msg arg¶
Set sending of a start and a stop message.
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 config module to use.
- --inventory-db arg¶
Load the inventory from the given database or file, format: [service://]location .
Do not use the database at all
Do not send any object.
Do not connect to a messaging server. Instead a station-locations.conf file can be provided. This implies --test and --playback
Flush origins immediately without delay.
Do not send any object.
Flush origins immediately without delay.
- --ep file¶
Name of input XML file (SCML) with all picks and origins for offline processing. The database connection is not received from messaging and must be provided. Results are sent in XML to stdout.
Allow picks with evaluation status ‘rejected’ for nucleation and association.
- --station-locations arg¶
The station-locations.conf file to use when in offline mode (started with --offline). If no file is given the database is used.
- --station-config arg¶
The station configuration file. Examples are in @DATADIR@/scautoloc/
- --grid arg¶
The grid configuration file. Examples are in @DATADIR@/scautoloc/
- --pick-log arg¶
The pick log file. Providing a file name enables logging picks even when disabled by configuration.
- --default-depth arg¶
Default depth for comparison with the depth after locating.
- --max-sgap arg¶
Maximum secondary azimuthal gap for an origin to be reported. The secondary gap is the maximum of the sum of 2 station gaps.
- --max-rms arg¶
Maximum travel-time RMS for a location to be reported.
- --max-residual arg¶
Maximum travel-time residual (unweighted) for a pick at a station to be used.
- --max-station-distance arg¶
Maximum distance of stations to be used.
- --max-nucleation-distance-default arg¶
Default maximum distance of stations to be used for nucleating new origins.
- --min-pick-affinity arg¶
- --min-phase-count arg¶
Minimum number of picks for an origin to be reported.
- --min-score arg¶
Minimum score for an origin to be reported.
- --min-pick-snr arg¶
Minimum SNR for a pick to be processed.
- --threshold-xxl arg¶
An amplitude exceeding this threshold will flag the pick as XXL.
- --min-phase-count-xxl arg¶
Minimum number of picks for an XXL origin to be reported.
- --max-distance-xxl arg¶
- --min-sta-count-ignore-pkp arg¶
Minimum station count for which we ignore PKP phases.
- --min-score-bypass-nucleator arg¶
Minimum score at which the nucleator is bypassed.
- --keep-events-timespan arg¶
The timespan to keep historical events.
- --cleanup-interval arg¶
The object cleanup interval in seconds.
- --max-age arg¶
During cleanup all pick objects older than maxAge (in seconds) are removed (maxAge == 0 disables cleanup).
- --wakeup-interval arg¶
The interval in seconds to check pending operations.
- --dynamic-pick-threshold-interval arg¶
The interval in seconds in which to check for extraordinarily high pick activity, resulting in a dynamically increased pick threshold.