Module for locating local earthquakes and man-made seismicity by DBSCAN cluster search.


Low-threshold monitoring

scanloc associates detected P and S phases from local and regional earthquakes and other seismic events for locating. It determines initial hypocenter solutions by cluster search based on DBSCAN [1]. Additional P and S phases are associated to existing internal solutions from cluster search or solutions incoming through the messaging system from external modules.

Due to the clustering and subsequent phase association scanloc facilitates low-threshold monitoring of high- and low-rate seismicity with high accuracy.


Figure 1: scolv Location tab with an automatic earthquake solution from scanloc based on P and S phases.

Teleseismic events

For teleseismic events scanloc can also be used to:

Travel-time tables

The scanloc package ships with densely sampled travel-time tables for LOCSAT [4] based on the IASP91 Earth model to enhance locating local earthquakes.

S phases

In order to deliver high-quality picks from S phases, the scanloc package also includes the saic plugin with the enhanced S-phase picker. The S-phase picker can be applied to detect S phases on the horizontal components or on the vertical component in case of 1-component sensors. In addition the scanloc package comes with the graphical debugger for the S-phase picker provided by the spickdbg plugin.

Auxiliary tools

The scanloc package also ships with auxiliary Python script for real-time or non-real-time playbacks or tuning. Read the dedicated section for more details.


  1. Buffering of picks and origins,

  2. Clustering of P picks:

    • cluster formation,

    • splitting of clusters in case of multiple P picks from the same station.

    Clustering is skipped in case of an external origin.

  3. Association of P and S picks to clusters and external origins.

  4. Locating origins and formation of internal events,

  5. Evaluation and sending of origins.


Figure 2: Simplified work flow of scanloc.

Pick and origin buffering

The entry point of scanloc is the addObject method which handles incoming objects from the messaging system. By default it is subscribed to the messaging group PICK and LOCATION. Depending on which object type (pick or origin) is incoming different working steps are proceeded.

  • In case a pick arrives, scanloc

    • tests the evaluation status. Rejected picks are ignored unless the command-line option --allow-rejected-picks is given.

    • adds the pick to the pick buffer keeping it for the time given by buffer.pickKeep or --pick-keep,

    • tries to use the pick for clustering,

    • checks if the pick can be associate to origins in the origin buffer exceeding a configurable minScore. In case the pick can be associated, the scores for all new origins are calculated and the origin with the highest score is selected.

  • In case an origin arrives, scanloc

Adjust the buffer.* parameters according to the times these objects are required for processing.


In case the pick cannot be associated, the cluster search is started. The cluster search is based on the algorithm DBSCAN [1] which takes the required number of neighbours (clusterSearch.minSize) and clusterSearch.maxSearchDist as configuration parameters.

The algorithm forms clusters of picks by searching for neighboring stations that have picks. Internal origins are formed from clusters. The number of origins from cluster search is limited by the configuration parameter clusterSearch.maxOrigins.

The cluster search considers picks from stations by distance with:

distance \le maxSearchDist

where maxSearchDist is given by the configurable parameter clusterSearch.maxSearchDist. distance is the vector sum of the time difference \Delta t between the picks in units of seconds and of a potential travel time tt between the stations in units of seconds:

distance = \sqrt{\Delta t^2 + tt^2}


tt = \Delta x / v

where \Delta x is the spatial distance between the stations in units of km and v is the clusterSearch.averageVelocity in units of km/s. Therefore distance and clusterSearch.maxSearchDist take units of seconds.

As the cluster search is done over time and location, the additional configurable velocity parameter, clusterSearch.averageVelocity, is required to transform the input parameters of the cluster search in the same dimension (time). The velocity should represent the average apparent horizontal P-wave velocity of the crust.


When the number of buffered cluster origins reaches clusterSearch.maxOrigins, no more new origins can be formed and warnings are issued. Adjust accordingly:

Limiting in time

In real time picks are received in the order of their creation times. They are considered for clustering if their pick times are within a time window before the cluster reference time. The time window is defined by clusterSearch.maxPickDelay but the cluster reference time is defined either by the

Thus, when setting clusterSearch.referenceTimeMode = ‘MaxPickDelay’ re-setting the cluster reference time is delayed depending on the amount and density of incoming picks. With this option picks which have a larger delay can be considered. Such delays occur e.g. due to larger data delays or larger record lengths.

pick delay = creationTime - pickTime


  • pick.creationTime:time at which the pick was made,

  • pickTime: actual time of the phase arrival.

Picks available within a trapezoid-like time window are considered for clustering. For a pick with zero delay, the cluster reference time is initially set and picks within the blue trapezoid (figure below) are considered. Normally, picks have some delay which delays defining the trapezoid. This makes accessible other picks available with some delay, too, allowing these picks to be considered (green trapezoid). Subsequently, the trapezoid is extended until the cluster reference time is updated. This may be the next pick with a larger pick time (olive trapezoid, clusterSearch.referenceTimeMode = ‘LastPick’) or the time of the pick which is preceded by at least clusterSearch.minSize picks within clusterSearch.maxPickDelay (yellow trapezoid, clusterSearch.referenceTimeMode = ‘MinPickDelay’). Thus, picks which have a long delay do not fall within the relevant trapezoid and cannot be considered for clustering as they are not available at the time of clustering.

The trapezoid is set with respect to the cluster reference time, CRT1 in the figure below, considering the delay of the defining pick and the time until the next relevant pick which updates the reference time (CRT2):

The longer the time until the update, the more picks with larger delays can be considered for clustering, e.g. the delayed clustered pick in the figure below.


Figure 3: Pick time vs. pick delay time for of picks for clustering. The cluster reference time determines the trapezoid within which picks can be considered for clustering. Here, the delayed clustered pick only becomes part of the cluster with clusterSearch.referenceTimeMode = ‘MaxPickDelay’.


  • For small and similar delays of all P picks, clusterSearch.maxPickDelay can be directly read from travel-time curves. A small margin should be added account for differences in delay.

  • In offline XML playbacks, the creation times may not be representative of real-time conditions. Therefore, pick times may be used for the timing instead of creation times. Read the section Examples and Playbacks for more details and the consequences.

If picks arrive with a larger delay than others, there is a risk that they cannot be condsidered anymore for the cluster. When only few picks are available the events may then be missed. To overcome the issue, you may increase clusterSearch.maxPickDelay or set the parameter clusterSearch.referenceTimeMode = “MaxPickDelay”. While increasing clusterSearch.maxPickDelay may slow down the clustering and increase the risk to cluster unrelated picks, clusterSearch.referenceTimeMode = “MaxPickDelay” will only increase the cluster reference time if at least clusterSearch.minSize P picks are available in the considered time window. Run scanloc on the command line with the --cluster-search-log-file to learn about the cluster reference times and the considered picks. For more options read the section Tuning and optimization.

Within one cluster, the difference in the pick times between the cluster reference time and any other pick must thus not exceed clusterSearch.maxPickDelay. Otherwise the pick is rejected from clustering. The parameter clusterSearch.maxPickDelay has a big impact on the performance of the cluster search. Choosing the parameter as small as possible will speed up scanloc and will reduce the complexity of the cluster search.

The DBSCAN algorithm can deliver multiple pick clusters. The cluster search can be disabled using clusterSearch.maxPickDelay:

# Maximum allowed difference between P pick and cluster reference time(latest pick time).
# The cluster search ignores all picks which exceed the value. Using "-1" enables all picks
# regardless of the delay. Unit: seconds.

clusterSearch.maxPickDelay = 0

Then, only external origins can be considered for phase association.

Limiting in space

The cluster search can be constraint to stations within a region given by the coordinate of a central point and the radius around that point. The region constraint is configured through clusterSearch.regionFilter. Applying this parameter will disregard picks from stations outside the region for cluster search increasing the speed and the complexity. Nevertheless, the excluded picks are available for phase association.

For running the cluster search in several regions in parallel, different instances of scanloc taking picks from the same of different pickers can be created and started.

Cluster splitting

Clusters may contain P picks from the same station. Therefore, the clusters are split separating clusters with only one pick per stations. All new clusters are considered new origins. By activating clusterSearch.checkOrigins, all new clusters are checked again and clusters not meeting the configured cluster criteria are removed from the buffer. The check imposes an additional overhead on the cluster search but it typically lowers the chance for fake solutions and it also lowers the load on the phase association.

Tuning and optimization

Use the option cluster-search-log-file to store detailed information on the clustering process in a file, e.g. cluster.log. The given values can be used to optimize the cluster search parameters.

scanloc --ep picks.xml -d [database] --cluster-search-log-file cluster.log > origins.xml

For optimizing the configuration of the parameter clusterSearch.maxPickDelay use the default value first:

clusterSearch.maxPickDelay = -1

The given output file contains the clusters with the pick details. After each cluster the maximum time interval between the first and the last pick in the cluster is provided. A summary at the end of the file shows the largest value, e.g.:

+ cluster source: -69.6279, -21.4715, 1231891115.191
 + pick ID: *20090113.235827.36-AIC-CX.PB01..HHZ X: -69.4874 Y: -21.0432 time: 1231891107.368 distance: 14.715 s
 + pick ID:  20090113.235832.91-AIC-CX.PB02..HHZ X: -69.8960 Y: -21.3197 time: 1231891112.918 distance: 8.443 s
 + pick ID:  20090113.235839.53-AIC-CX.PB07..HHZ X: -69.8862 Y: -21.7267 time: 1231891119.538 distance: 10.677 s
 + pick ID:  20090113.235840.94-AIC-CX.PB09..HHZ X: -69.2419 Y: -21.7964 time: 1231891120.940 distance: 14.645 s
   + 1 split cluster
     + cluster
       + 20090113.235827.36-AIC-CX.PB01..HHZ
       + 20090113.235832.91-AIC-CX.PB02..HHZ
       + 20090113.235839.53-AIC-CX.PB07..HHZ
       + 20090113.235840.94-AIC-CX.PB09..HHZ
       + maximum pick time interval for this cluster: 13.572 s
     + end
   + end
  + end
 + end
 + summary:
   + maxPickDelay: maximum experienced value: 40.840 s

The summary value can be used as a lower proxy to set clusterSearch.maxPickDelay.


Clusters are located by the configured locator. If the location fails, the origin is ignored unless clusterSearch.preliminary is active. Then, preliminary values are chosen:

  • Origin location is the center of the detecting stations,

  • Origin time is the time of the first phase pick,

  • Status is set to preliminary.

The status will be unset if more phases can be associated and the new origin can be located.

Phase Association

When a cluster of P picks meeting association.minPhase is found or an external origins arrives, scanloc associates additional picks from P and S waves which are buffered. The new set of picks are used for relocating.

In case the buffered pick is a P pick the algorithm directly attempts to associate the pick solely based on the residual. It tries to relocate the solution after each successful association. P picks with travel-time residuals larger than association.maxResidual are rejected. After the P-picks are associated and relocated, scanloc tries to associate the S picks. This association is not based on the residual but on the P pick referenced by the S pick. The S pick is only associated in case the reference P pick is already associated to the origin. Also after each S pick a relocation is done. In case the relocation fails or the event residual is larger than maxRMS, the S pick is associated with a weight of 0. The score of the resulting origin is compared with scores of origins belonging to the same event. In case the score is higher than the rest of the origins, the origin is send out.

In addition to origins from the cluster search, scanloc can also treat external origins that are created by other associators, e.g. scautoloc [10]. In case an such origin is received scanloc tries to associate all picks in the buffer to the origin. The association and the following processes are the same as described above. See figure Simplified work flow of scanloc. for an overview.

Only picks from stations within a configured time window and a maximum epicentral distance range are considered. The time windows are computed from the predicted arrival times of P and S waves and the margins given by association.maxPResidual and association.maxPResidual, respectively. The maximum expicentral distance is configured for all stations by association.maxDist. However, this parameter can be overruled per network and station by providing a station table in a file. The file name is configured by association.stationConfig. As in scautoloc each line of the table consists of the network code, the station code, a switch and the maximum epicentral distance in degrees. Wildcards can be used for the network and the station code. The switch causes the associator to consider (=1) or to ignore (=0) a network or a station. The last occurrence of an item in a table overrules previous ones, e.g.

* * 1 180
GR * 1 60
GR GRA1 1 20
Z3 * 0 180

For associating the picks, travel times from look-up tables are used. The association.tableType and the association.table can be configured to provide specific tables which may be more appropriate for specific regions. Currently, only travel-time tables of association.tableType from LOCSAT and libtau are supported. scanloc provides densely-sampled travel-time tables for LOCSAT.

Travel times from other sources can be considered by a plugin exposing the travel times to the travel-time interface. The considered table must provide the time for all considered phases.

Example configuration (scanloc.cfg):

# Type of travel-time tables for phase association. May be different from locator.
# Use e.g. libtau or LOCSAT.
association.tableType = LOCSAT

# Name of travel-time table used for phase association. May be different from locator
# profile.
association.table = iasp91_scanloc


location of tables






Travel-time tables used during association and location may be different. Therefore the travel-time residuals visible after relocating may be different from the travel-time residuals considered during association. The differences must be considered when configuring association.maxPResidual and association.maxSResidual.

In order to make the alternative locator available to scanloc, the respective plugin must be loaded. The list of available locators can be provided by scanloc:

seiscomp exec scanloc --locator-list

Note: Computational speed can be an issue when alternative locators are used and when many picks are to be tested during association. In this case scanloc can be configured with LocSAT but screloc [16] may be used along with the preferred locator and profile to relocate the origin. The locator NonLinLoc [17] is certainly too slow for being used in scanloc but is a good option for screloc.

Status of origins

The status of origins can be set during pick processing

  • Normally, the status of origins is unset.

  • The status of origins from cluster search which cannot be relocated is preliminary.

  • The status of origins which can be located is set to unset if the origin status of the origin was previously set.

However, the evaluation status may be later changed at different times by different modules, e.g. the gempa module sceval. In order to track this history a journal entry is created and sent when running scanloc with a connection to the messaging or added to the XML output long with the origins. In future versions of SeisComP such journal entries will be made accessible in scolv.

Sending of origins

Before sending a new internal origin to the messaging or to XML output (–ep) it is tested against the configuration:

The remaining internal origins are evaluated based on scoring. The best origin of the same internal event is the one which has the highest score at the time of availability. When meeting the parameters ignoreDepth, maxRMS and minScore it is sent to the SeisComP messaging [6] or to stdout in case of XML playbacks (–ep).

The sending of origins may be delayed allowing to find new origins with higher score. The delay reduces the amount of origins in the SeisComP system and the load of other modules. It is controlled by the publication.* configuration parameters.


In XML-based playbacks, the publication.* configuration parameters are ignored and all origins are sent.

Internal Origins and Events

scanloc forms

  • Internal origins from the locations and the associated picks (arrivals) of new arrival sets,

  • Internal events are formed from the internal origins based on the eventAssociation.* parameters. Only if the score of a new origin exceeds the score of the last sent origin of the same internal event, the new origin is send out.

Locating Origins

scanloc locates internal origins based on the configuration by the locator.* parameters. Consider a fast locator (locator.type), e.g. LOCSAT or Hypo71 [2] and appropriate travel-time tables locator.profile, e.g. the provided dense travel-time tables. If the location fails and locator.fixDepth is active, the location depth is fixed to defaultDepth and the origin is relocated.

Example configuration (scanloc.cfg):

# The locator type to use
locator.type = LOCSAT

# The locator profile to use
locator.profile = iasp91_scanloc

Scoring Origins

Each internal origin is evaluated by calculating a score. The score is calculated as a weighted sum from the number of associated P and S picks (pCount and pCount), of loosely associated P and S picks (p0Count and s0Count) which are not used for locating, depth (depthFactor) and residual (residualFactor):

score =\  &score.weights.p \times pCount + score.weights.p0 \times p0Count \\
             +\ &score.weights.s \times sCount + score.weights.s0 \times s0Count \\
             +\ &score.weights.depth \times depthFactor \\
             +\ &score.weights.residual \times residualFactor;

The weight factors score.weights.p , score.weights.p0 , score.weights.s , score.weights.s0 score.weights.depth and score.weights.residual can be configured.

The values for depthFactor and residualFactor are derived from considered depth and residual and the configured values for ignoreDepth and association.maxResidual. Higher weight is given to origins with shallower depth. Adjust score.weights.depth to form the score independent of depth, e.g. in regions with shallow and deep seismicity:

score.weights.depth = 0

Association of Teleseismic Phases

Dense local networks used to monitor local seismicity are often able to catch also a significant number of phases from earthquakes at teleseismic distances. Such phases include Pdiff or PKP. Especially PKP may contain a significant amount of energy at higher frequencies. Therefore PKP is often detected by networks that are tuned to detect local earthquakes. Due to the steep incidence and the low horizontal slowness of these phases, they are sometimes located as fake deep earthquakes below the network. scanloc can be used to suppress this type of fake events.

In a 2-pipeline setup, scanloc can associcate such teleseismic phases recorded by the local network with origins that were found by the pipeline for monitoring teleseismic earthquakes. Then scevent [13] will associate the origins from the teleseismic pipeline with the fake origins from the pipeline for local monitoring to the same event. The assumption is that the origins from the teleseismic pipeline win over the origins from pipeline for local monitoring because they have more associated arrivals. In this case the origins from pipeline for teleseismic monitoring that has most phases becomes the preferred origin for the event. This scanloc feature requires an extended license.

Setup of a 2-pipeline system

  1. Generate a 2-pipeline system involving at least scautopick [10], scanloc and scevent [13] :

    • Pipeline 1 monitors teleseismic earthquakes using scautopick, scautoloc, scanloc and default message groups.

    • Pipeline 2 monitors local earthquakes using l1autopick, l1autoloc and l1scanloc using the message groups L1PICK and L1LOCATION.

  2. Let scanloc not perform cluster search (clusterSearch.maxOrigins = 0) but allow scanloc to only associate P picks from pipelines 2 based on origins from scautoloc (connection.subscriptions = “LOCATION, L1PICK” in the global module parameters). Configure scanloc to associate the picks from pipeline 2 as picks with zero weight when they are, e.g., in the PKP or Pdiff distance range. Use one zeroWeight profiles per phase.

    In order to facilitate association of teleseismic picks, the picks and the origins must be kept in memory for sufficient time. Increase buffer.pickKeep and buffer.originKeep accordingly, e.g. to 1800 s.

    In this way zero-weight picks will not be used for locating the event but are part of the origin and can be considered by scevent.

  3. Configure scevent to listen to the message groups from both pipelines (e.g. LOCATION and L1LOCATION) and activate the scevent module parameter eventAssociation.allowLooseAssociatedArrivals (scevent.cfg).


    Figure 4: Parameter exchange in a 2-pipeline system. The messaging system, responsible for the parameter exchange, is representated by the circles, indicating the message groups. Teleseismic monitoring is configured with scautopick, scanloc, scautoloc and local monitoring with l1autopick, l1scanloc, l1autoloc.

Playback using picks and amplitudes from 2-pipeline system (real-event examples)


Figure 5: Location tab in scolv with zero-weight picks associated by scanloc as PKP phases.


Figure 6: Event tab in scolv showing the origins from the pipelines for local and teleseseismic monitoring. The preferred origin located near the Solomon Islands is shown in bold on top. Fake origins in Europe located by pipeline for local monitoring based on PKP phases falsely considered P phases are associated to the event but do not form the preferred origin at any time.

Examples and Playbacks

  • Run scanloc during real-time processing:

    seiscomp start scanloc
  • Run scanloc on the command line for pick playbacks or debugging output:

    scanloc --debug


In playbacks of picks in XML files the performance of scanloc may differ from real-time operation based on messaging:

  • In real-time operation, the picks are made e.g. by scautopick at some time and considered by scanloc according to their creation times. Delayed picks may become irrelevant for the processing. Configure buffer.pickKeep and buffer.originKeep accordingly.

    However, the creation times of picks may be obscured when created in a scautopick playback and picks may have almost identical creation times independent of their pick times.

  • In message-based playbacks, picks are provided to scanloc via the messaging system. When created in real time, the creation times of picks form a realistic time reference for scanloc and is therefore considered.

  • In offline XML playbacks (--ep), scanloc considers picks by default according to their actual pick times. For picks created in an offline playback this is most reasonable as creation time is not a valid time reference anymore. However, referencing to pick time may result in a behavior which is different from real-time conditions.

    Therefore, for mimicking real-time conditions in playbacks of picks obtained in real-time conditions consider the command-line option --timing creationTime.

Real-time XML playbacks

Real-time playbacks are useful to test the behavior of scanloc in real time based on picks generated before. This type of playbacks is supported by auxialiary scripts shipped with the scanloc package.

  • Use phase picks obtained in real-time

    1. Read real-time picks from the database and store them in picks.xml for later playback:

      dump_picks -r -90,-180,90,180 -d [database] -t "2015-08-17 08:03:00.00~2015-08-17 08:04:00.00" -o picks.xml
    2. Play back picks stored in XML format at normal speed (with seiscomp messaging), start scanloc separately for debug messages on the command line considering default timing by creation time of the picks:

      seiscomp stop
      seiscomp start scmaster scamp scmag scevent
      scanloc --debug
      playback_picks picks.xml
  • Play back picks with amplitudes originating from different pipelines [7] at normal speed (with SeisComP messaging). Picks and amplitudes in XML format are sent to the separated message groups PICK, AMPLITUDE and L1PICK. scanloc and l1scanloc listen to picks from PICK and L1PICKS, respectively. scautoloc [9] additionally needs the pick amplitudes from the subscribed amplitude groups.

    1. Create the pick XML files including the pick amplitudes in an offline playback by the modules as in your 2-pipeline system.

    2. Start all required modules including the scanloc instances

    3. Execute playback_picks with --timing pickTime for sending the picks and amplitudes created by different pickers at different times.

    scautopick --ep --playback -I [your_file] -d [database] > picks.xml
    l1autopick --ep --playback -I [your_file] -d [database] > l1picks.xml
    seiscomp start scmaster scamp scmag scevent scautoloc l1autoloc scanloc l1scanloc
    playback_picks picks.xml:PICK:AMPLITUDE l1picks.xml:L1PICK:AMPLITUDE --timing pickTime

Offline XML playbacks

In offline XML playbacks (--ep), the picks are provided to scanloc in an XML file. scanloc write the results in XML format to stdout which can be re-directed into XML files.


When picks are created in an offline playback use scanloc with default timing based on pick time corresponding to --timing pickTime! Otherwise you may use scanloc with the command-line option --timing creationTime.

  • Play back picks stored in XML format to locate events and to determined the magnitude. Intermediate results are stored in XML files.

    1. Events do not exist in the database, use scdb [11] to populate the database with events in events.xml. The messaging system is not running.

      scautopick --ep --playback -I [your_file] -d [database] > picks.xml
      scanloc --ep picks.xml -d [database] > origins.xml
      scamp --ep origins.xml -d [database] -I [your_file] > amps.xml
      scmag --ep amps.xml -d [database] > mags.xml
      scevent --ep mags.xml -d [database] > events.xml
      scdb -i events.xml -d [database]
    2. New events not existing yet in the database shall be created, existing ones shall be updated with new origins. Run the messaging system and all modules that shall process the new parameters of the origin, e.g. scamp [8] scmag [14] , scevent [13]. Use scdispatch [12] to send the new objects to the messaging system. Get the picks from a scautopick playback or use dump_picks. Execute scanloc with the appropriate timing.**

      # either
      scanloc --ep picks.xml -d [database] > origins.xml
      # or
      scanloc --ep picks.xml -d [database] --timing creationTime > origins.xml
      seiscomp start scmaster scamp scmag scevent
      scdispatch -H host -i origins.xml

      Instead of the origins, other parameters created by the procedures in (1.) may be dispatched, e.g. mags.xml.

  • Play back picks stored in XML format, without a database.

    1. Store the station inventory and the binding configuration from a database in an XML file.

      scxmldump -fI -o inventory.xml -d [database]
      scxmldump -fC -o config.xml -d [database]
    2. Continue with the examples above replacing the database parameter -d [database] with --inventory-db inventory.xml --config-db config.xml.



scanloc inherits global options.


Modules/plugins may require a license file. The default path to license files is @DATADIR@/licenses/ which can be overridden by global configuration of the parameter gempa.licensePath. Example:

gempa.licensePath = @CONFIGDIR@/licenses

Type: boolean

Ignore external origins received from messaging or from XML playback.

Default: Accept external origins from messaging and associate more phases. Default is false.


Type: float

Unit: km

Default used for locating. Default is 5.0.


Type: float

Unit: km

Depths larger than ignoreDepth will be ignored. Default is 650.0.


Type: float

Unit: s

Maximum allowed overall residual. Default is 1.5.


Type: float

Score to be reached to send origin. Default is 0.0.


Type: float

Unit: s

Time to keep picks in the internal buffer. Time comparison is based on the pick times. In non-real time playbacks the time to keep picks is usually compressed. Default is 180.0.


Type: boolean

Ignore manual external origins received from messaging or from XML playback.

The parameter “ignoreOrigins” must be inactive for this option to be effective. Default is true.


Type: float

Unit: s

Time to keep origins in the internal buffer. Time comparison is based on the origin times. In non-real time playbacks the time to keep orgins is usually compressed. Default is 180.0.


clusterSearch.* Parameters controlling the cluster search based on P phase picks.


Type: int

Minimum number of core points (P picks) to form a cluster. Default is 4.


Type: float

Unit: s

Maximum allowed difference between P picks and cluster reference time (latest pick time). Optimum values can be derived from travel times.The cluster search ignores all picks which exceed the value. Using “-1” enables all picks regardless of the delay. Default is -1.0.


Type: string

Mode to set the cluster reference time. Read the documentation for the details. Available modes:

LastPick: The pick time of the last incoming P pick is the cluster reference time.

MaxPickDelay: Setting the cluster reference time is delayed until clusterSearch.minSize picks are available. Default is LastPick.


Type: list:double

Cluster only picks which sensor locations are inside the defined region. The region is defined by latitude, longitude and a radius in km. By default the region filter is disabled.

Example: 50.1,12.3,20


Type: float

Unit: km/s

Average velocity used for distance calculation. Default is 4.0.


Type: float

Unit: s

Maximum allowed distance over all core points and maximum allowed distance for neighborhood search. Both account for traveltime difference, inter-station distance and the configured averageVelocity. Default is 60.


Type: uint

Maximum allowed origins derived from cluster search. Set this option to zero to disable the cluster search completly. Default is 128.


Type: boolean

Send origins based on cluster search as preliminary origins if the location fails. Otherwise those origins are ignored. Consider activating “checkOrigins”. Default is false.


Type: boolean

Check, if derived origins fulfill the cluster search criteria anymore. Activating this option may lower the number of events and suppress fake events. Default is false.


Type: float

Unit: s

By default the algorithm creates a new arrival set when there is already a pick with the same stream id assigned. Use this option to ignore surrounding picks. Default is 0.0.


association.* Parameters controlling the association of P and S phases to cluster origins or external origins.


Type: int

Number picks in cluster origin to be reached for starting to associate more P nd S picks. Default is 4.


Type: float

Unit: km

Maximum epicentral distance to associate P and S picks. Default is 1000.0.


Type: path

The station configuration file contains lines consisting of network code, station code, weight (0 or 1) and maximum association distance given in degree. The maximum association distance is the distance in degrees from the origin up to which this station may contribute to a new origin. This parameter overrides the global parameter association.maxDist. If this distance is 180 deg, this station may contribute to new origins world-wide. However, if the distance is only 10 degree, 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 association distance. The last item found in the list overrules previous ones. Network and station codes may be wildcards (*) for convenience. E.g.:

* * 1 10

GE * 1 180


Type: float

Unit: s

Maximum allowed difference between measured and predicted arrival times for associating P phases to origin. Larger values allow significant correction of initial locations. Default is 4.0.


Type: float

Unit: s

Maximum allowed difference between measured and predicted arrival time for associating S phases to origins. Larger values allow significant correction of initial locations. Default is 4.0.


Type: float

Unit: s

Maximum allowed time residuals of picks after association and relocation. Picks will be removed at exceedance starting with largest residual and origins will be relocated. Default is 2.0.


Type: string

Type of traveltime tables for phase association. May be different from locator. Use e.g. libtau or LOCSAT. Default is LOCSAT.


Type: string

Name of traveltime table used for phase association. May be different from locator profile. Using a different table/profile may result in increased runtime. Default is iasp91.


Type: list:string

zeroWeight-profile name for associating the configured phases with zero weight to origins. Multiples profile names may be set separated by comma. The order of names determines order of checked phases. Each profile can have different parameters.


association.zeroWeight.* zeroWeight profiles containing the parameters for associating phases with zero weight to origins.


association.zeroWeight.$name.* $name is a placeholder for the name to be used and needs to be added to zeroWeight.profiles to become active.

zeroWeight.profiles = a,b
association.zeroWeight.a.value1 = ...
association.zeroWeight.b.value1 = ...
# c is not active because it has not been added
# to the list of zeroWeight.profiles
association.zeroWeight.c.value1 = ...

Type: String

One phase type to be associated with zero weight. Examples: PKP or Pdiff.


Type: float

Unit: degree

Minimum epicentral distance. Default is 120.0.


Type: float

Unit: s

Maximum time residual of the associated phase. Default is 5.0.


locator.* Parameters controlling the locator for locating scanloc origins.


Type: string

The locator type to be used. Use e.g. LOCSAT or Hypo71. Default is LOCSAT.


Type: string

The locator profile to be used. Using a different profile/table for locating and associating may result in increased runtime. Default is iasp91.


Type: boolean

If enabled, the locator fixes the depth to the configured default value “defaultDepth” in case that all previous attempts to relocate fail. This option may result in many more origins. It prevents “ignoreDepth” from beeing effective if “defaultDepth” < “ignoreDepth”. Default is false.


eventAssociation.* Parameters controlling the association of interal scanloc origins to internal scanloc events.


Type: boolean

This parameter is only used in conjunction with eventAssociation.maximumMatchingArrivalTimeDiff. If a station has multiple associated arrivals for a particular event, this flag defines if the time distance of a new pick to all arrivals must be within eventAssociation.maximumMatchingArrivalTimeDiff or if one matching arrival is enough. Default is false.


Type: int

Minimum number of matching picks between two origins to be associated to the same event. Default is 3.


Type: float

Unit: s

If this time window in seconds is negative, pickIDs are compared to find matching arrivals. A non negative value (including 0) compares pick times regardless of the pickID. Pass: |pick1.time - pick2.time| <= threshold. Default is -1.


Type: double

Unit: km

Allowed location difference between an incoming origin compared with preferred origins to get associated. Default is 500.0.


Type: double

Unit: s

Associates an origin with an existing event if the origin time differs not more than 60 seconds unless the minimumMatchingArrivals criteria matches. Default is 60.0.


score.* Formula to calculate the internal origin score. Configurable are the weighting factors for the following components: used P-phase (score.weights.p), unused P-phase (score.weights.p0), used S-phase (score.weights.s), unused S-phase (score.weights.0), depth (score.weights.depth) and residual (score.weights.residual).


Type: float

Defines the weight of p arrivals for scoring. Default is 1.0.


Type: float

Defines the weight of p arrivals with a weight of zero for scoring. Default is 0.5.


Type: float

Defines the weight of s arrivals for scoring. Default is 2.0.


Type: float

Defines the weight of s arrivals with a weight of zero for scoring. Default is 0.5.


Type: float

Defines the weight of the depth for scoring. Default is 1.0.


Type: float

Defines the weight of the residual for scoring Default is 1.0.


Type: boolean

Increase the weight for manual picks by a factor of 1.001. This gives preference to manual picks in case automatic ones co-exist for the same station. Default is false.


publication.* Parameters controlling the publication of internal scanloc events as new origins to the messaging system.


Type: double

Unit: s/count

Parameter “a” in the equation t = aN + b.

t: time interval between sending updates of an origin

N: arrival count of the origin

Increasing the value reduces the amount of sent origins. With the option –ep (playback mode) this value is set to 0. Default is 0.5.


Type: double

Unit: s

Parameter “b” in the equation t = aN + b.

t: time interval between sending updates of an origin

N: arrival count of the origin

Increasing the value reduces the amount of sent origins. With the option –ep (playback mode) this value is set to 0. Default is 0.0.


Type: int

Unit: s

Integer interval to check the origin buffer for sending origins if no other origins have been created.

Reducing the value may be required in EEW: it increases the load on scanloc but allows to send origins more rapidly. Default is 5.

Command Line

scanloc [options]


-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 &.


--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

--print-component arg

For each log entry print the component right after the log level. By default the component output is enabled for file output but disabled for console 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 mode: –verbosity=4 –console=1


Trace mode: –verbosity=4 –console=1 –print-component=1 –print-context=1

--log-file arg

Use alternative log file.


-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.

--start-stop-msg arg

Sets 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 configmodule to use.

--inventory-db arg

Load the inventory from the given database or file, format: [service://]location


Do not use the database at all


--pick-keep arg

Overrides configuration parameter pickKeep.

--origin-keep arg

Overrides configuration parameter originKeep.


Allow processing of picks with evaluation status ‘rejected’. Otherwise these picks are ignored.


Filter picks by author and only consider picks created by the given author. Empty string considers all authors. The option allows operation of scanloc based on picks from a specific picker module where only picks from one picker should be used, e.g. in tuning scanloc for a pipeline.

--ep arg

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 as XML to stdout.

--timing arg

Offline processing reference timing mode: Use pickTime and creationTime for sorting picks according to pick time and creation time, respectively. scanloc uses creationTime in real-time processing.

Default: pickTime


--locator-type arg

Overrides configuration parameter locator.type. The locator type to use. Default: LOCSAT.

--locator-profile arg

Overrides configuration parameter locator.profile. The locator profile to use. Default: iasp91.


List all registered locators.



Limit result set to final origins only. This option is available for offline processing only.


Don’t publish origins, write them to stdout. Useful for tuning.

--cluster-search-log-file arg

File name to output detailed cluster search information. Useful for tuning.