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Seismometer Data

All seismometer data is routed directly to IRIS, after passing through a military-controlled driver machine (see the Diversion of Hydrophone and Seismometer data for more information on diversion). The seismometer data products offered via Data Search and Data Preview are produced by calling IRIS webservices to get the data. Users can refer to direct links to the IRIS seismometer pages that appear at the top of Data Search Step 2 to access more data. The data products offered here are used to provide plots for Data Preview and rudimentary, accessible data for users.

Oceans 2.0 API filterdataProductCode=SD

Revision History:

  • 20160704: Initial release

Data Product Options

The selected seismomemter filter is applied before receiving the data from IRIS:

For more information, see the IRIS URL builder page and click on the usage button: https://service.iris.edu/irisws/timeseries/docs/1/builder/ Here are the options:

High-Pass 0.5 Hz: A 0.5 Hz high-pass filter is applied to all requested data.

Oceans 2.0 API filterdpo_filteringOptions=HP_0.5

High-Pass 1 Hz: A 1 Hz high-pass filter is applied to all requested data excluding low-rate data of 1 sample per second (LHZ, LHN, LHE). Due to the nyquist frequency of 1 sample per second data being 0.5 Hz, only a high-pass filter of 0.5 Hz is applied to the low-rate data.

Oceans 2.0 API filterdpo_filteringOptions=HP_1

Low-Pass 1 Hz: A 1 Hz low-pass filter is applied to all requested data excluding low-rate data of 1 sample per second (LHZ, LHN, LHE). Due to the nyquist frequency of 1 sample per second data being 0.5 Hz, no filter is applied to the low-rate data.

Oceans 2.0 API filterdpo_filteringOptions=LP_1

Band-Pass 0.01-1 Hz: A 0.01 – 1 Hz band-pass filter is applied to all requested data excluding low-rate data of 1 sample per second (LHZ, LHN, LHE). Due to the nyquist frequency of 1 sample per second data being 0.5 Hz, no filter is applied to the low-rate data.

Oceans 2.0 API filterdpo_filteringOptions=BP_0.01_1

No Filter: No filter is applied to the data.

Oceans 2.0 API filterdpo_filteringOptions=

File-name mode field

'LP', 'HP' or 'BP' is added to the file name (at the end, after the date, separated by a '-'). The option value is added as well, for example '-BP_0.5_1', or '-HP_0.5'.

 

The selected seismometer channel option is applied before receiving the data from IRIS:

The Seismometer Channel Option allows to you specify which channel(s) you would like to receive data for. An explanation of seismometer channel codes https://ds.iris.edu/ds/nodes/dmc/tools/data_channels/#. Here are the options:

Vertical Velocity - High-Rate/Low-Rate (Overlaid In Plots): High-rate and low-rate vertical velocity data will be overlaid and plotted on one graph. For broadband seismometers, this will be HHZ for the high-rate channel and MHZ or LHZ for the low-rate channel depending on the requested time range. For short period seismometers, this will be a high-rate channel of EHZ and a low-rate channel of MHZ or LHZ.

Oceans 2.0 API filterdpo_seismometerChannel=*Z

High-Rate Vertical Velocity: High-rate vertical velocity data will be plotted on one graph. For broadband Seismometers, this will be channel HHZ. For short period seismometers, this will be channels EHZ.

Oceans 2.0 API filterdpo_seismometerChannel=HHZ

Low-Rate Vertical Velocity: Low-Rate vertical velocity data will be plotted on one graph. For broadband and short period seismometers, this will be channel MHZ or LHZ depending on the requested time range.

Oceans 2.0 API filterdpo_seismometerChannel=MHZ

High-Rate Velocity - All Three Components: All high-rate velocity data will be plotted on separate graphs. For broadband seismometers this will be channels HHZ, HHN, HHE. For short period seismometers this will be channels EHZ, EHN, EHE.

Oceans 2.0 API filterdpo_seimometerChannel=HH*

Low-Rate Velocity - All Three Components: All low-rate velocity data will be plotted on separate graphs. For broadband and short period seismometers this will be channels MHZ, MHN and MHE or LHZ, LHN and LHE.

Oceans 2.0 API filterdpo_seismometerChannel=MH*

All Channels - High-Rate/Low-Rate Channels (Overlaid In Plots): The All Channels Option will plot all available channels for the seismometer including velocity, accelerometer data, as well as pressure data. The high-rate and low-rate velocities and accelerations will be overlaid with matching orientations. If the selected output format is MAT file or miniSEED, then mass position will also be included. 

Oceans 2.0 API filterdpo_seismometerChannel=All

Note: A change in sample rate occurred in 2013 for all seismometers causing the low-rate channels to change from LHZ, LHE, LHN, LNZ, LNE and LNN to MHZ, MHE, MHN, MNZ, MNE and MNN. 

File-name mode field

The IRIS channel code is applied in the the file mode field at the end of the file name after the date, separated with a '-'. If there is more than one, then they are listed (only occurs for overlaid plots), example: '-EHZ-MHZ'.

Formats

Seismometer data is available as miniSEED binary files, MAT files, and PNG/PDF plots.

miniSEED

MiniSEED is a file format used in seismology. SEED is an acronym for the Standard for the Exchange of Earthquake Data. MiniSEED is version of the SEED format with the metadata removed except for the time series identification and the state-of-health flags. More information on miniSEED can be found here: http://ds.iris.edu/ds/nodes/dmc/data/formats/seed/

Oceans 2.0 API filter: extension=miniseed

These files are produced by IRIS and acquired by IRIS webservice. We use rdmseed.m to convert these files to MAT files.

MAT

The seismometer MAT data files are produced by rdmseed.m and some specialized code to align the miniSEED sections into a single time series per channel. The file also includes a channel metadata struct that is produced by a call to IRIS's metadata service and the generic MAT file Metadata structure - Complex. See the MAT file description for more information on the generic format. Here is a breakdown of all the structures and fields in the MAT file:

Data: a structure array containing the following fields:

  • dat: An array of doubles containing seismic scalar data.
  • time: An array of doubles containing time stamps for the seismic scalar data.
  • Channel: Struct containing seismometer channel information.
  • Channel.name: A string containing the channel code of the channel responsible for the seismic scalar data and time stamps.
  • Channel.azimuth: A double containing the azimuth of the seismometer.  
  • Channel.dip: A double containing the dip of the seismometer. 
  • Channel.sensorDescription: A string containing the make and model of the seismometer. 
  • Channel.scale: A double containing the scale factor applied to the scalar data.
  • Channel.scaleFreq: A double containing the scale frequency in Hz.
  • Channel.scaleUnits: Units of the the scalar data before the applied scaling factor.
  • Channel.sampleRate: Sample rate of recorded scalar data in samples per second.

Data: here is what the Data structure looks like in MATLAB:

 

Meta: a structure array containing the following metadata fields:
  • deviceID: A unique identifier to represent the instrument within the Ocean Networks Canada data management and archiving system.
  • creationDate:Date and time (using ISO8601 format) that the data product was produced. This is a valuable indicator for comparing to other revisions of the same data product.
  • deviceName: A name given to the instrument.
  • deviceCode: A unique string for the instrument which is used to generate data product filenames.
  • deviceCategory: Device category to list under data search ('Echosounder').
  • deviceCategoryCode: Code representing the device category. Used for accessing webservices, as described here: API / webservice documentation (log in to see this link).
  • lat: Fixed value obtained at time of deployment. Will be NaN if mobile or if both site latitude and device offset are null. If mobile, sensor information will be available in mobilePositionSensor structure..
  • lon: Fixed value obtained at time of deployment. Will be NaN if mobile or if both site longitude and device offset are null. If mobile, sensor information will be available in mobilePositionSensor structure.
  • depth: Fixed value obtained at time of deployment. Will be NaN if mobile or if both site depth and device offset are null. If mobile, sensor information will be available in mobilePositionSensor structure.
  • deviceHeading: Fixed value obtained at time of deployment. Will be NaN if mobile or if both site heading and device offset are null. If mobile, sensor information will be available in mobilePositionSensor structure.
  • devicePitch: Fixed value obtained at time of deployment. Will be NaN if mobile or if both site pitch and device offset are null. If mobile, sensor information will be available in mobilePositionSensor structure.
  • deviceRoll: Fixed value obtained at time of deployment. Will be NaN if mobile or if both site roll and device offset are null. If mobile, sensor information will be available in mobilePositionSensor structure.
  • siteName: Name corresponding to its latitude, longitude, depth position.
  • stationCode: Code representing the station or site. Used for accessing webservices, as described here: API / webservice documentation (log in to see this link).
  • locationName: The node of the Ocean Networks Canada observatory. Each location contains many sites.
  • dataQualityComments: In some cases, there are particular quality-related issues that are mentioned here. This is distinct from QAQC information contained in the data structure.
  • MobilePositionSensor.name: A cell array of sensor names for mobile position sensors. If not a mobile device, this will be an empty cell string.
  • MobilePositionSensor.sensorID: An array of unique identifiers of sensors that provide position data for mobile devices - this data may be used in this data product.
  • MobilePositionSensor.deviceID: An array of unique identifiers of sensors that provide position data for mobile devices - this data may be used in this data product.
  • MobilePositionSensor.dateFrom: An array of datenums denoting the range of applicability of each mobile position sensor - this data may be used in this data product.
  • MobilePositionSensor.dateTo: An array of datenums denoting the range of applicability of each mobile position sensor - this data may be used in this data product.
  • MobilePositionSensor.typeName: A cell array of sensor names for mobile position sensors. If not a mobile device, this will be an empty cell string. One of: Latitude, Longitude, Depth, COMPASS_SENSOR, Pitch, Roll.
  • MobilePositionSensor.offset: An array of offsets between the mobile position sensors' values and the position of the device (for instance, if cabled profiler has a depth sensor that is 1.2 m above the device, the offset will be -1.2m).
  • MobilePositionSensor.sensorTypeID: An array of unique identifiers for the sensor type.
  • MobilePositionSensor.correctedSensorID: An array of unique identifiers of sensors that provide corrected mobile positioning data. This is generally used for profiling deployments where the latency is corrected for: CTD casts primarily.
  • deploymentDateFrom: The date of the deployment on which the data was acquired.
  • deploymentDateTo: The date of the end of the deployment on which the data was acquired (may be omitted if still deployed).
  • samplingPeriod: Sampling rate of the instrument in seconds (maybe omitted on some devices that have no scalar sensors).
  • samplingPeriodDateFrom: matlab datenum of the start of the corresponding sample period (maybe omitted on some devices that have no scalar sensors).
  • samplingPeriodDateTo: matlab datenum of the end of the corresponding sample period (maybe omitted on some devices that have no scalar sensors).
  • searchID: unique number tracking this search request (not normally included).
  • Attribution: A structure array with Attribution information, ordered by importance and date. For internal users, go to the Network Console to configure the attributions. If an organization has more than one role it will be collated. If there are gaps in the date ranges, they are filled in with the default Ocean Networks Canada citation. If the "Attribution Required?" field is set to "No" on the Network Console then the citation will not appear. For data products with a attribution (except MAT files) and for users making products from a MAT file, if the special attribution is blank/null, then the company default attribution will be used and if it is also blank/null, then the final attribution will consist of the organization name and role: "Ocean Networks Canada (Owner, Collaborator)". Here are the fields:
    • acknowledgement: the acknowledgement text, note that if the special acknowledgement blank/null, the default acknowledgement is used.
    • startDate: datenum format
    • endDate: datenum format
    • organizationName
    • organizationRole

Oceans 2.0 API filter: extension=mat

PNG / PDF: Seismometer Daily Trace Plots

The 24-hour time range is broken down into 48 half-hour line plots. The line colour changes from blue to red every two hours to improve readability. , while the small text below the plot indicates the option selected (in some cases they may differ depending on filter and channel availability). If a channel option is selected which states that the channels will be overlaid, the high-rate and low-rate data of the same orientation will be overlaid. This is to fill in the gaps on high-rate data that has been diverted by the military with the low-rate data. When overlaid, the high-rate data is brought to the front and coloured blue and red. The low-rate data is coloured grey. The line spacing is specified below the plot, in a comment footer, to provide users an indication of scale. Also in this text below the plot is a comment stating a change in low-rate filter if one occurred (the title of the plot indicates the channel(s) and filters actually used). The line spacing is dependent on the channels being plotted. If the time range is after March 1st, 2013 for Barkley Canyon, Clayoquot Slope or Main Endeavour Field, or after September 5th 2013 for Cascadia Basin, the sample rates are 200 samples per second (H* channels) or 8 samples per second (M* channels), and the line spacing is 2.9e-06 m/s (vertical velocity), 3.2e-06 m/s (horizontal velocity) and 125 m/s2 (acceleration). If the time-range is before March 1st 2013 for Barkley Canyon, Clayoquot Slope or Main Endeavour Field, or before September 5th 2013 for Cascadia Basin, the sample rates are 100 samples per second (H* channels) and 1 sample per second  (L* channels). All velocity line spacing is 5e-05 m/s and all acceleration line spacing is 0.125 m/s2. The difference in line spacing is due to difference in noise on the channel and in attempt to produce a clear plot with a consistent scaling. Scale factors are accessible in device attributes and are easily modified. Here is an example of a seismometer daily trace plot:

 

Oceans 2.0 API filter: extension={png,pdf}

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