Data access

 

Datasets across the AlpArray Region - the AlpArray Seismic Network

The AlpArray region is defined as the region within 250 km distance from a smoothed 800m contour line around the Alps. The polygon describing this is shown below

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Within this region, there are stations operated by existing permanent networks that are complimented by the dense AlpArray Seismic Network temporary experiment. Together, the permanent and temporary networks are the AlpArray Seismic Network (AASN).

With very few exceptions, all broadband stations operating within the AlpArray limits belonging to permanent seismic networks are available to the community (and hence also the AASN) without restriction, and the highest available sampling rates - in general this means HH? channels with sampling rates of at least 100sps. All these permanent stations have realtime communications and data is available in the archive typically within minutes of realtime. Data can be downloaded from these stations using EIDA tools ( EIDA data access portal, arclink_fetch, fdsnws). These stations are operated under their usual network codes, eg. CH for the National Swiss Network, FR for RESIF etc.

The AlpArray temporary network has network code Z3, all stations in the temporary stations use this network code independent of where or whom has installed and operates the station. All Z3 stations are broadband - at least 30s corner period, though the majority are at least 120s, and are sampled at at least 100sps. Around half of Z3 stations stream data in realtime or with small delays, the rest have no communications. For stations with no communications, its is targeted to make data available within 3 months maximum. All Z3 data are permanently archived at EIDA nodes, and the waveforms are available using arclink_fetch and the EIDA data access portal.

The official period of the AASN started on 1.1.2016 and ended on 1.4.2019. Despite the official end of the AASN, data collection is expected to continue into 2020 at many stations.

Data Restriction for Z3 network

Z3 station data is available as soon as it is included in EIDA with password protection via EIDA services to registered members of institutions part of the Core Group in order to carry out research following approved topics. Data access via group password has been supported via Arclink protocol since the start of the project. Since June 2019, access via indiviudal token via FDSN webservices is also supported.

At latest one year after operation of the AlpArray Seismic Network has ended (by decision of the Core Group) the waveform data will be freely shared among the entire AlpArray Working Group. This will be on 1.4.2020.

Three years after operation of the AlpArray Seismic Network has ended (by decision of the Core Group) the waveform data will be freely available to the public. This will be on 1.4.2022.

Virtual Network Code _ALPARRAY 

In order to identify and facilitate easy and rapid access to all AlpArray Seismic Network stations, we have created a virtual network for AlpArray - _ALPARRAY. This network code can be used using both the EIDA data access portal and scripts using fdsn_fetch or arclink_fetch.

The rules defining which stations are included in _ALPARRAY are:

- include all permanent stations that are within the 250km distance polygon AND providing HH? channel data AND  operational at any time between 1.1.2016 and 1.1.2020

- include all Z3 network code stations (temporary AlpArray stations)

There are a number of exceptions that are also included (whitelisted):
- G.ECH, RD.LOR, RD.ORIF, RD.PGF (stations only recording at 20sps)
- CR.BRJN, CR.KALN, CR.MOSL, CR.NVLJ, CR.OZLJ, CR.PTJ, CR.RIY, CR.UDBI, CR.ZAG (stations only recording at 50sps)
- CR.HVAR, CR.KIJV, CR.MORI, CR.STON (50sps AND outside polygon)
- HS.ERNH (station just outside polygon)

Data Access - Summary of Data Archival 

  • all temporary AASN stations are collected using network code Z3 (note Complementary Experiment have their own network codes, eg  XT for EASI)
  • Z3 waveform data is archived across various EIDA Nodes. The EIDA node archiving a particular station depends on the agency that collects the data rather than the country the stations are placed in.
    • SED / ETHZ EIDA node archives SED/SEG ETHZ data
    • INGV node archives INGV data
    • RESIF node archives data collected by French institutions
    • GFZ / BGR / LMU nodes archives data collected by German institutions
    • ODC node archives data collected by institutions from Austria, Hungary, Czech Republic.
  • waveform data is available (only using password) via the EIDA arclink portal OR arclink_fetch OR fdsnws/event
  • station metadata can be explored using EIDA fdsnws (see http://www.seismo.ethz.ch/en/research-and-teaching/products-software/fdsn-web-services/ for details on fdsnws:station). Eg.:

http://eida.ethz.ch/fdsnws/station/1/query?&net=Z3&station=*&format=text&level=sta&startafter=2015-01-01&nodata=404

Data Access - General Information

  • Data from the permanent networks in the region is openly available from EIDA and can be accessed using fdsnws or arclink. Both methods require passwords
  • AlpArray Z3 data is restricted to participants in the AASN Core Group of AlpArray
  • Method 1: fdsnws: <preferred> Restricted AlpArray Z3 data can be downloaded via fdsnws using personal tokens
  • Method 2: Arclink: <will become obselete> Z3 Access Credentials are in the form of a unique keyword for each institution.
  • If you would like access to Z3 data, ensure you are listed in the table of registered persons at http://www.alparray.ethz.ch/seismic_network/backbone/management/. This is done by having the represntative of the Core Member (indicated in the table) contact Stefan Heimers ( heimers AT sed.ethz.ch ) and John Clinton ( jclinton AT sed.ethz.ch ). 

Data Access - Access Details 

  1. Fdsnws: detailed infromation is at https://geofon.gfz-potsdam.de/eas/. In order to get access you have to first create a B2access account yourself as described at the link mentioned above, and then request being added to the Alparray group by email to heimers AT sed.ethz.ch and jclinton AT sed.ethz.ch. Details on how to proceed can be found in the following document: B2ACCESS-AlpArray-GFZ-ETH-LMU-ODC
  2. EIDA Portal (target: exploring datasets, irregular download)
  • http://www.orfeus-eu.org/eida/webdc3/
  • supports both fdsn token and arclink keyword (keywork replaces your e-mail address)
  • can select specific network codes, eg. CH or Z3, or _ALPARRAY
  1. arclink_fetch (target: advanced users - for scripting and batch jobs)
  • instead of your e-mail address, use keyword uniquely provided to each AASN Core Member
  • this keyword allows you access all closed Z3 data, and can also be used also to download unrestricted (open) data from permanent networks.
  • Waveform data is retrieved in either mseed of full seed format. Metadata can be retrieved as Dataless Seed or inventoryXML.
  • arclink_fetch requires installing a small piece of software locally
  • arclink_fetch is part of SeisComP3 software. Information, including download and installation info, can be found at http://www.seiscomp3.org/wiki/download. The full SeisComP3 package is not required, just the arclink_fetch part. Scroll to very bottom of page to get the latest version of arclink, e.g. arclinkfetch-2015.300.tar.gz
  • Installation information is at http://www.seiscomp3.org/wiki/doc/applications/arclink_fetch - if using a mac, download the full source.
  • Note: there is no need to install the M2Crypto egg file as Z3 data is not encrypted.
  • an example for Z3, downloading 5 minutes of full seed HHZ data from the M4.6 Bosnia Earthquake on 2016/2/14:
$ arclink_fetch -k fseed -u XXXXXXX -o reqZ3_quake_20160214.seed -v reqZ3_quake_20160214.txt -g -p

where XXXXXX is the AASN keyword, txt is a text file in the same directory and contains the following lines:

2016,02,14,14,51,30 2016,02,14,14,56,30 Z3 * HHZ *
2016,02,14,14,51,30 2016,02,14,14,56,30 SL BOJS HHZ *
2016,02,14,14,51,30 2016,02,14,14,56,30 MN BLY HHZ *
  • the first line only can also be used to retrieve only the Z3 stations. Z3 can also be replaced by _ALPARRAY

 

  1. Obspy Arclink client (target: Obspy users - for scripting and interactive use)

Below a quick example on how to query data and visualize data with Obspy. A more complete documentation of Obspy refer to http://docs.obspy.org/ or more details specifically on the Arclink client and a comprehensive list of parameters, see http://docs.obspy.org/packages/obspy.clients.arclink.html#module-obspy.clients.arclink. The example below is for ObsPy 1.0.0.

  • Import Obspy and the client
import obspy
from obspy.clients.arclink import Client
# set to the secret user provided
user_Z3 = '<secret user>'
  • Example data
t1=obspy.UTCDateTime('2016-02-21')t2=obspy.UTCDateTime('2016-02-21T01:00')
net='IV'sta='ACER'loc=''cha='HH*'
# Or an example of Z3 datanet='Z3'sta='A313A'loc='*'cha='*'
  • Setup client for in routing mode
client = Client(user=user_Z3)
# or use one specific server for the first contact (routing)client = Client(user=user_Z3, host='eida.rm.ingv.it') 
  • Query data
st=client.get_waveforms(net,sta,loc,cha,t1,t2,route=True)
# print as summary (list of traces) of the retried Stream objectprint(st) # Quick plot of the tracesst.plot()  
  • Setup client for in proxy mode (use proxy server at port 18001)
client_proxy = Client(user=user_Z3, port=18001, institution='INGV')
  • Query data (proxy mode)
st=client_proxy.get_waveforms(net,sta,loc,cha,t1,t2,route=False)
print(st)st.plot()