User Guide

Introduction

The WebDC3 web interface is primarily a tool for obtaining seismic waveforms. As the name suggests, it offers an easy interactive point-and-click interface which is convenient for when you are exploring the available data, or for smaller requests. But it can be used in a few interesting additional ways too.

There are a couple of ways to use WebDC3:

  1. Event based - for exploring a catalog of seismic events (earthquakes), or for when you are looking for waveforms recorded near the time of one or more specific events. You can select events by multiple criteria, then pick from channels available at those times.
  2. Station-based - to explore inventory to see what stations/streams are available and their parameters.
  3. Time-span based - e.g. for obtaining station metadata over fixed periods of interest.
  1. To examine the status of your requests.

There is some on-line help available as pop-ups in the [?] box at the top right of each box in the web interface. Clicking on this takes you to the appropriate part of the help page. Also you can click on the link in the top right corner to see the whole help page.

Note

The web interface is highly configurable. Your site operator may customize its appearance in many different ways. The instructions here are written with the GFZ interface in mind, but the basic work flow described below should be applicable to most sites’ implementations.

Using the web interface requires a relatively modern web browser, due to its use of JavaScript. We have used it successfully on:

  • Firefox 16 on openSUSE 11, Firefox 7 on Ubuntu 11.04
  • Chromium version 27 on openSUSE 11
  • Internet Explorer 10 and 11 on Windows 7
  • Opera 18 on Windows 7
  • Opera 12.16 on Ubuntu 11.04
  • Safari/8536 on iPhone OS 6.1.x

Some problems:

  • Opera 11.52 on openSUSE 11 - adding stations fails.

It will not work on:

  • Internet Explorer 8 or earlier.

Getting started

Visit http://eida.gfz-potsdam.de/webdc3 or your local webinterface site. The screen should look something like this:

_images/generic-overview.png

There are different areas visible. Most prominent is the world map which will show stations and events as they are selected. On the left are different “control” boxes to pick stations and events, and submit your data request when you are ready. Below the map is status information and a summary of the stations and events you have selected.

Request types

There are two different types of information that you can get from this system:

  • waveform data: there are two formats in which you can download, mini-SEED and full SEED.
  • inventory metadata: there are also two formats in which you can download the information, dataless SEED and ArcLink Inventory XML.

In order to be able to create any type of request you need to have at least one channel selected.

Making a request

On the “Submit Request” tab, you must first select the request type. You may enable bzip2 compression. Compression is recommended for text-based formats like dataless SEED and XML. In the case of dataless and full SEED, you can elect to use a response dictionary; this makes SEED metadata of some networks substantially smaller, but may cause compatibility problems.

Next you can select an absolute or relative (to P and S waves) time window. If you haven’t selected any events, then the absolute mode is the only choice, otherwise you almost certainly want to use the relative mode.

Finally click “Review” or “Submit”. “Review” opens an additional pop-up window, where further adjustments to the final request can be made. Clicking “Submit” skips this review step.

At this point, it is checked whether the request size is within configured limits. If the check is passed, multiple Arclink requests are created and routed to different data centers. WebDC refers to this set of Arclink requests corresponding to a single submit action as a “request group”.

Status/download

On the “Download data” tab, in the “Recent Requests” box, you should now see a line corresponding to the request group created during the previous step. Once routing is complete, you can click on the line to open a pop-up showing the status of the request group.

Sometimes copies of data are stored in multiple data centers; in this case there are multiple routes to the data. If the first route returns no data, it is possible to reroute the request to the next data center.

The following buttons are attached to each request group:

  • Reroute: tries to send all lines with NODATA and RETRY status to alternative data centers if possible. If there are no (more) alternative routes, you’ll see “No more routes found” on the console.
  • Retry: same as Reroute, except that lines with RETRY status are sent to the same data center again.
  • Resend: send the same request group again. This might be helpful if there are transient errors. Note that the re-sent request does not include lines which could not be routed originally because no routes were found (those lines are not part of the request group).
  • Delete: deletes the request group in all data centers involved.
  • Refresh: contacts the server(s) to update the processing status of the request group. If you click here during a big request, you will likely see the number of “PROCESSING” lines increase and the number of “UNSET” lines decrease.

In the “Manage Requests” box, you can display the status of all requests associated with your user ID (currently, e-mail address) in all EIDA data centers. Here you also have the option of downloading all data volumes with a single click if you have jDownloader running.

Note

You can get jDownloader from <http://jdownloader.org/>. We recommend that you avoid the Windows exe installer and to use the MULTIOS zip instead. You can execute the jar file directly using “java -jar -Xmx512m JDownloader.jar”.

Limitations

Using WebDC3 you can generate requests which involve many time windows for many streams/channels. These large requests may be rejected by the underlying Arclink server. In this case you will see an alert box.

At GFZ, the current limits are

  • 500 events
  • 10000 total request lines (traces)

The web interface can break large events up into chunks, but it is still possible for very large requests to exceed limits.

Footnotes

[2]Remember, the web interface sits on top of Arclink, and Arclink inventory generally begins on 1 January 1980.