Remembering that in a fit of hysteria last year the Electronic Seismologist (ES) promised to provide reviews of seismological analysis software and formats, he attended the IRIS-sponsored FISSURES workshop this past spring with hopes of finding useful review material. As reported in the July-August issue of SRL, the ES came away from this workshop inspired, confused, depressed, and impressed by the state of software development in the field of earthquake seismology.
While there was much material presented on which to base several review articles, a much better situation presented itself. Discussions with Torild van Eck from the Observatories and Research Facilities for EUropean Seismology (ORFEUS) Data Center in the Netherlands revealed that their efforts to compile a Seismological Software Library (SSL) were far beyond any other known similar effort. While this resource is not a specific review of any given application or system, it is a wonderfully comprehensive list of seismological and related software organized by topics with URL pointers to the sources. If the Electronic Seismologist's own seismosurfing ( http://www.geophys.washington.edu/seismosurfing.html) is a good reference list for sources of seismic data, then this Seismological Software Library ( http://orfeus.knmi.nl/working.groups/wg4) is a great software-surfing list. Not only is the list long, but each item has a very brief description and many packages are mirrored in their FTP areas. This reference list will be of particular interest to U.S. readers since it is a much more international list than most Americans tend to be familiar with.
So, in the tradition of getting someone else to write his column for him, the Electronic Seismologist hosts Torild van Eck as the guest author this month.
THE ORFEUS SEISMOLOGICAL SOFTWARE LIBRARY
Torild van Eck
A seismologist's work is largely done on a computer, from gathering and processing, to analyzing data. Therefore, modern seismology requires an extensive hardware and software knowledge on par with professional computer and software engineers. This is also amply demonstrated by the large number of seismologists who end up in (well paid) jobs within the information technology industry. Much software has been and is developed by seismologists. This is especially true within the exploration industry, where large commercial dedicated packages have been developed and applied. Within the largely academic earthquake seismology community, on the other hand, software is often developed ad hoc, meeting specific needs and with little prospect of commercial benefits.
Improved and increased data volumes require increasingly complicated and specialized software for a small (low-budget) market. This poses a delicate problem. Should one stick to old tested programs and programming techniques, or invest heavily in software development to open new analysis opportunities? The first alternative is often favored as, among others, seismology Ph.D. students have to finish their degrees within their subject and within a limited time schedule. The alternative of large investments in software (development) is unrealistic for individual academic institutions. The recent IRIS DMC initiative, called FISSURES, recognizes this. Some find solutions in using commercial packages as a basic framework (Matlab --> MatSeis) or implementing them into their software (Numerical Recipes). Many, fortunately, share their codes, a policy that probably has borne most fruit. In some instances this has resulted in well documented freely distributed successful packages (SAC, GMT).
Sharing software is probably the best approach for the future. The success of GNU and, more recently, Linux is ample evidence of the truth of this statement. Unfortunately, sharing software often puts a large burden on the original programmer with regard to maintenance and support. Such activities are seldom part of the author's normal duties. Also, some dedicated pieces of software, for example, based on new theoretical developments, may be sold by third persons in commercial applications without prior consultation. The Free Software Foundation (GNU) has solved this last problem partly by including with their software copyright agreements (also useful for public domain seismological software). With Linux, maintenance and support is provided by individuals and by nonprofit and commercial organizations, while the Linux Documentation Project ensures a proper documentation standard. I do not know of any similar approach within (small) scientific communities, i.e., a consortium that coordinates (free) license agreements and software development. I understand FISSURES is an initiative to create such a framework in which each scientist can create and maintain his or her favorite module while having easy access to all the other freeware modules within this framework. Both on the IRIS (http://www.iris.washington.edu/HTM/other.htm) and ORFEUS Web sites (http://orfeus.knmi.nl/working.groups/wg4) you can find detailed information on FISSURES and ongoing discussions regarding it.
A general overview of available seismological software is a good thing to start with. Steve Baum at the Department of Oceanography at the University of Texas maintains a Web site (http://www-ocean.tamu.edu/~baum/software-listing.html.gz) containing one of the most complete overviews of software packages for number-crunching, data analysis, and graphics that I have seen. It includes both commercial packages and shareware and, not the least important, it is well maintained. However, specific seismological application software is not found there. Therefore, a working group within ORFEUS created a Seismological Software Library (SSL) focused on earthquake seismology. The Web site for this library can be found through the ORFEUS home page (http://orfeus.knmi.nl). Presently, it consists of three sections: a list of Web- and ftp-links to available software, an ftp (orfeus.knmi.nl) site with regularly updated mirrors of software sites, and a (tentative) overview of format conversion software.
We organized the library according to subject. Although programs do not always fit within this strict regime, it renders a practical oriented library. We aim at keeping the links up to date, but in order to keep our workload realistic we found it necessary to adhere to some (subjective) guidelines. 1. Mainly freely available software. Notable exceptions are some generally used commercial software like NAG, Numerical Recipes, and MatLab. 2. Avoiding repetition. Therefore, for mathematics, physics, and statistics, for example, we refer to some excellent professional libraries like HENSA, netlib, CERN, and statlib. 3. Relevancy. Although obviously subjective and stretchable, in practice it is not so difficult. 4. Only short concise descriptions.
At its present stage the SSL is fairly complete in references to professional sites in related subjects, and it contains, among others, references to standard programs for hypocenter determination, focal mechanisms, synthetics (Herrmann, Kennett, Cerveny), graphics, a fairly complete overview of well established (but not necessarily known) analysis programs, SEED utilities, and data management programs. Further we have MatLab tools, Hazard references, and Macintosh and Linux programs. We also refer to freeware alternatives for commercial packages. For example: Octave for MatLab and Slatec for Numerical Recipes.
Our Web statistics show that, although only six months old, the SSL site is very popular. This encourages us to continue improving it. The quality and usefulness benefits from contributions, suggestions, corrections, etc. from the users. We thank all those who contacted us, gave us permission to mirror their site, and proposed corrections, additions, etc.
We have some ideas and hopes for additional developments for these pages. Format conversion software is tricky. Much is available, but not everybody knows where to find it and it seldom comes in handy toolboxes. The ORFEUS tentative overview on conversion software needs improving. A library of SAC macros seems to us a useful addition. Other helpful addition might be programmers' documentation and plans, users' reports on software performance, and bug repairs.
Also we are presently working at installing a simple Web site search tool. Should you have any other suggestion, please contact us (email@example.com). Provided it benefits the ORFEUS related community, we will try it.
The existing list of software links is too long and changes occur too often to motivate a print-out of this list or even parts of it here in SRL. Instead, I refer the reader to the Web URL (http://orfeus.knmi.nl/working.groups/wg4). Should you wish to receive a printed list, please contact us by e-mail or snailmail and we will send you the most recent one.
SRL encourages guest columnists to contribute to the "Electronic Seismologist." Please contact Steve Malone with your ideas. His e-mail address is firstname.lastname@example.org.
Posted: 22 January 1999