- © 2008 by the Seismological Society of America
The Seismological Society of America (SSA), originally organized in 1906 with 12 members (Howell 2002), has grown to roughly 2,000 members in 2007. The objectives of our society (reproduced in full inside the front cover of this issue) include the scientific investigation of earthquakes and promoting public safety in the face of earthquake hazards. The objectives are not directed to the United States in particular. The membership now represents 63 countries including the United States, as well as nearly every state of the United States. Annual meetings of the SSA, held in April of each year, attract roughly 20% of its members; although they mainly attract the U.S. members, many of the SSA's non-U.S. members attend these meetings also.
The demographics of the SSA membership are important to achieving the SSA mission. They are also important for meeting planning. The analysis presented here was first motivated by a very simple question: what location would minimize the sum of travel distances of SSA members to the annual meeting? This question, however, led to an expanded analysis of SSA demographics.
We map the raw state and country distribution and compute the “centroid” of the SSA membership as a useful piece of information. The distribution of SSA members is naturally skewed by the main foci of our work, which are primarily earthquake and explosion physics and earthquake hazard. Unlike some professions, which have a fairly uniform distribution of members when normalized to local population statistics, the SSA membership is expected to be heavily weighted to areas of high earthquake activity. Here we quantify this assumption, using geographic information system (GIS) tools to produce maps of SSA membership.
We requested the membership list of the SSA from the office staff in May 2007. The list was valid for January 31, 2007. We requested only …