This Science in Developing Countries Program Award will support Professors Vindell Hsu and Stanley N. Williams of Louisiana State University in a research collaboration with several Colombian seismologists from the Colombian Volcano Observatory (OVC). The researchers intend to study the Nevado del Ruiz volcano by deploying 5 portable digital seismographs to supplement existing analog stations. The digital instruments will enhance the location capability of an existing network so that seismic sources can be better assessed for both their level of activity and their relations to magma chambers. Another important phase of the cooperation is to deploy digital instruments directly above several seismically active areas that have been detected by the existing network. By doing so, the researchers expect to record digital data for analysis of source and/or path effects that may be responsible for the various types of seismic signals recorded at Nevado del Ruiz. The researchers will work closely with Colombian seismologists who will supply manpower as well as local logistical support. The recorded data should help in the effort of modeling the various types of volcanic seismic events observed before and after the 1985 eruption of Nevado del Ruiz and also surrounding the September 1, 1989 eruption. Most important of all, the researchers will accumulate data about Ruiz which is quite unique and not yet thoroughly studied. The effort should help in characterizing the seismicity associated with the volcano and, therefore, be useful in the future in terms of predicting eruptions at Ruiz and other andesitic volcanoes.