The Nicaraguan Seismic Network registered in March, 1998, a number of 239 seismic events. The majority of them were located in the subduction zone off coast of the Pacific Ocean A strong seismic event (ML=4.6) probably of tectonic origin occurred on March 1 near Momotombo volcano. It was followed by an aftershock swarm which lasted several days. Seismic events occurred in the volcanoes San Cristóbal, Telica, Cerro Negro.
The volcano‑seismic activity of San Cristóbal volcano continued on a high level though with considerable daily variations.
The volcano‑ seismic activity at Telica volcano remains on a low level. Only 20 events were detected in this month.
The Nicaraguan Seismic Network counts now with 20 telemetric seismic stations, 10 of them are located in volcano complexes. The data are digitally recorded and processed at Managua data center, which in turn has also a set of seismometers . Any seismic event detected by the data acquisition routine is processed regularly within a short time by the seismologist on duty. In case of a strong event the system emits an acoustic signal and the seismologist determines immediately the parameters of the event and sends within minutes a report to the Nicaraguan authorities and the mass media. Any unusual behavior of the seismic signal in the volcanoes would also be reported to enable preventive measures against the negative effects of dangerous phenomena in the volcanoes (beginning eruption, land slides, strong degassing).
The Monthly Bulletin is published in the first days of the following month, after having revised the preliminary data. It is distributed in Nicaragua to governmental organizations and mass media, in Central America to cooperating institutions in Guatemala, El Salvador, Honduras, Costa Rica, Panama. Furthermore it is sent to several cooperating institutions in South America, North America and Europe. Phase data and waveforms can be obtained writing to the address on the front page.