Abstract

Seismicity

- The seismological shift was maintained around the clock during all the year. This system guaranteed the rapid and correct information to authorities and the public about the seismic activity and other important geologic phenomena in Nicaragua. During 2004, the seismic network registered 2,107 seismic events, most of them associated with the subduction zone and the volcanic chain of Nicaragua.  1,629 events were  located and at least 30 events were felt by the population.

- The most important seismic event with magnitude ML= 6.8 occurred on October 9. It was located in the Pacific Ocean, in front off El Astillero. It was felt in wide parts of Western Nicaragua and also in Northern Costa Rica.

- On December 26, the large earthquake was registered which caused the disastrous tsunami in the South of Asia.

 

Volcanoes

- The seismic surveillance in the active volcanoes continued by means of seismic monitoring, visual observations, temperatures measurements, Web cameras and meteorological monitoring. With 101 visits to the active craters, fumaroles and other places in the volcanoes numerous measurements of temperature, gases samples and visual observations were obtained.

- In 2004 occurred no dangerous volcanic process of importance in Nicaragua. The volcanoes San Cristobal, Telica and Masaya presented activity of low intensity with emission of ashes and gases. During the months of November and December Momotombo volcano presented some unusual seismicity.  Concepcion volcano was relatively calm.

 

Landslides

- On May 21 occurred a lahar at Concepcion volcano. The highway between the community of San Marcos and Altagracia was cut temporarily.

 

Project work

A variety of projects of development and geoscientific investigations were carried out, together with foreign institutions:

- The TUCAN project of seismological investigations of seismicity and structure of the earth’s crust, with Boston University, Brown University, and Center of Seismic Instrumentation PASSCAL (all from USA)

- The "Hazard Map of Masaya Volcano," was elaborated together with the Institute of Geophysics of the UNAM.

- Seismic and digital communications equipments for 12 seismic broad band stations were donated by the Government of Japan through JICA.

- With support of King’s College/London INETER became the Central American Center for Volcano Monitoring by means of satellite images.

- In cooperation with the Tsunami Warning Center in the Pacific a sea gauge was installed in Corinto.

- MOVIMONDO/ECHO donated seismic equipments, sea gauges, and Web cameras which are used to improve seismic and volcano monitoring and the tsunami warning system.

- The development of the Geographical Information System for Geo-Risks (SIG) was continued in cooperation with the Federal Institute of Geosciences and Natural Resources (BGR/Germany)

- In cooperation with the Czech Geological Survey, a study of Geology and mineral deposits was executed in the area of Somoto.

- Two projects were executed in support to the House Building Program of the Institute of the Urban and Rural Housing (INVUR).

- INETER/Geophysics supervised the project of the Seismic Vulnerability of Managua which is financed by the World Bank and administrated by SINAPRED.

- Together with GEOMAR (Kiel, Germany) a study was continued on the process of subduction and the relationship with the volcanic activity in Nicaragua and Central America. Geologic indications for the occurrence of tsunamis en Lake Managua were detected.

 

Development of the monitoring and early warning system for dangerous geologic phenomena

- The seismic network was maintained and further developed. Ten seismic stations were installed in the active volcanoes San Cristobal, Telica, Cerro Negro, Momotombo, Masaya, and Concepcion.

- In the last week of December, four Web cameras were installed for the monitoring of the volcanoes San Cristobal, Masaya y Concepcion.