Sismos Tectónicos en Nicaragua y América Central
La Red Sísmica de Nicaragua registró en este mes de mayo 172 eventos sísmicos. La actividad se concentró en la zona de subducción, en el Océano Pacífico y en la Cadena Volcánica Cuaternaria. En el volcán Momotombo se registró un enjambre sísmico que inició el primero de mayo.
El día 01 a las 10:48 am, tiempo local, se registró un sismo localizado en el volcán Momotombo. Posteriorermente se produjo un enjambre sísmico que duró hasta el día 3 de mayo. No se observaron otros fenómenos volcánicos en el volcán.
El volcán San Cristóbal mantuvo su actividad eruptiva de manera continua con salida de ceniza y gases. El volcán presentó nivel alto de tremor sísmico y número de eventos. A partir del 13 de mayo ocurrieron deslaves en los flancos Sur y Suroeste del volcán, producto de fuertes lluvias. Cenizas acumuladas durante la reciente erupción se mezclaron con arena y rocas en las barrancas existentes, formaron lahares que entraron en los cauces al pie del volcán y llegaron hasta la carretera Chinandega-León. Los lahares fueron registrados por las estaciones sísmicas al Este y Sur del San Cristóbal.
Los volcanes Telica, Cerro Negro y Concepción, se mantuvieron en relativa calma. El volcán Masaya presenta emisión de gases en grandes cantidades.
The Nicaraguan Seismic Network registered a total of 172 seismic events in May 2000. The majority of them were located along the subduction zone off the Pacific Coast of Nicaragua and along the Nicaraguan volcanic chain. A seismic swarm activity occurred at Momotombo volcano.
On May 01, at 10:48 am, local time, the seismic swarm activity began at Momotombo volcano and continued the following days. No other extraordinary volcanic phenomena were observed at the volcano.
San Cristóbal volcano continued with its low intensity eruption, and presented a high level of seismic tremor. Strong rain falls triggered the occurrence of lahars on the southern and southwestern flanks of the volcano. The first lahars occurred on May 13. Volcanic ashes accumulated during the recent eruption came down the existing gullies and dry rivers and reached the highway Chinandega-León, at 15 km distance to the volcano. The lahars were detected by seismic stations installed near San Cristóbal volcano.
The volcanoes Telica, Cerro Negro and Concepcion showed no extraordinary activity. Masaya volcano continued with the intense emission of volcanic gases.
The effects of the lahars which occurred in May 2000 at San Cristóbal volcano are described. No important damages to properties were observed. The lahars at San Cristóbal volcano weresuccesfully monitored with seismic stations.
The first time it geologists of INETER succeeded to observe visually the movement of lahars at San Cristóbal and at the same time seismologists monitored the generated seismic signal at the Seismic Data Center at INETER, Managua; both groups communicated by cellular telephone.
The Carbon Dioxide concentrations were measured in the villages in the Southwest of San Cristóbal volcano and compared with previous measurements. No significant changes were observed, the values are below hazardous levels.
Landslide areas in the Northern part of Nicaragua were done; it was found that the slide activity in San Simón de Palsila and Dipilto continues, but with relatively low velocities.
The seismicity at Momotombo volcano lately seems to experiment changes. There are now periods of several hours with seismic tremor of low amplitud. And, “ tornillos” appeared – special seismic signals typical at some volcanoes.
We give a short note about the historical activity of Momotombo volcano.
A seismic experiment was launched for the study of the earth crust in the Nicaraguan subduction zone. This activity is part of the project “Tsunami generation and tsunami warning system in Nicaragua”.
The field work for the project “Geological mapping and volcanic hazards in the Western part of Nicarcagua” was continued in the area of the volcanoes Telica, Rota, Cerro Negro, Las Pilas and El Hoy. The proyect is carried out in cooperation with the Czech Geological Survey.
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