Report on Masaya (Nicaragua) — October 2003
Bulletin of the Global Volcanism Network, vol. 28, no. 10 (October 2003)
Managing Editor: Edward Venzke.
Masaya (Nicaragua) Fumarole temperatures unchanged; landslides, incandescence in Santiago crater
Please cite this report as:
Global Volcanism Program, 2003. Report on Masaya (Nicaragua) (Venzke, E., ed.). Bulletin of the Global Volcanism Network, 28:10. Smithsonian Institution.
11.984°N, 86.161°W; summit elev. 635 m
All times are local (unless otherwise noted)
This report summarizes the activity at Masaya during June-September 2003. Activity was generally constant, with fumarole temperature measurements similar to those from previous months (BGVN 28:08). In June, July, and August, during visits made every two weeks, Jaime Cárdenas of Masaya Volcano National Park measured the fumarole temperatures at the Comalito and San Fernando craters (table 4). No changes were observed from previous months. During these months, seismic tremor remained constant with 20 units RSAM. No earthquakes were registered, but on both 21 June and 21 July landslides were reported in the Santiago crater. In September, temperatures obtained from the Santiago crater with a Pyrometer were 187°C and 123°C. It was noted during this visit that the lava sounded like ocean waves, and incandescence was observed at night. Temperatures at El Comalito remained moderate.
|Date||EC 1||EC 2||EC 3||EC 4||EC 5||EC 6||SF 1||SF 2||SF 3||SF 4|
|10 Jun 2003||65.4||74.5||76.8||72.5||73.4||60.2||59.2||54.8||57.2||55.8|
|28 Jun 2003||66.4||75.4||78.4||73.6||73.8||60.4||60.2||55.6||58.8||56.7|
|12 Jul 2003||55||76||78.2||74||73.6||60||60||60.2||59.5||57|
|26 Jul 2003||66.8||78.4||79.4||75.6||74.2||61||61.2||61.4||60.2||58.2|
|15 Aug 2003||66.6||78.2||79.5||76||74.5||61.5||59.7||59.7||57.2||56.2|
|29 Aug 2003||67.8||75.6||76.6||74.8||76.4||64.2||59.3||57.4||56.9||57|
|22 Sep 2003||68.6||72.3||68.3||65.2||--||--||--||--||--||--|
Geologic Background. Masaya is one of Nicaragua's most unusual and most active volcanoes. It lies within the massive Pleistocene Las Sierras pyroclastic shield volcano and is a broad, 6 x 11 km basaltic caldera with steep-sided walls up to 300 m high. The caldera is filled on its NW end by more than a dozen vents that erupted along a circular, 4-km-diameter fracture system. The twin volcanoes of Nindirí and Masaya, the source of historical eruptions, were constructed at the southern end of the fracture system and contain multiple summit craters, including the currently active Santiago crater. A major basaltic Plinian tephra erupted from Masaya about 6500 years ago. Historical lava flows cover much of the caldera floor and have confined a lake to the far eastern end of the caldera. A lava flow from the 1670 eruption overtopped the north caldera rim. Masaya has been frequently active since the time of the Spanish Conquistadors, when an active lava lake prompted attempts to extract the volcano's molten "gold." Periods of long-term vigorous gas emission at roughly quarter-century intervals cause health hazards and crop damage.
Information Contacts: Virginia Tenorio, Instituto Nicaragüense de Estudios Territoriales (INETER), Apartado Postal 2110, Managua, Nicaragua (URL: http://www.ineter.gob.ni/).