lamatepec is the largest of El Salvador's 23 volcanoes and at 2,381 metres above sea level the volcano is the highest point in El Salvador.
It is a massive andesitic-to-basaltic stratovolcano immediately west of Coatepeque caldera, and situated in a major coffee-growing area about 40 miles west of the capital, San Salvador.
According to various news media it now (i.e. 1 October) erupted for the first time in a century with its last eruption being in 1904. According to the Global Volcanism Programme page at http://www.volcano.si.edu/world/volcano.cfm?vnum=1403-02= where you can find more information about the volcano the last known eruption however was in 1920. It has been increasingly active since last year.
OUSG (U.S. Geological Survay) also has information about this and other El Salvador volcanoes at http://vulcan.wr.usgs.gov/Volcanoes/ElSalvador/description_el_salvador_volcanoes.html