Masaya volcano (Nicaragua) - Smithsonian / USGS Weekly Volcanic Activity Report for 18 April-24 April 2001 (New Activity / Unrest)

At 1426 on 23 April a small explosion at Masaya's Santiago crater lasted for ~2 minutes and occurred in three phases. During the first phase volcanic gas under high pressure was explosively released and created a new vent in the bottom of Santiago crater. The eruption sent rock fragments up to 60 cm in diameter as far as 500 m from the crater.
Several vehicles parked at a visitors platform near the crater were damaged by the ejecta and one person suffered minor injuries. During the second and third phases a mixture of hot volcanic gas, pieces of lava, and ash ignited dry vegetation near the crater. INETER personnel who monitored the seismic activity before the eruption and scientists from Cambridge University who were working in the crater one hour before the eruption did not notice any unusual activity at the volcano.
INETER personnel monitored the volcano after the eruption and found that several small explosions, gas outbreaks, and minor collapses of the crater wall occurred. They warned that further explosions may occur that could affect areas near the crater (within ~500 m).

Sources: Instituto Nicaragüense de Estudios Territoriales (INETER), Associated Press
---
From: Global Volcanism Program, 2001. Report on Masaya. In: Mayberry, G (ed.), Weekly Volcanic Activity Report 18 April-24 April 2001. Smithsonian Institution and US Geological Survey.