Sinkholes in MASS are caused by five factors
• Population growth: MASS experienced an unexpected surge in population around their
civil war from 1980-1992
• Tierra blanca joven (TBJ): MASS is built on 50cm - 50m of fine, silicate volcanic ash
• Hydrological systems: Both human made and natural systems easily erode TBJ
• Maintenance: The city is unable to keep up with increasing maintenance as pipes age
• Earthquakes: About 20 earthquakes of medium intensity are felt annually in El
Salvador. Earthquakes crack water pipes.