Villarrica Volcano is one of the most active volcanoes in south-central Chile. There are many hazards related to the volcano, but its main hazard for humans through Villarrica’s history have been the lahars. Since the arrival of the Spanish colonists (1550) to the towns beside the volcano, it have been reported hundreds to thousands of casualties and the towns were repeatedly destroyed by lahars. From the necessity to understand its behaviour for future events and reconstruct its past. Short and long sediment cores were taken from the lakes beside the volcano –Villarrica and Calafquén–. For studying them, pictures were taken from the original cores and a histogram equalization was applied for having more visual information. CT-scans of the cores were obtained to analyse in high detail. Also the magnetic susceptibility curve was obtain and compared to the other information. It has been concluded that the distribution of the clay caps of recent well-known lahar events (during 20th century) show that they are deposited by a combination of under- and interflows. After measuring the thickness of the lahars of Holocene age in the long cores in both lakes show that the general trend in both lakes is similar that is to increase progressively. They are linked to rainfall (climate), but also for example the Pucón eruption (which changed the morphology of the volcano) changed the frequency of the events in the centuries after the eruption in both lakes, with first a quiescence of approximately 700 years to Lake Calafquén.