In November 2015, the Fundão dam near the city of Mariana in Brazil collapsed, unleashing a torrent of mud and mining waste and killing 19 people.

Entire communities were destroyed in one of the worst environmental disasters in Brazilian history.

As the flood swept towards her village, Paula Geralda Alves jumped on her motorbike and raced from house to house warning people to flee, earning her the nickname 'the human siren'.

Paula tells Helen Ledwick how she helped save lives.

Witness History is a short BBC World Service podcast about history that takes you inside big moments from the past through first-hand testimony and archive. Each weekday, in around nine minutes, we revisit one moment that helped shape the world and hear it through the voice of someone who was there. Scientists, artists, campaigners, soldiers, leaders and everyday people tell their true stories.

When you subscribe to Witness History, you’ll be taken inside turning points in world affairs from West Africa’s fight back against Boko Haram in 2015 to the behind-closed-doors talks that led to the US-Cuba “thaw” and the surprise announcement of restored relations. You’ll discover what it was like to experience disasters and how people recovered from them, including the Tabasco floods in Mexico, Portugal's worst train disaster, and the huge clean-up after the Chernobyl nuclear disaster. You’ll explore culture and ideas too: Sweden’s Expedition Robinson, often credited as the first modern reality TV game show; the friendship between The Beatles’ George Harrison and Indian sitarist Ravi Shankar; and the night a tiger attack brought Las Vegas superstars Siegfried and Roy’s show to a sudden end. And if you’re curious about inventions, we’ll tell you how air fryers, BlackBerry, YouTube, Alexa, GPS, superglue, the shopping cart (shopping trolley) and bubble tea were created.

If you’re new to Witness History, the appeal is simple: real voices, one strong true story, and a fresh way to understand today through events from history – all in the time it takes to enjoy a cup of tea or a walk around the block. Join millions of BBC World Service podcast listeners around the globe and enjoy the insight, context and detail Witness History will bring you.

(Photo: The village of Bento Rodrigues, in Mariana. Credit: Christophe Simon/AFP via Getty Images)