Welcome to the inquiry on the BBC World Service.

I'm Tanya Beckett.

Each week, one question, four expert witnesses,

and an answer. At six o'clock in the evening on Tuesday the 4th of August, smoke was seen billowing out of the port of Beirut. A hangar storing

fireworks was thought to have caught fire. A call went out to the city's fire

brigade.

Nine male firefighters and a female paramedic raced towards the port.

Then came the blast.

An explosion so large that it could be heard 200 kilometers away in Cyprus. It ripped through Beirut causing widespread destruction across the city.

2,750 tons of ammonium nitrate that had been sitting in storage at the port for six years had exploded.

Over 200 people lost their lives and one in six of the city's 2 million inhabitants were made homeless.

The rescue workers stood no chance of surviving. In the outpouring of grief and rage that followed,

Lebanese people railed at a political system whose negligence and corruption had already plunged

countless people into poverty before the disaster at the port.

In this week's inquiry we're asking,

what has gone wrong in Lebanon? on rock bottom.

I was driving up over a bridge the other day and I thought, well what if the bridge collapses? My sense of imagination is completely now taken up with all of the possible things that could go wrong.

Our first expert witness is Lena Munza, a Lebanese writer and translator who lives in Beirut.

She describes the trauma that people in the city are suffering weeks after the blast.

It really feels like there's absolutely no solid ground to stand on.

I feel the earth shaking constantly,

sort of as like an after shock.

...