3 Pearl River Delta, China: 
This near-unbroken urban conglomeration, including Hong Kong, Shenzhen, Dongguan, Macau and Ghangzhou, is home to more than 42 million people. 
One of China’s economic jewels (estimated GDP: $690bn or Dh2.5 trillion) is spread across a flood plain threatened by all manner of natural disasters: 
it is the number one metropolitan area for storm surge, with 5.3 million people affected, the third-highest for cyclonic wind damage (17.2 million), and the fifth riskiest city for river floods.

4 Osaka-Kobe, Japan: 
Osaka-Kobe is home to 14.6 million people living under the threat of earthquakes such as the one that killed thousands of people in 1995. It also suffers from brutal storms and the risk of river flooding. 
And then there are the storm surges, in which heavy winds from typhoons of the kind that hit east Asia whip up gigantic waves: the metropolitan area’s location on a large coastal plain means three million people are at risk. It is also the third-most tsunami-prone city in the world.

5 Jakarta, Indonesia: 
Fully 40 per cent of Jakarta is below sea level; it lies in a flat basin with soft soil near a fault line. This means earthquakes can be particularly dangerous to its 17.7 million inhabitants, as the soft soil can magnify the intensity of the tremors. 
Quakes can also liquify Jakarta’s poorly drained soil, causing the ground to lose its structural integrity and react like a liquid. Add to that Jakarta’s risk of river flood and it becomes one of the most exposed cities on the planet.

6 Nagoya, Japan: Tsunami risk dominates in the Pacific. The most exposed cities, dotted along the active faults of the western ocean, are in Japan – led by Tokyo-Yokohama and Nagoya, each with around 2.4 million people potentially affected. 
With 12 million people in total at great risk, tsunamis affect by far the fewest people of the great five natural disasters analysed here – but the death tolls can be enormous.

7 Kolkata, India:
River floods also affect Kolkata, with 10.5 million people at risk – but the eastern Indian city is also fifth in terms of tsunami risk, with more than half a million people exposed. 
It is also threatened by hurricanes, human-made disaster like fire and  rampant transportation vehicle accidents.

8 Shanghai River, China: 
With so many cities built on flood plains and river deltas, flooding is the most common risk they face. India and China face the most significant risks; with 11.7 million residents directly threatened, Shanghai is a particular hot spot for flooding, but other such risky cities include Bangkok, Mexico City, Baghdad, Paris and Doha.

9 Los Angeles, United States: 
Its location on the San Andreas Fault makes Los Angeles one of the most earthquake-prone cities – although not as vulnerable to tsunami as might be expected. Subduction zones, where oceanic plates dive underneath the continental crust, generally create much larger tsunamis than so-called “strike-slip” faults such as the San Andreas and Northern Anatolian faults. 
Small comfort to the 14.7 million inhabitants of the area threatened by earthquake.

10 Tehran, Iran: 
San Andreas fault or the Pacific Ring of Fire as being the riskiest zones for earthquakes, but not everyone is immediately aware that the Northern Anatolian fault is one of the most dangerous in the world. 
The entire 13.6 million population of Tehran is exposed, as are the residents of Bucharest, Tashkent, the capital of Uzbekistan, and much of Turkey. 
The last quake in Tehran was in 1830, and its building regulations are shakily followed at best – making it a city living on borrowed time.

Source: Agencies