Satellite photos are providing an increasingly important role in humanitarian emergencies, revealing the level of destruction and allowing a very visual before and after comparison.
Firstly check out the gallery of before and after satellite photos from Syria published by BBC News
These photos come from a report published by the UN's Institute for Training and Research (Unitar), which it says "depicts with no uncertainty the terrible human suffering to which the people of Syria are exposed".
Markets, power supplies, schools and hospitals are among sites destroyed amid the country's conflict, Unitar's analysis of the images found. For example ...
The area around the Khalid ibn al-Walid Mosque, one of the most famous mosques in Homs, Syria's third largest city, has been a target of numerous attacks. View more before and after photos
Oxfam is part of the #WithSyria coalition who are calling for the UN Security Council to do more to help Syria.
Secondly check out the gallery of before and after satellite photos from Vanuatu published by the NZ Herald
These photos superimpose the before and after photos with a slider that allows you to change how much of each to show. View more before and after photos
Oxfam New Zealand has launched a full scale appeal to help the many thousands of people affected by the devastating cyclone.