( CNN ) -- Four years since a 9.0-magnitude earthquake spawned massive walls of water that swept across the Indian Ocean , leaving more than 230,000 dead according to a United Nations estimate , improvements can be seen in many of the devastated areas , humanitarian groups said . Laborers work on a construction site in a fishing village in Indonesia 's Aceh on December 21 . Hundreds of thousands were left homeless and jobless after the tsunami , and poor and isolated communities were left even worse off . Today , new schools have been constructed , and armies of workers -- many of them volunteers -- have cleared and rebuilt homes and towns , and helped get people back to work . `` The tsunami , despite being a horrific event , also provided a lot of opportunities for those countries , '' said Jonathan Cauldwell , chief of UNICEF 's Tsunami Transition Support . `` It brought a peace dividend within Banda Aceh ( Indonesia ) where you still see peace in an area which had long term localized conflict in place . It allowed those areas to be built up as well , to have investments in the infrastructure in the social sectors ... , '' he added . Agencies such as UNICEF said that while the immediate emergency was over , they remain committed to improving the lives of millions of children across the region . `` The lessons of the tsunami will never end . The funding will end , we can complete the construction , we can complete the project , but the intervention never ends ... , '' Cauldwell said . Oxfam International , which said it will close its response to the tsunami at the end of December , said it has provided housing to tsunami survivors in Aceh , helped restore the livelihoods of people in India and Sri Lanka , and funded the reconstruction of eight tsunami-affected secondary schools . `` The money we received allowed us not only to help meet the immediate emergency needs of tsunami-affected populations , but also to try to address the factors that made them vulnerable : not least poverty and a lack of influence over their own lives , '' Barbara Stocking , chair of the Oxfam International Tsunami Fund Board , said in a statement . `` What has been achieved is astounding . Hundreds of thousands of people are now living in better conditions than they were in before the tsunami ... , '' she added . UNICEF said the basic needs of children affected by the tsunami have been met -- more children are going to school as a result of improved facilities , and better nutrition , post-natal care and other life-saving interventions are helping those countries worst hit transition to developing regular services and programs . But long-term improvement of water and sanitation is critical , the agency said , and so is building new schools that are better able to withstand earthquakes . According to UNICEF and Oxfam , the response to the tsunami and the lessons learned have changed the way they deal with such emergencies . It highlighted the need for better coordination among partners and other organizations , and contributed to reforms in the way humanitarian relief is delivered .
The devastation of the 2004 tsunami stretched across the Indian Ocean . Hide Caption 8 of 12 Photos:Photos: Humanitarian groups have helped rebuild schools , homes , and get people working . Groups say long-term improvement of water and sanitation is critical .