- The death toll has passed 17,000 in Syria and Turkey,

- Hundreds of thousands have been left homeless in the middle of winter,

- The first UN aid convoy has crossed into north west Syria from Turkey,

- A Turkish official said the disaster posed "very serious difficulties" for the holding of an election scheduled for May 14,

- British crews have arrived to carry out a humanitarian effort,

- Access to Twitter has now been restored after a blackout.

The DEC, an umbrella group of UK charities which coordinate appeals, has announced it will be looking to help in this way.

Saleh Saeed, of DEC, said “humanitarian assistance, including food, water and shelter,” was now the focus with it looking increasingly difficult to see futher survivors being saved from the rubble.

Meanwhile, the first United Nations convoy carrying aid to Syrians stricken three days ago by a deadly earthquake crossed from Turkey on Thursday, witnesses and a border crossing official said.

The convoy entered Syria at the Bab Al Hawa crossing, the sources said. Turkish authorities said they would open other crossing points in two days if security was sound.

The Turkey / Syria earthquake came to a magnitude of 7.8, making it one of the most destructive of this century. Here are five others that have shaken the world.

INDIAN OCEAN TSUNAMI

A 9.15 magnitude earthquake off Sumatra on December 26, 2004, triggered a tsunami that barrelled into Indonesia, Thailand, India, Sri Lanka and many other countries in the region, killing at least 230,000 people, leaving 43,000 missing and devastating villages and tourist islands.

HAITI 2010 EARTHQUAKE

A 7.0 magnitude earthquake on January 13, 2010, devastated Haiti's capital Port-au-Prince and killed about 316,000 people. The United Nations estimated 80,000 buildings in Port-au-Prince and surrounding areas were destroyed.

MYANMAR CYCLONE

Cyclone Nargis swept across the Irrawaddy Delta and southern Yangon, the former capital, on the evening of May 2, 2008, with winds of 240 kph (150 mph). Nearly 140,000 people died and 2.4 million were severely affected.

CHINA QUAKE

A 7.8 magnitude earthquake hit China's Sichuan province on May 12, 2008, killing about 87,600 people.

PAKISTAN QUAKE

A 7.6 magnitude quake that struck northeast of Islamabad on October 8, 2005, killed at least 73,000 people. The quake also rocked Indian Kashmir, killing 1,244 there.

Accounts of news sources now suggest the number of fatalities in both Syria and Turkey comes to more than 17,000.

Around 14,000 of those are in Turkey - where 63,000 have been injured.

Experts have said the figure is likely to rise from the 17, 176 is currently stands at.

The World Health Organisation has put forward the importance for humanitarian organisations to act quickly.

Robert Holden, incident response manager, said many are surviving “out in the open, in worsening and horrific conditions”.

“We are in real danger of seeing a secondary disaster which may cause harm to more people than the initial disaster if we don’t move with the same pace and intensity as we are doing on the search and rescue side,” he added. “People need the basic elements to survive the next period.”

British crews completing rescue missions in Turkey have reported finding live victims, which is “surprising and encouraging”.

David O’Neill, head of the UK International Search and Rescue team in Turkey, said the fact a lot of people were in bed when the blast hit is a good sign as they are already wrapped in blankets.

He said: “We are still finding live victims. It is surprising, but it’s encouraging the way these buildings have collapsed. The people that were recovered yesterday were very dehydrated, slightly hypothermic because of the extremely cold conditions here. They’re still alive.”

A Turkish official said the disaster posed "very serious difficulties" for the holding of an election scheduled for May 14 in which President Tayyip Erdogan has been expected face the toughest challenge in his two decades in power.

On the ground, many people in Turkey and Syria spent a third night sleeping outside or in cars in freezing winter temperatures, their homes destroyed or so shaken by the quakes they were too afraid to re-enter. Hundreds of thousands of people have been left homeless in the middle of winter.

The number of people killed by the quake, which struck in the dead of night and was followed by powerful aftershocks, is on course to be larger than in 1999 when a similarly powerful tremor killed 17,000 people in Turkey's more densely populated northwest.

Syrians impacted by the deadly earthquake that struck their country and Turkey on Monday need "more of absolutely everything" in terms of aid, the United Nations' special envoy Geir Pedersen said on Thursday.

The UN had been assured the first assistance would cross from Turkey into Syria on Thursday, he told a briefing in Geneva, calling for assurances that there would be no political hindrances to getting aid to where it was most needed.

Meanwhile, in Turkey a block has reportedly been put on Twitter.

The first convoy of humanitarian assistance for people in northwest Syria since Monday's devastating earthquake is en route to the southern Turkish border with the hope of crossing on Thursday, two aid sources told Reuters.

One source said the convoy included six trucks.

A Turkish official said the Bab al-Hawa border crossing was open for humanitarian aid and authorities will open a few more crossings after two days if security is sound.

The United Nations has described access to the opposition-controlled area of Syria through Bab al-Hawa as a "lifeline" for some 4 million people who it says rely on humanitarian assistance.