More than 4,000 people have lost their lives following the 7.9-magnitude earthquake and after shocks that rocked Nepal on Saturday (25Apr15).

Sheridan's brother, Zachary, was near Mount Everest when the earthquake struck and the Packed to the Rafters actor has not heard from him since 22 April (15).

In a posting on Instagram.com, he writes, "Thank you everyone for your messages and your kind words. I'm on my way to Nepal now and will head toward base camp to try and find Zachary.

"I will be with a small crew helping with a chopper (helicopter), a dr (doctor) and we will have a satellite phone available for any Australian there who needs to reach home and tell their loved ones they're ok, I know so many of us are still waiting to hear but communication is down.

"Stay positive everyone, I feel optimistic that he is alive and stuck. I know that the news (outlets) have been eager to talk to my mum but it would be respectful to leave her alone at this time. My heart goes out to every family who is still waiting to hear, I can't imagine how they feel at Mt Everest. I'm looking forward to seeing my little brother and getting him out safely."

Meanwhile, filmmaker Tom Taplin is the third American to be confirmed dead in the earthquake.

Actress Sophia Bush's ex-boyfriend, Google executive Dan Fredinburg, was also killed in an avalanche triggered by the earthquake.