In pictures: Jack London's 1906 quake journey

"Jack and Charmian were like children - they thought the trip was a bit of a lark," says Mr Fradkin, who is also the author of the recent book The Great Earthquake and Firestorm of 1906.

He says the couple embarked on the adventure to prove how hardy and tough they were.

"They boxed and called each other 'Mate'. Jack was proud of his wife - it was a very gruelling journey," says Mr Fradkin.

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