According to online birth records, Hazel P. Dingle was born in San Franciso 5/17/1911 and her mother's maiden name is listed as "Koull".
In addition to the online records of Earthquake deaths, I have a listing from the Sacramento Bee. Most of the names are the same, but the online records have some that are not on my list, and my list has some that are not on the online list. Mine also includes a list of missing, not confirmed dead, but there is nothing close to Krull/ Koull.
There may be a couple of different reasons for this. During the earthquake, for health reasons, many of the dead were buried before they could be identified; some were badly burned from the fire that followed the earthquake and could not be identified.
Also, some families have secrets they want to hide and it might be told they died in the earthquake to hide something else (I know this from personal experience - my great grandmother who my father was told "died in childbirth" was actually murdered by her husband.