Atocha is a Spanish name, coming from the Marian title of Our Lady of Atocha, worshiped in Madrid (she is one of the patroness of Madrid).
The name of the title comes from the Spanish word
atocha, another name for the esparto grass (
Stipa tenacissima), which usually is named
esparto in Spanish, and it was applied as Marian title because the statue was found in a esparto grass field.
It is a name almost exclusively known as given name and used in Madrid (in the rest of Spain, it is known as railway station name, because it is the main station of Madrid and most of the national routes go to Atocha). It is really surprising a Mexican girl with this name but maybe she is daughter or grand-daughter of Madridian people.
Lumia
http://onomastica.mailcatala.com