Fahrenheit 451 quote

I need an answer for each of these questions.

“Montag could not move. A great earthquake had come with fire and leveled the house and Mildred was under there somewhere and his entire life under there and he could not move. The earthquake was still shaking and falling and shivering inside him and he stood there, his knees half bent under the great load of tiredness and bewilderment and outrage, letting Beatty hit him without raising a hand” (112).

Question :

2. What is meant by “... and Mildred was under there somewhere …”?