What If?: Serious Scientific Answers to Absurd Hypothetical Questions to make them shatter on contact?" The book was received positively by critics. Ethan Gilsdorf of the "Boston Globe" stated that "it’s fun to watch as Munroe tackles each question and examines every possible complication." According to Gilsdorf, "What If?" gives a view into "Munroe’s playful yet existentially-tinged worldview" by contrasting cataclysmic scenarios with more heady ideas, such as examining the effects of a magnitude minus-7 Richter scale earthquake. The "Huffington Post" remarked that "What makes Munroe's work so fantastic is a combination of two elements: his commitment to trying to answer even the weirdest question with solid science, and
Richter magnitude scale used by astronomers. Second, he wanted a magnitude of zero to be around the limit of human perceptibility. Third, he specified the Wood-Anderson seismograph as the standard instrument for producing seismograms. Magnitude was then defined as "the logarithm of the maximum trace amplitude, expressed in microns", measured at a distance of 100 km. The scale was calibrated by defining a magnitude 3 shock as one that produces (at a distance of 100 km) a maximum amplitude of 1 micron (1 µm, or 0.001 millimeters) on a seismogram recorded by a Wood-Anderson torsion seismograph. Finally, Richter calculated a table of distance