The differences in travel time from the epicenter to the observatory are a measure of the distance and can be used to image both sources of earthquakes and structures within the Earth. Also, the depth of the hypocenter can be computed roughly. P-wave speed
Upper crust soils and unconsolidated sediments: 2–3 km (1.2–1.9 mi) per second
Upper crust solid rock: 3–6 km (1.9–3.7 mi) per second
Lower crust: 6–7 km (3.7–4.3 mi) per second
Deep mantle: 13 km (8.1 mi) per second. S-waves speed
Light sediments: 2–3 km (1.2–1.9 mi) per second in
Earths crust:4–5 km (2.5–3.1 mi) per second
Deep mantle: 7 km (4.3 mi) per second

Seismic wave arrival
As a consequence, the first waves of a distant earthquake arrive at an observatory via the Earths mantle. On average, the kilometer distance to the earthquake is the number of seconds between the P- and S-wave times 8. Slight deviations are caused by inhomogeneities of subsurface structure. By such analysis of seismograms, the Earths core was located in 1913 by Beno Gutenberg. S-waves and later arriving surface waves do most of the damage compared to P-waves. P-waves squeeze and expand the material in the same direction they are traveling, whereas S-waves shake the ground up and down and back and forth. Earthquake location and reporting
Earthquakes are not only categorized by their magnitude but also by the place where they occur. The world is divided into 754 Flinn–Engdahl regions (F-E regions), which are based on political and geographical boundaries as well as seismic activity.
A notable example is Heinrich von Kleists classic novella, The Earthquake in Chile, which describes the destruction of Santiago in 1647. Haruki Murakamis short fiction collection After the Quake depicts the consequences of the Kobe earthquake of 1995. The most popular single earthquake in fiction is the hypothetical "Big One" expected of Californias San Andreas Fault someday, as depicted in the novels Richter 10 (1996), Goodbye California (1977), 2012 (2009) and San Andreas (2015) among other works. Jacob M. Appels widely anthologized short story, A Comparative Seismology, features a con artist who convinces an elderly woman that an apocalyptic earthquake is imminent.Contemporary depictions of earthquakes in film are variable in the manner in which they reflect human psychological reactions to the actual trauma that can be caused to directly afflicted families and their loved ones. Disaster mental health response research emphasizes the need to be aware of the different roles of loss of family and key community members, loss of home and familiar surroundings, loss of essential supplies and services to maintain survival. Particularly for children, the clear availability of caregiving adults who are able to protect, nourish, and clothe them in the aftermath of the earthquake, and to help them make sense of what has befallen them has been shown even more important to their emotional and physical health than the simple giving of provisions.