Final answer:
The exact number of faults within a 10-km radius of Valparaíso cannot be determined from the provided reference materials, as they do not give a direct count of faults around the city but instead discuss tectonic activity and fault behavior in various regions.
Step-by-step explanation:
Your question about how many faults are within a 10-km radius of Valparaíso is quite specific, and the answer would typically require access to detailed geological maps and databases specific to the region of Valparaíso, which are not provided in the reference materials. Generally, the available data shows information on earthquake occurrences, the velocity of tectonic plates, and fault activity in various locations such as California and central Chile, but it does not give a direct count of faults around a specific city like Valparaíso.
For an accurate count of faults, one would need to perform a site-specific study using seismic data, fault maps, and possibly field observations. The provided information demonstrates the complexity of tectonic activity and the significant differences in fault behavior across regions, emphasizing the importance of local geological investigations to understand fault density and potential earthquake risks in a specific area.