1. A smart home system network comprising: a plurality of smart-home devices that are distributed among a plurality of homes within a geographic region, the plurality of smart-home devices including: a thermostat that is located in a first home, the thermostat having a primary function of controlling a temperature within the first home; a smoke detector that is located in a second home, the smoke detector having a primary function of detecting smoke within the second home; and a camera that is located in a third home, the camera having a primary function of video monitoring for the third home; wherein: the thermostat includes a primary sensor that senses conditions related to controlling the temperature of the first home and also includes a secondary sensor that is disposed within the thermostat and that senses conditions that are not related to controlling the temperature of the first home, the secondary sensor of the thermostat being one or more sensors selected from the group consisting of: a seismic sensor, an audio sensor, an acceleration sensor, and a radiation sensor; the smoke detector includes a primary sensor that senses conditions related to detecting smoke within the second home and also includes a secondary sensor that is disposed within the smoke detector and that senses conditions that are not related to detecting smoke within the second home, the secondary sensor of the smoke detector being one or more sensors selected from the group consisting of: a seismic sensor, a temperature sensor, an audio sensor, and a humidity sensor; and the camera includes a primary sensor that senses conditions related to video monitoring for the third home and also includes a secondary sensor that is disposed within the camera and that senses conditions that are not related to video monitoring for the third home, the secondary sensor of the camera being one or more sensors selected from the group consisting of: a temperature sensor, a seismic sensor, an acceleration sensor, and a radiation sensor; and an event detection processor programmed and configured to detect an event from sensor measurements gathered within the geographic region from the secondary sensors of the thermostat, the smoke detector, and the camera according to the steps of: receiving said sensor measurements from said secondary sensors of the thermostat, smoke detector, and camera; analyzing selected ones of said sensor measurements from said secondary sensors of said thermostat, smoke detector, and camera to determine whether an event has occurred, wherein the event is a geographically distributed event selected from the group consisting of: an earthquake, a tornado, a power outage, and a local weather event; and generating at least one alert identifying the detected event based on said analysis of selected ones of said sensor measurements from said secondary sensors of said thermostat, smoke detector, and camera; wherein the determination that the event has occurred requires processing of said sensor measurements of said secondary sensors from each of the thermostat, smoke detector, and camera.