The rumble of volcanic magma, the action of ocean waves, the reverberations of a concussion. Connected sensors are watching—and translating everything into data.
Location: Kaena Point, Hawaii Volcanoes National Park, Hawaii
Coordinates: 19°17’18” N, 155°7’45” W
Sensor type: Analog seismometer and data logger
Data: Seismic, including tectonic and volcanic earthquake magnitudes and depths
On the coastal plain just south of lava-scarred Holei Pali cliff, the Kaena Point seismic station is one of 59 quake-detecting posts on Hawaii’s Big Island. Two conduits run from a solar panel—the one here snakes its way to an instrument box with a data logger, battery, and radio; the other heads underground to a vault-protected seismometer. Small magma- or tectonic-induced quakes occur daily. When the ground shakes, the seismometer produces a voltage output, which the data logger digitizes and streams back to Hawaiian Volcano Observatory headquarters. Data from all the detection posts is crunched to determine the epicenter and depth of a quake. Given its location along the eastern rift zone of the Kilauea Volcano, Kaena Point is of particular interest to scientists studying magma flow and the gradual slippage of the volcano into the Pacific.
Murmurs of Earth 
by Ofer Wolberger
Location: Maloney Field, Laird Q. Cagan Stadium, Stanford University, California
Coordinates: 37°25’59” N, 122°9’28” W
Sensor type: Accelerometer- and gyroscope-equipped device that’s worn behind the ear
Data: Impact forces
Concussions have become a huge issue in sports, but little is actually known about this type of traumatic brain injury. The xPatch should change that. The wearable sensor, developed by X2 Biosystems, adheres to the bony area behind the ear and measures impact forces throughout the skull. Should a player get hit, the patch measures the force and severity of the blow and feeds that information back to coaches and team physicians with iPads on the sidelines. Based on that individual’s particular impact history, they can make appropriate decisions about whether the player should stay in the game. The xPatch is already being used by the Stanford women’s lacrosse team and many other collegiate and amateur sports organizations. These athletes are part of a massive data-collection initiative. The goal is not just to track trauma for players who are exposed to head injury but also to gain preventative and diagnostic insights.
Locations: 130 stations across the US
Coordinates: 37°47’0″ N, 122°25’19” W
Sensor type: High-volume air sampler with sodium iodide detector and meteorological instruments
Data: Levels of gamma radiation in the atmosphere
When the Fukushima meltdown occurred on March 11, 2011, the EPA’s RadNet was one of the first systems to track the spread of airborne radiation in the US. This network of 130 monitors, scattered throughout densely populated areas, measured gamma radiation in the air from late March through late July. The near-real-time data was made available to the public through the EPA website. (Only low levels of radioactive material were detected.) RadNet was originally created to sniff for evidence of nuclear tests. But today it monitors national and regional ambient radiation levels; some fixed stations like the one here are located at sites where precipitation is also collected for testing. That information is then combined with EPA data on radiation in milk and drinking water and analyzed for abnormalities that could pose a risk to the public.
Locations: 34 nautical miles west of Kailua-Kona, Hawaii
Coordinates: 19°35’26” N, 156°35’7″ W
Sensor type: Tsunameter
Data: Seafloor pressure
The day after Christmas 2004, a magnitude-9.1 earthquake off the coast of Indonesia triggered a massive tsunami that killed an estimated 230,000 people. Back then there was no detection system in the Indian Ocean. Today, what started out as an array of six to eight sensors in the Pacific has morphed into a worldwide network, known as the DART (Deep-Ocean Assessment and Reporting of Tsunamis) Buoy Array, which provides ample warning to coastlines in danger of inundation. Each node consists of a tsunameter on the ocean floor, which gauges wave height by measuring the pressure of the water above it, and a surface buoy with satellite telecom capabilities. In the event of a tsunami, the data from the buoy would be transmitted to the World Meteorological Organization’s Global Telecommunication System. Anyone with web access, from scientists to emergency and evacuation personnel, can look up the info to assess the threat to coastal communities.
Location: Foothill Road and West Las Positas Boulevard, Pleasanton, California
Coordinates: 37°40’32” N, 121°55’17” W
Sensor type: Microwave
Data: Presence and location of cyclists in car traffic
Cyclists pedaling through the town of Pleasanton probably won’t notice anything unusual at this intersection, but something is certainly taking note of them. Mounted on traffic masts like this at four locations around the town are microwave sensors capable of tracking and differentiating cars and cyclists. Traffic signals hooked into the data can then adjust accordingly—keeping a green light on longer, for example, to allow a slower-moving bike to get through. The result: safer and more efficient intersections. Each unit—known as an Intersector—monitors up to eight detection zones and starts tracking vehicles at about 400 feet away. In the future, these sensors could also be used to record information about intersection approach and exit speeds, lane distributions on approach, and even precise turning paths of bikes and other vehicles.
Location: Washington Street, between Battery and Davis, San Francisco
Coordinates: 37°47’46” N, 122°23’57” W
Sensor type: Magnetometer
Data: Location of vacant parking spots
It’s estimated that one in three drivers on the streets of San Francisco is searching for a parking space. Enter SFpark, a federally funded initiative that aims to solve this problem by gathering parking data and then tweaking parking prices. The pilot program employs several thousand in-ground sensors from an outfit called StreetSmart Technology. The ultralow-power mesh network magnetometers (which have been running nonstop for more than two years) are embedded in some of the most congested neighborhoods. They detect whether a car is directly above them and make that data available to smartphone users looking for a spot. The city uses this info to adjust meter rates and garage pricing to match demand (more demand = higher prices). Increasingly, the stored data is also being combined with citation stats, sales and parking tax data, fuel prices, and even pricing elasticity models to gauge the project’s influence on everything from public transit reliability to economic vitality.
Murmurs of Earth by Ofer Wolberger
