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NetQuakes—Extending seismic monitoring with citizen science

April 12, 2013

Map showing locations of USGS NetQuakes recorders and epicenter of M3.2 earthquake occurring on April 3, 2013. Around the map are plots of the strongest shaking recorded at each of the NetQuakes sites associated with this earthquake. The plots are not adjusted to reflect differences in shaking among the individual sites. (USGS)

The following is this week’s edition of “Volcano Watch” from the Hawaiian Volcano Observatory (USGS).

At 9:28 a.m., HST, on April 3, 2013, the Hawaiian Volcano Observatory’s (HVO) seismographic network recorded a magnitude-3.2 earthquake. This earthquake occurred roughly 14 km (9 mi) west of HVO on one of the faults comprising the Kaʻōiki fault system that lies between Kīlauea and Mauna Loa volcanoes.

Hundreds of earthquakes each year are associated with faults in the Kaʻōiki system. This area is also where some of the largest earthquakes ever recorded in Hawaiʻi have occurred. We view the April 3 earthquake as part of the background earthquake activity occurring in the Kaʻōiki system as the volcanoes evolve and the Earth’s crust responds.

The April 3 earthquake is noteworthy because HVO recorded it on all of our deployed NetQuakes sensors. In late March, we completed installations of our current allotment of NetQuakes seismic recorders in Hawaiʻi County. This is a significant advance for the U.S. Geological Survey (USGS) and HVO in seismic monitoring and our partnerships in citizen science.

The concept of the NetQuakes recorders arose from a need to better understand details of strong earthquake shaking and its effects on structures by recording damaging earthquakes on greater numbers of instruments deployed in affected areas. In order to achieve this, it was necessary to try something new.

Seismic Hazard Map for the Hawaiian Islands. (USGS)

Traditional seismic monitoring involves deploying many expensive sensors connected to a central data processing computer facility (like HVO) via expensive radio links. If we augment this coverage with less precise, but cheaper, sensors, however, we could improve our monitoring coverage at a low cost.

Not only are NetQuake sensors cheap, but they use the Internet, rather than radios, to send the data to the monitoring center. This is where USGS citizen science is key.

From generous responses to earlier Volcano Watch articles and to the NetQuakes Website (http://http://earthquake.usgs.gov/monitoring/netquakes/), we have been able to find volunteer hosts who have agreed to house our instruments in their homes. The USGS provides and installs the instrument, and the hosts provide AC power and Internet access. When there is no seismic activity, the instruments send scheduled status messages to the California computers.

Significant shaking triggers the NetQuakes instrument. Data are stored in memory and written to CompactFlash cards. After the strong shaking subsides, each NetQuakes sensor automatically sends its data over the public Internet to USGS computers in California. The data are subsequently posted to the Web, where they can be viewed at the NetQuakes site.

Data associated with a recognized earthquake, like the April 3 earthquake here, are distributed to other USGS computers for further processing. At HVO, the NetQuakes data are incorporated into our earthquake location and magnitude post-processing.

Headquarters of the Hawaiian Volcano Observatory at the summit of Kilauea. (USGS)

HVO, for example, records large numbers of earthquakes originating from the Puna District on the eastern side of the island of Hawaiʻi. However, the slope and breadth of Kīlauea’s rift zone and adjacent flank have made this area difficult to establish stations with the requisite lines of sight for radio data transmission. Additional seismic stations are needed to improve our understanding of earthquake and volcanic processes there.

Thanks to our NetQuake citizen hosts, we now have a number of additional seismic stations in lower Puna. While we anticipate that these stations will provide very important recordings of large, damaging earthquakes like those occurring beneath Kīlauea’s southeast flank—most recently in 1989 and 1975—we have also demonstrated that we can use the NetQuakes data in our studies of smaller earthquakes, as well.

Because of limited numbers of available NetQuakes, we already have more volunteers than instruments to deploy. At the same time, we ask that interested members of the community indicate their willingness to help by filling out a volunteer form at the NetQuakes Website named above. As we receive instruments, we will deploy them according to our monitoring requirements.

Visit the official website of the Hawaiian Volcano Observatory

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