In the aftermath of Hurricanes Maria and Irma, much of Puerto Rico still suffers from lack of electricity and cell phone signals, not to mention clean water for many of its millions of residents. Houses were ripped apart, farms were decimated, and nearly 30,000 salaried jobs were lost in the wake of two of the strongest and long-lived landfalling hurricanes on record in the Atlantic Ocean.
A month after Hurricane Maria’s 20 September landfall, 72% of the island was still without water. Nearly 3 months after the devastating storm, most residents live day by day, scraping together enough money to buy fuel for their generators and searching for potable water. Even as power transmission towers get repaired, the island has faced outage after outage, slinging them back into conditions like those first few weeks after the hurricanes.
“Make no mistake—this is a humanitarian disaster involving 3.4 million [U.S.] citizens,” Puerto Rico governor Ricardo Rosselló said on 25 September, the Monday after Maria hit.
In the midst of all this, another problem weighs on seismologist Alberto López, a geophysicist at the University of Puerto Rico: the damage done to the island’s seismic network.
López estimates that the University of Puerto Rico’s network has lost three seismometers, three accelerometers (which also measure seismic waves), 13 solar panels, one GPS antenna, and a few more instruments. As of 21 November, the network was 60% operational, but sometimes “it goes a bit down, depending on the power availability at sites,” López said.
The loss of much of the island’s cellular network gave López another problem to consider. Currently, the island’s seismic network relies mostly on radio and broadband Internet to transmit data from seismometers to the home base at the Puerto Rico Seismic Network (PRSN) in Mayagüez, on the western side of the island. However, because some of the seismic stations are far away from a building that could host an Internet connection, among other reasons, the scientists had started converting the network into one that transmits data via the cellular network. This network sends data over radio waves via clumps or “cells” of transmitters and receivers; it’s the same network your cell phone uses.
But in the wake of the devastating hurricanes and considering how quickly they knocked out these cell sites, López and others started rethinking that plan. Perhaps, he wonders, it’s best not to rely solely on one way in which to transmit data.
López’s colleague Elizabeth Vanacore will present an assessment of the seismic network’s capabilities on Wednesday, 13 December, at the American Geophysical Union’s 2017 Fall Meeting in New Orleans, La.
Shaking Up Data Transmission
Puerto Rico’s seismic network consists of seismometers that detect ground shaking, geodetic instruments that determine how much the ground moves, and tide gauges to monitor sea level. These instruments rely on Internet, radio, and cellular networks to relay information back to the University of Puerto Rico in Mayagüez, where the seismic network is based. GPS antennas, which receive signals from satellites, help the seismometers stay in sync.
When an earthquake strikes, the seismometers relay their data to scientists at the university. “As soon as the analysts locate the earthquake, they just publish that on the [university’s] website,” López said. The scientists also post earthquake information on Facebook.
Researchers depend on the networks’ data to locate earthquakes. The earthquake’s location, in turn, helps to identify active faults and properly assess damage. Seismometers offshore can also help scientists determine tsunami potential, López explained.
These data are especially important in hazard communication because “the initial reports of damage or casualties are quite often wrong or estimated in the wrong place” thanks to social media and old-fashioned rumor, said David Simpson, president emeritus of the Incorporated Research Institutions for Seismology. Without the seismometers or the GPS instruments in the vicinity to tell scientists an earthquake’s exact location, “you’re driving blind” should an earthquake strike.
But along came Hurricanes Irma and Maria, which not only damaged some of the network’s instruments but also exposed hidden vulnerabilities in how the network’s information is relayed.
“Most of damage has been associated with the strong winds,” López noted. Hurricane Maria’s wind speeds reached 175 kilometers per hour (about 108 miles per hour). They knocked over or bent GPS and data transmission antennas and sent pieces of debris crashing into solar panels. The cost of the damage may reach $70,000, López said
“During the hurricanes, there are pieces of wood, panels from different places,” hurtling through the air, López said. “Many of these things…fly with the speed of the wind. The antennas that are used to transmit the data to a receiving point or to our headquarters—these are the ones that have suffered the most.”
The seismometers, meanwhile, are buried underground in concrete structures and are safe from the howling winds, but a few were damaged by the subsequent flooding. Water that pooled during the storms seeped into the concrete caverns and destroyed the seismometers.
All Eggs in One Basket?
López wonders whether relying solely on the cellular networks to transmit data was the best idea in a disaster-prone area. “Before the hurricane, we were starting to rely more on cell [communications] and were going to install more sites with such communications. We are now seriously reconsidering that strategy given the current state of cell networks.”
The utility of cell networks is that they bring people, ideas, and information together. But in the wake of a disaster, there’s a keen irony: “If you rely on this type of technology and then something like [a hurricane] happens, then you’re still alone,” López said.
—JoAnna Wendel (@JoAnnaScience), Staff Writer
Wendel, J. (2017), Hurricanes expose vulnerabilities in Puerto Rico Seismic Network, Eos, 98, https://doi.org/10.1029/2017EO088687. Published on 12 December 2017.
Text © 2017. The authors. CC BY-NC-ND 3.0
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