Nav: Home

Repeating seismic events offer clues about Costa Rican volcanic eruptions

May 17, 2018

Repeating seismic events--events that have the same frequency content and waveform shapes--may offer a glimpse at the movement of magma and volcanic gases underneath Turrialba and Poas, two well-known active volcanoes in Costa Rica.

At the 2018 SSA Annual Meeting, Rebecca Salvage of the Observatorio Vulcanologico y Sismologico de Costa Rica presented an analysis of these repeating signals from the volcanoes since July 2016.

When these repeating events are identified at a seismic station, researchers assume that these "events are all produced by a single mechanism and at a similar location at depth ... and by a source which is either non-destructive or able to quickly renew itself," Salvage noted. "Therefore, the identification and an understanding of repeating seismicity may allow us some insight into which parts of the volcanic system at depth are active, and the frequency content of the repeating seismicity may be indicative of processes occurring at depth."

At Turrialba, for instance, Salvage and her colleagues identified a type of repeating event called "drumbeat seismicity," characterized by a very short time interval between events. In January 2017, drumbeat seismicity at the volcano lasted less than three hours but contained hundreds of events. Eight hours later, there was a small eruption at Turrialba. In this case, the drumbeat seismicity may have been a "precursor signal" of the eruption, related to magma moving toward the surface, Salvage said.

"However, not all eruptions are preceded by these types of earthquakes, and often these earthquakes occur with no identifiable eruptive activity," she added. "A better understanding of drumbeats in terms of the conditions under which they do occur, and statistical analysis on inter-event times and occurrence rates will allow us to better assess whether these can actually be used as a warning tool."

At Poas, the researchers noted another interesting halt in six families of repeating seismic events, just two hours after a swarm of magnitude 2.7 and higher earthquakes was recorded very near the volcano. In this case, Salvage and her colleagues think that the earthquakes may have influenced the stress field around the volcano in a way that halted the repeating events. The stress field may have changed when the earthquakes generated small displacements on local faults that created similar small diversions in magmatic gas and ash rising to the surface.
-end-
The 2018 Annual Meeting, held May 14-17 in Miami, Florida, is a joint conference between the Seismological Society of America and the Latin American and Caribbean Seismological Commission (LACSC).

Seismological Society of America

Related Earthquakes Articles:

Earthquakes in slow motion
A survey of slow-slip events in Cascadia reveals new insight into the recently discovered phenomenon.
Earthquakes can be predicted five days ahead
An international team of researchers, which includes physicists from HSE University and the RAS Space Research Institute (IKI), have discovered that, with an impending earthquake, the parameters of internal gravity waves (IGWs) can change five days before a seismic event.
Stanford researchers explain earthquakes we can't feel
Researchers have explained mysterious slow-moving earthquakes known as slow slip events with the help of computer simulations.
Solved: How tides can trigger earthquakes
Some earthquakes along mid-ocean ridges are linked with low tides, but nobody could figure out why.
Measuring iceberg production with earthquakes
An international team led by French researchers from the CNRS and Paris Diderot University came up with the idea of using earthquakes generated when icebergs break away -- felt hundreds of kilometres off -- to measure this ice loss.
Injection wells can induce earthquakes miles away from the well
A study of earthquakes induced by injecting fluids deep underground has revealed surprising patterns, suggesting that current recommendations for hydraulic fracturing, wastewater disposal, and geothermal wells may need to be revised.
Earthquakes can be weakened by groundwater
Researchers from EPFL and the Ecole Normale Supérieure in Paris have found that the presence of pressurized fluid in surrounding rock can reduce the intensity of earthquakes triggered by underground human activities like geothermal energy production.
UH researchers report new understanding of deep earthquakes
Researchers from the University of Houston have for the first time reported a way to analyze seismic wave radiation patterns in deep earthquakes to suggest global deep earthquakes are in anisotropic rocks.
International collaboration studies the predictability of earthquakes
At four centers in California, New Zealand, Europe and Japan -- and in countless labs across the globe -- CSEP's experiments and its rigorous testing procedures have shed light on the predictability of earthquakes, according to a special focus section published June 13 in Seismological Research Letters.
Machine listening for earthquakes
In a new study in Science Advances, researchers at Columbia University show that machine learning algorithms could pick out different types of earthquakes from three years of earthquake recordings at The Geysers in California, a major geothermal energy field.
More Earthquakes News and Earthquakes Current Events

Top Science Podcasts

We have hand picked the top science podcasts of 2019.
Now Playing: TED Radio Hour

Risk
Why do we revere risk-takers, even when their actions terrify us? Why are some better at taking risks than others? This hour, TED speakers explore the alluring, dangerous, and calculated sides of risk. Guests include professional rock climber Alex Honnold, economist Mariana Mazzucato, psychology researcher Kashfia Rahman, structural engineer and bridge designer Ian Firth, and risk intelligence expert Dylan Evans.
Now Playing: Science for the People

#540 Specialize? Or Generalize?
Ever been called a "jack of all trades, master of none"? The world loves to elevate specialists, people who drill deep into a single topic. Those people are great. But there's a place for generalists too, argues David Epstein. Jacks of all trades are often more successful than specialists. And he's got science to back it up. We talk with Epstein about his latest book, "Range: Why Generalists Triumph in a Specialized World".
Now Playing: Radiolab

Dolly Parton's America: Neon Moss
Today on Radiolab, we're bringing you the fourth episode of Jad's special series, Dolly Parton's America. In this episode, Jad goes back up the mountain to visit Dolly's actual Tennessee mountain home, where she tells stories about her first trips out of the holler. Back on the mountaintop, standing under the rain by the Little Pigeon River, the trip triggers memories of Jad's first visit to his father's childhood home, and opens the gateway to dizzying stories of music and migration. Support Radiolab today at Radiolab.org/donate.