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Volcanic Earthquake Swarms, I Have Also Been Located Near Dormant Volcanoes

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Volcanic Earthquake Swarms, I Have Also Been Located Near Dormant Volcanoes Thunder underground Dr Helena Buurman, a volcano seismologist, shares the details of her research on earthquake swarms and eruptions in Alaska, and explains why the summer field season is particularly important in the far north only place in the world where a 2,000 km What is next for scientific research stretch of subduction zone is systematically in Alaska? monitored in real-time. Most studies of DR HELENA BUURMAN volcanic activity are focused on only one or As our understanding of volcanic systems two volcanoes at a time. But thanks to the increases and we become more confident monitoring efforts of the Alaska Volcano in our abilities to monitor and even predict Observatory and the Alaska Earthquake volcanic activity, the challenge turns to Center, we have data available for almost putting this knowledge into practice and the entire length of a subduction zone. The helping communities that live in the shadows Aleutian arc is therefore the only place in the of volcanoes better understand and prepare world where we have sufficient data (spanning for volcanic activity. There are many small, over 20 years) to be able to study volcanic extremely remote communities scattered activity on a regional scale. In the study of along the Aleutian arc, many of which are volcanic earthquake swarms, I have also been located near dormant volcanoes. It is crucial able to incorporate data from other parts of that we as scientists communicate our research the globe, including Iceland, Mexico, the US and interpretations of volcanic activity Pacific northwest and Kamchatka. to those who will be directly affected by volcanic hazards. How close is the connection between There is a wide range of expertise in the staff earthquake swarms and volcanic activity, at the Alaska Volcano Observatory! When I Your research examines tectonic settings; and what importance does this have on the was a student I was exposed to a variety of specifically, whether a volcano is located in ability to predict eruptions? different disciplines when people needed field a subduction zone, hot spot or near a fault assistants to help collect their data, and these zone, etc. How might this contribute to the I don’t know of any volcanic eruptions that different experiences definitely helped shape characterisation of earthquake swarms? have happened without any sort of precursory the way I think about volcanic systems. Could you discuss some of the findings from earthquake activity. This means that they can your research that were presented at the be used to predict eruptions, but the tricky I recently co-authored a study of volcanism American Geophysical Union (AGU)’s 2013 part for volcano monitoring lies in being in the Aleutian arc that correlated patterns in fall meeting? able to tell whether a swarm isn’t leading up volcano seismicity with volcano geochemistry to an eruption, so that we don’t issue false with Chris Nye, Mike West and Cheryl I compared swarms in different tectonic eruption predictions. Cameron. Chris Nye is an expert in Aleutian settings – subduction zones, hot spots, geochemistry and has spent decades thinking spreading centres – to determine how much Which regions of the world are you about bigger picture processes that can result of an effect the tectonic setting had on swarm studying in particular? Who is supporting in systematic differences along the Aleutian characteristics. I used statistical comparisons your studies? arc; it was really exciting for us when we of the location and magnitudes of earthquakes realised our two very separate datasets (his in different volcanic swarms, and found that Most of my work has been in Alaska, studying geochemical data and my volcano-seismic the tectonic setting had very little influence volcanoes in the Aleutian arc. This is the data) were closely correlated. on swarm characteristics. This wasn’t a big 86 INTERNATIONAL INNOVATION DR HELENA BUURMAN The swarming warning surprise – scientists have been studying swarms for decades and would presumably have come across correlations between tectonic setting and swarm behaviour long ago. This was also a little disappointing – while proving that correlations don’t exist has just as much scientific value as discovering new connections between datasets, it is not nearly Seismological researchers based at the University of Alaska Fairbanks as exciting or satisfying! are investigating the predictive value of earthquake clusters or ‘swarms’ Do you have any upcoming events that you in determining when volcanic eruptions will occur; work which has are particularly excited about? already had profound consequences for improved surveillance Right now we are gearing up for our summer field season, which is my favourite part of the VOLCANIC AND SEISMIC disruptions can Alaska’s south coast towards the Kamchatka year. Alaskan winters are particularly hard on be among the most cataclysmic events in Peninsula. Caused by the tectonic subduction seismic equipment, and we often need to fix nature. Coupled with this extraordinary power of the Pacific plate beneath the North American our seismic stations that have been damaged is a dangerous unpredictability; the forces and plate, this volcanic arc is particularly active, by wind, snow, ice or even bears. These remote processes that give rise to volcanic eruptions with an average of two eruptions occurring sites send continuous seismic data back to and major earthquakes are hugely complex and every year. the lab using on-site radios. These seismic usually very difficult to observe. Modelling and data are used by both the Alaska Volcano predicting these events, therefore, is a difficult Using data from the Aleutian arc as well as Observatory and the Alaska Earthquake Center task indeed. Nonetheless, seismologists are other volcanoes around the world, one group to monitor volcanic and earthquake activity frequently concerned with better understanding of scientists is aiming to get to the bottom across the state. For me, feet-on-the-ground the processes that produce these spectacular of earthquake swarms and what they signify experience is equally valuable as the time and disastrous events, with the ultimate goal once and for all. Based at University of Alaska spent behind a computer looking at data, since of identifying early-warning systems for use in Fairbanks’ Geophysical Institute, postdoctoral it gives me a feel for volcano activity in the high-risk areas. research fellow Dr Helena Buurman and her past (you learn a lot about what a volcano can collaborators hope to develop a consistent do by looking at old lava flows and craters) One possible predictor of volcanic eruption approach for evaluating the characteristics of and therefore how big of an impact it can comes in the form of the earthquake swarm. earthquake swarms and their relationship to have on its surroundings. This also helps me Earthquakes in a swarm share a similar volcanic eruptions. By bringing this approach to understand the subtle signals seen on specific magnitude, and occur over a short period of swarms in various volcanic and tectonic settings, seismic stations – for example, one station time in a localised region of the Earth’s crust. they will provide statistically meaningful on Augustine Volcano is located close to When such a swarm takes place beneath an information for a number of different geographic the shore, and is able to pick up signals from active volcano, this is usually a telltale sign regions, and could ultimately develop methods cracking sea ice on the beach that none of the that hot gas and magma escaping from the for distinguishing between benign swarms and other stations are close enough to record. underlying mantle are being redistributed in the those predicting eruptions. crust. Most of the time these redistributions are benign: the superheated materials simply find THE MISSING METRIC their way to new reservoirs, and the pressure stabilises. Sometimes, however, the pressure is Although Buurman’s work on the current project too much, and there is nowhere left to go but began in June 2013, it was seven years prior to up. When this is the case, earthquake swarms this that she came up with the novel seismic precede volcanic eruptions that expel these metric capable of highlighting eruptive swarms. materials violently onto the surface. While working as part of a group studying the 2006 eruption of Alaska’s Augustine Volcano, the seismologist found that a good metric to THE ALASKAN ARC distinguish between different types of volcanic The problem is that scientists are not sure earthquake was based on the frequency content whether there are characteristics that can of the seismic signals detected. distinguish pre-eruption swarms from benign swarms, and a large quantity of data would be Buurman dubbed this value, which was derived needed to answer this question more definitely. by measuring the ratio of high- to low-frequency One very promising area from which to gather energy in a particular earthquake, the ‘frequency such data is the Aleutian arc, a volcanic arc that index metric’. With time, and the reapplication of exists on the boundary between the Pacific this metric across volcanic sites around the world, and North American plates, which runs along it has emerged that certain frequency index types WWW.RESEARCHMEDIA.EU 87 INTELLIGENCE VOLCANIC EARTHQUAKE SWARMS OBJECTIVES • To predict volcanic eruptions using earthquake swarms • To investigate how volcanic earthquake swarms relate to the movement of magma through the Earth’s crust KEY COLLABORATORS Dr Michael West, Alaska State Seismologist and Research Associate Professor, University of Alaska Fairbanks FUNDING National Science Foundation (NSF) – award number 1044930 CONTACT Dr Helena Buurman do appear to have unique associations with In the process of data collection for this project, Principal Investigator volcanic activity. Buurman has gathered datasets from volcanoes Geophysical Institute all over the world, including Iceland, the US Pacific University of Alaska Fairbanks In the current project with collaborator Dr northwest, the Kamchatka Peninsula in the Russian 903 Koyukuk Drive Michael West, Buurman applies this metric to Far East and Mexico.
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