Takeaway from the Case Study Restaurant and other assorted thoughts

My thanks to this website for this gorgeous picture: http://www.georama.com/blog/fire-and-ice-volcanoes-of-iceland/

Welcome to the final stretch of this project. There is less than a month before I present my research... Wow.

This week I thought I would synthesize the lessons from my case studies and discuss some of the answers to questions I had that I received from Dr. Tina Neal.

I have discussed the eruptive styles, activity, and type of monitoring at the following four volcanoes: Mauna Loa and Kilauea, Hawaii, and Cleveland and Pavlof, Alaska. Each volcano has been active within the last 45 years. Each has its own "normal" behaviours. Each has the ability to erupt and affect thousands of people, whether that is destroying homes or grounding flights or somewhere in between. 

From my observations and research, the most widely used monitoring technique is the measurement of seismic activity. All the volcanoes I studied have some sort of seismic array that allows geologists to detect changes in the intensity and frequency of seismic activity. Usually (remember volcanoes are rebels- they don't always do what we expect), the seismicity increases in intensity and frequency before an eruption. This could happen minutes or months before the eruption. Sometimes one of the two (intensity and frequency) happens or the other. Despite the deviations from normality in volcano activity, the measurement of seismic activity seems to the best baseline form of monitoring.

I would say that the measurement of ground deformation is the next important monitoring technique. It provides geologists with an idea of the happenings within a volcano as magma moves in the subsurface. Depending on the volcano, inflation or deflation of the summit and flanks of the volcano precede eruptions. This technique seems to be used on volcanoes that are closer to people and observatories, but it is another key into unlocking the mysteries of volcanic eruptions.

Satellite monitoring is the up and coming technique. It is best for geologists in places like Alaska where many volcanoes are a great distance from the observatory. Satellite's infrared and thermal sensors are able to detect ash plumes and thermal anomalies sometimes before they are reported by pilots. Using computer models and simulations, geologists are able to predict where ash will be dispersed and thus, warn of ash deposits and clouds. This will also keep air traffic away and safe from ash clouds. Satellites provide constant coverage of all volcanoes around the world; however, there is not enough of them to always be photographing volcanoes. The expense is also high to put them into orbit and operation. Yet, Francis and Rothery (2000) believe that a satellite dedicated to volcanology is needed to meet requirements of aviation safety and volcano monitoring.

Other forms of monitoring I have mentioned are important, but do not make appearances in literature as much as the three discussed above. As part of my research I asked Dr. Christina Neal-the current Scientist-in-Charge (SIC) of HVO and was the previous SIC of AVO- some questions about monitoring.

My questions are bolded and her emailed responses are italicized. 

How many seismometers and seismic stations are needed to properly monitor an active volcano?
This is a very difficult question. In a perfect world, several dozen seismometers (and other kinds of monitoring instruments) would monitor every potentially volcano, but this is very expensive and likely never to happen.  You can do adequate monitoring to detect unrest and eruptions with as few as 6 if they are working consistently.  Some of our volcanoes have only 1!  It depends on how much lead time you wish to have - you cannot locate earthquakes with very small networks.  Largely, it is a decision based on economics and the trade off of time.  And, as other techniques like infra sound come to fruition, there will be other combinations of instrumentation used to monitor volcanoes.  

 

What are your opinions on satellite tools for monitoring?

This is a very important and growing technique – for detecting actual eruptions (lava, ash clouds) or in some cases the precursors (increased heating, gas output, ground deformation using Interferometric Satellite Radar or InSAR).  I foresee this becoming a larger part of Observatory operations in the future.  AVO and HVO are both leaders in developing alarm systems that utilize satellite data to inform scientists when activity may be occurring. 

I find it interesting how many sesimometers are actually needed to detect the tiny tremors within the earth. I only know of one seismic station within the SFVF and that is the one for Sunset Crater at Wupatki (see Sunset Crater a millennial). But this discussion on Flagstaff monitoring strategies will continue this week and next.

Pavlof

See ya,
Rachel

Sources:

Email correspondence with Dr. Neal in March 2016

Francis, Peter, and David Rothery. "Remote sensing of active volcanoes." Annual Review of Earth and Planetary Sciences 28, no. 1 (2000): 81-106.