NASA's Terra satellite recently analyzed the remnant low pressure area previously known as Tropical Depression 01W in infrared light as […]
Fri, Jan 13, 2017
For centuries drought has come and gone across northern sub-Saharan Africa. In recent years, water shortages have been most severe […]
Mon, Jan 09, 2017
NASA's Terra satellite collected this natural-color image of fires in Argentina with the Moderate Resolution Imaging Spectroradiometer (MODIS) aboard on […]
Fri, Dec 23, 2016

ASTER Researcher: Dr. Michael Ramsey

Michael Ramsey

Dr. Michael Ramsey is an Associate Professor in the Department of Geology and Planetary Science at the University of Pittsburgh.  He also heads one of the premier state-of-the-art image analysis centers in the nation, which includes infrared spectroscopy and GPS technologies.  In addition to teaching remote sensing courses to under-graduate and graduate students at the University, he also travels all over the over the world to study volcanoes.

What do you study?

MR: My primary area of study is physical volcanology focusing on eruptions, volcanic processes, and monitoring using thermal infrared (TIR) remote sensing.  Of specific interest to me is the linkage between the renewal of activity at an explosive volcano and the ability of remote sensing to detect that activity and help monitor subsequent hazardous activity.  I have helped initiate a rapid response program using data from MODIS and AVHRR to trigger emergency ASTER observations of volcanoes and other natural disasters.  In addition to the satellite image analysis, the tools employed include laboratory-based infrared spectroscopy, field-based TIR imaging and differential global positioning system (dGPS) data collection. I have focused on the multispectral thermal IR data of ASTER in order to map composition and micron-scale roughness of volcanic surfaces. No other sensor can capture this information, which is important to a better understanding of the activity conditions present at active lava domes and flows.

Why is the study of volcanoes important?

MR: Although volcanoes do not kill as many people as earthquakes or large tropical storms (more than 70,000 deaths from volcanic eruptions occurred last century compared to more than that in just one large earthquake), there are several important reasons to study them. The first is hazard mitigation – over a half a billion people live directly in harms way of typical volcanic activity. This number grows significantly when one considers the much larger (but more rare) eruptions that have happened over time. The second reason is that volcanism is a primary geologic process that has operated throughout most of the Earth’s history (along with impact cratering). For a geologist, studying volcanoes can lead to important insights into the solid Earth processes that have operated over geologic time and are ongoing at depth under every active volcano.

What are some effects of volcanic eruptions on the global climate?

MR: I do not study the climate aspects of volcanic eruptions directly since I am more interested in the geology. However volcanoes can produce large amounts of carbon dioxide, water, and sulfur dioxide as well as ash.  The first two are major greenhouse gases, which can impact climate change. Volcanic ash can cause major disruptions to air traffic (as was seen in Iceland in 2010), can render lands around the volcano unusable for decades, be a major irritant to human health, and can cause structures to fail due to the weight of the ash.

Volcano eruptions disperse gas, liquids, and particles into the lower atmosphere.  One of the expellants is sulfur dioxide (SO2.)  What are the effects on the environment?  
MR: Sulfur dioxide generally does not last for long periods in the atmosphere. However, if mixed with NO2, it can form acid rain. Even directly, its presence can be a major irritant to breathing and kill local vegetation.

Compared to other Earth-observing satellites, what makes ASTER the “œpremiere instrument” to study volcanoes?

MR: There are five critical factors that make ASTER the premiere instrument to study volcanoes. I document these in detail in the Ramsey and Dehn (2004) paper: “œSpaceborne observations of the 2000 Bezymianny, Kamchatka eruption: The integration of high-resolution ASTER data into near real-time monitoring using AVHRR”. First, and perhaps the most critical, is the strategy of routine night time acquisition data for all high-temperature targets. This allows far more data to be collected. Second, ASTER has a cross-track pointing capability, allowing an increased temporal frequency for any target as well as data collection up to 85 degrees latitude. Third, the instrument can generate along-track digital elevation models (DEMs) by way of one backward-looking telescope. Fourth, ASTER data are acquired using one of several dynamic ranges in order to mitigate data saturation over very hot target targets. Finally, ASTER provides more than two bands in the TIR for the first time from space, which is important for compositional mapping of volcanoes.

As a volcanologist, you travel all around the world to study volcanoes.  How do you merge field work and data you collect from ASTER?

MR: ASTER data commonly drives where and how my field work is performed. It can be used as simply as a base map from which to target certain thermal and compositional anomalies for field-based data collection. We also schedule ASTER observations while in the field in order to validate the thermal IR data collected on the ground or to better understand the larger picture of the volcano’s activity over the time when we are there. In a new study, we have merged airborne and ASTER thermal IR data collected from the Shiveluch Volcano, Russia. By comparing the ASTER data over the first six months of the eruption to the thermal IR data collected in the field, we were able to document the volume of the extruded lava dome and how its position changed following the eruption.

Finally, what motivated you to study volcanoes?

MR: I had always been interested in geology since I was a child, however my undergraduate degree was in Mechanical Engineering at Drexel University in Philadelphia. My interest in geology was rekindled there after taking a course in Engineering Geology. I took several more classes in geology and went on to do a Ph.D. in the field at Arizona State University. I was not focused on remote sensing or volcanology when I started there, but ended up with two main advisors (one in remote sensing – Phil Christensen and one in volcanology – Jon Fink). It was a natural progression to merge the two fields and study active volcanic eruptions using thermal IR data. This was a few years prior to the launch of Terra, but once ASTER started returning data it became the best way to study small-scale volcanic processes globally.

Posted in News and Events Tagged with: