Volcanoes

Okmok Deformation Monitoring

I’m most interested in surface deformation monitoring which is why I chose this case study. My interest is interferometric synthetic aperture radar, but GPS stations are the primary method of tracking surface movement at volcanoes currently. Compared to InSAR, GPS measurements are accurate and highly reliable. However, these are expensive to maintain and only provide point data. There are only three deformation monitoring stations on Okmok (they are shown on following hazard map). The advantage of InSAR is that it provides regional information. The downside of course is that this technology is relatively new and the processing algorithms needed to extract this data are still maturing.

Beget, J.E., Larsen, J.F., Neal, C.A., Nye, C.J., and Schaefer, J.R. Preliminary volcano-hazard assessment for Okmok Volcano, Umnak Island, Alaska: Alaska Division of Geological & Geophysical Surveys Report of Investigation 2004-3, 32 p., 1 sheet, scale 1:150,000. 2005.

The following image shows the progressive InSAR deformation time series retrieved from two different TerraSAR-X tracks after the 2008 eruption (Qu et al., 2015). Each image subsequent image is cumulative, where reds correspond to uplift and blue to subsidence. The gray relief map shows through in many areas because the pixels decorrlated between the image aquisitions, so these areas can’t be reliably tracked. Nonetheless, there are some pixels in the caldera that are coherent and show significant deformation. Considering this is following the 2008 eruption, the pattern of uplift at the eastern part of the caldera is as expected. The magma recharge started very soon after the eruption. I will be interested to see how this trend continues until the next eruption and at which maximum deformation relative to 2008 that this happens.

Qu, F.; Lu, Z.; Poland, M.; Freymueller, J.; Zhang, Q.; Jung, H.-S. Post-Eruptive Inflation of Okmok Volcano, Alaska, from InSAR, 2008–2014. Remote Sens. 2015, 7, 16778-16794.

Volcano Island Game

The game is informative and quite fun to play. I learned that it is vital to evaluate the accessibility of resources in the case of an emergency. Authorities must have extra money to use for emergency supplies and post-event.

I don’t think that it is helpful to compare popularity under certain circumstances. I don’t believe that, in reality, a mayor can make reasonable decisions under pressure. In particular, if a mayor does not give a lot of credibility about a scientific point of view.  There are protocols to follow before issuing an evacuation alert.  Overall, the game is an excellent educational resource to simulate evacuation preparedness.

Mount St. Helens Volcanic Eruption

My case study is on the Mount St. Helens volcanic eruption. The eruption occurred on May 18, 1980 Washington state, a couple hours drive south of Seattle. The volcano formed from the subduction that occurred due to a convergent plate boundary. This event was an explosive volcanic eruption that caused widespread damage. The most interesting thing I have learned so far is that the earthquakes leading up to the eruption caused a massive debris avalanche, which is the largest to occur on Earth in recorded history. Source Used:

https://volcanoes.usgs.gov/volcanoes/st_helens/st_helens_geo_hist_99.html

Case Study 1 – Assignment 3

The disaster that I chose for my case study was the Mt. Pinatubo Eruption. The volcano is found on the Island of Luzon in the Philippines in South East Asia, and the eruption occurred on June 15, 1991.

Mt. Pinatubo is one of a chain of volcanoes known as the Luzon volcanic arc (hot spot), which is the result of the Oceanic Philippine Plate being subducted under the lighter Continental Eurasian Plate. The volcano is slightly offset from the plate boundary. When the Oceanic plate is subducted it is melted and forced away as molten magma by the high pressures exerted on it. It then resurfaces as the density of the molten magma becomes lower than that of the rock. It pushes upwards through the small cracks and explodes out through the volcano. 48 hours before the eruption, progressively shallower earthquakes and the extrusion of a small lava dome and low level ash emission occurred. The volcano exploded on June 15th when highly gas-charged magma reached the surface. Ash clouds rose 28 miles into the air and blanketed the countryside. In addition to this, pyroclastic flows and lahars, which flowed down the mountain, devastated infrastructure and agriculture.

One of the most interesting things I learned about this event was the ways in which the eruption was monitored and predicted, as well as how the impending hazard was communicated to the people of the area. Weeks before the volcano blew, scientists were using all sorts of technology like the typical seismometers, to spectrometers (typically used for smokestack emissions) to gather all sorts of data. Before the 1991 eruption, there was no baseline information or eruptive history about the volcano.  Scientists faced a huge problem because of this. They conducted extensive research on the area surrounding the volcano, testing rocks and mapping the land. From these studies, the scientists were able to figure out that the volcano had exploded in the last six eruptive periods over the past 5,000 years. Using this information, and I’m sure much much more, they were able to evacuate many people in the area and saved lots of money by preparing a bit ahead of time before the volcano actually erupted.  From hurdling obstacles like the language barrier and convincing people that Mt. Pinatubo was actually a volcano, scientists were able to communicate the impending hazard of the volcanic eruption. They found it easiest and most effective to show people what had happened in other places in the world, rather than have a scientist stand up in a crowd and try to explain it with “interpretive dance and hand gestures.” This aspect of the study was super interesting to me!

Okmok Eruption 2008

Okmok is a large shield volcano and caldera located on Umnak island, just west of Unalaska in the Aleutians. In 2008, it produced a large VEI 4 eruption that lasted for about a month. This eruption is not the largest at this volcano in more than 700 years, but it’s also interesting due to the way the caldera’s hydrology interacted with the eruption, producing a phreatomagmatic component. Personally, I’m interested in this volcano due to its deformative nature and the ability to use InSAR to measure its regional deformation trends.

Case Study 1 – Week 1

My first case study is on the April 10, 1815 eruption of Mount Tambora in Indonesia.  Mount Tambora is a stratovolcano located north of the Java Trench, where the Australian Plate subducts underneath the Sunda Plate.  The eruption was estimated at a VEI of 7 and was the most powerful eruption in recorded human history.  Around 10,000 people were killed in the eruption, with over 80,000 later killed from indirect affects, as the ash cloud caused global cooling, which in turn caused crop failure and starvation.  The most interesting part of the event for me is that the eruption was so loud that it was heard from over 2000 km away.

Case Study Week 1

I studied the March 2009 eruption of Mt. Redoubt in the Aleutian chain of Alaska. The mountain is situated along the subduction zone where the Pacific plate subducts underneath the North American plate. The most interesting thing I have learned thus far is that the eruption was really a series of eruptions over a few months, which I found wild. I feel like the popular image of volcanic eruptions is one massive event. Obviously, that is not (always) the case!

Case Study 1 – White Island, NZ eruption – W1

Whakaari, White Island volcanic eruption in New Zeland happened on December 9th, 2019. New Zealand is in the Pacific-Australian convergent plate boundary, and the subduction process characterizes the interaction of these two plates. The White Island volcano has a wet type of eruption. I learned that this type of explosion generates a lot of steam because of the percolation of seawater. This causes a lot of steam and explosive interactions. This interaction creates a phreatic eruption where magma heat surrounds fluids without erupting at the surface. I learned that New Zealand in an excellent laboratory to study slow-slip earthquakes. Unlike major earthquake events that do not happen continuously. Slow-slip earthquakes happen at a constant rate. Lastly, I learned that tourism had been an issue in terms of safety and sustainability.

Unit 5 Week 1 Hazard Topic: Mount St. Helens Eruption

For my Unit 5 Case Study 1 I chose the May 18th, 1980 eruption of Mount St. Helens. Mount St. Helens is a Stratovolcano that is part of the Cascade Mountain Range located in Skamania County, Washington State. Activity leading up to the major eruption started on March 27th, with earthquakes and a series of phreatic blasts and steam-venting episodes from the summit. On May 18th an earthquake caused the weakened north face to slide away, creating the largest landslide ever recorded. An eruption column rose to 80,000 ft. depositing ash in 11 states. The eruption melted snow, ice, and several glaciers forming large lahars that reached as far as the Columbia river 50 miles away. 57 people were killed during the eruption.

The Cascade Mountain Range and the volcanoes in them like Mount St. Helens were formed by the denser Jaun de Fuca oceanic plate subducting below the North American continental plate. the Juan de Fuca plate begins to melt when it enters the asthenosphere. The now magma begins to rise to the surface in cracks where it reaches the surface at stratovolcanoes like Mount St. Helens.

The one thing new I found interesting was how widespread the ash from the eruption traveled. It covered 11 states and part of British Columbia. Several airports in eastern Washington had to shut down due to the ash accumulation and poor visibility. Air travel was disrupted for up to two weeks after the eruption. The fine ash even caused power outages by causing short circuits in electrical transformers. 2.4 million cubic yards of ash was removed from the highways and airports in Washington.

Unit 4 Case Study Topics

The two case study topics that I chose were Volcanoes and Landslides/Avalanches!

Volcanoes:

The event that I chose was the Mount Pinatubo volcanic eruption. This volcano, located in the Philippines, erupted on June 15, 1991, brought on by some serious earthquakes that occurred in that area the year prior. I chose this event because after doing some research and reading up on the incident, the eruption seemed to have some HUGE affects on things like the atmosphere, the weather, agriculture, infrastructure, and the general civilization. There were so many things that happened in light of this eruption, things that the area and its people are still experiencing to this day! The Mount Pinatubo eruption was such a massive event that deserves my research and further investigation.

Some things I would like to learn by the end of this case study include how volcanoes affect agriculture specifically. The ash I know is composed of minerals that I’m sure would effect plants and crops and things like that. It would be interesting to read about how agriculture is impacted by volcanic eruptions.

I would also like to learn how volcanic eruptions are brought on. Whether that be earthquakes or some other geologic process, I am curious how the entire process works.

Lastly, I would like to learn how researchers and scientists study volcanoes and the ways in which they are monitored. This has always been an interest of mine and I would read up on it some more!

Landslides/Avalanches:

The event that I chose was the Nevados Huascaran avalanche. This event happened in May of 1970, and it occurred on Mount Huascaran, Yungay Province in Peru. I chose this event because the avalanche was so devastating in terms of death toll. I always hear about avalanches here in Alaska or in some mountain area somewhere that have killed some hikers or snowmachiners. But never have I heard of an avalanche that killed near 22,000 people.

I would like to learn about the science behind an avalanche or a landslide. Specifically why do they happen in the first place.

I would also like to learn about the different kinds of avalanches. Apparently there are three different kinds, (powder, slab, and wet)which I was completely unaware of!

Lastly, I would like to learn about avalanche safety and what to do if you encounter an avalanche.