Friday, November 29, 2013

If there was ever a tornado going on when a volcano is erupting…

Then there are questions that could only come from children who are learning, but haven't learned much, and have no fear about asking questions about things that are scarey/fascinating to them. The following "improbable" is actually not that far from the probable.

Q: Hello my name is Thorin and i have a question for my geography class.

If there was ever a tornado going on when a volcano is erupting, can the tornado, so to speak, pick up the lava erupting from the volcano. I hope you guys respond to my question.  Thanks, - Thorin T

A: Hi Thorin,

Tornadoes don't usually occur where there are volcanoes. Tornadoes generally require pretty flat terrain or ocean (not common in volcano territory) and a complex mix of warm and moist air, with cold and dry air coming from another direction. Again, this is not common in volcano territory like the Pacific Cascades, Kamchatka, or Japan. That said, however, it has been reported that tornadoes can pick up cars and carry them hundreds of meters away - even kilometers - and then drop them. Three tornado-hunter scientists from Denver were killed that way this last May (2013).

So. IF there was an erupting volcano, AND a tornado passed through nearby, it's conceivably possible that a tornado could pick up a bit of lava. However, lava is pretty dense. By comparison a car is much less dense (it has a lot of air space in it). More likely, the tornado would pick up ash and tephra (tephra is cooled lava filled with gas bubbles, so it is not very dense) and throw these around.

Something like this is not all that unreasonable, actually. There was a tropical cyclone (a Pacific hurricane) passing through the Philippines when Mount Pinatubo erupted in 1991. The effect of the hurricane-force wind, the HUGE amount of water that the cyclone brought with it, and the really huge volcanic eruption made quite a mess of the island of Luzon. It basically destroyed Clark airbase and badly damaged the nearby Subic Bay naval facility - and even though evacuations had been ordered, it still killed a lot of people.


Thorin later replied:

Thank you very much Jeff and it answers my question in great detail. Thank you for taking your time to answer my question and give me a very helpful answer.


Friday, November 22, 2013

What states are safe from earthquakes?

Where are you safe? Really nowhere. If you live in the Pacific Northwest, tornadoes are extremely rare, and hurricanes non-existent - but you are at risk of a large subduction earthquake and floods. If you live in the Southeast, you generally don't have to worry about earthquakes, but you are certainly living in Hurricane Alley. When I first took up my 5-year assignment to serve as chief scientist for volcano hazards in Vancouver, WA, in 2002, I was frequently asked the question: will we have a big eruption soon? I told everyone that I had voted with my feet, made an informed decision, and bought a house in Clark County. Two years later, of course, Mount St Helens erupted. While it briefly threatened the Johnston Ridge Observatory north of it, it was never really a threat to people in Clark County... though an ash-plume erupted on March 5, 2005 did apparently intersect an aircraft flight-path near Roseburg, WA. At least three Boeing 747 aircraft have lost all or almost all of their engines when they flew through a volcanic ash cloud. The aircraft flying over Roseburg was diverted to a nearby airport, thoroughly checked out, and found to be OK however.

Q: I saw on your website that 39 states are endanger of earthquakes, what 11 are not and why?
 Kaitlyn S, 8th grade Endeavor Charter School student

A: Hi, Kaitlyn,

If you go to this web-page you will see a map of earthquakes in the United States:

You can count 11 states that have no recent seismicity (no red circles) - but this doesn't necessarily mean they are earthquake-free. 

The longer answer to your question is that earthquakes happen where there is crustal movement: mountains rising (Hawaii and Utah, for instance), crustal slabs sliding past each other (California), or continents riding over oceanic plates (most of the West Coast). If you look at this map, you will see states that have no apparent earthquakes. This is because they are in the center of a very old, stable continental crust, and not on the tectonically active margins. However the map of RECENT seismicity could fool you into thinking that Oregon is relatively free of risk. In fact, the same subduction fault off the coast from northern California to British Columbia threatens the western sides of three American states and one Canadian province. This kind of fault may not rupture for centuries at a time. However, when it does break it will be a real attention-getter. 

One thing to keep in mind is that distance from a fault offers increasing protection: Western Washington State is at much greater risk than eastern Washington State, for instance. This is because the energy of the earthquake falls off with distance, just like sound does. Sit on the edge of your bed and have your brother kick the edge next to you. If he then goes around and kicks the other side, it will not feel nearly as uncomfortable to you. 

Friday, November 15, 2013

Are tsunamis and volcanic eruptions a result of other catastrophic natural disasters?

Catastrophes are often related: a drought in southern California leads to wildfires, and within a year the denuded terrain is damaged further by floods and landslides because the vegetation that preserves and protects the ground surface is missing. A massive earthquake in Haiti leads to a devastating cholera epidemic, because people are displaced and water sources are compromised. The following query is from a thoughtful young man trying to understand some of these relationships.

Q: hello, my name is Brendan and i have a question related to geology in which i would like u to answer. so ya, here it is: Why do tsunamis and volcanic eruptions often act as a result of other catastrophic natural disasters? ya so please respond to this. Oh and btw I am a student at endeavor charter school, just to let you know. alright well thanks for your time and i hope to get a response. – Brendan J

A: Hi, Brendan - I can provide some brief answers.

Tsunamis are caused by SOME volcanic eruptions and by SOME earthquakes:

1. Thera volcano in the eastern Mediterranean erupted catastrophically around 1,500 BC. It triggered a tsunami that destroyed the Minoan civilization based on Crete. The 1883 eruption of Krakatau volcano in Indonesia sent a tsunami into the island of Java that scoured everything within 10 kilometers of the coastline and swept it all back to the sea. Contemporary descriptions said that you could walk across the Sunda Strait because of all the bodies (people, livestock) and logs floating there. MOST volcanic eruptions, however, do NOT cause tsunamis. For one thing, the volcano must be adjacent to an ocean for this to be possible. 

2. The tsunami that destroyed the Fukushima Di-Ichi nuclear powerplant, and destroyed much of the Sendai, Japan, coast, was caused by the Great Tohoku earthquake of 2011. The tsunami happened because a 200 km by 600 km slab of ocean floor was suddenly uplifted several meters by a sudden slip on a subduction fault offshore. The displaced seawater slopped onto the nearby coast, and a security camera showed a 15-meter (nearly 50 foot) wave crashing into the facility, wreaking nearly incomprehensible damage - that is still evolving as I write this. MOST earthquakes, however, do NOT cause tsunamis. There must be an uplift or down-drop of a large piece of ocean floor for this to happen.

Volcanoes are connected indirectly to subduction earthquakes - the Pacific Ring of Fire is an example of how they are related. A down-going section of oceanic crust, being over-ridden by a lighter-density continental crust (Sendai, Japan, and the coast of Washington State in the US, for instance), gives rise to volcanoes. The oceanic crust is heated up as it works its way deeper and deeper into the hot Mantle, and fluids in that down-going slab of oceanic crust contribute to partial melting. This is where lighter component elements of the oceanic floor float up until they burst through the overlying continental crust. Think of a lava lamp: it's the same general principle. Just offshore of North America, Kamchatka, Japan, the Philippines, and Indonesia (and many other places) there is a subduction fault where a continental section is riding over an oceanic crust. Just INLAND from these subduction faults you will find chains of volcanoes paralleling the same coastal margin - the Cascades Range extending from California to British Columbia is an example. One may not directly cause the other, but they are certainly related nevertheless. 

An earthquake was closely associated with to the 1980 eruption of Mount St Helens, but to this day geologists still argue about it. Did the earthquake trigger the eruption of the highly-unstable volcano? Or did the eruption cause the largest earthquake in recorded human history? 

Friday, November 8, 2013

Polluted wells

It’s hard to think of something closer to a personal threat than pollution in the water you drink. It’s also hard to comprehend that several billion people on this planet do not have safe water to drink. When a natural disaster hits, cholera frequently follows – because water sources are compromised. They can be compromised biologically or chemically. The following is an example query in this area of direct personal impact.

Q: Hi,
I'm trying to understand the concept and possible problems with groundwater and thought of a few questions,

So first, say there is a contamination in the groundwater and people notice it in their well, now what would a heavy spring rains do to this? Would it further contaminate it? 

What happens in case of drought, would you think the contamination would wear off?
Thanks.  - Banion

A: Good questions, and like all good questions, the answer(s) fall into an "it depends" range. That is to say, there are a lot of unknowns not clear from your question.

Let me try to answer via possible scenarios:
- A shallow well vs. deep well;
- Fracking may or may not be an issue;
- The pollutant was introduced externally, as opposed to via the well itself;
- The groundwater is recharged or not - a rainy vs. an arid environment;
- The pollutant is chemical (DNAPL/LNAPL/PAH), or it is Biologic.

Keep in mind that mitigation of a groundwater pollutant could fill at least a book by itself; with rare exceptions like some PAH's (Polycyclic Aromatic Hydrocarbons), water pollution rarely "wears off".

Here are just some possible scenarios with comments:

1. The well is shallow, and the pollution does not come from the well itself - in other words it was not introduced via the well:
    If you are just beginning to notice the pollution the odds are that a lead element of a pollution plume has just intersected the well. Continued drawing from the well will just pull more of the plume towards the well-head. In short: it will only get worse. The well may be lost, depending on the nature of the pollutant. If you can identify the source and it can be localized, there are steps you can take to isolate and mitigate the problem - but these steps are usually expensive and complicated.

2. The well is shallow, and the pollution was something inadvertently or deliberately dumped into it:
    Pumping will reduce the concentration gradually - but then you need to dispose of the polluted water that you draw up. If you simply dump it on the ground, it will eventually seep back to the water table, which in many environments is recharged from rain. The earth can function as as filter just so far.

3. The pollutant is biologic in nature (E. coli, for instance):
    Biological systems tend to equilibrate - and persist. If there is something like phosphates and nitrogen for the E. coli to feed on, it will grow. If no support is available (materials to feed on, warm temperatures to propagate in) then the biologics may go dormant - but they can be very long-lived as they wait around for a more favorable growth environment. If the biologic was introduced via the well itself, you would likely have to "shock" it with a chemical like chlorine (think of a complicated swimming pool), then pump until the well water passed a biological safety test - and treat the water that was pumped out, before it is disposed of. If the biologics arrive via the groundwater from a nearby feedlot, say, you may have to abandon the well. Industrial-scale pig farms are a true biological time-bomb.

4. The pollutant is a DNAPL, LNAPL, or PAH:
    A DNAPL (Dense Nonaqueous Phase Liquid) is one of a group of organic substances that are relatively insoluble in water - they will sink in water, are immiscible in but will not dissolve in water. An example would be a ruptured diesel fuel tank. A NAPL or LNAPL is similar, but not denser than water, and tend to remain shallow. These can all be really serious problems, though generally localized, and always very expensive to deal with.
    Instead of writing about this for a few days, let me instead point you at some useful links:

5. The pollutant is radioactive:
    Now we are talking about a Super Fund site, and the billions of dollars being poured into the World War II-era Hanford site in south-central Washington State is an example of this. During and following the World War, radioactive waste was buried in the ground in barrels, and dumped into single-walled tanks at Hanford and other sites around the country. This has happened all over the world. There is a vast region of the Caucasus in Russia and another near Chernobyl in the Ukraine that are both off-limits to human occupation, and the Great Tohoku tsunami of 2011 has made a significant area on the Sendai coast of Japan a dangerous wasteland. Plutonium may be the most toxic metal in the entire periodic table: micrograms can kill. At one point, plutonium was at detectable levels downstream from Hanford in the nearby Columbia River where I occasionally kayak.

6. Deep wells: 
    The water you are drawing is likely fossil - that is the recharge is slow at best, and that water has already been there for a long time (centuries or millennia). The groundwater may or may not be recharged. If you live in Saudi Arabia or Central Arizona, it's the latter case, and the well will eventually dry up. The ground itself will subside (damaging roads and buildings), and any pollution will likely stay with the water wherever it ends up. If you live in the Pacific Northwest of the USA, the groundwater is constantly being recharged via rain and snow. Any pollution will likely reach a steady state and then decline over time as it is diluted, but you may still have to abandon a polluted well. Most municipalities take extensive precautions to protect their reservoir watersheds for this reason.

7. Fracking:
    Fracking is hydraulic fracturing of "tight" geologic formations (like shale) to open them up and release trapped hydrocarbons. The process is technically complex, and involves injecting water and sand - as well as "proprietary" chemicals - at very high pressure into these tight formations. I might add here that if fracking is taking place anywhere near your water well, then your water is only protected as long as the fracking is deep, and the horizon being exploited is not connected to your groundwater - something that is nearly impossible to guarantee. It goes without saying that the fracking wells must be assiduously cemented and sealed - and subsequently monitored. We've all seen the videos of people turning on water in their kitchen sinks and literally igniting them with a match or lighter. 


Friday, November 1, 2013

I think I've found an impact crater

After "what is this rock", one of the most common queries we receive at Ask-a-Geologist is this: "I've found a circular structure on my property or on Google Earth. I think I've found an impact structure."

Q: Hello AAG,
I've been sitting in my room recovering from an accident so I've been "traveling the world" using Google Earth. But I believe I may have found an impact crater in New Mexico.

The coordinates are 35 53 52 N 104 53 22 W

If this is, in fact, confirmed to be an impact crater, I would love to name it 'Noble Crater' as this is becoming an increasingly rare trait in modern society and hope this discovery will IMPACT young, budding geologists in a positive way...pun intended.
Thanks!  - Dustin K

A: Hi, Dustin - hope you're getting better. 
You probably wouldn't be surprised to know you're not the first person to try doing this... or even the millionth. Gene Shoemaker, the "Father of Astrogeology", started an impact site search using air photos in the late 1950's, and started using LANDSAT when it became available in the early 1970's. When he died in 1996, he and his wife Carolyn had already spent many years trying to map all the impact sites in Australia, the best-exposed ancient continental craton on the planet - just to get a sense of how frequently the Earth gets whacked as a function of time. If you're being shot at, it helps your planning a bit if you know how often.

To the case at hand:
If you go to the geologic map of New Mexico ( will see that your target area is in a large sedimentary province. A quick scan at the surrounding terrain shows that there has been significant tectonic activity (folding and uplifts, etc.) in this region. 

If you look at the Earth Impact database (, you will see that there is just one confirmed impact site in New Mexico - the Santa Fe impact structure (6 - 13 km in size, over a billion years old, located at N 35° 45' W 105° 56'). 

The level of geologic mapping in New Mexico (and pretty much all of North America for that matter) is such that it's highly unlikely that an impact in New Mexico hasn't been previously discovered by the literally hundreds if not thousands of geologists who have been roaming it for the past century or so. That doesn't mean every impact has been found, nor does it mean that you haven't found something round. The problem is really two-fold:

1. There are a LOT more, simpler reasons for a round-ish geologic structure than an asteroid impact. These include tectonics, halokinesis (salt diapirs or domes), dissolution, magmatic intrusions, and even human involvement. Any circular structure in a sedimentary province is far more likely to be caused by any of these.

2. For this reason, it's really, really difficult to prove that a circular feature is an impact site to the satisfaction of other geologists. For starts, most of the known impact sites are ancient, and have been highly modified if not mostly erased by tectonics and erosion over time. We should look like the Moon, but we don't - and tectonics and our atmosphere are why. Only about 15 of the ~180 known impact features are "meteorite impact structures" - that means that parts of the original bolide are still present - the rest are just "impact structures". The ginormous Tunguska event in Siberia in 1908 flattened a forest the size of Rhode Island - but left no crater nor any measurable fragments. It was an atmospheric detonation. Thus it's typical for impacts to be lacking any obvious "smoking gun" evidence. 

Here is some helpful content for recognizing the subtle evidence of an impact feature:

There is more information, including some helpful images, in an article I wrote for Scientific American:

From what I can see of your feature, it is an intersection of folds in sedimentary rock - but subsurface dissolution could also be involved. I have insufficient information about the local stratigraphy to say if this could be caused by halokinesis. 

My suggestion for YOU, however, is not to give up, but KEEP EXPLORING. You really deserve praise for not feeling sorry for yourself - but for instead trying to DO something. For this effort you get five stars ***** from a US Geological Survey scientist. Keep up that attitude.