Tuesday, December 31, 2013


Anyone who has read 3 Nephi 8, especially if they are aware of some of the details of Mount St Helens' 1980 eruption, have pondered expressions such as "...there were exceedingly sharp lightnings...", "...the city of Moroni did sink into the depths of the sea...", "...the whole face of the land was changed...", "...there was darkness upon the face of the land...", and the "...the inhabitants thereof who had not fallen could feel the vapor of darkness..." that engulfed the Nephites nearly 2,100 years ago.

Central America, of course, is an integral part of the Pacific Ring of Fire, so-called because of the string of volcanoes that all lie just inland from the Pacific Ocean margins. The Ring includes hundreds of volcanoes, among them the huge Cerro Hudson in southern Chile, Masaya in Nicaragua, Shasta in California, Mount Rainier in Washington, Mount Edgecumbe near Sitka, Alaska, and Kenai and Veniaminof, the monster volcanoes of the Aleutians. Farther east, on the other side of the Pacific Ocean, the Ring of Fire includes Bezymiani, Sheveluch, and Mutnovski-Gorely in Kamchatka, and Alaid and others in the Kuriles. The Ring includes Usu, Fuji, and Sakura-Jima, the best-known volcanoes in Japan. We can't leave out Mount Pinatubo in the Philippines, whose 1992 eruption lowered the world wide temperature by two degrees centigrade, and we must include the long arc of volcanoes in Indonesia, including the monster Toba. The phenomenal eruption of the Toba supervolcano around 72,000 years ago may have reduced the proto-human population on Earth to as few as 2,500 individuals.

All these volcanoes (except for Indonesia) lie just inland of the Pacific Ocean margins because they lie just above their sources: the down-going Pacific Ocean seafloor that is being over-ridden by continental margins all around it. Linking the over-riding continental plates with their subducted oceanic plate are huge subduction faults. These are the sources of the largest earthquakes in Earth's recorded history, including the magnitude 9.5 Valdivia earthquake of 1960 in Chile (whose tsunami destroyed downtown Hilo, Hawai'i, about 8 hours later). Other subduction earthquakes include the magnitude 8.7 to 9.2 Cascadia event of 1700, which sank an entire forest in Puget Sound, and whose "Orphan Tsunami" destroyed villages on the Japanese east coast. The magnitude 9.0 Tohoku Earthquake of 2010 triggered the meltdown of the Fukushima-Di-Ichi nuclear plant and devastated the northeastern Japanese coast. The huge magnitude 8.6 Aceh subduction earthquake of 2004 created a tsunami that killed at least 250,000 people along the Indian Ocean margins.

During the Spanish era, regional Central American capitals such as Santiago de Guatemala and Nicaragua, Honduras, were repeatedly destroyed and rebuilt. To say that earthquakes and related volcanic tephra-falls changed the face of the land in Central America would be an understatement.

Since the 1963 eruption that created the island of Surtsey, Iceland, and the 1980 eruption of Mount St Helens, volcanologists have known that lightning storms are closely associated with Plinian eruptions. This is because of the vast electric charge lofted along with the prodigious amounts of volcanic ash that are transported to the stratosphere.

But what caused the "vapor of darkness" described by Nephi? This was almost certainly a smothering blanket of volcanic ash. Mount St Helens, 1980, was a relatively small (VEI 5) eruption. It lofted about 3 cubic kilometers of material, and left nearly a meter-thick blanket of ash in Yakima, Washington, 244 kilometers to the east, within a few hours of its eruption.

To get a handle on a smoking gun for 3Ne:8, we must examine the largest volcanic eruptions in Central America. One way to do this is to accumulate information on tephra falls that reached out great distances - the larger the reach, the greater the eruption. Two events stand out:

  • Masaya volcano, Nicaragua, about 2,100 years ago, left tephra as far as 170 km distant.
  • Chiletepe volcano, Nicaragua, about 1,900 years ago, left tephra as far as 570 km distant.
Note that these dates are somewhat approximate (they come from Kutterolf et al, 2008, Geochemistry, Geophysics, Geosystems). The Masaya eruption lofted approximately 8 cubic kilometers of ash and tephra, nearly three times more than Mount St Helens. Interestingly, ancient human footprints have been found at Acahualinca - these are 2,100-year-old fossils discovered along the shores of Lake Managua, Nicaragua, frozen in the volcanic ash from Masaya. Both these volcanoes lie eastward of the subduction zone where the Cocos Plate is being over-ridden by the Caribbean Plate at a rate of nearly 7 cm/year. This rate is nearly three times faster than the Cascadia subduction rate, which means that there are proportionally more frequent earthquakes and volcanic eruptions in Nicaragua than in Washington and Oregon. 

I'm just struck by that name: Masaya. 


Friday, December 27, 2013


For Bilbo Baggins, an Adventure made life worth living.

For many human beings, adventure is often just being able to claim you were that first at something: the first on a new pitch at Smith Rocks, Oregon, the first to summit K2 in Nepal, the first to free-climb Half Dome in Yosemite...

There are several books at home that I cherish, including

  • "Undaunted Courage" - the Lewis and Clark expedition,
  • "Sailing Alone Around the World" - Joshua Slocum's first one-man circumnavigation of the Earth,
  • "Tigrero" - Alexander Siemel's hunt for man-eating Jaguars in Brazil's Matto Grosso,
  • "Endurance" - Earnest Shackleton's Antarctic expedition and Worsely's incredible navigation across 800 miles of the terrible Southern Ocean to South Georgia Island.
There are others, but these are the ones I re-read every couple of years.

I have pondered a definition of "Adventure."  In my opinion it means going off to someplace where few if any have gone.  It does NOT mean a day-trip, or going somewhere that a cell-phone can call for help from. Importantly, it means going someplace where you are on your own.  If something goes bad, it's up to you and your expedition members to work out your own survival. Fail, and there is no record of the fact that you perished - or like the Franklin Expedition to seek the Northwest Passage, archeologists reconstruct your grim demise a century later. 

According to this definition, I and many of our family members have had some adventures:

  1. My first, 10-day sojourn in the deep Amazonas forest of southern Venezuela. It was full of amazing wonders, but I nearly died.
  2. Jared, Val, and I hiked to - and summited - Mount Roraima ("The Mother of Waters") on the Venezuelan, Guyana, and Brazilian triple-frontier. The trip covered over 50 kilometers on foot, and the last pitch required climbing a crack up a 700-meter (2,000-foot) cliff to an eerie Moonscape at 3,000 meters (9,600 feet) elevation.  Wearing T-shirts, we were promptly engulfed in a sleet-storm. 
  3. Louise and Lisa made that same trip the following year - Lisa wore flip-flops most of the way.
  4. Louise and Val hiked to the great Auyantepuy - the greatest cliff-sided mountain on Earth - and climbed it - and both nearly drowned in Devil's Canyon on the way.
  5. My first trip into the roadless Amazonas Territory of southern Venezuela. I was nearly consumed by insects on this trip, but the real sticker was an encounter with a pair of murderous bandits... who counted us at least three times before they decided there were too many of us (about 20) to cleanly kill. Our Venezuelan counterparts also reminded the bandits that we were American diplomats - and there would certainly be follow-up if we didn't return. 
  6. The first Summer Crossing of the Empty Quarter (there are only a handful of true crossings on record). This required driving 1,700 kilometers (over 1,000 miles) over continuous sand dunes in the hottest desert on earth - even Bedouin only venture into the fringes, and only in winter. Neither fixed-wing nor rotary aircraft can venture into this desolate place; we had only intermittent HF radio contact with the outside world. We camped one night in northern Yemen during its 1994 Civil War - because the Saudi border map placed one guard-post fully 72 kilometers (45 miles) from where it actually was. I completed a magnetic survey over an asteroid-impact site called Wabar when the temperature reached 61 degrees C (142 degrees F) - and according to my companions, was unconscious for 20-30 minutes from heat-stroke afterwards. The next day we visited a "weather station" that was so radioactive that my Geiger Counter went off-scale at its highest setting when my back was against the outside wall.
  7. The first overnight camping expedition inside Mount St Helens volcano, just as the 2004 - 2006 eruption was ending. I did this to help a crew of desperate geophysicists, but unlike them I chose to walk out, and not take the return helicopter. This meant hiking in incredibly-dissected, unconsolidated boulder fields for nearly 20 kilometers with a 30-kg backpack. I lost a toe-nail and blew out a knee doing it, and no, there was no cell-phone reception. 

I have cherished photos of these trips, and the book Louise and I wrote about Venezuela has 45 photos in it, many from other-worldly Mount Roraima. We made many more wilderness trips, but in most (but not all) cases we had cell-phone or sat-phone access in case of an emergency.

But here's the thing about adventure: there is the up-side (the excitement, the discovery), but there is also a downside: danger, perhaps death. My personal journal while in Venezuela is full of annotations like "I was nearly killed again today..."

If you push the statistical envelope by doing this too often, You. Will. Die.


Sunday, December 22, 2013

Earthquakes only during the day?

According to my calculations, the 6th grade means students are around 11-12 years old. If so, then the Rising Generation is full of people a lot smarter than I was at that age. The question below from Ask-a-Geologist is just one of many like it:
Q: Dear Geologist,

Our name is Arianah and Cray and we are sixth grade students at Preston Middle School in fort Collins, Colorado. We are currently learning about how the Earth’s surface changes over time. We are curious about earthquakes. We have a couple questions for you. Is there a common time when earthquakes happen during the day? Also, why did you become a geologist?

Yours sincerely, Arianah and Cray :D
1. Earthquakes are essentially random. We understand why they happen, we understand where they happen, but we do NOT understand WHEN they will happen. There are always aftershocks following a main event, of course, but the main event cannot be predicted. Extensive research has shown that there is no correlation between earthquakes and certain times of the day or external * events - for instance there is no correlation with either the location of the Sun, or of the Moon, or with tides (alignments of celestial bodies, which cause neap tides or spring tides, is called syzygy). Some of the brightest minds on this planet have been searching for more than a half century for some evidence that main event earthquakes can be predicted, but without success. They can be forecast #, but not predicted.
2. I was a solid-state physicist and realized that if I didn’t do something drastic, I would be stuck inside a laboratory all my life with radioactive sources and high-pressure cells. This was brought very much to my attention one day when I had a high-pressure cell blow out and spew Cobalt-60 all over the inside of our lab, and had to call in a special Spill Team. Also, by this time physics as a profession was drifting into a dead end with string theory, and I saw relatively little value to humanity to spending billions of dollars to see if another exotic particle existed. I checked out break-offs of physics, including astrophysics, hydro-geophysics, weather physics, and geophysics, and found the last one to be very exciting. It also got me out into exotic places, like the Venezuelan jungle, the southeastern Alaska panhandle, the Empty Quarter of Saudi Arabia, etc. Geoscience gives me amazing opportunities to visit these places and many more. But even more interesting to me is to be a detective – to be the first to discover something beneath the ground or the seafloor. I was the first to say where the groundwater was beneath the San Pedro Basin in Arizona and Sonora, Mexico, and the first to map where titanium sands lay beneath the seafloor off the coast of South Africa. That’s ever so cool.
* It has been shown that if you inject fluids into certain formations (e.g., deep sediments northeast of Denver, CO), you can trigger swarms of micro-earthquakes. Basically this is the ground shuddering to equilibrate and adjust itself to a slightly new stress regime. However these sorts of events are so small that they are almost never felt.They really are not earthquakes as the general public understands earthquakes.
# A forecast: in other words, there is an X% chance that there will be a magnitude Y event on the Z fault zone in northern California within the next 30 years. This is very, very different from saying that there will be a Magnitude Y event at Z location on X day - that would be a prediction. We can't do that.

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 (http://geology.about.com/library/bl/maps/n_statemap_NM.htm) ...you 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 (http://www.passc.net/EarthImpactDatabase/NorthAmerica.html), 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: http://www.passc.net/EarthImpactDatabase/Criteria.html

There is more information, including some helpful images, in an article I wrote for Scientific American: http://volcanoes.usgs.gov/jwynn/1998SciAm-Wabar.pdf

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.