International Volcano
Research Centre

Apache Junction, Arizona USA

OUR LAST MAJOR EXPEDITION

Volcanoes

SUNSET CRATER, nr. Flagstaff, Arizona, United States

35o 22' 12.0" N 111o 30' 00.0" W , 2,447 m (8,028 ft.)

&

HUMPHREYS PEAK, Flagstaff, Arizona, United States

35o 20' 35.2" N 111o 40' 53.0" W, 3,851 m (12,633 ft.)

17 May 2008

THE TEAM:

Participating in the expedition were INTLVRC's Principal Research Volcanologist, Dr. R. B. Trombley, Senior Technical Assistant, Andy R. Morckel & Volcano Technician, Jakob E. White.

THE VOLCANOES:

Sunset Crater cindre-cone volcano.  Humphreys Peak strato volcano.
Sunset Crater photo taken by the National Park Service.
Humphreys Peak photo courtesy of the Rocky Mountain Research Station, Flagstaff Lab.

Sunset Crater: Sunset Crater cinder-cone volcano is the youngest of more than 400 volcanoes of the San Francisco volcanic field in north-central Arizona. San Francisco Peaks, the high mountains 8 miles west, dominate the field and are regarded as sacred by the Navajo and Hopi peoples of today. The cones and lava flows, which cover about 2,000 square miles of the southwestern Colorado Plateau, resulted from several million years of volcanic activity. These powerful forces changed the landscape dramatically beginning in 1080 C.E.. Sunset Crater is a colourful volcanic cone composed of lava fragments called cinders. It was created when molten rock spewed from a crack in the ground, high into the air, solidified, then fell back as cinders or ash. Over the next 200 years, the heavier debris accumulated around the vent creating the 1,000-foot cone. During this period, these eruptions spewed volcanic ash , the lightest and smallest of the particles, over an 800 square mile area of northern Arizona .

As spectacular as the original eruptions were, two subsequent lava flows also occurred: Kana-a Lava Flow flowed to the northeast for seven miles in 1064-65 C.E.. The Bonito Flow occurred in three stages starting in 1180. The Lava Flow Trail passes through a portion of this flow. The processes that created the crater and lava flows also created a geologic wonderland at its base. As new gas vents opened suddenly, small spatter cones and fumaroles sprouted from the ground. Moving lava developed a crust on the surface where it cooled, and lava caves were formed where the hotter material underneath drained away. Partially cooled lava, pushing through the cracks like toothpaste from a tube, solidified into wedge-shaped squeeze-ups, grooved from scraping against the harder rock. The final eruptions of Sunset Crater around 1250 spewed forth lava containing red oxidized iron, which fell back as brilliant red cinders upon the about the summit. This gave the rim the appearance of a permanent "sunset" so bright that the cone appears to glow, as John Wesley Powell noted more than a century ago.

Humphreys Peak: The summit of Humphrey's Peak is the highest elevation in Arizona at 12,633 feet and one of the scenic rises among the San Francisco Peaks just north of Flagstaff, Arizona. Humphrey's, according to many avid hikers is the "best hike in Arizona" where those that reach the summit are rewarded with distant views of the Grand Canyon and Oak Creek Canyon as well as a 360 degree panoramic of the valley of beauty just below the Peak. Large composite volcanoes, such as Humphreys Peak, can collapse into debris avalanches even if alteration is absent and an eruption is not in progress or imminent. At San Francisco Mountain, Arizona, a large valley that penetrates the core of the volcano is at the apex of a large fan of bouldery volcaniclastic deposits. A 115-m-thick layer sampled in a borehole that penetrates the fan is composed of dense and unaltered lithic clasts in proportions similar to the bulk composition of the andesitic volcano; pumiceous clasts are absent. Within this layer, a 20-m-thick deposit consists mostly of clasts from two dacite extrusions that predate the valley: a flank flow and an inferred summit dome. This dacite-rich deposit may be from a debris avalanche that originated by failure of the summit and northeast flank of the volcano in a repose interval during the last eruptive stage, which was about 0.43 to 0.22 Ma. Preconditions for slope failure include top loaded by massive lava flows and summit dome and cone inflated by intrusions. Only lower-flank and base extrusions followed the initial breach, which was enlarged by mass wasting, erosion, and glaciation.

THE MISSION:

1. Determine the North American Plate Motion With Respect to Pacific Plate With Reference at the Sunset Crater.

2. Compare with respect to previous measurements of movement of the Sunset Crater.

3. Conduct the second in a series of magnetometer readings of the Humphreys Peak volcano.

4. Compare these magnetometer readings with the second readings taken on 22 September of 2007 in both the horizonatal & vertical direction.

THE WORK:

Research almost never stops on the volcanoes here at the INTLVRC ! This is especially true for our experienced senior staff members like Dr. R. B. Trombley & Dr. Jean-Paul Toutain. who are always trying to make contributions and do training to our colleagues and fellow volcanologists.

Some of the scenes at the Sunset Crater cinder-cone volcanic site ........
First some of the scenes --


The left view shows Dr. R.B. pointing out a collapsed lava tube from the bridge while Jakob looks on.
On the right, Jakob gets a closer inspection of a spatter cone at the volcanic site.

Left photo taken by Andy R. Morckel. Right photo taken by Dr. R. B. Trombley.


The left photo pictures Andy & Jakob checking out yet another spatter cone at the complex
while the right photo shows Jakob taking a GPS reading at the base of the Sunset Crater.

Both photos taken by Dr. R. B. Trombley.

Some of the work at the Humphreys Peak volcanic site ........
Here's one of the scenes --


Here Jakob takes his first magnetometer reading.

Photo taken by Dr. R. B. Trombley.

THE EXPERIMENT RESULTS:

1. Determine the North American Plate Motion With Respect to Pacific Plate With Reference at The Sunset Crater -- Our annual reading of the crater was taken with the GPS unit. The results indicate that the North American Plate is still moving at approximately 42.39mm/yr at a direction of 318.73o .

2. Compare with respect to previous measurements of movement of the Sunset Crater. -- A total of Eight (8) different GPS readings, all a the same point and were recorded. The results at this time indicate that average Speed is 42.39 mm/yr (s=0.00), the Azimuth averages 318.73o ( s=0.00), North velocity average is 31.86 mm/yr (s=0.00), and lastly, the East velocity averages -27.97 mm/yr (s=0.01).

3.Conduct the second in a series of magnetometer readings of the Humphreys Peak volcano. -- Two different sites were selected at the Humphreys Peak volcano for these magnetomter measurements. The first site was at the so-called "Snow Bowl" and the second site was near the base of the volcano.

4. Compare these magnetometer readings with the second readings taken on 22 September of 2007 in both the horizonatal & vertical direction -- The results indicate that there was a 400 nT difference in the Vflux from the September 2007 reading. No significant deviation for Site #1. There was a 100 nT difference in the Vflux from the September 2007 reading. No significant deviation for Site #2. There was a 530 nT difference in the Hflux from the September 2007 reading. No significant deviation for Site #1. There was a 32 nT difference in the Hflux from the September 2007 reading. No significant deviation for Site #2. There was only a 2.4 nT solar influence on any parameter on this date and set of readings. And lastly, there was a 0.6o difference in magnetic declination from Digital Compass vs. V1.03 results.

An excellent set of work and interesting experiments were completed on this expedition.

Upcoming Planned Expeditions for Year 2008 .........

February, 2008   COMPLETED UBEHEBE CRATER, Death Valley, CA, USA (Misc. experiments.)
March, 2008      COMPLETED TAAL, Philippines, (CO2 & Temperature imaging.)
March, 2008      COMPLETED 18th Geological Conference of the Caribbean, Dominican Republic, Caribbean.
April, 2008      COMPLETED COLORADO PLATEAU, Arizona, USA (Tertiary lava sampling.)
April, 2008      COMPLETED SUPERSTITIONS, Canyon Lake area, USA  (Level-Transit survey.)
May, 2008        COMPLETED SUNSET CRATER, Arizona, USA (GPS Measurements.)
May, 2008        COMPLETED HUMPHREYS PEAK, Arizona, USA (Plate motion & magnetometer - Part II.)
June, 2008       CANCELLED CAPULIN CRATER, New Mexico, USA (Fuel costs.)
June, 2008       COMPLETED SILLY MOUNTAIN, Apache Jct., Arizona, USA (Magnetometer experiments.)
June, 2008       COMPLETED MERAPI, Java, Indonesia (Gas sampling & monitoring station set-up.)
July, 2008       COMPLETED SUPERSTITIONS, Lake areas, USA  (pH, Electrical Conductivity, Temp. survey.)
August, 2008     CANCELLED SILLY MOUNTAIN, Apache Jct., Arizona, USA (Funding.)
September, 2008            MERAPI, Java, Indonesia (Gas sampling, High Temp., & monitoring station set-up.)
October, 2008              Mt. ETNA, Sicily, (Mercury determination, elementary fluxes & isotropic compositions.)

Planned Expeditions for Year 2009 .........

February, 2009             SUNSET CRATER, Flagstaff, AZ, USA (Plate motion.)
March, 2009                UBEHEBE CRATER, Death Valley, CA, USA (Plate motion, Misc. experiments.)

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