“Mmm,” murmured Liz as she scanned the digital wizardry on the liquid crystal display in the Yellowstone Volcano Observatory lab at the Mammoth Hot Springs complex. The computer modeler, Germaine Yardley of the U.S. Geological Survey Volcanic Hazards Team, flailed at his workstation keyboard, his warm coffee-colored fingers a blur. On the screen, a three-dimensional digital matrix, skewed to greatly exaggerate recent elevation inflation in the region around the lake, rotated slowly so the professionals could study the graphic representation from every angle.
Seated beside Yardley was a trim, athletic man. The director of the Cascades Volcano Observatory, Frederick Womack, had just arrived from Vancouver, Washington to assess the Lake Village-area steam explosion and the extent of harmonic tremor activity. He had been consulting with Wesley and Liz since his arrival and had settled down with Yardley to watch the digital graphic master at work as the day waned.
The modeler pointed a pen to an area of several square miles just north of the western bulbous, finger-like projection in the lake known as West Thumb. “That’s the Mallard Lake resurgence dome now,” the graphic virtuoso noted. He directed his pen to a second area on the screen to the east of the lake. He said matter-of-factly, “That’s Sour Creek dome there.”
Yardley let the computer program work its pixel magic as the foursome conversed, ate microwave pizza and drank tepid coffee and Mountain Dew well into the evening. In the false color graphic image, the two regions Yardley had pointed out appeared as true bulges, as if they were hematoma swellings of the skin after a bruising punch.
“So, Ms. Embree,” asked Womack as he chewed a slice of chilling pizza, “now that we’ve gone through all the data, you think the old Mallard Lake and Sour Creek, those resurgence zones, are really just separate old real estate riding a much larger and evolving structure? We should be focusing on something bigger that’s affecting the whole region between the domes.”
“Uh huh. That’s what I think is the case.”
“And you think the steam explosion in the lake was a symptom of the developing phenomena and that it is having an adverse impact on the lake?” Womack turned to look directly at the tall woman behind him.
“That’s what I believe, yes.”
“Would you give us your grand view, Ms. Embree?” Couch asked.
“Okay,” she replied. “We’re seeing a continuous harmonic tremor sequence spanning the entire lake region at and between the domes and to the east as well. Data indicate magma is on the move, we all agree. It’s shallowing and flowing laterally, influencing surface heat outflow and effluent runoff. Tremors are trending eastward toward the park boundary in step with heat flow. Things are trending hot, hot as the Norris Basin from the old domes, down the Firehole, under the lake strata to the Brimstone Basin area, particularly Brimstone. Also, from Brimstone and Park Point to the eastern park boundary, we have rapid topo inflation. That’s touching off the old faults in the uplands above Brimstone and near the eastern shore of Southeast Arm. They’re jittery. Same with the old Sedge Bay and Lake Butte faults to the northeast. Water and air chemistry is undergoing a pronounced shift, and water infiltration into the low country from Park Point to the Yellowstone River inlet is well-documented. We’ve got lots of noise, folks, some of which we’ve been feeling.”
“Now, Germaine,” asked Liz, “could you overlay the seismic profile over this image?”
The modeler turned to his computer and snapped a few keys. The graphic changed instantly, its surface covered with a swarm of small dots, some colored but most black, representing epicenters of hundreds of low-level earthquakes over the recent decade. The target zone was saturated with dots.
“There,” motioned Liz, “overlay the seismic data and you can see that much of the recent swarm activity and heavy harmonics are massed at the resurgence domes, the lake terrain and Brimstone eastward. It coincides with the Mallard Lake and Sour Creek formations and the Mary Bay and Frank Island regions under the lake. Yet the swarms extend, there, to the southeast into the old fault zones at Brimstone and to the northeast to the east entrance. Surface topography is rising, except in the region from Park Point through the Southeast Arm to the river inlet. Those lands are being tilted, pitched to the southeast.”
The hydrothermal specialist tingled with delight over the power of the graphic technology. The digital display, she felt, was a work of fine art, backlit colors set dancing by bits and bytes that could reveal in seconds what might take hours for her and her colleagues to ferret out of hard data. She urged Yardley to pull up overlays of the earthquake fault line grid of the park and the University of Utah’s surface heat outflow data.
Several more keystrokes and the bulging regions on the graphic were suddenly heavily laced with spidery fault lines and shimmered with blistering tones of red, orange and yellow, representing subterranean heat finding its way to the surface at levels far above that of the surrounding country. On the screen, a yellow amoeba-shaped line traced the heavily eroded or buried rim of the huge 630,000-year-old Lava Creek caldera at the very heart of Yellowstone. The hot tones of the computer model encompassed four-fifths of the old caldera boundary and spilled over into other regions. The great geyser and hot spring fields at Norris glowed scarlet. Other areas, not associated with the steamy basin, were also pulsing with warm hues. The modeler punched more keys, and Celsius temperature readings displayed across the graphic.
“No wonder the place is breathing,” said Wesley, enthralled by the computer graphic. “It’s one hot-blooded thing.”
“It’s the beast,” Yardley marveled. “She looks hot. She is hot, compared to ten years ago,” he added. “The beast is getting a little restless, all right.”
Liz was drawn to a shallow crescent of brilliant vermillion on the monitor that rested within an image of a depressed plain between the folds of mountainous uplands east of the lake. The narrow shape was as searing red as any area on the digital topography and it snaked toward the eastern lakeshore. She pointed to the bright color streak. “What do you think is going on there?” she asked the men. All three studied the hot spot for a moment.
“I’ll tell you,” said Wesley slowly, “that’s where we’ve got the big band of forest die-off going on. The fumarole fields have been extremely active of late. Run-off reads increasingly acid and hot. In fact, very hot. We’ve recorded near boiling point in the streams there.”
The modeler flailed away, banging the keys, retrieving data into the park’s computer center at Mammoth Hot Springs offices, a system tied to one of the most advanced and extensive seismograph arrays on earth, the Yellowstone Seismic Network. The University of Utah, in partnership with the Park Service and the US Geological Survey, maintained and helped monitor twenty-two recording stations equipped with sophisticated instrumentation designed to be sensitive to volcanic and subsurface processes at Yellowstone. Yardley was playing with the data that had been relayed around the West and was now being downloaded from the campus of the university at Provo.
CVO director Womack studied the graphic images as they changed in response to Yardley’s deft strokes, then posed a question. “Not since the Pleistocene has a volcanic vent opened here. It’s been 630,000 years since the caldera blew out and collapsed. We know the great eruption events in this neighborhood occur at roughly similar-duration cycles. Topographic rise is at historic highs right now as are thermal readings in some basins. For argument’s sake, do you think the conditions we’re experiencing right now are precursors to some inordinately large eruptive event, or is Yellowstone simply misbehaving a bit more than usual?”