Lascelia Dacres
ESC 6206
Final Analysis: Geysers
E>H>A>E
There are only 50 geyser fields that exist on Earth; two-thirds of these
geyser fields have five or less active geysers (See Figure 1 for different
locations of geyser fields). This equates to fewer than 1000 geysers
worldwide. Geysers are thermodynamically and hydrodynamically
unstable. Geysers need three basic elements in order to be active. The
three basic elements are a water supply, a heat source, and a reservoir
(See Figure 2). Geyser fields are usually located near rivers such as
Figure 2: Cross Section of the Basic Elements of a Geyser
the Madison River; the rivers serve as the geysers main water supply.
Other sources that supply water to geysers are rainfall and circulating ground water. According
to Streepy (1996), the groundwater expelled from geysers show a tridium content that is
approximately 500 years old. Therefore, it takes an extensive amount of time for the
groundwater to circulate, heat up, and then move up to shallow levels in order to be expelled by
geysers. Most geyser systems have two separate water sources. One of the water sources brings
in cool and large amount of shallow water and the other brings in small amounts of hot boiling
in-depth water (See Figure 3). The waters from both sources mix with the less dense boiling
water moving upward and the cooler more dense cool water moving downward in the basin. The
waters in the system move in a convection-like pattern until the reservoirs fills and the
temperature increases. The water will continue to heat to a critical temperature and a small
amount of the upward-moving hot water will keep enough of the heat energy to stay at boiling
point. The water will then change into steam as it approaches the surface of the geyser. This
leads to agitation in the geyser’s water as more hot water begins to rise, the geyser will erupt.
Figure 1: Locations of
different Geyser Fields.
Equates to less than
1,000 geysers.
Figure 3: The water
sources of geysers
The thermal and hydrological activities that cause a columnar geyser to erupt are
quantitatively analyzed using the information depicted in table below.
Equation
Definition
1. T h = T s + (r/c)
r = heat of vaporized water
T s = temperature of steam
C = specific heat of water
2. p (dV/dt) = q1
q1 = rate of flow of hot and
cold water ( qh +qc)
p = density of fluid
3. pV(dT/dt) = qh (Th-To) +
qc(Tc-To)
qh = rate of influx of hot H2O
qc = rate of influx of cold
H2O
4. Te1 = (qcTc + qhTh)/q1
Te1 = temp. after mixing
Table 1 calculation of columnar geysers eruptions
As depicted in Table 1 (equation 1), after a columnar geyser erupts, the reservoir refills with the
mixed cool and hot water or steam. If the source of the heat is steam, after condensation the
temperature of the heat source will be equal to the temperature of the water. Equation 2
illustrates the calculation for the amount of hot and cold water in the reservoir as it increases at a
steady rate as the reservoir or basin fills. Furthermore, as the reservoir fills with water, its
temperature changes (Equation 3) and becomes balanced after mixing (Equation 4). Geysers only
become active when the temperature of the cool and hot water is greater than the temperature of
the residual water, Te1 > To.
As stated earlier, steam affects geysers. Eighty to hundred percent of all gas in a geyser
is carbon dioxide. Along with carbon dioxide, there is also oxygen, carbon monoxide, hydrogen,
and hydrogen sulfide etc. These gases can affect the hydrostatic pressure of a geyser system by
allowing the water to boil at a temperature that is much lower than its initial boiling temperature.
As a result, the gases may cause geysers to erupt because they become the heat source. These
geysers are known as gassy geysers.
Allen, E.T. and Day, A.L. (1935) Hot Springs of Yellowstone National Park, Publ. 466. Carnegie
Institute of Washington, Washington, D.C., p. 525.
Hurwitz, S., Kumar, A., Taylor, R., & Heasler, H. (2008). Climate-induced variations of
geyser periodicity in Yellowstone National Park, USA. The Geological Society of
America, 36(6), p.451-454.
Rinehart, J.S. Geysers and Geothermal Energy (1980). Springer-Verlag, p. 223.
Streepy, M. (1996). Geysers and the Earth’s Plumbing Systems. Retrieved from
www.umich.edu/~gs265/geysers.html.
L > E > H >L > E
The Hegben Lake earthquake that occurred in 1959 provided strong evidence for the
correlation between earthquakes and geyser activities. The epicenter was only 50 km away from
Yellowstone and immediately following the earthquake, all of Yellowstone’s geysers erupted
and all geysers, except for Old Faithful, changed their eruptive behavior. Old Faithful has
however responded to earthquakes much farther away such as the earthquake in Alaska in 1964
that had a magnitude of 8.4. According to some scientists, this shows that changes in geyser
activities that are caused by earthquakes are not necessarily due to slippage along the faults but
may be cause by changes in regional strain.
In November 2002, the Denali earthquake, with a magnitude of 7.9, occurred in central
Alaska and ruptured the Denali fault. Regardless of the 3100km distance between the epicenter
of the Denali earthquake and Yellowstone geysers, significant changes in Yellowstone geysers’
eruptive behavior was observed. Small hotsprings that were not known to be geysered suddenly
spewed hot boiling water up to 1 meter high. Following the eruption, in the winter of 20022003, 22 geysers eruptive behaviors were monitored by placing temperature sensors in their
channels. The result of the observation has been displayed in Table 2.
Number of Geysers Monitored in
Yellowstone National Park: Winter 0203
Observation
8
Changed eruption intervals; significant change in standard of error of eruption
intervals when compared to observation made prior to the Denali earthquake
4
Too inconsistent in data to show effects
10
No significant changes observed
Table 2 Observation of monitored geysers in Yellowstone National Park
Furthermore, geysers are very unique and individualized systems-no two geysers are
exactly alike. As a result, no major common patterns were found after the Denali earthquake.
For example as shown in Figure 4 and 5, Daisy Geyser in the Upper Geyser Basin decreased
rapidly in its eruption intervals after the Denali Earthquake. It took a few weeks after the
earthquake for the Daisy Geyser to return to its Pre-Denali eruption cycles. On the otherhand,
geysers located in the Upper Geyser Basin such as Castle, Plate, and Plume geysers along with
the Pink Geyser located in the Lower Geyser Basin showed irregularities in their eruption
behaviors that lasted for only a few days after the Denali Earthquake. In the West Thumb
Geyser Basin where the Lone Pine Geyser is located, eruption intervals peaked even three weeks
after the Denali Earthquake. Additionally, geysers whose eruptive behaviors were affected by
previous earthquakes such as the 1959’s Hebgen Lake, Montana of 7.5 magnitude and the 1983’s
Borah Peak, Idaho of a 7.3 magnitude were not affected by the Denali Earthquake.
Figure 4: Yellowstone
Major Geyser Basin: YLYellowstone Lake; UPUpper Geyser Basin; LBLower Geyser Basin; NSNorris Geyser Basin; WTWest Thumb Geyser Basin.
Colored circles are
triggered earthquakes
during the 1st 6h of Denali
earthquake.
Figure 5: Depicts a change
in eruption interval of the
Daisy Geyser in the Upper
Geyser Basin following the
Denali fault earthquake.
At the Yellowstone National Park, earthquakes occur near major geyser basins (See
Figure 6). This indicates that hydrothermal fluids may influence the offset of earthquakes. For
instance, fluctuation of gas bubbles within the hydrothermal fluid may increase local pore
pressure through diffusion and the highly pressurized two-phased fluid of steam and liquid may
cause fracture of the surrounding land. These are factors that may trigger earthquakes in
Yellowstone and as a result, disrupt the eruption intervals of geysers.
Figure 6: Cumulative
number of triggered
earthquakes at geyser
basin in Yellowstone
followed by the Denali
Earthquake
Husen, S., Taylor, R., Smith, R.B., and Healser, H. (2004). Changes in geyser eruption behavior
and remotely triggered seismicity in Yellowstone National Park produced by the 2002 M
7.9 Denali fault earthquake, Alaska.
Streepy, M. (1996). Geysers and the Earth’s Plumbing Systems. Retrieved from
www.umich.edu/~gs265/geysers.html
A>E>H>A>B
Geysers erupt when the temperature of their conduits go beyond normal boiling point. In
the case of a columnar geyser, as steam bubbles and rises, the steam becomes trapped and
constricted in the plumbing system of the geyser. As the constriction of the steam continues and
pressure builds up, water is exerted out of the geyser’s channel so that the steam can escape.
When the water is exerted out of the geyser this causes the pressure build-up in the geyser to
decrease which also leads to a decrease in the boiling point of the remaining water in the
reservoir. The remaining water in the reservoir which is already boiling continues to do so until
more steam bubbles form. In a short period, the steam expands causing pressure build-up and
the geyser erupts again. Eruptions of the geyser will continue until the reservoir is completely
out of water or the temperature of the geyser drops below its boiling point. The number of
geyser eruptions can be monitored by Geyser eruption intervals (GEIs). GEIs are used to
analyze the relationship between water, heat, and rock permeability and how they impact the
eruption of geysers. According to GEI data, geysers are affected by decadal and short-term
seasonal precipitation patterns. As shown by Figure 7, factors such as air temperature, snow, and
river discharge affect the intervals of geyser eruptions. In years of drought, there are less geyser
eruptions compared to years of frequent precipitation that leads to more geyser eruptions.
Figure 7. A: Average monthly temperature and snowfall
in Old Faithful; B: Average monthly Madison River
discharge; C: Average monthly GEIs for Old Faithful;
D: Average monthly Daisy Geyser scaled GEI; E:
Average monthly Aurum Geyser GEI; F: Average
monthly Depression Geyser scaled GEI
The Firehole River flows through the main geyser basins in Yellowstone National Park
and has been subjected to their heating effects for hundreds of years. As the river flows through
the geyser areas, the temperature of its waters has been recorded to be up to 12 degrees higher
than the unheated portion of the river. Table 3 below depicts the temperature and water analysis
of Firehole River as it flows through Old Faithful geyser in Yellowstone.
3
Old Faithful Geyser
Old Faithful
Table 4 further depicts the change in temperature during spring and summer months as the river
flows through Old Faithful.
4
Based on the data presented in the two tables above, as the Firehole River flows through Old
Faithful, its temperature increases as there is a change in seasons from Spring to Summer. This
leads to an increase growth rate of benthic algae. Furthermore, according to Boyle and Brock
(1973), the growth rate of benthic algae increases in the warmer portion of the river, up to five
times faster, than it does in the cooler portion of the river. Along with high temperatures, the
chemical composition of the Old Faithful aids the growth of the benthic algae.
Boyle, C.W. & Brock, T.D. (1973). Effects of thermal additions from the Yellowstone Geyser
Basins on the benthic algae of the Firehole River. Ecology 45(6), pp.1282-1291.
Hurwitz, S., Kumar, A., Taylor, R., & Heasler, H. (2008). Climate-induced variations of
geyser periodicity in Yellowstone National Park, USA. The Geological Society of
America, 36(6), pp.451-454.
Streepy, M. (1996). Geysers and the Earth’s Plumbing Systems. Retrieved from
www.umich.edu/~gs265/geysers.html