Glossary and Abbreviations

Geyser Terminology

The following words are commonly used to describe eruptive activity. Geyser terminology is not always applied consistently to different geysers, but the following definitions will provide you with a starting point.

Term	Description
geyser	A feature that periodically erupts a mixture of water and vapor.
perpetual spouter	A feature that continuously erupts a mixture of water and vapor.
bubble shower	Vigorous boiling at the surface of a pool (e.g. activity at Beach Spring and Crested Pool).
preplay	Splashes that occur prior to an eruption.
eruption start	The beginning of the water phase, usually the first burst of water. Note: Its defintion is geyser-specific (e.g. "one-meter boil" for Great Fountain).
water phase	The part of an eruption dominated by water.
steam phase	The part of an eruption dominated by vapor.
eruption end	The end of the water phase and for eruptions with a steam phase, the transition to steam phase.
duration	The time between the start of the eruption and the end of water phase.
interval	The time between two eruption starts.
quiet interval	The time between an eruption end and the start of the following eruption.
series	A group of eruptions with similar intervals separated by a relatively long interval (e.g. Lion and Dome). The first eruption in a series is usually called the initial.
burst	A segment of a single eruption that is separated by a brief pause (e.g. Grand). Note: Bursts are called series at Great Fountain.
post-eruptive	The state of a geyser after it has finished an eruption. Experienced observers may be able to assess post-eruptive behavior to determine an approximated start time of a missed eruption.
major and minor	Eruption types. Major eruptions are usually defined by their greater intensity, taller height, and/or longer duration (e.g. Castle and Lone Star). Note: The designation of major eruptions at a certain geyser does not necessarily imply that the other eruptions are designated minor, and vice versa.
long and short	Major and minor eruptions of Old Faithful. Short eruptions last for ≤2.5 minutes and long eruptions last for >2.5 minutes. This distinction is important because Old Faithful has a bimodal interval distribution, and the eruption type controls whether the next interval will be shorter (average 68m) or longer (average 94m).

Time Code

Code	Description
ie	In eruption. Eruption was observed, but not from start.
ns	Near start. Eruption was observed within a minute of the start.
E	Electronic. Eruption was determined using monitoring data (e.g. runoff temperature).
A	Approximate. Eruption was observed, but exact time not noted and therefore later approximated, or eruption not observed and inferred from post-eruptive activity.
wc	Webcam. Eruption was observed via webcam.
ini	Initial. Eruption was the first eruption in a series of a geyser known to erupt in series.
(?)	Questionable. Observer thinks that an eruption occurred, but isn't sure.
maj	Major. Eruption was a major eruption of a geyser with different eruption types.
min	Minor. Eruption was a minor eruption of a geyser with different eruption types.

Duration Code

Code	Description
~	Approximately. Eruption is known to have lasted about the given time.
>	Greater than. Eruption is known to have lasted at least the given time.
<	Less than. Eruption is known to have lasted no more than the given time.

Grand Code

Code	Description
D#	Turban Delay. The interval between Turban eruptions was 25m or greater. The number after the letter "D" is the number of Turban eruptions until Grand started after the delay.
V#	Vent Delay. Vent overflowed but Grand didn't start even though it was time for Turban or Turban started. The number after the letter "V" is the number of Turban eruptions until Grand started after the delay.
G	Grand. Eruption was initiated by Grand.
T	Turban. Eruption was initiated by Turban which started shortly before Grand.
*	Star. Duration of the second burst was 1m15s or greater.
#	Pound. Duration of the third burst was 1m15s or greater.
C	Continue. Vent & Turban continued after the eruption.
Q	Quit. Vent & Turban quit after the eruption.

note

The following examples may help to clarify the meaning of the codes:

• T2*C: Turban started before Grand, two bursts, second burst was >1m15s, Vent and Turban continued
• V2/G1Q: Grand erupted two Turban cycles after a Vent delay, Grand started before Turban, one burst, Vent and Turban quit
• D5/D2/T1C: Turban delay, then another Turban delay five cycles later, then Grand erupted after an additional two Turban cycles, Turban started first, one burst, Vent and Turban continued

Great Fountain Code

Code	Description
p=#	Pause. The quiet pause between the "one-meter boil", the start of the eruption, and the first burst of water. The number after the equal sign is the interval of the pause in minutes.

Geyser Group Abbreviations for Yellowstone

Abbreviation	Geyser Group
BBG	Biscuit Basin
BSB	Black Sand Basin
CDG	Cascade Group
CGG	Castle, Grand and Sawmill Groups
CLC	Chain Lakes Complex
CLX	Culex Basin
DSG	Daisy Group
FCG	Fairy Creek Groups
FLG	Black Warrior (Firehole Lake) Group
FTN	Fountain Group
GFG	Great Fountain Group
GHG	Geyser Hill Group
GIB	Gibbon Geyser Basin
GNT	Giant Group
GRG	Grotto Group
HFG	Heart Lake's Fissure Group
HLG	Heart Lake's Lower Group
HMG	Heart Lake's Middle Group
HRG	Heart Lake's Rustic Group
HUG	Heart Lake's Upper Group
IMP	Imperial Group
KLD	Kaleidoscope Group
LSG	Lakeshore Group
LST	Lone Star Group
MGB	Midway Geyser Basin
MGG	Morning Glory Group
MHG	Marshall's Hotel Group
MMG	Morning Mist Group
MMS	Morning Mist Springs
MYR	Myriad Group
NBK	Norris Back Basin
NPR	Norris Porcelain Basin
OFG	Old Faithful Group
ORG	Old Road Group
OSG	Orange Spring Group
PBG	Punch Bowl Group
PIN	Pine Springs
PMG	Pipeline Meadows Group
PNK	Pink Cone Group
POT	Potts Hot Spring Basin
QAG	Quagmire Group
RSG	Round Spring Group
RVG	River Group
SDP	Serendipity Springs
SHO	Shoshone Geyser Basin
SMG	Sentinel Meadows Group
SPR	Sprinkler Group
TGG	Tangled Geysers
THD	Thud Group
UPG	Upper Springs
WCG	White Creek Group
WDG	White Dome Group
WSG	Westside Group
WTL	West Thumb Lower Group

Other Abbreviations

Abbreviation	Description
UNNG	Unnamed Geyser
TD	Temporary Designation
UGB	Upper Geyser Basin
LGB	Lower Geyser Basin
NGB	Norris Geyser Basin
GT	GeyserTimes
GOSA	Geyser Observation and Study Association
OFVEC	Old Faithful Visitor Education Center
OFVCL-EV	Old Faithful Visitor Center Log - Electronic Version
RTED	Ralph Taylor Electronic Data
VR	Visitor report. Used in the comments or observer fields when the entrant received word about the geyser activity from a Yellowstone visitor.
FRS	Family radio service. Used in the comments or observer fields when the entrant received word about the geyser activity over a radio and cannot identify the observer.
YNM	The code for the seismometer housed in the Norris Museum.
YNB	The code for the co-located seismometer and infrasound station in the Ragged Hills on the western side of Norris Geyser Basin.
YNR	The code for the seismometer just east of Norris Geyser Basin.
YFT	The code for the seismometer nearest to Old Faithful.