[Geysers] Geyser Report: Fan & Mortar details for 7/19 and 7/22

[Tara Cross]

This is a quick summary of the activity I have observed at Fan & Mortar this 
summer.  Of course none of the patterns I have observed are set in stone; in 
fact, the current interval has broken several of the trends I was beginning 
to notice.  I am merely reporting what I have seen.

With all the nighttime eruptions, a group of dedicated gazers has been 
making sure that Fan & Mortar are being actively watched from about 1 day 18 
hours on.  That has translated to 40-50 hours of continuous observation 
prior to the past 2 eruptions.  It isn't easy to get up at "cold dark 
hundred" (as Kitt puts it) and stumble down to F&M but the geyser has 
rewarded us.  Thanks to everyone who put in time at Fan & Mortar!

In general, event cycles have been occurring every 4-12 hours, which is 
roughly the same pace as seen in 2001 and 2002.  Thus far I have observed 4 
F&M intervals this summer and there is usually an event cycle around the 
1.5-day mark that is fairly strong, followed by event cycles of varying 
strength.  Most of the time the water levels have bottomed out when there 
will be no eruption, though there have been a few where the water levels 
stayed up for 18 to 20 minutes after River before dropping.

Because of all the overnight eruptions, only five eruptions have been 
observed from the start so far this summer (6/16, 6/22, 6/29, 7/19, 7/22).  
All of them started from a classic lock.  Full information about the 
eruption cycle is known about four eruptions.  Three eruptions took place 
after a double River Vent pause and one followed a triple River Vent pause.  
Main Vent splashing has preceded eruptions by 60-70 minutes.  The time from 
River to start thus far has been 22-28 minutes.  Only one eruption cycle 
included true eruptions from Bottom Vent (6/29) and those were short 
duration (less than 90 seconds).

Finally, some weirdness.  The event cycle that took place about 10 hours 
prior to the July 19 eruption was a big strange.  It was a triple pause with 
two GOLD pauses and a River pause.  I have personally never seen this before 
and upon asking other experienced observers, no one else could remember 
seeing it either.  Usually triple pauses are either three River Vent pauses 
or one Gold and two River Vent pauses.  I am not saying this means anything, 
but I just thought I would put it in the record.

Here is the data for the two most recent eruptions:

July 19

0234 Main Vent splash
0244 River on
0253 River off (River pause)
0259 River on
0309 River off (River pause)
0316 River on
0328 Gold on
0329 Angle on
0340 High vent in lock
0344 FAN AND MORTAR

The Main Vent splashing was very consistent until River Vent came on the 
final time.  However, since it was dark it was difficult to tell just how 
strong the splashing was.  Bottom Vent splashed periodically during the 
events but did not have any true eruptions.  A slight breeze blew the steam 
away from the trail making for excellent viewing by flashlight.  The 
eruption was Mortar-dominated; Lower Mortar was humongous, reaching at least 
30 or 40 feet tall and sending an angled column onto the rock embankment.  
In contrast to many eruptions last year, and the most recent eruption (on 
the 22nd), Mortar did not pause at the beginning of the eruption but 
remained strong throughout.

July 22

~1310 Everything off after a normal cycle; Angle had a few spits and then 
quit
~1330 Main Vent begins to gently huff steam, slowly building to convincing 
roars
1340 Main Vent splash
1350 River on
1356 River off (River pause)
1404 River on
1412 River off (River pause)
1424 River on
1429 Gold on
1431 Angle on
1440 High vent in lock
1452 FAN AND MORTAR

The Main Vent splashing was mostly of the slow steady variety though there 
were several splashes that were large enough for me to see while I was 
watching for River Vent from the bridge.  The water levels started out 
looking very good.  As I was making a call that High Vent had been erupting 
to 1 foot steadily for about a minute, it went into lock.  Lock lasted a 
whopping 11 1/2 minutes (to the relief of Mike Lang, who was furiously 
pedaling to F&M as I called that the vents were going into lock), during 
which time it kept getting stronger, until High was jetting to over 10 feet 
and Gold was erupting powerfully to 6-8 feet, with Angle in steam.

As Lynn reported, the eruption started with 24 seconds of East Vent by 
itself and was dominated by Fan.  Mortar was also very nice, once it finally 
started.  It was one of the best soakers I have ever seen.

--Tara Cross
fanandmortar at hotmail.com