[Geysers] Fan & Mortar, July 22 @ 2345

[Tara Cross]

The following report describes the events leading up to the
July 22 eruption of Fan and Mortar.

 

Events seen prior to the eruption:

 

July 20

 

~1700 River pause, splashing in Main Vent, Bottom Vent
eruptions
Fan & Mortar were not watched overnight.
 

July 21

 

~1000 River pause, splashing in Main Vent, Bottom Vent
eruptions

~2100 Brief Main Vent splashing, short Bottom Vent
eruptions, no pause

 

Fan & Mortar were not being watched between 2130 and
0500.

 

July 22

 

~0630 River pause, splashing in Main Vent, Bottom Vent
eruptions

~1200 River pause, huffing in Main Vent but no splashing, no
Bottom Vent

~1500 Splashing in Main Vent, Bottom Vent eruptions, no
pause

~1800 Splashing in Main Vent, Bottom Vent eruptions, no
pause

 

After the evening events, a huge storm with lightning and
heavy rain blew through and drove everyone inside.  But before darkness set in, the clouds had
moved off, and conditions were good enough that I decided to spend a few hours
at F&M before heading in for the night. 
Upon my arrival, I heard Angle splashing, but after a while things grew
quiet and then I heard a light roar from Main Vent. But when I pulled out my
maglite to have a look, the batteries went dead almost immediately, so I had to
rely on my head lamp to follow the rest of the events, so some of them are a
bit sketchy.  Here’s what happened:

 

~2230 Main Vent light roars

2235 River on, followed within a minute or two by Gold

~2248 River and Gold off, for what I’m pretty certain was a
Gold pause

~2250 Main Vent began roaring

2258 Bottom Vent (d=24m, that was all one eruption with no
breaks)

2300 Main Vent continued to make sounds like it was having
splashes

2323 Bottom Vent, this time it started and stopped several
times

2330 River on, Gold pause lasted approximately 42 minutes

2331 Gold on

2333 Angle on

2339 Water levels were better than they’d been for any other
cycle in the interval

2343 High Vent in lock, joined about a minute later by Gold

2345 FAN AND MORTAR

 

Fortunately, the Strassers came down to F&M with
flashlights so the viewing for the eruption was pretty good.  It was a strong eruption overall, though
Mortar dominated, with an angled jet from Lower Mortar landing on the benches
at the top of the embankment.  Once
again, Mortar did not ever completely stop during the eruption.

 

Prior to this eruption, it had seemed that extended activity
by Bottom Vent was not a good thing, because the event cycles leading to prior
eruptions had not included long Bottom Vent eruptions.  This time, Bottom Vent lasted a full 24
minutes before pausing and then continued erupting after that, but Fan &
Mortar still erupted.  The other notable
thing about the event cycle was that it was only 15 minutes from the start of
River to the start of the eruption.  For
those wondering how long they have after River starts, it’s been getting
shorter—19 minutes for the July 18 eruption and 15 minutes on July 22, as
opposed to 32 minutes on July 14.

 

Just as a reminder to everyone, Fan & Mortar’s eruptions
since the spring slowdown have been:

 

June 24 @ 0646ie, I>57d

June 28 @ 0714, I~4d00h28m

July 2 @ 1433, I=4d07h19m

July 8 @ 0710, I=5d16h37m

July 11 @ 0901ie, I~3d01h51m

July 14 @ 1951, I~3d10h50m

July 18 @ 0531, I=3d09h40m

July 22 @ 2345, I=4d18h14m


--Tara Cross
fanandmortar at hotmail.com

 

 


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