[Geysers] Fan & Mortar 8/21/08 details

[Tara Cross]

This report will cover Fan & Mortar's eruption on 8/21/08 and a few other geyser notes from that day.

Grand erupted at 1055 on 8/21, and a lot of people left the geyser basin to eat, rest, or just get out of the blustery wind that had been insistently beating on us while Grand had an interval just short of 11 hours.  I had not been planning to go to Fan & Mortar until about 1500, but Jeff Davis decided he would walk down and wait the afternoon there.  Karen Low had forgotten her radio, so she went back to get it and then headed down to try to catch Riverside.  I am mentioning all of this because it is very likely that no one would have seen Fan & Mortar if Jeff hadn't been waiting there and Karen hadn't arrived with a radio to call events.  So big thanks to both of them for allowing the rest of us to catch F&M on a short interval, probably about 2d10h, plus or minus.

The following data comes from Jeff Davis:

~1155 Splashing in Main Vent and activity in Bottom Vent and Lower Mortar on arrival
1158 River on
1205 River off, River pause
1211 River on
1224 River off, double River pause
1230 River on
1241 Gold on
1242 Angle on
1255 Water levels mediocre, Gold went into steam briefly but High still had a little water
1259 High vent steady, water levels in Gold still variable
1304 Lock, High and Gold steady with lots of water, Angle alternating water and steam
1307 Main Vent had two large splashes, lock continued as before
1313 Fan & Mortar

Main Vent initiated the eruption with several large cone-filling surges, joined maybe 5 seconds later by East Vent.  Lower Mortar had a surge at the start of the eruption and there was a little water in Upper Mortar, but Upper Mortar did not have its usual surge that covers the cone.  For the first few minutes of the eruption, only Fan was erupting.  This was actually advantageous to those watching from the bridge, because a stiff breeze was blowing the steam right at the boardwalk, making viewing both geysers at once difficult.  Those of us who tried got very wet.

For whatever it's worth, this is the second time that I have been really surprised to see F&M erupt because the water levels had not been looking very good.  On 8/16 and again on 8/21, Gold had essentially lost its water and gone into steam for maybe 30-45 seconds before the water levels came back and High started looking much better.  After the eruption, Lynn pointed out that High had never completely lost its water, so even when Gold went into steam there was still hope.

A few other notes from 8/21:

We were quite surprised to get Beehive in the afternoon on an interval of roughly 11 hours, Indicator 1627, Beehive 1644.

Uncertain erupted at 0803 and again at 1852 for what was probably a closed interval of just under 11 hours.

Once again, Grand had two 2-burst eruptions in daylight.

There might be a change happening at Fountain; I walked up on an eruption at 1414 and if Morning's Thief erupted, it was before my arrival.  Clepsydra's steam vent was so loud before the eruption that I could hear it from the parking lot when I arrived, and Fountain's duration was only 27 minutes.  Also, according to the electronic data Fountain has gotten a bit more erratic, and a lot of the double and triple intervals I've been getting have been on the longish side.

--Tara Cross
fanandmortar at hotmail.com



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