Appendix I: Bathymetric and geophysical program field notes (observer logs)

F2-99-NC Medicine Lake, California
15 to 19 September, 1999

Overview
A bathymetric and geophysical survey was conducted over Medicine Lake in Siskiyou County, north central California. A concurrent shallow-water sampling program was also conducted.

Equipment included:
R/V Fast Eddie, 22-foot whaler with dual 70 hp outboards
Differential GPS positioning
YoNav survey management software and data logging
Elics two-channel seismic acquisition
Lowrance 1000 fathometer and temperature sensor (hull mounted)
SeaCat CTD (conductivity-temperature-depth) sensor
Geopulse acoustic source
Benthos 12-element, 3-meter streamer
Seistec line-in-cone receiver
Hand gravity corer

Staff (all USGS):
Jon Childs, geophysicist Coastal and Marine Geology (C&MG)
Pat Hart, geophysicist C&MG
Larry Kooker, electronic technician C&MG
Gerald OíBrien, boat driver C&MG

On shore and sampling:
Larry Phillips, geologist (sampling) C&MG
Jake Lowenstern, geologist (sampling) Volcanic Hazards Team (VHZ)
John Barron, geologist Climate Change Program (VHZ)
Scott Starratt, geologist Climate Change Program (VHZ)
Jim Rytuba, geochemist Western Geologic Mapping

Daily notes:

JD 257 Tuesday, September 15
Travel from Redwood City to Medicine Lake

JD 258 Wednesday, September 16
Morning spent deploying Fast Eddie with bimini top, cowling, and installing electronics. Boat launched about 1245 local (1945 GMT). Weather conditions excellent: v. Light clouds, ~ 70-75° F, sunny, light wind.

SeaCAT CTD instrument started logging approx. 1245 local; in the water 1300 GMT).

First line consisted of a circumnavigation of the lake at 3.5 to 4 knot. Ran into shallow water twice. NW end of the lake very broad and shallow. Returned to the dock at 1400. Deployed Geopulse and back in the water at 2215z. Finished surveying at 259/0000 (1700 PST).

258/1945 Start logging CTD.
258/2000 Leave dock, commence circumnavigation of lake; CTD in water
258/2101 Complete circumnavigation, arrive dock; CTD out of water
258/2241 Leave dock, testing reflection system; CTD back in water
259/0000 Arrive dock; CTD out; end of day

Problems with Geopulse power supply limited reflection profiling. Changed out the power supply at the end of the day for the EG&G unit.

JD 259 Thursday, September 17
Weather conditions remain excellent: v. Light clouds, ~ 70-75° F, sunny, wind slightly greater than Wednesday and gusting 5-10 mph.
Acquiring reflection data with Geopulse and Benthos streamer (one channel). A grid of east-west lines was generated for the survey area at a N-S spacing of ~50 meters. The "A" lines were north of the lake centerline; the "B" lines south. Steering the lines accurately proved problematic because of wind conditions and the filter response of the YoNav line-following algorithm.

259/172800 Start logging CTD
259/173000 Leave dock, commence deploying Geopulse and Benthos streamer
259/173700 CTD in water
259/174600 commence acquisition of EW lines
259/182430 stop acquisition of EW lines
259/183000 CTD out of water
259/183300 CTD in water
259/183700 continue acquisition of EW lines
259/195400 stop acquisition of EW lines
259/195500 CTD out of water
259/200000 arrive dock, break for lunch
259/212500 leave dock, CTD in water
259/214900 continue acquisition of EW lines
260/000400 complete acquisition of EW lines
260/000500 CTD out of water

JD 260 Friday, September 18
Weather conditions remain excellent: v. Light clouds, ~ 70-75° F, sunny, wind calm.

Acquiring reflection data with Geopulse source, Benthos streamer and Seistec receiver (two-channels). Survey lines run approximately NNE-SSW along arbitrary lines chosen by line of sight. Lines at eastern end of lake spaced closer (approx. 25-50 meters), at western end of lake wider (approx. 50-100 meters). CTD data not logged.

260/173000 depart dock, deploying and tuning Seistec at east end of lake
260/181200 commence acquisition of NS lines
260/211400 complete acquisition of NS line
260/212000 arrive dock

JD 261 Saturday, September 19
Weather conditions remain excellent: v. Light clouds, ~ 70-75° F, sunny, wind calm.
Sampling and temperature profiles acquired. Two sampling sites selected based on geophysical profiles:
latitude longitude water depth profile day/time
1. 41° 34.9911' -121° 35.4420' 37 m 259/1846
2. 41°.34.8866' -121° 35.5590' 10 m 259/1916

261/1715:21 41° 34.866' N 121° 35.582' W ---> Dropping Core 1 here
261/1729:03 41° 34.880' N 121° 35.556' W ---> Dropping again here
261/1738:46 41° 34.986' N 121° 35.438' W ---> Core site 2 drop here ~38M
261/1801:34 41° 34.999' N 121° 35.419' W ---> drop long barrel core at 42.1 meter depth
261/1824:55 41° 34.996' N 121° 35.465' W --->site 2 core #10 first try
261/1842:58 41° 34.991' N 121° 35.467' W ---> Site 2 core 10 try 2
261/1853:06 41° 34.971' N 121° 35.503' W ---> CTD drop here
261/1857:42 41° 34.967' N 121° 35.526' W ---> Start to pull up ctd here
261/1858:46 41° 34.962' N 121° 35.526' W ---> CTD at surface
261/1903:09 41° 34.995' N 121° 35.494' W ---> ctd drop 2 here
261/1903:46 41° 34.994' N 121° 35.492' W ---> ctd on bottom-was not on bottom long enough
261/1904:44 41° 34.992' N 121° 35.503' W ---> ctd at surface
261/1904:54 41° 34.991' N 121° 35.505' W ---> ctd drop 3
261/1905:49 41° 34.987' N 121° 35.512' W ---> ctd coming up
261/1906:27 41° 34.985' N 121° 35.513' W ---> ctd at surface
261/1915:53 41° 34.969' N 121° 35.449' W ---> drop core10 try 3

JD 262 Sunday, September 20
Demobilization and travel from Medicine Lake to Redwood City
 
 

Appendix II: Summary of seismic-reflection profile lines

F2-99-NC Reflection Profile Start/End Line Times and Field File Numbers

Following table shows the times for each line segment, the line numbers assigned to the segment, the field file ("ping") numbers in the original field recording, and the plotting direction (N - normal, R - reverse) to create reflection images that have west and south to the left. Lines 101 thru 117 were acquired on JD 259; Lines 201 thru 223 on JD 260.
 
 

Appendix III: ASCII Bathymetric Data File

ASCII data file with time, position and depth (This is a big text file: 2.6 Mbytes!!!!).