Questions:
Gravity:
Methods: Just need to understand two program methods. One is Montaj and gave the colored contour
map seen in PP, the other is GM-SYS and gave the cross-section profiles seen in PP.
Results:
Where did 38 m offset and 70 degree dip and max vert offset of 105 m come from? Wrong.
Correct:
Started with basin depth plot from grav team to get apparent dip of bedrock at the intersection of the
cross-section plane with the bedrock plane. Apparent dip of bedrock surface: Tan inverse of 2000/500 =
20 degrees
Then estimate true dip of bedrock: true dip = apparent dip / cos (angle btx az angle of apparent dip dirx
and az angle of true dip dirx). (20 degrees / cos (14) = 20.6 degrees)
Then get apparent dip of the intersection of the fault plane with the bedrock plane: apparent dip = true
dip * cos 76 = 5 degrees. (76 degrees is from az of fault dip dirx of 148 degrees – az of the true dip dirx of
72 degrees).
Then use max vert depth of 105m (from plot) and apparent dip of 5 degrees to get horiz offset, which is
h = 105m/tan (5) = 1200m
Two gym-sys models – conclusion about the two models (yellow plot)? Use version 2 bc it eliminates
first point that was in the canyon and too rough.
Excel – removed trend to see anomalies in first plot? Nope, looking at all data.
Is trend removed from first plot? No
How convert from SBA to thickness? Simple Bouger anomaly, like we did in a lab
SBA map – is colored map showing depth to bedrock? No, shows mGal anomaly. Shows a 9 mGal diff
along grav line, from light pink (-189 mGal ) to light green (-198 mGal). That map needs a color
bar/legend.
Generated with which program? Geosoft Montaj
PP – how getting horiz offset? See above
Which trough corresponds to fault? Lower bump on SBA vs distance plot (upper one is probably range
front fault). On cross-section profile it’s the deep trough.
Reflection/refraction:
Methods: need final draft or at least processing method.
Is diff btw refl/refr just in processing? Yes
Results: need results draft
PP – What do you see in records with lines drawn on them? Refractions bc they are first arrivals
Depth converted? Processing step
What do disturbances show? Show, in un-migrated stack, which these are, “later termination of
reflection” and the defraction, both from margin/edge of fault. Correction: Vert exag is actually horiz
exag (horiz exag = inverse of vert exag). This will give different angles – Louie said he would fix.
What velocity do you expect in bedrock?
On Google Earth image, which line is lineation and which is line connecting disturbances?
What would reflx possibly have shown?
ReMi:
Methods: good
Results:
What is “phase velocity”? velocity at a particular freq
How far from source before get Rayleigh waves?
How get Rayleigh waves so close to source? Shoot from both directions to get Rayleigh waves, which
show up further away from source.
How do you explain slower velocity in western part of basin and faster on eastern side, across fault, if
just going to 30 m depth? This is velocity in basin fill. Different because of different material due to past
proximity to range/drainages (my interpretation: basin fill from closer to the mountain is clast supported
boulders, and further from the mountain is more sand. This explains slower velocity on southwest part.)
PP – What does velocity vs frequency show? Compares obtained data with the 6Hz known data to show
that difference in velocities is not just error, since velocities are within error.
Vs30 vs Distance, distance from what, what does it show? From first point. Shows change in velocity
over distance
Resistivity:
Methods:
What is sounding? Change center of array and change a-spacing to get vert profiling bc goes deeper with
increased spacing
What is profiling? Set electrode spikes and leap-frog laterally at a set spacing to get horizontal profiling
bc always getting info from same depth
Imaginary component? Factor of error
Results:
Need kmz file. Tyler sent it.
PP – K-type definition? Is box 1 plot showing an anomalous resistivity at depth than other lines? Yes
Does this mean you were on the fault with that one line and not with other parallel lines? Yes
What is inverted data?
Corrected inverted?
Direction and numbering of line points on box 3 lower plot? These seem backwards
What do you see on this plot? The preferred H model shows that resistivity decreases, and then
increases, and it is not known how deep this increase goes for or what happens to the resistivity. This
also conflicts with the magnetic model.
GPS:
Do you want separate methods and results for GPS, or can we just include it in our gravity stuff? Up to
us.