borehole seismology in urban setting
TRANSCRIPT
BOREHOLE SEISMOLOGY IN URBAN SETTINGS
Peter Malin & IESE Staff
Institute of Earth Science & Engineering
University of Auckland
and many SAFOD, LVEW, Basel, and other collaborators
ISTANBUL UNIVERSITY ENGINEERING SCIENCES - 19 SEPT 2011
IESE Staff
Talk Outline
Background:
What’s the problem – why borehole seismology in urban settings…..???
Harrat Rahat
Auckland
Two examples….
….living in Istanbul, you can probably think of a third!
Talk Outline
Background:
What’s the problem – why borehole seismology in urban settings…..???
Seismic city-noise in Auckland New Zealand
Tea Time ….2 times a day
Day
Night
Talk Outline
Background:
What’s the problem – why borehole seismology in urban settings…..???
Surface seismic station – Riverhead, Auckland. NZ
Results of test station installed at Riverhead, NZ, depth of 245m
Same small event M~1
REASON #1. NOISE REDUCTION!
BoreholeSurface
1 minute1 min
Talk Outline
1. More Background:
i. Installation map
ii. Observatory versus depth chart
iii. Current standard seismographs
2. Motivation for borehole observatories
i. Detection
ii. Location
iii. Imaging
iv. Research
3. Some Examples
i. Basel Switzerland
ii. In progress – CAGS Donghai 5.2 km Observatory
Where does IESE work?
“x, y”
Surface Net
“z”
Vertical Net
“ x, y, z”
Borehole Net
1 2 4 8 16 32 64No. of stations
4096
2048
1024
512
256
128
64
32
16
4
2
1
Depth
In meters
PBO
(113) StationsPBO
Definitions
x & y = Surface
z = Borehole
PUNA PALM LOMA KRAFLA LV97 SAFODOZ
LVEW
SAFOD PH
TCDP
SAFVA
PALM
ORO&QH
In Progress
1.ii Observatory versus depth chart
SPEC
MONTY PARKFIELD
COSO
KRAFLA
SUMA PUNA
WAIRAKEI
GIPPS
PARALANA
SAFOD MH
BASEL
SCO2
BASEL
SAFOD MH
PARALANA
CCDP
ICO2
SAUDI
Current Standard
5.2 km 195 C 4.5 Hz
Shallow –
“posthole” – 1-to-10 m depths
Fixed (ungimbaled) sensors
+ 10 vertical installation
60 mm OD sonde
3-and 6-component sensors
seismometers &/or accelerometers
2 Hz seismometers up to 500C
MEMS accelerometers to 800C
4.5 & 15 Hz seismometers to 1950C
1.iii Current standard instruments
40 cm
•
1.iii Current standard instruments
Deep –
“Observatory” – 1-to-5 km depths
Gimbaled sensors
90 mm OD sonde
+ 200 tilted borehole
3-and 6-component sondes
seismometers &/or accelerometers
2 Hz seismometers up to 500C
MEMS accelerometers to 800C
4.5 & 15 Hz seismometers to 1950C
110 cm
Multilevel – pipe installation
“Array” – 0-to-2 km depths
8-to-24 Fixed sensors
60 mm OD sonde
+ 900 tilted borehole
Passive 3-component sensors
seismometers
15 Hz seismometers to 800C
1.iii Current standard instruments
pipe cable
sensor
skid
cable & spool
recorder & boffins
1.iii Current standard instruments
Cableless – downhole recorder
“Autonomous” – 0-to-2 km depths
Gimbaled sensors + 24 bit 2 kHz recorder
110 mm OD sonde
+ 200 tilted borehole
3-and 6-component autonomous sondes
Seismometers/accelerometers/recorder
0.1 Hz enhance SM64 up to ?
2 Hz seismometers up to 500C
MEMS accelerometers to 800C
4.5 & 15 Hz seismometers to 800C
Sensors
Recorder
Batteries
Talk Outline
1. More Background:
i. Installation map
ii. Observatory versus depth chart
iii. Current standard seismographs
2. Motivation for borehole observatories
i. Detection
ii. Location
iii. Imaging
iv. Research
3. Some Examples
i. Basel Switzerland
ii. In progress – CAGS Donghai 5.2 km Observatory
Basel1 C1
Basel1 C2
Basel1 C3
Basel1 C4
500 ms
4661 m
Depth
What happens to a seismic wave as it approaches the earth’s surface?
MEQ Recorded in 4.66 km stimulation Well – Basel
Spectral analysis of Basel MEQ versus station
500 ms2740 m
500 m
542 m
317 m
553 m
1213 m
< 100 Hz
< 20 Hz
Surface seismograph
Borehole seismograph
M ~ 0.5 MEQ Data from 3.3 km deep LVEW
see: http://quake.wr.usgs.gov/cgi-bin/heliexp.pl
What happens to a seismic wave as it approaches the earth’s surface?
12.5 25 50
100
Hz
12.5 25 50
100
Hz
0 m
100 m
200 m
300 m
400 m
Borehole Seismic
Array
Spectral Content as a function of depth - Note Log scales
0
S
400
4
0/4
0
P
400
S
&
P
>50 Hz
15Hz
>50 Hz
25Hz
SIGNAL REDUCTION BY INTRINSIC ATTENUATION
1 MIN
M~ 1 limit of ~ 15 station surface net
M~ -1 in 2.7 km observatory
M~ -2 in 2.7 km observatory
. Event Detection – 3.3 km borehole in Mammoth CA
Event Detection – 3.3 km borehole in Mammoth CA
Net of Reasons 1 - 3: Signal-to-Noise Improvement with Depth & Signal Frequency
1 Hz 10 Hz 100 Hz 1000 Hz
+ +
Signal-to-Noise
loss due to scattering & attenuation
Depth
meters
4096
2048
1024
512
256
128
64
32
16
4
2
11 2 4 8 16 32 128 256 512
Signal to Noise Ratio
LVEW December 2007 Seismicity on 2.7
km deep 4.5 Hz 3-component- sonde
vertical channel. Analog chart display
M~ 1
M~ -1
1 MIN
The Gutenberg-Richter Relation.
Depth
meters
4096SAFMH SAFMH
2048 BASEL LVEW
SAFPH
1024 TDPA
512 BASEL
SAFVA
256 MONTY PARK PBO
PALM
128 COSO
KRAFLA KRAFLA GEYSERS
64 ORO-QH
32 PUNA PUNA
16
4
2
1 PUNA PALM LOMA KRAFLA LV97 SAFDBS
1 2 4 8 16 32 64
No. of stations
Detection & Location Improvement with Depth
-2 -1 0 1 2 3
Magnitude
??
IMAGING OF SUBVERTICAL VELOCITY STRUCTURE & EVENT LOCATION!
Depth
meters
4096SAFMH SAFMH
2048 BASEL LVEW
SAFPH
1024 TDPA
512 BASEL
SAFVA
256 MONTY PARK PBO
PALM
128 COSO
KRAFLA KRAFLA GEYSERS
64 ORO-QH
32 PUNA PUNA
16
4
2
1 PUNA PALM LOMA KRAFLA LV97 SAFDBS
1 2 4 8 16 32 64
No. of stations
Statistics Locations Tomography
Source Rupture Propagation
Seismotectonics
Fault Structure
EQ Physics
Depths vs. No. of Seismic Stations: Monitoring Objectives
Some Lessons Learned Along the Road to Seismology in the Source
Lesson I: How the road divides
Low Road Middle Road High Road
Inside casing wireline Inside casing wireline Outside casing tubing
Few levels <10 Several Levels >10 Many Levels >100
Digital component Digital component Digital component
at surface at analog sensors Fully (e.g. MEMS)
Analog components Analog components Analog components
Armored Cu cables Hybrid OF to surface -Sensors Cu between levels
No Power Power Power
Low T & P Mid T & P High T & P
< 100 C ~ 150 C > 150 C
< 3 km ~ 3 km > 3 km
Donated winch Used winch Special installation winch
Local Univ. & Industry Nat. Institutes & Industry Internat. Organ. & Industry
Some Lessons Learned Along the Road to Seismology in the Source
Lesson II: The Do’s, Don’ts, and Maybe’s
Do’s Maybe’s Don’ts
Triple fluid barriers Double fluid barriers Single fluid barrier
Welded seals Metal-metal seals O-ring seals
clamping/weight>>1 clamping/weight >1 clamping/weight ~1
Passive clamps Hydraulic ram clamps Electrical ram clamps
Passive TS Cu cable Single power cable Multiple power cable
Armor+jacket+fill cable Jacket+fill cable jacket cable
Passive sensors Low power sensors High power sensors
electrically isolated case grounded case downhole ground
for High T & P for Mid T & P for Low T & P
> 150 C ~ 150 C < 100 C
> 3 km ~ 3 km < 3 km
Special winch Used winch Donated winch
Internat. Institutes & Ind. Nat. Institutes & Industry Local Univ. & Industry
...and don’t forget the SAKE test...
Talk Outline
1. More Background:
i. Installation map
ii. Observatory versus depth chart
iii. Current standard seismographs
2. Motivation for borehole observatories
i. Detection
ii. Location
iii. Imaging
iv. Research
3. Some Examples
i. Basel Switzerland
ii. In progress – CAGS Donghai 5.2 km Observatory
The Big Boom in Basel
or
How Earthquakes (Nearly) Sank a Major EU Industry: Is Turkey Next?
Peter Malin, Eylon Shalev, and Dan Kahn
Institute of Earth Science and Engineering University of Auckland, New Zealand
BIG BOOM
IN
BASEL
With many thanks to the staff of
Geopower Basel
Basel from space
“Hot/Dry Rock” well
BIG BOOM IN BASEL
Induced Earthquakes and Geothermal in
Downtown Basel, Switzerland
The challenge at, for example, St Johann: Seismology and meat packing
The challenge at, for example, St Johann: the Swiss rail service
MEMS AccelerometerGal’perin Seismometer
Stress Member
Signal Cable
Fishing Tower
WeakLink
Serious Seismologist
A typical 400 m installation: St. JohannRailroad track
OT-2 deep well: 2754 m 155º C
Basel network
OT-1,2
OT-2
OT-1
Map view N
Injection site
Injection site
Block view
BIG BOOM IN BASEL – the connection between earthquakes and fluid flow
MAP CROSS SECTION
Injection well
Microearthquakes
“Cementing” Microearthquakes
Injection well
D J F M A M J J A S O N D J F
What happened? December 2006
03 04 05 06 07 08 09 10 11 12 13 14
December 2006 – February 2008
200
100
4
2
0
4
3
2
1
0
300
200
100
0
Number of event per hour:
Detected
Located
Magnitude
Magnitude
Legal Limit = 3.4
Water Pressurebars
1 every 20 s
Legal Limit = 3.4
October 18, 2006 - 7:56 AM News
Swiss emergency officials have been participating in a huge earthquake preparedness exercise .......
.... disaster simulation coincides with the 650th anniversary of the
great Basel earthquake of October 18, 1356 – a 6.5 magnitude quake which destroyed most of the city.
December 9, 2006 - 6:43 PM
Man-made tremor shakes Basel !
Drilling for a planned geothermal power plant triggered a small earthquake that caused minor
damage to buildings.
......The Basel City prosecutor has launched an investigation to find if the company behind the Deep Heat Mining project should pay for repairs.....
Prosecution
.....The prosecutor's office launched its investigation on Friday evening. The police have already seized computer data....
Hand over those earthquakes, you seismologist scum...
But sir!I was just working on my PhD...
You said “stick’em up!”
Good heavens...I am borehole seismologist, not a social psychologist!
The situation downunder?