borehole seismology in urban setting

BOREHOLE SEISMOLOGY IN URBAN SETTINGS

Peter Malin & IESE Staff

Institute of Earth Science & Engineering

University of Auckland

p.malin@auckland.ac.nz

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?