srl-2019123_supplement.pdf

Supplement

ary Material

Title

A P

lan for a

ong

erm

, Automated, Broadband Seismic Monitoring Network on the Global

eafloor

Authors

: M. D. Kohler, K. Hafner, J. Park, J.

C. E.

Irving, J. Caplan

Auerbach, J. Berger, J. Collins,

B. Romanowicz, B. Woodward, A. M. Tréhu

This is the

supplementary material

for

A Plan for a Long

Term, Automated, Broadband Seismic

Monitoring Network on the Global Seafloor

Section I

shows

survey

questions and the percentage

breakdowns of respondents’ answers to each question

described in the main

manuscript

text

Sec-

tion II

shows

additional maps produced for different types of seism

ic phases, analogous to Figure

the main

manuscript

Sec

tion I

Survey

question

s and answers

Please

describe

what

you

perceive

the

most

important

unan-

swered

question

global

seismology

where

significant

advancement

could

made

with

five

(5)

new,

long

term

seafloor

seismometers

small

aperture

seafloor

arrays.

Answered: 51

Skipped: 4

How

much

serpentinization

of the

mantle

occurs

at mid

ocean

ridges, and

does

serpentinized

layer ac-

quired

at the

ridge

crest persist as

low

velocity

anisotropic

layer,

the

plate

migrates

across

ocean

basin?

resolve

anisotropic

crustal structure

well with

receiver functions, we need

100+

good

body

wave

code. Experience

with

OBS

year deployment on

the

Hawaii Swell

(Leahy

et al., 2010) suggests

that the

deployment should

years. Would

desire

stations

deployed

off the

ridge

axis

~30

plate

for ridges

of waying

spreading

rates, e.g., East Pacific

Rise

(fast), Atlantic

Ridge

(slow), SW

In-

dian

Ridge

(very

slow), Carlsberg

Ridge, etc. Leahy,

M., J. A. Collins, C. J. Wolfe, G. Laske, and

S. C. Solomon

(2010), Underplating

of the

Hawaiian

Swell:

Evidence

from

teleseismic

receiver functions, Geophys. J. Int., 183, 313

–

329,

doi:10.1111/j.1365

246X.2010.04720.x.

4/17/2018

9:46

What

controls

the

symmetry/asymmetry

of the

oceanic

lithosphere

away

from

the

spreading

4/17/2018

9:43

center?

what are

the

time

constants

of the

ocean

wave

spectrum

that couple

into

the

solid

Earth?

4/17/2018

9:40

where

Earth's

hum

generated?

4/17/2018

9:38

study

of deep

mantle

and

core

structure

4/17/2018

9:36

How

does

the

seismic

structure

of oceanic

lithosphere

change

with

age?

4/17/2018

9:34

mid

ocean

magnetic

sensors

4/17/2018

9:31

Study

of earthquake

sources

4/17/2018

9:29

What is

the

true

nature

of undersea

marine

plateaus, e.g., Ontong

Java

Plateau, Hess

Rise,

3/22/2018

4:44

Shatsky

Rise, Kerguelen

Plateau, etc?

They

are

thought to

large

outpourings

of mantle

derived

magma, but Korenaga

(2011) concluded

that Ontong

Java

could

not easily

made

with

one

stage

partial melt of Earth's

mantle.

stage

of further igneous

or metamorphic

reprocessing

required.

This

means

that the

velocity

layering

of Ontong

Java

important, e.g.,

frozen

melt layers

or multiple

Moho

interfaces.

Tharimena

et al. (2016) claims

detect a

mid

lithospheric

discontinuity

within

Ontong

Java

with

precursors.

At Kerguelen, Pettersen

and

Maupin

(2002)

interpret surface

wave

polarization

anomalies

terms

of pervasive

anisotropy

within

this

marine

plateau. So

need

worry

about detecting

anisotropy

the

oceanic

plateau

structure

well.

detect anisotropic

layering

robustly

with

receiver functions, we

will need

at least a

100

good

body

wave

coda. The

experience

of Leahy

et al (2010) on

the

Hawaii Swell OBS

deployment was

that 10

good

receiver functions

could

gleaned

from

year deployment.

Assuming

that

improved

siting

and

data

analysis

can

increase

this

yield

events

years, we

would

want to

install the

stations

years.

Korenaga, J. (2011), Velocity

depth

ambiguity

and

the

seismic

structure

of large

igneous

provinces: a

case

study

from

the

Ontong

Java

Plateau,

Geophys. J. Int.,

185, 1022

–

1036, doi:10.1111/j.1365

246X.2011.04999.x.

Leahy, G. M., J. A.

Collins, C. J. Wolfe, G. Laske, and

S. C. Solomon

(2010), Underplating

of the

Hawaiian

Swell:

Evidence

from

teleseismic

receiver functions, Geophys. J. Int., 183, 313

–

329,

doi:10.1111/j.1365

246X.2010.04720.x.

Pettersen, O., and

V. Maupin, (2002), Lithospheric

anisotropy

the

Kerguelen

hotspot track

inferred

from

Rayleigh

wave

polarisation

anomalies, Geophys. J. Int., 149,

225

–

246,

doi:10.1046/j.1365

246X.2002.01646.x.

Tharimena, S., C. A. Rychert, and

N. Harmon

(2016), Seismic

imaging

of a

mid1744

lithospheric

discontinuity

beneath

Ontong

Java

Plateau,

Earth

and

Planetary

1745

Science

Letters, 450, 62

70.

Long

term

Seafloor instruments

could

potentially

help

improve

distance

range

and/or azimuthal

3/19/2018

11:56

gaps

for studying

specific

deep

mantle/core

structure

and

or core

anisotropy

while

improving

the

amount of data

the

regional distance

ranges

while

completing

the

azimuthal gap

for

important/specific

events/regions.

RESPONSES

DATE

Mapping

the

structure

of plumes

from

the

CMB

the

seafloor.

3/19/2018

10:00

what does

tremor in

subduction

zone

settings

signify

3/15/2018

6:17

Seismic

structure

below

Pacific

and

Atlantic

oceans

3/14/2018

10:51

The

nature

of major hotspots, and

their underlying

structure. Geochemistry

making

new

3/14/2018

3:59

advances

this

area, and

high

pressure

science

getting

better at interpreting

what is

going

at depth. But we

still lack

crucial seismic

constraints

owing

limited

coverage. Deployments

around

the

Hawaiian

islands

or Iceland, for example, help

reveal shallow

mantle

structure

and

support a

mantle

plume

origin

but leave

deeper questions

unanswered

such

how

deep

the

plume

rooted, or what detailed

structure

exists

between

what is

imaged

the

CMB

region

and

the

shallow

mantle?

Small arrays

could

used

illuminate

the

deeper structure

of plumes

from

one

direction, by

placing

them

the

opposite

side

of a

hotspot from

active

seismic

sources. For

example, park

small array

further north

of Hawaii and

use

the

sources

Tonga

Fiji to

reveal

deeper structure

(especially

the

shallow

lower mantle). Then

move

it to

the

of Hawaii to

illuminate

it with

Japan

Kamchatka

seismic

radiation. And

on.

How

get high

fidelity

ocean

bottom

seismic

records

seems

the

most relevant

question

3/14/2018

12:10

(probably

not the

most important, but necessary).

What are

the

dominant length

scales

of mantle

convection, and

the

relationship

of the

convection

3/14/2018

12:03

mantle

melting

and

compositional heterogeneity?

Potentially

improve

the

resolution

of tomographic

seismic

anomalies, especially

the

lower

3/14/2018

9:52

mantle, for regions

where

ray

coverage

poor (e.g. lower hemisphere). SKS

splitting

measurements

and

receiver function

studies

can

also

proposed

and

help

identify

and/or

constrain

mantle

discontinuities

and

heterogeneities

the

whole

mantle.

CMB

Structure

Properties

3/14/2018

9:42

enhancing

global mantle

flow

models

3/14/2018

9:42

1) Providing

accurate

locations

of subduction

earthquakes, most networks

are

land

and

this

3/14/2018

8:33

may

make

locations

skewed

and

biased.

2) Providing

data

regions

of the

Earth

where

land

stations

not sample. 3) Oceanic

lithospheric

ridge

structure

Detailed

subduction

plate

geometry

and

tremor 5) Outer ridge

seismicity

and

its

relationship

the

earthquake

cycle

How

are

earthquake

cycles

at oceanic

transform

faults

controlled

the

thermal and

compositional

3/14/2018

8:22

structures

and

far

field

stress

loading?

earthquake

dynamic

near the

trench

3/14/2018

7:42

I can

not answer that, I am

not familiar that much

of what is

the

situation

at the

moment,

3/14/2018

7:35

regarding

the

OBS

instrumentation.

There

are

still many

places

Earth

that still need

studied

detail with

respect to

trench

3/14/2018

7:31

subduction, roll

back, and

oblique

kinematics.

What is

the

fate

of the

subducting

slab

along

highly

curved

arcs?

For instance, the

Puerto

Rico

trench, a

place

highly

studied

the

60's

and

regarded

one

of the

first laboratories

for testing

developing

marine

geophysical equipment back

then,

have

not seen

much

happening

since

those

early

days

when

Harry

Hess

visited

those

areas.

Now,

after 30

years

of seismic

catalogs, we

are

able

define

regions

of peculiar seismicity

that is

still

intriguing

and

have

not been

focused

with

expensive

studies

understand

it further.

The

same

thing

happens

with

other parts

of the

world, for

example, The

Scotia

and

Sunda

Arcs, having

extremeley

curved

morphological expressions.

What is

the

heat flux

carried

plumes

3/14/2018

3:06

If earthquakes

occur in

the

mantle

3/14/2018

2:22

Improving

data

coverage

the

oceans

for global tomography

(and/or studies

of the

Earth's

3/14/2018

2:14

interior) where

huge

gaps

currently

exist

LAS

structure

Subduction

system

(w/ geodesy) Oceanic

LIP

3/13/2018

9:40

What is

the

origin

of along

strike

variations/segmentations

of spreading

centers/mid

ocean

ridges,

3/13/2018

8:47

which

are

the

places

where

the

new

oceanic

lithosphere

produced?

Understanding

oceanic

counterparts

of continental mantle

and

crustal structures

imaged

via

direct

3/13/2018

8:44

wave

observations, receiver function

analysis, and

seismic

tomography.

Depth

dependent seismogenesis

Improvement of parameters

of offshore

earthquakes

3/13/2018

8:33

what time

scale

does

Earth's

inner core

rotation

independent from

the

mantle?

3/12/2018

5:38

Deep

structure

of hot spot plumes.

3/12/2018

4:38

seismic

wavefom

intercept from

underground

explosion

source

ddmonstrated

problem

solved

3/7/2018

8:26

1. Collecting

data

that is

needed

for imaging

structures

the

mid

mantle

and

lower mantle.

Deter-

mine

the

cause

of the

India

Geoid

low.

3. Find

where

the

Indian

lithosphere

located

the

mid

and

lower mantle.

Mid

mantle

reflections

(discontinuities) and

dynamic

processes

the

mid

mantle.

3/7/2018

11:14

I don't feel comfortable

answering

this

question, there

are

likely

many

worthy

challenges

ad-

dress, from

understanding

subduction

zone

dynamics

and

deep

earth

structure

detailed

studies

of MOR

and/or hotspots.

3/7/2018

3:55

elucidation

of the

lithosphere

asthenosphere

system

beneath

the

ocean

3/7/2018

12:23

high

resolution

structure

of the

oceanic

lithosphere

asthenosphere

structure

3/6/2018

3:14

Lithospheric

studies

3/6/2018

12:54

Data

from

seafloor seismometers

would

improve

the

resolution

of both

the

elastic

and

anelastic

struc-

ture

of the

mantle.

3/6/2018

12:15

Improvement of hypocentres

for small

magnitude

earthquakes

(up

M5) located

away

from

conti-

nental landmasses.

3/6/2018

11:23

Can

global models

of seismic

anisotropy

trusted?

The

isotropic

component of seismic

velocity

ap-

pears

broadly

consistent between

models, but the

anisotropic

component

has

not proven

reliable.

3/6/2018

11:03

What are

the

dynamics

of the

oceanic

plates?

Are

they

dominated

traction

from

mantle

flows, or

ridge

push

and

slab

pull?

3/6/2018

10:43

Characterizing

propagation

for land

based

events

into

the

seafloor for OBS

observation. Array de-

sign

optimize

SNR

the

noisy

marine

environment.

3/6/2018

10:28

deployment in

the

Indian

Ocean

can

useful for investigating

structure

near the

CMB

and

ICB

re-

lated

heat transport across

these

boundaries

and

the

geodynamo.

3/6/2018

10:12

Structure

of the

lower mantle, informing

how

the

mantle

convects

3/6/2018

9:23

Dynamics

of the

Earth's

lower mantle.

3/6/2018

8:01

pattern

and

engine

of mantle

convection

3/6/2018

8:01

seismicity

of oceanic

dorsals

3/6/2018

7:13

Better resolution

of the

deep

structure

of the

Earth

3/6/2018

7:07

upper mantle

structure

3/6/2018

6:31

globally

distributed

and

independent of a

specific

tectonic

setting

(e.g., the

middle

of abyssal plain

seafloor setting

works

fine).

dependent on

particular tectonic

setting

for sampling

structure

directly

below

or near the

station

(e.g., near a

specific

mid

ocean

ridge

or subduction

zone

location).

dependent

particular geographic

location

for characterizing

earthquake

source

rupture

physics.

45.31%

40.62%

14.07%

ANSWER

CHOICES

RESPONSES

Total

Respondents:

55;

Total

Responses:

than

months.

at least 4

years.

at least 8

years.

ANSWER

CHOICES

Total

Respondents:

55;

Total

Responses:

RESPONSES

22.03%

55.93%

22.03%

100%

80%

60%

40%

20%

less

than

few

tens

seconds

several

weeks

sec-

onds.

days.

months,

or longer are

OK.

less

than

few

seconds.

tens

of seconds

days.

several weeks

months, or longer are

OK.

8.93%

21.43%

69.64%

ANSWER

CHOICES

RESPONSES

Total

Respondents:

55;

Total

Responses:

100%

80%

60%

40%

20%

even

possible

within

the

full 0

360

degree

range.

highly

uneven

distribution

OK.

does

not matter.

ANSWER

CHOICES

Total

Respondents:

55;

Total

Responses:

RESPONSES

45.76%

28.81%

25.42%

(0.05

1.0

sec)

0.2

( 0.2

sec)

0.033

0.33

sec)

0.008

0.2

120

sec)

0.0025

0.2

360

sec)

10.00%

37.00%

22.00%

18.00%

13.00%

ANSWER

CHOICES

RESPONSES

Total

Respondents:

55;

Total

Responses:

100

100%

80%

60%

40%

20%

sps

100

sps

200

sps

27.78%

37.04%

25.93%

9.26%

ANSWER

CHOICES

RESPONSES

Total

Respondents:

54:

Total

Responses:

ambient vibration

noise.

earthquake

body

waves.

surface

waves

and/or normal modes.

ANSWER

CHOICES

Total

Respondents:

54;

Total

Responses:

118

RESPONSES

27.12%

42.37%

30.51%

Total

Respondents:

42;

Total

Responses:

accelerometer

absolute

or differential

pressure

gauge

temperature

or other environmental sensor

ANSWER

CHOICES

RESPONSES

23.19%

47.83%

28.99%