BRIEFING ON THE M 6.0 SOUTH NAPA EARTHQUAKE Ben Brooks
USGS Earthquake Science Center, Menlo Park
Berkeley'
San'Jose'
San'Francisco'Oakland'
Menlo'Park'
Napa'Sonoma'
Santa'Rosa'
• 3:20'AM,'Sunday'24'August''• West'Napa'Fault'Mw'6.0,'11.3'km'depth''• 1898'M'6.3'near''Mare'Island''• 2000L09L03'M5.1''Yountville'earthquake''• >'>'$100M'damage''• InterLagency'response'cooperaSon/coordinaSon''
Green Valley!
source: Brad Aagaard!
Timeline Ezra%Brooks,%~3:24%am%
First&Human&
“We’re%a%li7le%ahead%of%the%curve%here%in%Northern%California”%%C%South%Park,%Ep.%1002%
EEW Performance
Shake Alert
• Hypocentral%Error:%<%~%3km%• Magnitude%Error:%<%0.2%within%11%s%of%origin%• Network%approach:%4%staPons%required%%for%alert%%• 3%of%4%triggering%staPons%would%have%been%faster%%if%upgraded%• Size%of%the%“zone%of%no%warning”%is%a%choice%based%%on%alert%thresholds.%
• VariaPon%in%data%transmission%latency%was%from%0.27s%(BK.CVS)%%to%2.62s%(NC.%NHC).%If%all%staPons%had%same%latency%as%BK.CVS%the%alert%could%have%been%out%in%half%the%Pme.%
source: Doug Given, Richard Allen!
Ground Motion
source: Brad Aagaard!
Shorter'duraSon'of'strong'shaking'at'N016'compared'to'NHC'is'consistent'with'northward'direcSvity'
DisSnct'pulses'with'separaSon'in'Sme'**independent'of'distance'from'the'rupture**'suggest'more'source'complexity'(i.e.,'two'asperiSes)'than'preliminary'rupture''models'indicate.'
Shake%Map%Fire%staPon%45%g%PGA%87%cm/s%PGV%
Main%street%Napa%64%g%PGA%34%cm/s%PGV%
Carquinez%bridge%98%g%PGA%22%cm/s%PGV%
Data%from%ShakeMap;%%ASK14=Abrahamson%et%al,%2014;%BSSA14=Boore%et%al,%2014%
1 10 100
10−4
10−3
10−2
0.1
1 PGA [g]
Distance [km]
PGA
[g]
East ComponentNorth ComponentAverage ComponentASK14 GMPEBSSA14 GMPE
Ground Motion
source: Annemarie Baltay!
'PGA'shows'small'residuals/typical'ground'moSons'at'close'distances,'implying'a'typical'stress'drop'consistent'with'the'NGAWest'data'(~'5'MPa).'N'components'larger'(true'at'all'periods),'consistent'with'the'direcSvity.'At'farther'distances,'a_enuaSon'in'the'napa/delta'region'is'stronger'than'GMPEs'predict.'Might'not'be'a'big'surprise,'since'the'NGA'west'GMPEs'are'created'with'data'that'is'sparser'in'NorCal'than'SoCal,'so'a_enuaSon'might'be'different.''
100 101 102
10−4
10−3
10−2
10−1
100
PGA [g]
Distance [km]
PGA
[g]
East ComponentNorth ComponentAverage ComponentASK14 GMPEBSSA14 GMPE
100 101 102
−3
−2
−1
0
1
2
ln residuals PGA
Distance [km]
ln re
sidu
al
BSSA residualASK residual
38.5° N
39.0° N
123.0° W 122.5° W 122.0° W 121.5° W 37.5° N
38.0° N
ln re
sidu
al
−2
−1.5
−1
−0.5
0
0.5
1
PGA%residuals%from%%ASK2014%GMPE%
Shake%Map%Fire%staPon%45%g%PGA%87%cm/s%PGV%
Main%street%Napa%64%g%PGA%34%cm/s%PGV%
Carquinez%bridge%98%g%PGA%22%cm/s%PGV%
Data%from%ShakeMap;%%ASK14=Abrahamson%et%al,%2014;%BSSA14=Boore%et%al,%2014%
1 10 100
10−4
10−3
10−2
0.1
1 PGA [g]
Distance [km]
PGA
[g]
East ComponentNorth ComponentAverage ComponentASK14 GMPEBSSA14 GMPE
Ground Motion
source: Annemarie Baltay!
'The'psa1.0'second'map'shows'strong'a_enuaSon'to'the'north,'but'also'a'possible'wave'guide'to'the'south'along'the'older'franklin/Southampton'fault'system.''In'both'the'PGA'and'psa1.0's'map,'and'the'distance'vs'PGA'plot,'you'can'see'the'few'staSons'pointed'out'on'the'shake'map'with'large'ground'moSons.'
100 101 102
10−4
10−3
10−2
10−1
100
PSA 1.0 seconds [g]
Distance [km]
PSA
[g]
East ComponentNorth ComponentAverage ComponentASK14 GMPEBSSA14 GMPE
100 101 102
−3
−2
−1
0
1
2
ln residuals PSA 1.0 seconds
Distance [km]
ln re
sidu
al
BSSA residualASK residual
38.5° N
39.0° N
123.0° W 122.5° W 122.0° W 121.5° W 37.5° N
38.0° N
ln re
sidu
al
−2
−1.5
−1
−0.5
0
0.5
1
PSA%1.0%s%residuals%from%ASK14%GMPE%
ï���Ý ï���Ý
��Ý
��Ý
0 50
km
.
���PP�������������2%6(59('���PP�������������2%6(59('Campaign sitescGPS sites
StaSc'displacements'nearly'double'ader'first'day'
P261%
source: Fred Pollitz!
GPS Geodesy
Fault Trace
InSAR: Cosmo-Skymed (x-band, ~3cm)
source: Andrea Donnellan!
• Cosmo-Skymed: X (~3cm) • Sentinel 1-A: C (~5cm) • UAVSAR: L (~20 cm)
Finite Fault Models
source: Doug Dreger!
source: Fred Pollitz,!Jessica Murray!
source: Bill Barnhart!
Triggered slip on Green Valley fault?
source: Ross Stein & Jian Lin!
Surface Rupture
7'km'
source: Dan Ponti%
source: Tim Dawson% source: Tim Dawson%source: Dan Ponti%
Pre-existing Scarp
Ron%Rubin,%Tim%Dawson%(CGS)%in%the%trench%at%Alston%Park%~1%month%prior:%%“I%guess%we’ll%just%have%to%wait%for%an%earthquake%to%show%us%where%the%fault%is”%
%
%C%Napa%Watershed%Airborne%Lidar;%NCALM,%2003,%1%pt/m^2;%see%Open%Topo%C%New%acquisiPon,%DWR/CGS/USGS/PEER+GEER,%20%pr/m^2%–%ask%Hudnut%
Afterslip
8/24/2014 8/25/2014
source: Tim Dawson!
Afterslip: Saintsbury Winery
source: Dan Ponti!
8/24/2014
9/1/2014
1 2
3 4
1
2
3 4
Subsurface & Surface Slip Distribution
0
10
20
30
40
50
60
70
80
90
100
Offs
et (c
m)
source: Morelan, Trexler, Brooks, Hudnut, Lienkamper, Barnhart !
JPL/Caltech ARIA Rapid GPS
2 cm displacement
Epicenter
source: A. Donnellan!
UAVSAR
UAVSAR & Surface Rupture
Fault trace interpretation from Dan Ponti
Red dots show locations of mapped offsets identified by USGS
source: Andrea Donnellan!
400#m#
75#m#
Mobile Laser Scanning
Legacy Airborne LiDAR Datasets PLENARY PRESENTATIONS
16 | Southern California Earthquake Center
Differential L iDAR – a new tool for mapping coseismic fault-zone deformation , Edwin Nissen (CSM), J Ramon Arrowsmith (ASU), Adrian Borsa (UCSD), Craig Glennie (Terrapoint), Alejandro Hinojosa-Corona (CICESE), Tadashi Maruyama (JAMSTEC), and Michael Oskin (UC Davis) Tuesday, September 9, 2014 (14:00) The recent surge in airborne laser scanning along active faults in California and elsewhere provides high-resolution topographic baselines against which future, post-earthquake LiDAR datasets can be compared, equipping us with a powerful new tool for mapping coseismic rupture-zone deformation. Here, we showcase its rich potential using synthetic datasets derived from the southern California “B4” survey and real examples from earthquakes in Baja California and Japan to illustrate. Point-cloud differencing procedures based on the Iterative Closest Point algorithm or on cross-correlation techniques can determine the surface deformation field in 3 dimensions, complimenting conventional InSAR and pixel-tracking techniques which measure line-of-sight and horizontal displacement components only. A further advantage is that differential LiDAR retains coherence in the presence of steep displacement gradients, such as close to surface ruptures, and it is therefore well-suited for probing the slip distribution and mechanical properties of the shallow part of the fault zone. Challenges include the treatment of vegetation and the reliance on older, "legacy" LiDAR datasets – third party surveys which were not optimized for earthquake studies and for which important data acquisition and processing metrics may be unavailable. The 4 April 2010 El Mayor-Cucapah (Mexico) earthquake was the first complete rupture with both pre- and post-event LiDAR coverage, and its resultant 3-D displacement field is used to explore whether significant slip occurred on low-angle detachment faults, as has been postulated by some field geologists. The 11 April 2011 Fukushima-Hamadori (Japan) normal-faulting earthquake is the second such example, and was studied with support from the Virtual Institute for the Study of Earthquake Systems (VISES), a joint initiative between SCEC and the Earthquake Research Institute and Disaster Prevention Research Institute of Japan. Here, coherent differential LiDAR displacements within the interior part of the fault zone are used to help bridge a critical observational gap between surface faulting offsets (observed in the field) and slip occurring at depths of a few kilometers (inferred from InSAR modelling). Near-fault displacements and rotations are consistent with decreased primary fault slip at very shallow depths of a few 10s of meters, possibly accounting for the large, along-strike heterogeneity in field measurements of surface offset.
Plenary Talk Presentation Wednesday
The IDEA Model: A Practical Tool for Designing Effective Early Earthquake Warning Messages , Deanna Sellnow (U Kentucky) and Tim Sellnow (U Kentucky) Wednesday, September 10, 2014 (08:30) The right message at the right time saves lives. These words are certainly true for early earthquake warnings. In this session, we will describe how we derived the IDEA model from the principles of effective risk and crisis communication, highlight some of the research we have done to inform our work, and explain how we are now using the model to design early earthquake warning messages to be delivered in 10 seconds or less on a smart phone app. We will also summarize the studies we have employed and conclusions drawn from them since beginning our work with the USGS SAFFR group July 2013. We will then engage in a Q&A discussion regarding next steps in research and development for rolling out the early earthquake warning app., as well as questions focusing on risk and crisis communication in general.
2003%AIRBORNE:%1%pt/%m^2%MLS:%500C1000%pt/%m^2%ALSCMLS%
Structure From Motion source: Mike Oskin!
source: Kate Scharer!
RelocaPons%with%tomoDD%(Zhang'and'Thurber,%2003):%3D%velocity%model%(Hardebeck'et'al.,%2007)%%+%relaPve%relocaPon.%
Black%lines:%projecPon%of%planes%fit%to%locaPons,%OADC%algorithm%(Ouillon'et'al.,%2008).%%
Black%line:%plane%intersecPon.%%
Aftershock Locations
source: Jeanne Hardebeck!
Aftershock Relocation
source: David Shelly!
While%the%oneCweek%aoershock%counts%for%the%South%Napa%event%are%relaPvely%low%,%there%is%a%fair%amount%of%variability%even%among%just%the%N.%CA%mainshocks.%%Magnitude%distribuPons%(leo)%show%relaPvely%similar%bCvalues%among%the%N.%CA%earthquakes%,%which%are%low%compared%to%the%S.%CA%earthquakes.%
Event# M# N(M≥1.8)# N(M≥4)# Mmaxa6#
2014#South#Napa# 6# 70# 0# 3.9#
2004%Parkfield% 6% 243% 6% 5%
1984%Morgan%Hill% 6.2% 102% 0% 3.85%
1980%Livermore%Valley%
5.8% 300% 7% 5.4%
1979%Coyote%Lake% 5.8% 77% 2% 4.3%
2000%Yountville% 5% 9% 0% 2.57%
1992%Joshua%Tree% 6.1% 1880% 9% 4.47%
1986%Palm%Springs% 5.7% 1153% 6% 4.3%
Aftershock Comparison
source: Andrea Llenos, David Schwartz!
• 1947%Manix:%ML%6.5,%6km%rupture;%shallow%
• 1975%Galway%Lake;%ML%5.0%6.8%km%rupture,%5.8km%depth%• 1987%Elmore%Ranch;%Mw%6.2,%10%km%rupture,%10.6km%%
source: Andy Lutz!
Coulomb Grape Stress
