EXPECTED SEISMIC ACTION IN ALMERIA AND …grupos.topografia.upm.es/sismo/data/2Poster2.pdfEXPECTED...
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EXPECTED SEISMIC ACTION IN ALMERIA AND GRANADA CITIES (SOUTHERN SPAIN) COMBINING REGIONAL- AND
LOCAL-SCALE INFORMATIONJ. M.Gaspar-Escribano1, B. Benito1, M. Navarro2, F. Vidal3
1 ETSI Topografía, Geodesia y Cartografía, Universidad Politécnica de Madrid, Spain2 Facultad de Ciencias, Universidad de Almería, Spain
3 Andalusian Institute of Geophysics, Granada University, Spain
A hybrid approach that relates results from a regional seismic hazard assessment study (SISMOSAN Project) with local-scale site-effect characterizations is presented (Figure 1). Results of a regional-scale probabilistic seismic hazard analysis ofSouthern Spain on rock conditions are disaggregated to infer hazard controlling earthquakes for different target motions. Acollection of controlling magnitude-distance pairs and the corresponding site-specific response spectra at main capital citiesof the region is obtained. These spectra are first-order approximations to expected seismic actions required in localearthquake risk assessments and earthquake resistant design.In addition, results of independent, local-scale studies mapping predominant soil periods of Almeria and Granada (SouthernSpain) are used to show areas where period-dependent resonant effects are likely to occur. Similarly, measurements ofbuilding vibration periods available in Granada city may be also used to anticipate buildings that are more prone to undergoresonant effects. In these cases, if a local seismic risk assessment study or an earthquake-resistant structural design is tobe developed, it is recommended to use different seismic actions on sites characterized by distinct predominant periods.
SUMMARY
Figure 1. Scheme of the proposed approach
1. REGIONAL - SCALE APPROACH (SISMOSAN PROJECT)
2. REGIONAL + LOCAL - SCALE APPROACH
ALMERIA
0.000.050.100.150.200.250.300.350.400.45
0.0 0.5 1.0 1.5 2.0Period (s)
SA (g
)
RockSoil II
CADIZ
0.00
0.05
0.10
0.15
0.20
0.25
0.30
0.35
0.40
0.0 0.5 1.0 1.5 2.0Period (s)
SA (g
)
SA RockSA Soil III
CORDOBA
0.00
0.05
0.10
0.15
0.20
0.25
0.30
0.35
0.0 0.5 1.0 1.5 2.0Period (s)
SA (g
)
SA RocaSA Suelo III
GRANADA
0.000.100.200.300.400.500.600.700.800.901.001.10
0.0 0.5 1.0 1.5 2.0Period (s)
SA
(g)
SA Rock
SA Soil IV-A
HUELVA
0.00
0.05
0.10
0.15
0.20
0.25
0.30
0.35
0.0 0.5 1.0 1.5 2.0Period (s)
SA (g
) SA RockSA Soil III
JAEN
0.000.050.100.150.200.250.300.350.400.45
0.0 0.5 1.0 1.5 2.0Period (s)
SA
(g)
SA RockSA Soil III
MALAGA
0.000.050.100.150.200.250.300.350.400.450.50
0.0 0.5 1.0 1.5 2.0Period (s)
SA
(g)
SA RockSA Soil III
SEVILLE
0.000.050.100.150.200.250.300.350.400.450.50
0.0 0.5 1.0 1.5 2.0Period (s)
SA (g
)
SA RockSA Soil IV-A
AlmeríaCádiz
Córdoba
GranadaHuelva
Jaén
Málaga
Sevilla
CITY TARGET MOTION (cm/s2 PR=475yrs)
Magnitude (Mw)
Distance (km)
ALMERIA PGA= 127 cm/s2 4.5-5.0 5-10 ALMERIA SA(0.2s)= 323 cm/s2 4.5-5.0 5-10 ALMERIA SA(0.5s)= 160 cm/s2 5.0-5.5 5-10 ALMERIA SA(1.0s)= 72 cm/s2 5.5-6.0 5-10 CADIZ PGA= 91 cm/s2 4.5-5.0 5-10 CADIZ SA(0.2s)= 231 cm/s2 4.5-5.0 5-10 CADIZ SA(0.5s)= 112 cm/s2 5.0-5.5 5-10 CADIZ SA(1.0s)= 60 cm/s2 5.5-6.0 5-10 CORDOBA PGA= 69 cm/s2 4.5-5.0 5-10 CORDOBA SA(0.2s)= 177 cm/s2 4.5-5.0 5-10 CORDOBA SA(0.5s)= 90 cm/s2 5.0-5.5 5-10 CORDOBA SA(1.0s)= 47 cm/s2 5.5-6.0 15-20 GRANADA PGA= 201 cm/s2 5.0-5.5 0-5 GRANADA SA(0.2s)= 506 cm/s2 4.0-4.5 0-5 GRANADA SA(0.5s)= 260 cm/s2 5.5-6.0 5-10 GRANADA SA(1.0s)= 112 cm/s2 5.0-5.5 5-10 HUELVA PGA= 70 cm/s2 4.0-4.5 5-10 HUELVA SA(0.2s)= 176 cm/s2 4.0-4.5 5-10 HUELVA SA(0.5s)= 87 cm/s2 5.0-5.5 5-10 HUELVA SA(1.0s)= 54 cm/s2 7.5-8.0 310-315 JAEN PGA= 97 cm/s2 4.5-5.0 5-10 JAEN SA(0.2s)= 247 cm/s2 4.5-5.0 5-10 JAEN SA(0.5s)= 127 cm/s2 4.5-5.0 5-10 JAEN SA(1.0s)= 60 cm/s2 5.5-6.0 5-10 MALAGA PGA= 113 cm/s2 4.5-5.0 5-10 MALAGA SA(0.2s)= 287 cm/s2 4.5-5.0 5-10 MALAGA SA(0.5s)= 146 cm/s2 5.0-5.5 5-10 MALAGA SA(1.0s)= 68 cm/s2 6.0-6.5 30-35 SEVILLE PGA= 71 cm/s2 4.5-5.0 5-10 SEVILLE SA(0.2s)= 180 cm/s2 4.5-5.0 5-10 SEVILLE SA(0.5s)= 69 cm/s2 5.0-5.5 5-10 SEVILLE SA(1.0s)= 50 cm/s2 6.0-6.5 25-30
Specific response spectra on soil conditions (M,D,ε)
0
100
200
300
400
500
600
700
800
900
0.0 0.5 1.0 1.5 2.0
Period (s)
SA
(cm
/s2 )
Almería (4.75, 7.5, 1.01)Cádiz (4.25, 7.5, 1.26)Córdoba (4.25, 7.5, 0.8)Granada (5.25, 2.5, -0.47)Huelva (4.25, 7.5, 0.82)Jaén (4.75, 7.5, 0.55)Málaga (4.75, 7.5, 0.81)Sevilla (4.25, 7.5, 0.85)
Specific response spectra on rock conditions (M,D,ε)
0
100
200
300
400
500
0.0 0.5 1.0 1.5 2.0
Period (s)
SA
(cm
/s2 )
Almería (4.75, 7.5, 1.01)Cádiz (4.25, 7.5, 1.26)Córdoba (4.25, 7.5, 0.8)Granada (5.25, 2.5, -0.47)Huelva (4.25, 7.5, 0.82)Jaén (4.75, 7.5, 0.55)Málaga (4.75, 7.5, 0.81)Sevilla (4.25, 7.5, 0.85)
GRANADA
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
0 0.5 1 1.5 2Period (s)
SA (g
)
UHS Soil (g)
SRS_PGA Soil (g)
SRS_SA0.2s Soil (g)
SRS_SA0.5s Soil (g)
SRS_SA1s Soil (g)
ALMERIA
0.0
0.1
0.2
0.3
0.4
0.5
0 0.5 1 1.5 2Period (s)
SA
(g)
UHS Soil (g)
SRS_PGA Soil (g)
SRS_SA0.2s Soil (g)
SRS_SA0.5s Soil (g)
SRS_SA1s Soil (g)
Regional-scale seismic hazard analysis on rockcondition (Benito et al., 2008), following the standardzonified method with a logic tree that accounts fordifferent zoning and attenuation models (Figure 2).
Figure 2. Seismic hazard map on rock conditions (SISMOSAN Project): Expected PGA for the 475-year return period
Regional-scale geotechnical classification map(Figure 3). Soils are sorted depending on their expectedamplification: I(A) stiffest material, lowest amplificationand IV(B) softest material, highest amplification .
Figure 3. Geotechnical amplification map (SISMOSAN Project)
Regional-scale seismic hazard assessment includingsoil amplification effects (Figure 4), resulting bymultiplying maps of Figures 2 and 3.
Figure 4. Seismic hazard map including soil amplification (SISMOSAN Project): Expected PGA for the 475-year return period
The uniform hazard spectra (UHS, 475-year return period)are derived from the regional-scale hazard study at capitalcities (Figure 5). These are approximate representations of theseismic action for risk studies or engineering applications.
Figure 5. UHS at capital cities on rock and soil conditions.
Hazard-controlling earthquakes for specific target motions are derived byhazard deaggregation (Table 1). These provide probabilistic earthquakescenarios that can be adapted to each site and expected target motion.Specific response spectra consistent with these controlling events may beobtained using the weighted combination of ground-motion model utilizedfor the direct hazard calculations (Figure 6). These SRS are hazard-consistent representations of seismic action particularised for a given siteand ground-motion level. Hence, SRS constitute a more refinedrepresentation of the seismic action than UHS for a given site and targetmotion (Gaspar-Escribano et al., 2008).
Figure 6. SRS at capital cities on rock and soil conditions for target motions equalling the expected PGA for the 475-year return period at each site.
Table 1. Controlling earthquakes for target motions expected for a 475-year return period.
ACKN
OW
LED
GEM
ENTS
: Th
e SI
SMO
SAN
Pro
ject
was
fina
nced
by
the
Gov
enm
ent o
f And
alus
ia (C
onse
jería
de
Gob
erna
ción
, Jun
ta d
e An
dalu
cía)
3. ALMERIA AND GRANADA SCENARIOSSome work on urban scale is already advanced in Almeria and Granada, where microtremor measurements, geotechnicalsoundings, Vs(30) measurements and (sub-) surface structural models are available and provide predominant period maps ofurban soils (Figure 7, Navarro et al., 2001, 2004). Moreover, measurements of fundamental vibration periods of buildings areavailable in Granada (Figure 9, Navarro et al., 2004).
Figure 9. Fundamental vibration period map of Granada.
Figure 8. SRS in Almeria (top) and Granada (bottom) for different hazard-consistent target motions.
Different SRS response spectra for different sitesof the city may be adopted depending on thehazard-consistent target motion considered(Figure 8).
Potential damaging scenarios, where soilpredominant periods and building vibration periodscoincide, may be anticipated. In such cases, it isrecommended to represent the seismic action bythe SRS corresponding to the hazard-consistenttarget motion of the same vibration period.
CONCLUSIONS
REF
EREN
CES
-Ben
ito, N
avar
ro, G
aspa
r-Esc
riban
o, V
idal
, Gón
gora
, Jim
énez
Peñ
a, G
arcí
a R
odríg
uez,
Pas
tor (
2008
). S
eism
ic h
azar
d in
And
alus
ia re
gion
(Sou
th S
pain
).
SIS
MO
SA
N P
roje
ct. 1
4WC
EE,
Bei
jing
-Gas
par-E
scrib
ano,
Ben
ito, G
arcí
a-M
ayor
dom
o (2
008)
Haz
ard-
Con
sist
ent R
espo
nse
Spe
ctra
in th
e R
egio
n of
Mur
cia
(SE
Spa
in).
Bul
l. E
arth
quak
e E
ng.,
6, 1
79-1
96.
-Nav
arro
, Eno
mot
o, S
anch
ez, M
atsu
da, I
wat
ate,
Pos
adas
, Luz
ón, V
idal
, Seo
(200
1). S
urfa
ce s
oil e
ffect
s st
udy
usin
g sh
ort-p
erio
d m
icro
trem
or o
bser
vatio
ns in
A
lmer
ia C
ity, S
outh
ern
Spa
in. P
ure
App
l. G
eoph
ys.,
158,
2481
-249
7.-N
avar
ro, V
idal
, Fer
iche
, Eno
mot
o, S
anch
ez, M
atsu
da (2
004)
. Exp
ecte
d gr
ound
–RC
bui
ldin
g st
ruct
ures
reso
nanc
e ph
enom
ena
in G
rana
da C
ity (S
outh
ern
Spa
in).
13
WC
EE, V
anco
uver
, Pap
er N
o. 3
308
CO
NTA
CT:
ETSI
Top
ogra
fía, G
eode
sia
y C
arto
graf
ía,
Uni
vers
idad
Pol
itécn
ica
de M
adrid
, SPA
IN
jgas
par@
topo
graf
ia.u
pm.e
s+
34
9133
6644
1
- The transition from regional- to local-scale seismic hazard assessment isattained by designing probabilisticearthquake scenarios by means of hazarddeaggregation.
- Specific response spectra correspondingto the controlling events may be used torepresent the seismic action in local-scalestudies.
- At municipal scale, the superposition ofpredominant soil period maps andbuilding vibration period maps helpsidentifying areas where resonant effectsmay be expected. Ad hoc SRS for thesescenarios may be adopted for planning ordesign purposes.
-This approach is specially suitable forlow-to-moderate seismic areas, where thedata quality required to perform more-detailed seismic hazard assessmentanalyses is very difficult to reach.Figure 7. Predominant period maps of
Almeria (top) and Granada (bottom).
1
2
3
+ =
Regional-scale seismichazard mapping of
Andalusia
Hazard-consistent, period-dependent response
spectra
• Hazard dissagregation
• Controlling earthquakes
• Specific Response Spectra
• Local-scale weak-motion measurements
• Vs(30) measurements
• (Sub-)surfacestructural model
Urban zonation in termsof predominant soil
periods
WORST-CASE SCENARIOS IN ALMERIA AND GRANADA
Building fundamental vibration periods