Intensity attenuation with distance for large subduction earthquakes: a
perspective based on earthquake ground effects from the 16 April
2016, Mw 7.8 Pedernales Earthquake (Ecuador).
Franz Livio, K. Chunga, M.F. Ferrario, A.M. Michetti, M. Mulas, F. Ochoa-Cornejo, D. Besenzon.
The
Apr.
16, 2
016
Pede
rnal
es e
arth
quak
e (M
w7.
8)
Earthquake-induced
EnvironmentalEffects (EEEs)Primary – coastaluplift;
Secondary - ground cracks, mass movements, lateral spreading,liquefactionphenomena, hydrologicalanomalies, tsunamis, and earthquake lights
Are EEEs and damages scaling similarly
with distance?
Papanikolaou et al 2009 (Geol. Soc. of London Sp. Publ. 316)
Pyrgos 1993 Ms 5.5 Kythira 2006 (Mw 6.7)
Murindo (Colombia),17 and 18 Oct. 1992 (Ms 6.6; Ms 7.3)Mosquera-Machado et al. 2009
- How traditional intensity scales and EEEs relate each other?- Same conclusions for continental vs subduction large earthquakes?- How to exactly integrate the two datasets?
Workflow1 - Data collection and treatment• EEEs• Traditional intensity data (EMS-98)
2 - Macroseismic field• ESI-07• EMS-98
3 - Collection of a reference dataset and attenuationanalysis• Instrumental earthquakes with good source parameters and
macroseismic fields
4 - Comparison of the reference dataset with EMS-98 and ESI-07
5 - An integrated macroseismic field and validationwith the reference earthquakes
Data collectionand analysis
1 - Data collection
2 - Macroseismic field
3 - referencedataset 4 – Comparison
5 - An integratedmacroseismic
field
Foto esempio da supplementary
Earthquake Intensity macroseismic field
1 - Data collection
2 -Macroseismic
field3 - reference
dataset 4 – Comparison5 - An integrated
macroseismic field
298 point observations(sites) – original data integrated with GEER-ATC, 2016
Grouping into ca. 50 IDPs(localities)
Hand-drawing of isoseismals
ESI-07
IGEPN original data; USGS and Colombian Geological Survey(«Did you feel it» questionnaire)
Grouping into 98 IDPs
Hand drawing of isoseismals
EMS-98 MM (Musson et al. 2010)
EMS-98
Ea
rthqu
ake
Inte
nsity
mac
rose
ism
ic fi
eld
EMS-98 ESI-07
Selecting and analyzing a set of referenceearthquakes
1 - Data collection
2 - Macroseismic field
3 -referencedataset
4 – Comparison5 - An integrated
macroseismic field
1 - Data collection
2 - Macroseismic field
3 -referencedataset
4 – Comparison5 - An integrated
macroseismic field
GIS analysis
- a GIS-based approach- IDPs number, distribution- Isoseismals as input data- Gridding (5x5 km)
- Distance statisticsfollowing Bakun and Wentworth (1997)
Intensity = 𝑎𝑎 − (𝑏𝑏 � 𝐷𝐷𝐷𝐷𝐷𝐷𝐷𝐷𝑎𝑎𝐷𝐷𝐷𝐷𝐷𝐷)
Intensity and epicentral distance
Intensity binning for a reference earthquake
(e.g., 1942 Mw 7.8)
0
100000
200000
300000
400000
500000
600000
700000
800000
900000
3 4 5 6 7 8 9 10
Dis
tanc
e(m
eter
s)
Intensity (MM)
1942 Mw 7.8
1 - Data collection
2 - Macroseismic field
3 - referencedataset
4 –Comparison
5 - An integratedmacroseismic
field
1 - Data collection
2 - Macroseismic field
3 - referencedataset 4 – Comparison
5 - An integrated
macroseismic field
Distance binning
Conclusions
1. The Pedernales earthquake produced a maximum intensity of IX ESI−07 along a 70-km-long coastal area.
2. As expected, we observed higher values for ESI-07 in the near field, whereas far-field intensity is well depicted by EMS-98 data.
3. We argue that this is mainly due to the improvement of building quality through time, resulting in a less vulnerable urban environment.
4. A merged database of EMS-98 + ESI-07 intensity data, depict a macroseismic field closer to a reference dataset, likely overcoming both the limitations of EMS-98 and ESI-07.
…further details and the
original datasets as supplementary material
Chunga et al., (2018) - BSSA
