Content uploaded by Iunio Iervolino
Author content
All content in this area was uploaded by Iunio Iervolino on Mar 17, 2023
Content may be subject to copyright.
1
PRELIMINARY ENGINEERING REPORT ON
GROUND MOTION DATA OF THE FEB. 2023
TURKEY SEISMIC SEQUENCE
Georgios Baltzopoulos,1 Roberto Baraschino,2 Eugenio Chioccarelli,3 Pasquale Cito,1 Antonio Vitale,1
Iunio Iervolino1,4 (iunio.iervolino@unina.it)
Warning: This report was based on data available on Feb. 24th 2023 and may be subjected to editing and
revisions as new data become available.
Index
1. Introduction ......................................................................................................................................................1
2. Evolution of the seismic sequence so far ..........................................................................................................3
3. The ground motion at a regional scale ..............................................................................................................6
4. Near-source ground motions ..........................................................................................................................12
5. Investigation for pulse like features ................................................................................................................37
6. Final remarks ..................................................................................................................................................54
7. Data and resources ..........................................................................................................................................54
8. Acknowledgements ........................................................................................................................................55
9. References ......................................................................................................................................................55
1. Introduction
On Feb. 6th 2023, at 1.17 UTC (local time 4:17 AM, UTC+3) a major earthquake whose moment magnitude was
estimated at M7.7 according to AFAD (see Data and resources) struck Turkey and nearby Syria. It started a seismic
sequence of hundreds of recorded earthquakes of magnitude larger than three and featured another event M7.6
(i.e., comparable to the first shock) and one M6.7. The area hit by the sequence, which extends over several
hundreds of square kilometers, is located in the south-eastern part of Turkey, close to Syria, part of which was also
affected by the shaking. This area, together with the North-Anatolian fault system and the western part of the
country, are the most seismically hazardous according to probabilistic seismic hazard assessment. In Figure 1, the
long-term seismic hazard in terms of peak ground acceleration (PGA) on rock with exceedance return period (
r
T
) equal to 476yr, according to a recent probabilistic seismic hazard assessment for Europe (ESHM20, Danciu et
1
Università degli Studi di Napoli Federico II, Italy.
2
Studio SPERI, Naples, Italy.
3
Università degli Studi Mediterranea di Reggio Calabria, Italy.
4
IUSS – Scuola Superiore Universitaria di Pavia, Italy.
Cite as: Baltzopoulos G., Baraschino R., Chioccarelli E., Cito P., Vitale A., Iervolino I. (2023) Preliminary engineering report
on ground motion data of the Feb. 2023 Turkey seismic sequence V3 – 17/03/2023.
2
al., 2021), is displayed, together with the rectangle framing the zone affected by the sequences. Figure 2 shows
the historical earthquakes in the area according to the catalog of Zare et al. (2014).
Figure 1. Seismic hazard map in terms of PGA with 475yr exceedance return period on rock soil condition and zone
subjected to the sequence (framed by rectangle).
Figure 2. Historical earthquakes in the area struck by the sequence according to the catalog of Zare et al. (2014).
Table 1 reports the coordinates of the epicenters of the three main events of the sequence, the hypocentral depth,
and the fault mechanism. On Feb. 7th, thirty-five hundred fatalities were reported (https://en.afad.gov.tr/press-
bulletin-about-the-earthquake-in-kahramanmaras-basin-bulteni-10); this number has grown sixfold in less than
five days, with about twenty thousand fatalities reported by Al-Jazeera
(https://www.aljazeera.com/news/liveblog/2023/2/10/turkey-syria-earthquake-live-news-death-toll-exceeds-
21000).
3
Table 1. Essential data about the four largest magnitude events in the sequence (data from EPOS; see Data and resources).
Date
Time
(UTC)
Magnitude
Long. [°]
Lat. [°]
Depth [km]
Mechanism*
06-02-2023
01:17:36
7.8 or 7.7
37.08
37.17
20
Strike-Slip
06-02-2023
01:28:19
6.7 or 6.6
36.81
37.13
40
Strike-Slip
06-02-2023
10:24:49
7.5 or 7.6
37.24
38.11
10
Strike-Slip
20-02-2023
17:04:29
6.3 or 6.4
36.16
36.02
10
-
* For now, based on fault models from literature (Gülerce et al., 2017).
This preliminary report aims at illustrating the main features of the sequence as recorded so far. In particular, the
recorded earthquakes in terms of magnitude, time and location are illustrated in the next section. Also, the ground
motion intensity, in terms of PGA, estimated by the USGS (see Data and Resources section) via ShakeMap (v4.0)
(Wald et al., 1999) for the M6.0+ events of the sequence, are compared to the ESHM20 hazard map to assess the
fraction of the country that has possibly experienced exceedance of the PGA from the considered map. Then, the
rest of the document focuses on the earthquakes in Table 1. Section 3 shows the attenuation with distance of peak
ground motion intensity for all of them, including a comparison with a ground motion prediction equation (GMPE)
calibrated for the region in question. Section 4 provides the elastic spectra and Husid plots for the ten recorded
ground motions closest to the epicenter of the event, for each earthquake. Finally, Section 5 investigates pulse-like
features. Some concluding remarks summarize the findings, although it should be noted that this is a live document
eventually updated as soon as more data become available (check document version).
Authors did not find coherency of all data from AFAD, as explained below, yet cannot explain these issues, at the
moment. Moreover, they cannot ascertain whether the displayed signals and derived information are from
instruments that operated correctly during the events.
2. Evolution of the seismic sequence so far
On Feb. 6th 2023, at 1:17 UTC (4:17 local time, UTC+3), a M7.7 (or M7.8, depending on data source) earthquake
struck Turkey’s Giazantep province. This event triggered a sequence numbering about two thousand eight-hundred
earthquakes above magnitude two, that had been recorded up to Feb. 22th (included), that is, about seven events
per hour, on average. The epicenters of the earthquakes within the sequence are shown in Figure 3 (top), while
Figure 3 (bottom) represents the trend of the sequence in the considered time interval (data were derived from
EPOS, see Data and resources).
In both panels, the size and color of the markers vary with the earthquake magnitude. The event initiating the
sequence is the largest magnitude one so far (commonly acknowledged as the mainshock), that is, no foreshocks
can be attributed to the sequence according to available data. About ten minutes after the mainshock, and at less
than 25 km away from its epicenter, a M6.7 event occurred. Data reveal that, in the first hour of the sequence,
eight earthquakes with magnitude above five were recorded. For a measure of comparison, the same number of
M5.0+ events was recorded during five months of the long-lasting 2016-2017 central Italy seismic sequence
(Iervolino et al., 2021a).
Back to the Turkish sequence, about one-hundred sixty events, most of which with magnitude below five, were
recorded up to 10:24 (UTC) of Feb. 6th. Then, the second strongest event of the sequence, M7.5, occurred about
one 100 km north of the mainshock, followed by five M5.0+ in the next ninety minutes. At this point, according
to recorded data, Tukey has been hit by about one-hundred eighty earthquakes, two of which with magnitude larger
4
than seven, in less than half a day. Starting from 12:00 (UTC) of Feb. 6th, sixteen earthquakes with magnitude
equal to or larger than five were recorded up to 14:20 (UTC) of Feb. 8th. The magnitude of the events recorded in
the next twelve days, about eighteen hundred in number, keeps below five. Then, on Feb. 20th, at 17:04 (UTC), a
M6.3 (M6.4, according to AFAD) earthquake occurred in the Turkey-Syria border region, about 150 km away
from the mainshock location according to the epicenter locations from EPOS, reported in Table 1. Data reveal that
the largest magnitude of the following events is 4.3, with most of them being below three, at least until the end of
Feb. 22th.
Figure 3. Evolution of the sequence in terms of location of recorded earthquakes up to Feb. 22th (top); evolution of the sequence
in terms of magnitude vs time of recorded earthquakes up to Feb. 22th (bottom).
In Figure 4, the evolution of the seismic sequence is compared with the expected value of aftershocks per day
provided by the modified Omori law (Utsu, 1961) with the parameters of Reasenberg & Jones (1989). The
considered earthquakes are those with magnitude equal or larger than 4 that occurred up to 22/02/2023 (included).
5
Figure 4. Comparison between the M4+ occurred events and the expected number of events per day according to the
modified Omori law with parameters calibrated on Californian data.
In the following, the fraction of the country that has possibly experienced at least one exceedance of the PGA with
476
r
T yr=
from the ESHM20 hazard map, due to the M6.0+ events of the sequence, is quantified. To do so, the
PGAs estimated by ShakeMap for the events of interest were enveloped (i.e., Iervolino et al., 2021b) and compared
to the values from the considered hazard map. In quantifying the exceedance area, the latter PGA values were
adjusted for the soil site conditions as accounted for by ShakeMap, via soil-specific coefficients provided by the
GMPE adopted by ESHM20, that is, the model of Kotha et al. (2020). Also, because such GMPE considers the
geometric mean of the two horizontal components of ground motion, hazard thresholds were adjusted for the
largest component, which is the metric used by ShakeMap, according to Beyer & Bommer (2006).
The envelope and the sought exceedance area, including that estimated for
50
r
T yr=
and
2500
r
T yr=
(the
hazard map, for these return periods, is not shown for the sake of brevity) are represented in the maps at the top
and bottom, respectively, of the central column in Figure 5. In fact, the leftmost and rightmost panels represent the
effect of ShakeMap uncertainty on the exceedance area. More specifically, the maps on the left were derived by
enveloping the ShakeMap for the M6.0+ events after having subtracted (in the logarithmic space) the value
representative of the uncertainty (provided by ShakeMap), while those on the right were obtained by enveloping
ShakeMap data with uncertainty being added.
The envelope maps show that, according to ShakeMap, the largest ground motion intensities are in proximity of
the areas hit by the M6.0+ events. For example, the largest PGA, equal to about 1.1g, is found in the Gaziantep
province, at about 35 km from the mainshock epicenter; however, at the same site, the inclusion of ShakeMap
uncertainty allows us reporting that the largest PGA of the sequence (due to the M6.0+ events, in fact) is in the
0.69g-1.60g range. The maps of the exceedance area show that the exceedance of the PGA from the ESHM20
hazard map has possibly occurred in different provinces, especially for
50
r
T yr=
and
476
r
T yr=
, while it
significantly reduces in the case of
2500
r
T yr=
, as expected.
6
Figure 5. ShakeMap envelopes for the M6.0 events of the sequence (top); maps of the area subjected to at least one
exceedance of the PGA from the ESHM20 hazard map (bottom). From left to right, the value representative of ShakeMap
uncertainty is: subtracted to ShakeMap estimates, not subtracted, added.
The estimated exceedance areas, normalized with respect to the area covered by the whole Turkey are given in
Table 2. In the table, lower and upper bounds denote the areas calculated when ShakeMap uncertainty values are
subtracted and added, respectively, to ShakeMap estimates. It can be seen that the fraction of the country exposed
to exceedance decreases by at least one order of magnitude when moving from one return period to another. In the
case of
50
r
T yr=
, it is in the 7.3%-21% range; for
476
r
T yr=
, the upper bound does not exceed 6%. Finally, for
2500
r
T yr=
, the lower bound of the exceedance area approaches to zero, while the upper bound is even (slightly)
smaller than 1%.
Table 2. Fraction of the country possibly exposed to exceedance of the PGA from the ESHM20 hazard map due to the M6.0
events of the sequence.
Exceedance area
Lower bound [%]
Estimated [%]
Upper bound [%]
50
r
T yr=
7.3
12.4
21.0
476
r
T yr=
0.2
1.5
5.9
2500
r
T yr=
0.01
0.1
0.9
3. The ground motion at a regional scale
The PGA of the horizontal recorded ground motions were computed from a set of the acceleration time-histories
recorded during the M7.7 event and available at AFAD
5
(see Data and resources). Such values are compared with
the mean (plus/minus one standard deviation) of the GMPM of Bommer et al., 2012 that is developed for Europe
and Middle East region. To allow such a comparison, the Joyner and Boore distance
( )
jb
R
was computed with
5
The data used here were directly available in tabular format. In the same website, the recorded ground motions are available.
Although there does not seem to be complete accordance between tabulated PGAs and those obtained from the accelerograms,
the ground motion records were not used to produce this plot, which relies on the AFAD tables.
7
respect to the source model provided by USGS (see Data and Resources section). The resulting comparison is
shown in Figure 6. The figure is divided in three panels in which the comparison for rock soil (shear wave velocity
in the upper 30m or
30s
V
is larger than 750 m/s), soft soil (
30s
V
≤360 m/s) and stiff soil (360<
30s
V
≤750m/s) is
reported, respectively.
Records from seventy stations were considered, those characterized by the highest PGA. Among those, 6 refer to
rock, 15 to soft soil, 34 to stiff and 15 were neglected because the
30s
V
was unknown. Shown data are from the
stations represented in Figure 7. Plots show a general agreement between recorded data and the GMPE results.
Figure 6. Comparison between PGA and Bommer et al. (2012) referring to, from left to right, rock soil, soft soil and stiff
soil data recorded during the M7.7 earthquake.
Figure 7. Maps of the stations providing the PGA values used in the previous figures.
Some of the ground motions recorded during the first earthquake (M7.7) are compared with the GMPE of Akkar
& Bommer (2010), according to the modified parameters of Bommer et al. (2012b). More specifically, for each
considered recording station, the acceleration response spectra of the two horizontal components, as provided by
the AFAD website, were combined to compute the geometric mean of each spectra acceleration ordinate, that is
the ground motion intensity measure considered by the cited GMPE. The resulting spectrum is compared with the
median spectrum (identified as
e
in the legend) provided by the GMPE. Moreover, the exponential values of the
logarithmic mean plus and minus one standard deviation (total) are also shown (
e
+
and
e
−
, respectively).
The GMPE is applied with respect to the Joiner and Boore distance that, for each station, was computed with
8
respect to the preliminary source model provided by USGS (see Data and Resources section). It should be noted
that the upper bound of the magnitude range of the GMPE is 7.6.
In the following figures, on the left the station location with respect to the rupture is shown together with the
network and the station codes, the computed
jb
R
and
30s
V
(data from stations with unknown
30s
V
are not
considered); on the right, the spectra from the GMPE and the geometric mean of those recorded.
Figure 8. Station location and acceleration response spectra for station 2703 (left) and 2704 (right).
Figure 9. Station location and acceleration response spectra for station 2707 (left) and 2708 (right).
9
Figure 10. Station location and acceleration response spectra for station 2709 (left) and 3134 (right).
Figure 11. Station location and acceleration response spectra for station 3137 (left) and 3138 (right).
Figure 12. Station location and acceleration response spectra for station 3143 (left) and 3144 (right).
10
Figure 13. Station location and acceleration response spectra for station 3145 (left) and 4611 (right).
Figure 14. Station location and acceleration response spectra for station 4615 (left) and 4616 (right).
Figure 15. Station location and acceleration response spectra for station 4617 (left) and 4618 (right).
11
Figure 16. Station location and acceleration response spectra for station 4620 (left) and 4621 (right).
Figure 17. Station location and acceleration response spectra for station 4624 (left) and 4625 (right).
Figure 18. Station location and acceleration response spectra for station 4629 (left) and 4630 (right).
12
Figure 19. Station location and acceleration response spectra for station 4632 (left) and 8002 (right).
Figure 20. Station location and acceleration response spectra for station 8003 (left) and 8004 (right).
4. Near-source ground motions
This section provides a graphical overview of the available near-source accelerometric data. Table 3 reports station
code for the M7.7 earthquake, the coordinates, PGA for two horizontal and one vertical components, and epicentral
distance, of the ten stations which recorded the highest values of the PGA. Figures from Figure 21 to Figure 28
show husid plot and 5% damping acceleration and displacement elastic spectra for all the stations. Table 4 and
Table 5 report data for the M6.6 and M7.6 events, respectively. Once again data refer to the ten recording stations
closer to the epicenter. From Figure 32 to Figure 41 and Figure 42 to Figure 51 show husid plot and 5% damping
acceleration elastic spectra for the stations under investigation for the two events respecitvely. It can be seen that
all these events produced actions which can challenge structures. It is interesting to note that large epicentral
distances do not always correspond to strong attenutation, likely due to the size of the ruptures.
It also be highlighted that there are some apparent discrepanciers between the tabulated values and the plotted
spectra. Because this report was prepared using an intermittent flow of data, involving updates and retractions, the
authors are not yet in a position to explain all such discrepancies at the time of writing. Similarly, authors are not
in the position to warrant that alla data plotted correspond to correct function of the recording instruments.
13
Table 3. Data of ten closest recording stations for the M7.7 event.
Code
Longitude
[°]
Latitude
[°]
PGA_NS
(cm/s2)
PGA_EW
(cm/s2)
PGA_UD
(cm/s2)
Repi
[km]
0201
38.27
37.76
276.12
375.25
202.48
120.12
2708
36.65
37.10
1294.82
914.31
675.08
40.77
3125
36.13
36.24
772.67
1072.01
1055.47
142.15
3126
36.14
36.22
1186.84
999.06
945.74
143.54
3129
36.13
36.19
1347.19
1205.87
709.75
146.39
3135
35.88
36.41
741.06
1314.69
574.88
142.15
3137
36.49
36.69
425.60
747.26
446.23
82.48
3141
36.22
36.37
991.76
835.76
668.26
125.42
3142
36.37
36.50
635.64
735.76
470.08
106.49
14
Figure 21. Time-history (upper left), Husid plot (upper right), 5% damping acceleration (bottom left) and displacement
(bottom right) spectra for the three components of the recorded ground motion.
Figure 22. Time-history (upper left), Husid plot (upper right), 5% damping acceleration (bottom left) and displacement
(bottom right) spectra for the three components of the recorded ground motion.
15
Figure 23. Time-history (upper left), Husid plot (upper right), 5% damping acceleration (bottom left) and displacement
(bottom right) spectra for the three components of the recorded ground motion.
Figure 24. Time-history (upper left), Husid plot (upper right), 5% damping acceleration (bottom left) and displacement
(bottom right) spectra for the three components of the recorded ground motion.
16
Figure 25. Time-history (upper left), Husid plot (upper right), 5% damping acceleration (bottom left) and displacement
(bottom right) spectra for the three components of the recorded ground motion.
Figure 26. Time-history (upper left), Husid plot (upper right), 5% damping acceleration (bottom left) and displacement
(bottom right) spectra for the three components of the recorded ground motion.
17
Figure 27. Time-history (upper left), Husid plot (upper right), 5% damping acceleration (bottom left) and displacement
(bottom right) spectra for the three components of the recorded ground motion.
Figure 28. Time-history (upper left), Husid plot (upper right), 5% damping acceleration (bottom left) and displacement
(bottom right) spectra for the three components of the recorded ground motion.
18
Figure 29. Time-history (upper left), Husid plot (upper right), 5% damping acceleration (bottom left) and displacement
(bottom right) spectra for the three components of the recorded ground motion.
In the end, the KHMN station derived from the ESM database (see Data and resources) for this event is also added
in Figure 30. At the time of the analysis of this record the event considered was given magnitude 7.8. This is the
NAR station according to AFAD.
Figure 30. Spectra and ground motion of the KHMN station as provided by the ESM database. This is the NAR station
according to AFAD.
AFAD also contained one record with one component with PGA>1g, while the others much lower. It appeared
from the signal that the recording could be affected by some problems and it was not included herein. Moreover,
the record from station 4614, shown in Figure 31, was removed from the AFAD website on Feb 7th. It is included
in this report for completeness only.
19
Figure 31. The very large spectrum of station 4614, which was removed from the data for the M7.7 event on Feb. 7th 2023.
It is included for completeness but it is not considered reliable.
Table 4. Data of ten closest recording stations for the M6.6 event.
Code
Longitude
[°]
Latitude
[°]
PGA_NS
(cm/s2)
PGA_EW
(cm/s2)
PGA_UD
(cm/s2)
Repi
[km]
2708
36.65
37.10
309.44
353.98
211.30
33.12
2712
36.73
37.18
432.22
338.42
331.08
21.27
2718
36.63
37.01
221.14
309.23
128.72
41.97
3123
36.16
36.21
140.19
175.43
62.06
138.82
3125
36.13
36.24
359.20
210.94
122.99
137.72
3126
36.14
36.22
202.45
300.51
109.62
139.22
3129
36.13
36.19
137.06
231.57
54.92
142.17
4616
36.84
37.38
234.00
264.39
149.39
10.74
4620
36.90
37.59
159.03
241.44
83.78
31.38
4624
36.92
37.54
146.34
181.37
78.98
25.81
20
Figure 32. Time-history (upper left), Husid plot (upper right), 5% damping spectral acceleration (bottom left) and
displacement (bottom right) spectra for the three components of the recorded ground motion.
Figure 33. Time-history (upper left), Husid plot (upper right), 5% damping spectral acceleration (bottom left) and
displacement (bottom right) spectra for the three components of the recorded ground motion.
21
Figure 34. Time-history (upper left), Husid plot (upper right), 5% damping spectral acceleration (bottom left) and
displacement (bottom right) spectra for the three components of the recorded ground motion.
Figure 35. Time-history (upper left), Husid plot (upper right), 5% damping spectral acceleration (bottom left) and
displacement (bottom right) spectra for the three components of the recorded ground motion.
22
Figure 36. Time-history (upper left), Husid plot (upper right), 5% damping spectral acceleration (bottom left) and
displacement (bottom right) spectra for the three components of the recorded ground motion.
Figure 37. Time-history (upper left), Husid plot (upper right), 5% damping spectral acceleration (bottom left) and
displacement (bottom right) spectra for the three components of the recorded ground motion.
23
Figure 38. Time-history (upper left), Husid plot (upper right), 5% damping spectral acceleration (bottom left) and
displacement (bottom right) spectra for the three components of the recorded ground motion.
Figure 39. Time-history (upper left), Husid plot (upper right), 5% damping spectral acceleration (bottom left) and
displacement (bottom right) spectra for the three components of the recorded ground motion.
24
Figure 40. Time-history (upper left), Husid plot (upper right), 5% damping spectral acceleration (bottom left) and
displacement (bottom right) spectra for the three components of the recorded ground motion.
Figure 41. Time-history (upper left), Husid plot (upper right), 5% damping spectral acceleration (bottom left) and
displacement (bottom right) spectra for the three components of the recorded ground motion.
25
Table 5. Data of ten closest recording stations for the M7.6 event.
Code
Longitude
[°]
Latitude
[°]
PGA_NS
(cm/s2)
PGA_EW
(cm/s2)
PGA_UD
(cm/s2)
Repi
[km]
0129
36.21
38.26
150.38
168.71
82.82
91.84
0131
36.12
37.86
404.24
325.03
84.52
101.83
0141
35.53
37.56
77.99
191.35
74.93
161.28
3802
36.50
38.48
193.07
217.69
119.79
77.41
4405
37.94
38.81
147.58
151.57
125.32
100.81
4406
37.97
38.34
444.75
382.47
284.86
70.17
4408
37.89
38.10
45.60
128.07
262.36
56.74
4409
37.49
38.56
252.05
193.85
85.90
56.86
4612
36.48
38.02
627.18
520.66
430.19
66.68
4614
37.30
37.49
160.59
197.56
80.15
67.35
26
Figure 42. Time-history (upper left), Husid plot (upper right), 5% damping spectral acceleration (bottom left) and
displacement (bottom right) spectra for the three components of the recorded ground motion.
Figure 43. Time-history (upper left), Husid plot (upper right), 5% damping spectral acceleration (bottom left) and
displacement (bottom right) spectra for the three components of the recorded ground motion.
27
Figure 44. Time-history (upper left), Husid plot (upper right), 5% damping spectral acceleration (bottom left) and
displacement (bottom right) spectra for the three components of the recorded ground motion.
Figure 45. Time-history (upper left), Husid plot (upper right), 5% damping spectral acceleration (bottom left) and
displacement (bottom right) spectra for the three components of the recorded ground motion.
28
Figure 46. Time-history (upper left), Husid plot (upper right), 5% damping spectral acceleration (bottom left) and
displacement (bottom right) spectra for the three components of the recorded ground motion.
Figure 47. Time-history (upper left), Husid plot (upper right), 5% damping spectral acceleration (bottom left) and
displacement (bottom right) spectra for the three components of the recorded ground motion.
29
Figure 48. Time-history (upper left), Husid plot (upper right), 5% damping spectral acceleration (bottom left) and
displacement (bottom right) spectra for the three components of the recorded ground motion.
Figure 49. Time-history (upper left), Husid plot (upper right), 5% damping spectral acceleration (bottom left) and
displacement (bottom right) spectra for the three components of the recorded ground motion.
30
Figure 50. Time-history (upper left), Husid plot (upper right), 5% damping spectral acceleration (bottom left) and
displacement (bottom right) spectra for the three components of the recorded ground motion.
31
Figure 51. Time-history (upper left), Husid plot (upper right), 5% damping spectral acceleration (bottom left) and
displacement (bottom right) spectra for the three components of the recorded ground motion.
On Feb. 20th 2023, at 5.04 UTC (local time 8:04 PM, UTC+3) a M6.4 earthquake according to AFAD rocked
Turkey’s province of Hatay and northern Syria. Table 6 reports station code, the coordinates, PGA for two
horizontal and one vertical components, and epicentral distance, of the ten stations which recorded the highest
values of the PGA. Figures from Figure 52 to Figure 61 show husid plot and 5% damping acceleration and
displacement elastic spectra for all the stations..
Table 6. Data of ten closest recording stations for the M6.4 event.
Code
Longitude
[°]
Latitude
[°]
PGA_NS
(cm/s2)
PGA_EW
(cm/s2)
PGA_UD
(cm/s2)
Repi
[km]
2716
36.69
36.86
54.62
36.00
27.15
98.51
3112
36.15
36.59
84.26
55.64
23.73
52.35
3115
36.16
36.55
109.00
117.27
73.81
47.99
3119
36.17
36.58
62.48
108.22
40.20
51.21
3124
36.17
36.24
406.01
445.02
219.80
15.78
3135
35.88
36.41
338.85
336.38
209.23
36.30
3136
36.25
36.12
299.55
218.67
134.73
15.57
3141
36.22
36.37
378.55
233.06
211.34
30.88
3142
36.37
36.50
38.26
47.72
27.78
49.42
3146
36.23
36.49
191.84
124.31
76.58
43.34
32
Figure 52. Time-history (upper left), Husid plot (upper right), 5% damping spectral acceleration (bottom left) and
displacement (bottom right) spectra for the three components of the recorded ground motion.
Figure 53. Time-history (upper left), Husid plot (upper right), 5% damping spectral acceleration (bottom left) and
displacement (bottom right) spectra for the three components of the recorded ground motion.
33
Figure 54. Time-history (upper left), Husid plot (upper right), 5% damping spectral acceleration (bottom left) and
displacement (bottom right) spectra for the three components of the recorded ground motion.
Figure 55. Time-history (upper left), Husid plot (upper right), 5% damping spectral acceleration (bottom left) and
displacement (bottom right) spectra for the three components of the recorded ground motion.
34
Figure 56. Time-history (upper left), Husid plot (upper right), 5% damping spectral acceleration (bottom left) and
displacement (bottom right) spectra for the three components of the recorded ground motion.
35
Figure 57. Time-history (upper left), Husid plot (upper right), 5% damping spectral acceleration (bottom left) and
displacement (bottom right) spectra for the three components of the recorded ground motion.
Figure 58. Time-history (upper left), Husid plot (upper right), 5% damping spectral acceleration (bottom left) and
displacement (bottom right) spectra for the three components of the recorded ground motion.
36
Figure 59. Time-history (upper left), Husid plot (upper right), 5% damping spectral acceleration (bottom left) and
displacement (bottom right) spectra for the three components of the recorded ground motion.
Figure 60. Time-history (upper left), Husid plot (upper right), 5% damping spectral acceleration (bottom left) and
displacement (bottom right) spectra for the three components of the recorded ground motion.
37
Figure 61. Time-history (upper left), Husid plot (upper right), 5% damping spectral acceleration (bottom left) and
displacement (bottom right) spectra for the three components of the recorded ground motion.
5. Investigation for pulse like features
This section covers a preliminary analysis of near-source ground motion waveforms from the three largest-
magnitude events of the sequence so far, which are investigated for potential pulse-like features. Pulse-like ground
motions are of particular engineering interest, as they exhibit peculiar spectral shape, characterized by narrowband
amplification for both elastic and inelastic spectra and known for imposing more severe inelastic demand on certain
structures than non-impulsive accelerograms, at least on average (Baez & Miranda, 2000; Iervolino et al., 2012;
Shahi & Baker, 2011). Perhaps the most notorious causes of impulsive ground motion waveforms, are certain so-
called near-source effects, such as rupture directivity or fling-step. Sites that are aligned with the direction of
rupture propagation along the fault may experience the near-simultaneous arrival of shear waves emitted from
different points on the rupture plane. This so-called directivity effect is conspicuously manifest in the ground
velocity time-history, where constructive wave interference can cause notable double-side pulses (Somerville et
al., 1997).
At this preliminary stage, lacking sufficient information on the finite-fault geometry of most events, the analysis
is limited to a characterization of certain near-source records as pulse-like based on the features of the ground
motion records alone, without circumspect consideration of the physical rupture process in relation to each
recording site’s location. In this sense, directivity can be considered as one of many possible causes of the
impulsive features detected in the records investigated.
Overall, ten records from each of the three considered shocks were included in this investigation, for a total of
thirty. Velocity time-histories were obtained via integration of the accelerometric series for both horizontal
components of motion, and the resulting vector was rotated over one-hundred and eighty degrees at a step of one
degree. For each orientation, a consolidated wavelet-based algorithm was applied to extract candidate pulse
waveforms from the velocity time series (Baker, 2007) and to assign a pulse indicator (PI) score to each one.
Ground motions were preliminarily characterized as pulse-like if they exhibited a consistently high score of
38
PI>0.90 over an arc of more than 60o, and also exhibited a satisfactory match of the pseudo-velocity spectra of the
ground motion and the candidate pulse wavelet, around the pulse period
P
T
(Baltzopoulos et al., 2020). In this
context, pulse period is defined as the pseudo-period of the highest-energy constituent Daubechies wavelet of the
candidate pulse.
Figure 62. Assumed fault plane and pulse indicator polarity for stations NAR and 4615 for the M7.7 shock.
This procedure led to the characterization of twenty-three as pulse-like for the M7.7 shock, out of the seventy
examined from that earthquake. Another four records were found to be pulse-like from the M7.6 and M6.6 shocks,
out of twenty records investigated from these events. The velocity time-histories of these records, rotated at the
orientation of the maximum PI score, are shown in the figures below. Two records from station codes NAR and
4615 from the M7.7 shock, whose velocity traces are shown Figure 65 and Figure 64, are of particular interest due
to their vicinity. Considering a preliminary estimate of finite fault geometry for the M7.7 rupture plotted below,
calculated by the USGS based on the moment tensor nodal plane and older fault mapping, that corresponds to
strike-slip faulting with a main segment exhibiting a strike angle of 52.0° and dipping at 80°, shows that the two
records are from nearby accelerometric stations that are both aligned with the presumed rupture propagation, both
along the strike and up-dip, thus apparently satisfying the theoretical premise and empirical expectation for rupture
directivity (Iervolino & Cornell, 2008). In fact, the two stations are only about 1800m apart, so the similar pulse
shape and period are not surprising at first glance. However, the polarity of the PI plots shown in the figure would
indicate that the NAR pulse-like velocity traces are more oriented towards the fault-parallel direction, while at
station 4615 towards the fault-normal.
34
°
E
35
°
E
36
°
E
37
°
E
38
°
E
39
°
E
40
°
E
35
°
N
36
°
N
37
°
N
38
°
N
39
°
N
Epicentre
Fault plane
NAR
Mediterranean Sea
4615
0.2
0.2
0.4
0.4
0.6
0.6
0.8
0.8
1.0
1.0
90
90
270
270
180
180 0
0
max PI orientation
max PI orientation
pulse indicator (PI) score
39
Figure 63. Velocity time-history recorded at NAR station during the M7.7 shock and extracted velocity pulse, with period
p
T
= 4.54s (azimuth of ground motion horizontal component 34o).
Figure 64. Velocity time-history recorded at station 4615 during the M7.7 shock and extracted velocity pulse, with period
p
T
= 5.17s (azimuth of ground motion horizontal component 157o).
All pulse periods identified are reported in the figures showing the velocity traces. The records from station 2708
were found to be pulse-like both during the M7.7 event and M6.6 event, but with shorter pulse period in the case
of the lower magnitude event (3.18s for M7.7 and 1.33s for M6.6), as theoretically expected for directivity-induced
pulses and reflected by regression models in the literature. For example, one such model would predict median
p
T
of 7.5s, 6.7s and 2.4s for M7.7, M7.6 and M6.6, respectively (Baltzopoulos et al., 2016). Figure 65 shows the
station locations where pulse-like ground motions were detected for the M7.7 event. In this context, it is also
noteworthy to comment on the consistently high-duration pulses of 7-9s found at stations 3137, 3138 and 3143,
which are also near to one-another. These pulses, being somewhat more one-sided than others of similar velocity
amplitude encountered here, could hint at some influence of fling-step effects.
The spectral pseudo-velocity (PSV), for the some of these impulsive ground motion components, are plotted in
Figure 89 onwards, along with the corresponding PSV of the wavelet-based extracted pulses. These figures show
that the extracted candidate pulses account for the local spectral shape around the peaks of the PSV, which is part
of the classification criterion as described above. Note that, for the most part, the identified pulse periods
p
T
are
close to the period of maximum PSV, denoted as
g
T
, as expected from earlier studies (Ruiz-Garcia, 2011). For
completeness, the same comparison of spectral shapes is performed for spectral displacements
( )
Sd
in the
remaining figures.
20 30 40 50 60 70 80
t (s)
-100
-50
0
50
100
Velocity (cm/s)
original signal
extracted pulse T
p=4.536s
20 30 40 50 60 70 80
t (s)
-100
-50
0
50
100
Velocity (cm/s)
original signal
extracted pulse T
p= . 6s516
40
Figure 65. Location of accelerometric stations where pulse-like ground velocity was detected during the preliminary
investigation of the M7.7 event’s records.
Figure 66. Velocity time-history recorded at station 2708 during the M7.7 shock and extracted velocity pulse, with period
p
T
= 3.18s (azimuth of ground motion horizontal component 113o).
35°N
36°N
37°N
38°N
39°N
35°E 36°E 37°E 38°E 39°E 40°E
Epicentre
2708
2715
2716
2718
3123
3125
3126
3129
3137
3138
3143
3145
4615
NAR
50 mi
50 km
Mediterranean Sea
Fault plane
extracted pulse
ground velocity
station location
direction of pulse-like component
3139
2712
3115
3116
3146
4616
4625
8002
50 55 60 65 70 75 80 85 90 95 100
t (s)
-150
-100
-50
0
50
100
150
Velocity (cm/s)
original signal
extracted pulse Tp
=3.178s
41
Figure 67. Velocity time-history recorded at station 2715 during the M7.7 shock and extracted velocity pulse, with period
p
T
= 6.72s (azimuth of ground motion horizontal component 90o).
Figure 68. Velocity time-history recorded at station 2718 during the M7.7 shock and extracted velocity pulse, with period
p
T
= 5.75s (azimuth of ground motion horizontal component 82o).
Figure 69. Velocity time-history recorded at station 3123 during the M7.7 shock and extracted velocity pulse, with period
p
T
= 2.62s (azimuth of ground motion horizontal component 22o).
20 25 35 40 45 50 55 60 65 7030 t (s)
-50
0
50
Velocity (cm/s)
original signal
extracted pulse T
p=6.72s
50 55 60 65 70 75 80 85 90 95 105100
t (s)
-100
-50
0
50
100
Velocity (cm/s)
original signal
extracted pulse Tp=5.754s
40 50 60 70 80 90 110 120100
t (s)
-150
-100
-50
0
50
100
150
Velocity (cm/s)
original signal
extracted pulse Tp=2.618s
42
Figure 70. Velocity time-history recorded at station 3125 during the M7.7 shock and extracted velocity pulse, with period
p
T
= 3.43s (azimuth of ground motion horizontal component 163o).
Figure 71. Velocity time-history recorded at station 3126 during the M7.7 shock and extracted velocity pulse, with period
p
T
= 3.28s (azimuth of ground motion horizontal component 168o).
Figure 72. Velocity time-history recorded at station 3129 during the M7.7 shock and extracted velocity pulse, with period
p
T
= 1.75s (azimuth of ground motion horizontal component 180o).
40 50 60 70 80 90 110 120100
t (s)
-100
-50
0
50
100
Velocity (cm/s)
original signal
extracted pulse Tp=3.43s
40 50 60 70 80 90 110 120100
t (s)
-100
-50
0
50
100
Velocity (cm/s)
extracted pulse Tp=3.276s
original signal
60 65 70 75 80 85 90 95 100
t (s)
-150
-100
-50
0
50
100
150
Velocity (cm/s)
extracted pulse Tp=1.75s
original signal
43
Figure 73. Velocity time-history recorded at station 3137 during the M7.7 shock and extracted velocity pulse, with period
p
T
= 9.14s (azimuth of ground motion horizontal component 158o).
Figure 74. Velocity time-history recorded at station 3138 during the M7.7 shock and extracted velocity pulse, with period
p
T
= 7.71s (azimuth of ground motion horizontal component 67o).
Figure 75. Velocity time-history recorded at station 3139 during the M7.7 shock and extracted velocity pulse, with period
p
T
= 2.97s (azimuth of ground motion horizontal component 14o).
40 50 60 70 80 90 110100
t (s)
-80
-60
-40
-20
0
20
40
60
80
Velocity (cm/s)
extracted pulse Tp=9.142s
original signal
40 50 60 70 80 90 100
t (s)
-150
-100
-50
0
50
100
150
Velocity (cm/s)
extracted pulse Tp=7.714s
original signal
40 50 60 70 80 90 100
t (s)
-150
-100
-50
0
50
100
150
Velocity (cm/s)
extracted pulse Tp=2.968s
original signal
44
Figure 76. Velocity time-history recorded at station 3143 during the M7.7 shock and extracted velocity pulse, with period
p
T
= 7.15s (azimuth of ground motion horizontal component 133o).
Figure 77. Velocity time-history recorded at station 3145 during the M7.7 shock and extracted velocity pulse, with period
p
T
= 4.2s (azimuth of ground motion horizontal component 71o).
Figure 78. Velocity time-history recorded at station 8002 during the M7.7 shock and extracted velocity pulse, with period
p
T
= 9.4s (azimuth of ground motion horizontal component 93o).
40 50 60 70 80 90 100
t (s)
-150
-100
-50
0
50
100
150
Velocity (cm/s)
extracted pulse Tp=7.154s
original signal
40 50 60 70 80 90 100
t (s)
-100
-50
0
50
100
Velocity (cm/s)
extracted pulse Tp=4.2s
original signal
30 40 50 60 70 80 90 100
t (s)
-40
-20
0
20
40
Velocity (cm/s)
extracted pulse T p=9.352s
origin al signal
45
Figure 79. Velocity time-history recorded at station 4625 during the M7.7 shock and extracted velocity pulse, with period
p
T
= 3.3s (azimuth of ground motion horizontal component 174o).
Figure 80. Velocity time-history recorded at station 4616 during the M7.7 shock and extracted velocity pulse, with period
p
T
= 8.0s (azimuth of ground motion horizontal component 119o).
Figure 81. Velocity time-history recorded at station 3146 during the M7.7 shock and extracted velocity pulse, with period
p
T
= 12.9s (azimuth of ground motion horizontal component 131o).
30 40 60 70 80 9050 t (s)
-80
-60
-40
-20
0
20
40
60
Velocity (cm/s)
extracted pulse T p=3.276s
origin al signal
20 30 40 50 60 70 80 90 100
t (s)
-100
-50
0
50
100
Velocity (cm/s)
extracted pulse T p=7.98s
origin al signal
30 40 60 70 8050 t (s)
-60
-40
-20
0
20
40
60
Velocity (cm/s)
extracted pulse T p=12.936s
original signal
46
Figure 82. Velocity time-history recorded at station 3116 during the M7.7 shock and extracted velocity pulse, with period
p
T
= 14.5s (azimuth of ground motion horizontal component 7o).
Figure 83. Velocity time-history recorded at station 3115 during the M7.7 shock and extracted velocity pulse, with period
p
T
= 14.4s (azimuth of ground motion horizontal component 108o).
Figure 84. Velocity time-history recorded at station 2717 during the M7.7 shock and extracted velocity pulse, with period
p
T
= 6.7s (azimuth of ground motion horizontal component 98o).
40 50 60 70 80 90 100
t (s)
-50
0
50
Velocity (cm/s)
extracted pulse T p=14.518s
original signal
30 40 50 60 70 80 90 110 120100
t (s)
-60
-40
-20
0
20
40
60
Velocity (cm/s)
extracted pulse T p=14.448s
origin al signal
30 40 50 60 70 80 90 100
t (s)
-60
-40
-20
0
20
40
60
Velocity (cm/s)
extracted pulse T p=6.72s
original signal
47
Figure 85. Velocity time-history recorded at station 4612 during the Mw7.6 shock and extracted velocity pulse, with period
p
T
= 5.75s (azimuth of ground motion horizontal component 151o).
Figure 86. Velocity time-history recorded at station 2708 during the Mw6.6 shock and extracted velocity pulse, with period
p
T
= 1.33s (azimuth of ground motion horizontal component 72o).
0 5 15 20 25 30 35 40 4510 t (s)
-150
-100
-50
0
50
100
150
Velocity (cm/s)
extracted pulse Tp=5.754s
original signal
0 5 15 20 25 30 3510 t (s)
-30
-20
-10
0
10
20
30
Velocity (cm/s)
extracted pulse Tp=1.33s
original signal
0 5 15 20 25 30 3510 t (s)
-20
-10
0
10
20
Velocity (cm/s)
extracted pulse Tp=1.876s
original signal
48
Figure 87. Velocity time-history recorded at station 2718 during the Mw6.6 shock and extracted velocity pulse, with period
p
T
= 1.88s (azimuth of ground motion horizontal component 75o).
Figure 88. Velocity time-history recorded at station 4616 during the Mw6.6 shock and extracted velocity pulse, with period
p
T
= 0.83s (azimuth of ground motion horizontal component 117o).
0 5 15 20 25 30 3510 t (s)
-20
-15
-10
-5
0
5
10
15
20
Velocity (cm/s)
extracted pulse Tp=0.826s
original signal
49
Figure 89. Comparison of pseudo-spectral velocity of the original ground motion and the extracted pulse (NAR station,
Mw7.7 shock, azimuth of horizontal component 34o).
Figure 90. Comparison of pseudo-spectral velocity of the original ground motion and the extracted pulse (station 4615,
Mw7.7 shock, azimuth of horizontal component 157o).
Figure 91. Comparison of pseudo-spectral velocity of the original ground motion and the extracted pulse (station 3126,
Mw7.7 shock, azimuth of horizontal component 168o).
0 1 3 4 5 6 72 T (s)
0
50
100
150
200
250
PSV (cm/s)
spectral pseudo-velocity of original signal, max at T
g=3.51s
spectral pseudo-velocity of extracted pulse with period T
p=4.536s
0 1 3 4 5 6 7 82 T (s)
0
50
100
150
200
250
PSV (cm/s)
spectral pseudo-velocity of original signal, max at Tg=4.03s
spectral pseudo-velocity of extracted pulse with period T
p=5.166s
0 1 3 4 5 6 7 82 T (s)
0
50
100
150
200
250
PSV (cm/s)
spectral pseudo-velocity of original signal, max at Tg=2.2s
spectral pseudo-velocity of extracted pulse with period T
p=3.276s
50
Figure 92. Comparison of pseudo-spectral velocity of the original ground motion and the extracted pulse (station 3129,
Mw7.7 shock, azimuth of horizontal component 180o).
Figure 93. Comparison of pseudo-spectral velocity of the original ground motion and the extracted pulse (station 3145,
Mw7.7 shock, azimuth of horizontal component 71o).
Figure 94. Comparison of pseudo-spectral velocity of the original ground motion and the extracted pulse (station 4612,
Mw7.6 shock, azimuth of horizontal component 151o).
0 1 3 4 5 6 7 82 T (s)
0
50
100
150
200
250
300
350
PSV (cm/s)
spectral pseudo-velocity of original signal, max at Tg=1.32s
spectral pseudo-velocity of extracted pulse with period T
p=1.75s
0 1 3 4 5 6 7 82 T (s)
0
50
100
150
200
250
300
PSV (cm/s)
spectral pseudo-velocity of original signal, max at Tg=3.14s
spectral pseudo-velocity of extracted pulse with period Tp=4.2s
0 1 3 4 5 6 7 8 92 T (s)
0
50
100
150
200
250
300
PSV (cm/s)
spectral pseudo-velocity of original signal, max at Tg=1.51s
spectral pseudo-velocity of extracted pulse with period Tp=5.754s
51
Figure 95. Comparison of pseudo-spectral velocity of the original ground motion and the extracted pulse (station 2708,
Mw6.6 shock, azimuth of horizontal component 72o)
Figure 96. Comparison of pseudo-spectral velocity of the original ground motion and the extracted pulse (station 2718,
Mw6.6 shock, azimuth of horizontal component 75o)
Figure 97. Comparison of pseudo-spectral velocity of the original ground motion and the extracted pulse (station 4616,
Mw6.6 shock, azimuth of horizontal component 117o).
0 0.5 1 2 2.5 3 3.5 41.5 T (s)
0
20
40
60
80
100
PSV (cm/s)
spectral pseudo-velocity of original signal, max at Tg=1.23s
spectral pseudo-velocity of extracted pulse with period Tp=1.33s
0 0.5 1 2 2.5 3 3.5 41.5 T (s)
0
10
20
30
40
50
60
PSV (cm/s)
spectral pseudo-velocity of original signal, max at T
g=1.66s
spectral pseudo-velocity of extracted pulse with period T
p=1.876s
0 0.5 1 2 2.5 3 3.5 41.5 T (s)
0
10
20
30
40
50
60
PSV (cm/s)
spectral pseudo-velocity of original signal, max at Tg=0.82s
spectral pseudo-velocity of extracted pulse with period Tp=0.826s
52
Figure 98. Comparison of spectral displacement of the original ground motion and the extracted pulse (NAR station, Mw7.7
shock, azimuth of horizontal component 34o).
Figure 99. Comparison of spectral displacement of the original ground motion and the extracted pulse (station 4615, Mw7.7
shock, azimuth of horizontal component 157o).
Figure 100. Comparison of spectral displacement of the original ground motion and the extracted pulse (station 3126,
Mw7.7 shock, azimuth of horizontal component 168o).
0 1 3 4 5 6 7 82 T (s)
0
20
40
60
80
100
120
Sd (cm)
spectral displacement of original signal
spectral displacement of extracted pulse with period Tp=4.536s
0 1 3 4 5 6 7 82 T (s)
0
50
100
150
200
Sd (cm)
spectral displacement of original signal
spectral displacement of extracted pulse with period Tp=5.166s
0 1 3 4 5 6 7 82 T (s)
0
20
40
60
80
100
120
140
Sd (cm)
spectral displacement of original signal
spectral displacement of extracted pulse with period T p=3.276s
53
Figure 101. Comparison of spectral displacement of the original ground motion and the extracted pulse (station 4612,
Mw7.6 shock, azimuth of horizontal component 151o).
Figure 102. Comparison of spectral displacement of the original ground motion and the extracted pulse (station 2708,
Mw6.6 shock, azimuth of horizontal component 72o).
Figure 103. Comparison of spectral displacement of the original ground motion and the extracted pulse (station 2718,
Mw6.6 shock, azimuth of horizontal component 75o).
0 1 3 4 5 6 7 8 92 T (s)
0
20
40
60
80
100
120
140
Sd (cm)
spectral displacement of original signal
spectral displacement of extracted pulse with period Tp=5.754s
0 1 3 4 5 6 7 82 T (s)
0
5
10
15
20
Sd (cm)
spectral displacement of original signal
spectral displacement of extracted pulse with period T
p=1.33s
0 1 3 4 5 6 7 82 T (s)
0
5
10
15
20
Sd (cm)
spectral displacement of original signal
spectral displacement of extracted pulse with period Tp=1.876s
54
Figure 104. Comparison of pseudo-spectral velocity of the original ground motion and the extracted pulse (station 4616,
Mw6.6 shock, azimuth of horizontal component 117o).
6. Final remarks
The sequence started with the M7.7 mainshock and counts about two thousand eight-hundred recorded earthquakes
in about two weeks. So far, the strongest events occurred in the first twelve hours, with data showing two M7.0+
events occurring 100 km from each other. Using ShakeMap data, including uncertainty, it was estimated that the
ground motion intensities, in terms of PGA, of the M6.0+ events caused at least one exceedance of the PGA from
the ESHM20 hazard map in a fraction of the country which is in the range 7.3%-21%, 0.2%-5.9% and 0.01%-
0.9% in the case of
50
r
T yr=
,
476
r
T yr=
and
2500
r
T yr=
, respectively. The three main events M7.7, M6.6,
and M7.6 have been preliminarily analyzed herein.
Recorded PGAs for the main event are generally in agreement with the results of a ground motion model.
The spectra of ten stations closest to the source show that all the main events produced actions generally
challenging for structures and that the epicentral distance, as it is well known, is not the best proxy for earthquake
whit large ruptures.
Investigation for pulse-like effect clearly identified near-source pulses, with pulses quite large with respect to those
natural of most structures, as expected for large magnitude events. Nevertheless, the attribution to these pulses to
rupture phenomena (e.g., forward directivity) can only be conducted in the wake of rupture models for the
considered events.
Finally, it should be noted that authors found some inconsistent information provided by AFAD about the same
recordings, and also cannot warrant that all signals used herein are from instruments properly working during the
events.
7. Data and resources
Ground motion records AFAD: https://tadas.afad.gov.tr/list-waveform (last accessed 18/02/2023 01:20 UTC).
EPOS earthquake data: https://seismicportal.eu/ (last accessed 23/02/2023 7:00 UTC).
ShakeMap data: https://earthquake.usgs.gov/earthquakes/map/ (last accessed 16/03/2023 11:00 UTC).
Probabilistic seismic hazard data: http://hazard.efehr.org/en/hazard-data-access/hazard-maps/ (last accessed
15/03/2023 17:00 UTC).
ESM Ground motion records: https://esm-db.eu/ (last accessed 07/02/2023).
0 1 3 4 5 6 7 82 T (s)
0
1
2
3
4
5
6
7
8
Sd (cm)
spectral displacement of original signal
spectral displacement of extracted pulse with period T
p=0.826s
55
Preliminary finite fault geometry from the USGS, (last accessed 08/02/2023 00:26:44 UTC):
https://earthquake.usgs.gov/earthquakes/eventpage/us6000jllz/finite-fault
The data used for the preparation of the various sections of the present report can be found as supplemental material
to this report on the Researchgate page of this report or can be asked to the corresponding author.
8. Acknowledgements
For data and the valuable insights, we would like to thank Lucia Luzi of the INGV.
9. References
Akkar, S., & Bommer, J. J. (2010). Empirical Equations for the Prediction of PGA, PGV, and Spectral
Accelerations in Europe, the Mediterranean Region, and the Middle East. Seismological Research Letters,
81(2), 195–206. https://doi.org/10.1785/gssrl.81.2.195
Baez, J. I., & Miranda, E. (2000). Amplification Factors to Estimate Inelastic Displacement Demands for the
Design of Structures in the Near Field. Proceedings of 12th World Conference on Earthquake Engineering.
Baker, J. W. (2007). Quantitative classification of near-fault ground motions using wavelet analysis. Bulletin of
the Seismological Society of America, 97(5), 1486–1501. https://doi.org/10.1785/0120060255
Baltzopoulos, G., Luzi, L., & Iervolino, I. (2020). Analysis of Near-Source Ground Motion from the 2019
Ridgecrest Earthquake Sequence. Bulletin of the Seismological Society of America, 110(4), 1495–1505.
https://doi.org/10.1785/0120200038
Baltzopoulos, G., Vamvatsikos, D., & Iervolino, I. (2016). Analytical modelling of near-source pulse-like seismic
demand for multi-linear backbone oscillators. Earthquake Engineering and Structural Dynamics.
https://doi.org/10.1002/eqe.2729
Beyer, K., & Bommer, J. J. (2006). Relationships between Median Values and between Aleatory Variabilities for
Different Definitions of the Horizontal Component of Motion. Bulletin of the Seismological Society of
America, 96, 1512–1522. https://doi.org/10.1785/0120050210
Bommer, J. J., Akkar, S., & Drouet, S. (2012a). Extending ground-motion prediction equations for spectral
accelerations to higher response frequencies. Bulletin of Earthquake Engineering, 10(2), 379–399.
Bommer, J. J., Akkar, S., & Drouet, S. (2012b). Extending ground-motion prediction equations for spectral
accelerations to higher response frequencies. Bulletin of Earthquake Engineering, 10(2), 379–399.
https://doi.org/10.1007/s10518-011-9304-0
Danciu, L., Nandan, S., Reyes, C., Basili, R., Weatherill, G., Beauval, C., Rovida, A., Vilanova, S., Sesetyan, K.,
Bard, P.-Y., Cotton, F., Wiemer, S., & Giardini, D. (2021). The 2020 update of the European Seismic Hazard
Model-ESHM20: Model Overview. https://doi.org/10.12686/a15
Gülerce, Z., Tanvir Shah, S., Menekşe, A., Arda Özacar, A., Kaymakci, N., & Önder Çetin, K. (2017). Probabilistic
Seismic‐Hazard Assessment for East Anatolian Fault Zone Using Planar Fault Source Models. Bulletin of
the Seismological Society of America, 107(5), 2353–2366. https://doi.org/10.1785/0120170009
Iervolino, I., Chioccarelli, E., & Baltzopoulos, G. (2012). Inelastic displacement ratio of near-source pulse-like
ground motions. Earthquake Engineering and Structural Dynamics. https://doi.org/10.1002/eqe.2167
56
Iervolino, I., Cito, P., Felicetta, C., Lanzano, G., & Vitale, A. (2021a). Exceedance of design actions in epicentral
areas: insights from the ShakeMap envelopes for the 2016–2017 central Italy sequence. Bulletin of
Earthquake Engineering, 19(13), 5391–5414. https://doi.org/10.1007/s10518-021-01192-z
Iervolino, I., Cito, P., Felicetta, C., Lanzano, G., & Vitale, A. (2021b). Exceedance of design actions in epicentral
areas: insights from the ShakeMap envelopes for the 2016–2017 central Italy sequence. Bulletin of
Earthquake Engineering, 19(13), 5391–5414. https://doi.org/10.1007/s10518-021-01192-z
Kotha, S. R., Weatherill, G., Bindi, D., & Cotton, F. (2020). A regionally-adaptable ground-motion model for
shallow crustal earthquakes in Europe. Bulletin of Earthquake Engineering, 18(9), 4091–4125.
https://doi.org/10.1007/s10518-020-00869-1
Montaldo, V., Faccioli, E., Zonno, G., Akinci, A., & Malagnini, L. (2005). Treatment of ground-motion predictive
relationships for the reference seismic hazard map of Italy. Journal of Seismology, 9(3), 295–316.
https://doi.org/10.1007/s10950-005-5966-x
Reasenberg, P. A., & Jones, L. M. (1989). Earthquake hazards after a mainshock in California. Science , 243(4895),
1173–1176.
Ruiz-Garcia, J. (2011). Inelastic displacement ratios for seismic assessment of structures subjected to forward-
directivity near-fault ground motions. Journal of Earthquake Engineering, 15(3), 449–468.
https://doi.org/10.1080/13632469.2010.498560
Shahi, S. K., & Baker, J. W. (2011). An empirically calibrated framework for including the effects of near-fault
directivity in probabilistic seismic hazard analysis. Bulletin of the Seismological Society of America, 101(2),
742–755. https://doi.org/10.1785/0120100090
Somerville, P. G., Smith, N. F., Graves, R. W., & Abrahamson, N. A. (1997). Modification of Empirical Strong
Ground Motion Attenuation Relations to Include the Amplitude and Duration Effects of Rupture Directivity.
Seismological Research Letters, 68(1), 199–222. https://doi.org/10.1785/gssrl.68.1.199
Utsu, T. (1961). A statistical study on the occurrence of aftershocks. Geophysical Magazine, 30, 521–605.
Wald, D. J., Quitoriano, V., Heaton, T. H., Kanamori, H., Scrivner, C. W., & Worden, C. B. (1999). TriNet
“ShakeMaps”: Rapid Generation of Peak Ground Motion and Intensity Maps for Earthquakes in Southern
California. Earthquake Spectra, 15(3), 537–555. https://doi.org/10.1193/1.1586057
Zare, M., Amini, H., Yazdi, P., Sesetyan, K., Demircioglu, M. B., Kalafat, D., Erdik, M., Giardini, D., Khan, M.
A., & Tsereteli, N. (2014). Recent developments of the Middle East catalog. Journal of Seismology, 18(4),
749–772. https://doi.org/10.1007/s10950-014-9444-1
