Citation: Hani, S. E., T. Hara, Y. Fujii (2023), Rapid determination of earthquake source parameters fortsunami early warning system for Egypt, Synopsis of IISEE-GRIPS Master’s Thesis.

RAPID DETERMINATION OF EARTHQUAKESOURCE PARAMETERS FOR TSUNAMI EARLYWARNING SYSTEM FOR EGYPT
Hani Saber ELBEHIRI1
MEE22711

Supervisor: Tatsuhiko HARA2*, Yushiro FUJII2**

ABSTRACT
Early warning systems in countries depend on how fast they can determine source parameters, especiallymagnitude. This study used SeisComP3 (SC3) to determine different magnitudes for 32 significant
earthquakes in the Mediterranean Sea. Different magnitudes (i.e., mb, Mwp, and mB) under different
computational times are compared with the Mww determined by the United States Geological Survey(USGS) for evaluation. Tsunami Travel Time (TTT) Software Package by ITIC was used to calculate
the tsunami wave arrival times on Egypt's coasts. The results obtained for mb confirmed the magnitude
saturation, especially for large earthquakes. We determined the relationship between Mww and Mwp
and between Mww and mB. We obtained Mw estimates from Mwp using the formula implemented in
SC3 and those using the relation of this study. Then, we evaluated the tsunami messages following theStandard Operational Procedures at different times and compared those for Mww from USGS. The
messages did not change much for the estimates from SC3 and those from the formula of this study. At
11 minutes after the origin times, for 28 events, the messages are accurate, and for 4 events, they are
under-estimates for both cases. For mB results at 11 minutes after the origin times, for 22 events, themessages are accurate, and for 10 events, they are false when the estimates from SC3 were used. The
number of false messages decreased to 6 when we applied the formula obtained by this study. These
results suggest that Mwp is more stable and accurate than mB. It takes more than 65 minutes for tsunamis
from the Hellenic and Cyprian arcs to reach the Egyptian coasts. Therefore, tsunami warnings around
11 minutes after the origin times are expected to be effective for tsunami countermeasures in Egypt.
Keywords: Tsunami Early Warning System (TEWS), Magnitude estimation, Mwp, mB, SeisComP3.
1. INTRODUCTION
The annual tsunami threat worldwide risks individuals and assets because violent and potent tsunamis
exact a heavy toll on humanity and infrastructure, devastating coastal areas. Egypt is in northern, eastern
Africa, boarded by the Red Sea from the east and the Mediterranean Sea from the north. The tsunamis
from the Mediterranean and Red Seas were recorded; the tsunami from the Red Sea is considered smaller
than that from the Mediterranean Sea. The Eastern Mediterranean (EM) is divided into the west and east
Hellenic arc, forming the Hellenic and the Cyprian arcs arranged from west to east (Tinti et al., 2005).
After the significant Ocean tsunami in India on December 26, 2004, and the World Conference on
Disaster Reduction in Kobe in 2005, the associated consequences were comprehensively analyzed andreviewed. Five national monitoring centers act as TSPs supporting the North-Eastern Atlantic and
1

National Research Institute of Astronomy and Geophysics (NRIAG), Egypt
International Institute of Seismology and Earthquake Engineering, Building Research Institute.
* Chief examiner, ** Examiner
2

1Mediterranean Tsunami Warning System (NEAMTWS) in cooperation with several task teams andtechnical working groups. By subscription, the focal points can receive tsunami alerts and warning
information. Egypt is one of the service recipients. This study investigates how to quickly and precisely
determine the earthquake source parameters (e.g., magnitude) as the first step in accomplishing atsunami early warning system for Egypt. We also compare different magnitude types that the NRIAG
might rely on to produce the first alert.
2. DATA
Many significant earthquakes in the Mediterranean Sea region produced tsunamis through theMediterranean coast. 32 significant earthquakes above 5.5 occurred in this region between 2012 and2022. The study area between 30° N and 38° N latitude and between 21° E and 36° E longitude wasselected for the automatic computation of the source parameters. These selected earthquakes were used
to check the SeisComP3 configuration and the magnitudes' computational time. The earthquake that
occurred on January 17, 2013, at 21:17:00 UTC with ~ Mb 4.9 magnitude was selected to test the
supposed travel time of the tsunami wave because it was the nearest earthquake to the Egyptian forecast
points at the Alexandria Station and Rashid town. With the SeisComP3 software, various configurations
were tested using different data sets. Initially, the data for this event list were archived through theFederation of Digital Seismograph Networks (FDSN) to be an SDS archive for many of the global
networks served by both the Incorporated Research Institutions for Seismology (IRIS) and the German
Research Centre for Geosciences (GFZ). Figure 1 depicts the globally configured stations used in
SeisComP3 (SC3, Olivieri & Clinton, 2012) for the automatic solution and source parametercomputation.

Figure 1. Distribution of seismic stations configured in SeisComP3.
3. METHODOLOGY
3.1. SeisComP3 Software
SC3 is an automatic earthquake solution tool developed for the German–Indonesian Tsunami Early
Warning System (GITEWS) project in the aftermath of the catastrophic 2004 Sumatra Tsunami
framework (Necmioğlu et al., 2021). SC3 exhibits a markedly modular architecture with developed
modules tailored for automated and interactive data processing. It integrates various essential
components, including versatile data acquisition capabilities, robust data quality control procedures, andefficient data archival systems. It also supports real-time data transfer protocols, automated algorithms
for precisely determining seismic event characteristics (e.g., location, depth, magnitudes, and rupture
parameters), advanced alerting mechanisms, and sophisticated visualization tools (Hanka et al., 2010).
This comprehensive integration facilitates comprehensive seismic data analysis and interpretation within
the scientific context of this work. SC3 can compute various magnitude types (i.e., ML, mb, mB,
Mw(mB), Mwp, Mw(Mwp), MLv, and Ms_20).

23.2. SeisComP3 Magnitude Determination
SC3 is used to detect earthquakes and determine hypocenters and magnitudes. The magnitudes analyzed
in this study are Mwp (Tsuboi et al., 1995), mB (Bormann & Saul., 2008), and mb (Gutenberg & Richter,1956). Mw(mB) is an estimate of moment magnitude from mB. The following conversion formula isimplemented
in
SC3.
(
SeisComP3,
Modules,
SCMAG,
https://docs.gempa.de/seiscomp3/current/apps/scmag.html):
Mw(mB) = 1.30 mB − 2.18

(1)

SC3 rapidly estimates the broadband moment magnitude (Mwp) from the first-arrival P
waves. The Mw(Mwp) is an estimate of moment magnitude from Mwp. The following conversion
formula is implemented in SC3.
Mw(Mwp) = 1.31 Mwp − 1.91

(2)

We used SC3 herein to estimate the different magnitude types and determine their
computational time and accuracy in detecting the most suitable magnitude type for our configuration.
The efficiency of an early warning system relies on both time and accuracy. Analyzing the previous
historical earthquakes in the Mediterranean Sea required SC3 playback. Accordingly, online and offline
playback ways were tested in SC3 under various trials.
3.3. Standard Operational Procedure and Decision Matrix
The earthquake source parameters (i.e., magnitude and epicentral distance) that could easily andautomatically be determined with SC3 control the alert level for the forecast points in coasts. The
earthquake magnitude is an essential source parameter for the first tsunami alert computational time.
The determined source parameters go through the standard operating procedures (SOP) for early warning.
In the Mediterranean Sea region, issuing tsunami alerts follows a decision matrix (DM) that the NRIAG
also looks forward to considering similar procedures in further steps for establishing the early warning
system. The DMs employed by the TSPs generally exhibit a shared underlying major structure, althoughsome minor variations exist. Table 1 shows the SOP by KOERI-TSP and the procedures that mainly
involve three different source parameters with three alert levels (Necmioğlu et al., 2021).
Table 1. KOERI-TSP decision matrix.
Tsunami Message
Depth< 100 kmEpicenter
Location

Local

Regional

Basin- Wide

< 100 km≥ 100 and ≤ 400 km> 400 km

Offshore or

5.5 ≤ M ≤ 5.9

Information

Information

Information≤ 40 km inland

6 ≤ M ≤ 6.4

Advisory

Information

Information

6.5 ≤ M ≤ 6.9

Watch

Advisory

Information

7 ≤ M ≤ 7.4

Watch

Watch

AdvisoryM ≥ 7.5

Watch

Watch

Watch

6 ≤ M ≤ 6.4

Information

Information

Information

M ≥6

Information

Information

Information

Offshore or≤ 100 km inland> 40 km and<100 km inland≥ 100 kmmagnitude≤ 100 km inland34. RESULTS AND DISCUSSION
mb Saturation

4.1. mb Magnitude Saturation

7.5

4.2. Comparison of Mwp and Mww

7
6.5

mb

Figure 2 shows the comparison between mb and Mww.
The mb is underestimated for the larger earthquakes(Mww ≥ 6.2). The saturation of mb was confirmed.
Hence, we excluded mb from the following early
warning system procedures because it is inefficient andshows low accuracy for large earthquakes.

6
5.5

Figure 3 shows the comparison between the Mwp
computed by SC3 and the Mww by the USGS for the
32 earthquakes in the Mediterranean Sea. The
relationship between them is presented in Eq. (3).

Figure 2. Comparison between Mww and mb.

Mwp =0.714 Mww(USGS) + 1.803

7.5

(3)

4.3. Comparison of mB and Mww

5

5.5

6

6.5
Mww

7

7.5

Mwp (SC3)

7

(4)

6.5

Mwp

Figure 4 compares the mB and the Mww by the USGS.
The relationship between them is presented in Eq. (4).

6

5.5

4.4. Decision Matrix Performance
The magnitudes values obtained by SC3 are used in the
SOP for the DM to produce tsunami messages. Watch,
Information, and Advisory are the three messages usedin the early warning SOP. Only two alerts, Information
and Advisory, are produced for the analyzed
earthquakes on Egypt's coasts. The watch alert message
was not produced for the earthquakes analyzed in thisstudy for Egypt. We used the USGS magnitude as areference magnitude to produce the actual alert level.
Tables 2 and 3 summarize the total number of accurate
and false alerts for the magnitude values estimated by
SC3 and this study, respectively. The used magnitude
values are the final estimates and those obtained around6 and 11 minutes after the origin times.

5
5

5.5

6

Mww

6.5

7

7.5

Figure 3. Comparison between Mwp and Mww.
mB (SC3)
7.5
7
6.5

mB

mB =0.868 Mww(USGS) + 1. 035

5

6
5.5
5
5

5.5

6

6.5
Mww

7

7.5

Figure 4. Comparison between mB and Mww.

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Table 2. Accurate and false alerts are estimated by SC3 results at different times for Mw(Mwp) andMw(mB).
6 Minutes
11 Minutes
Final Estimate
SC3 Alerts
Mw(Mwp) Mw(mB) Mw(Mwp) Mw(mB) Mw(Mwp) Mw(mB)Over-estimate False Alerts

1

1

0

1

0

1

Under-estimate False Alerts

4

9

4

9

3

9

Total False Alerts

5

10

4

10

3

10

Accurate Alerts

27

22

28

22

29

22

Table 3. Accurate and false alerts for Mw(Mwp) and Mw(mB) are calculated by the respective
relationships estimated in this study.
6 Minutes
11 Minutes
Final Estimate
This study result Alerts
Mw(Mwp) Mw(mB) Mw(Mwp) Mw(mB) Mw(Mwp) Mw(mB)Over-estimate False Alerts

2

1

0

1

0

1

Under-estimate False Alerts

4

5

4

5

3

4

Total False Alerts

6

6

4

6

3

5

Accurate Alerts

26

26

28

26

29

27

By comparing the results, the numbers of false alerts for Mw(Mwp) are smaller than or equal
to those for Mw(mB). Therefore, Mwp is considered more accurate than mB. The comparison between
6 and 11 minutes after the origin times is essential to evaluate the time for producing the early warning
system for Egypt. By using SC3 estimates, Mw(Mwp) produced 5 false alerts within 6 minutes after theorigin time, and the false alerts reduced to be 4 false alerts within 11 minutes. Using this study's estimates,
Mw(Mwp) produced 6 false alerts within 6 minutes and 4 false alerts within 11 minutes. Consideringthat all the false alerts occurred for smaller events (Mww≤5.9), Mw(Mwp) estimates obtained within
11 minutes are effective for tsunami early warning for Egypt's coasts.
4.5. Tsunami Travel Time Evaluation
The tsunami travel times of the analyzed
earthquakes shown by the red stars in Figure
5 were compared to those necessary for
magnitude estimation. We used the Tsunami
Travel Time (TTT) Software Package by
ITIC to calculate the tsunami travel times.
The bathymetry data for the Mediterranean
region were downloaded using (GEBCO
Compilation Group, 2023). The tsunami
waves will take more than 65 minutes to reachthe supposed forecast point (Alexandria
Station). We calculated the TTTs for the small
event (Mww=4.9) near Egypt (the green starin Figure 5). The tsunami waves will take 45
minutes to reach Alexandria and 35 minutes toreach the nearest town, Rashid.

Figure 5. Tsunami travel time for the 32 earthquakes.

55. CONCLUSIONSIn this study, we analyzed the 32 earthquakes (Mww ≥ 5.5) in the Mediterranean Sea between 2012 and2022 to evaluate how fast we can precisely determine the source parameters, especially the magnitude
values. Different magnitude types were automatically computed in SC3. We confirmed that mb issaturated for large earthquakes. The relationships for Mwp and Mw and mB and Mw were obtainedusing the final magnitude estimates to reduce their systematic differences for the Mediterranean
earthquakes.
We used the magnitude estimates and Standard Operational Procedure to obtain the tsunami
messages. We used Mww from the USGS as a reference and obtained 1 advisory message and 27
information messages, and no messages for 3 earthquakes.
The number of false alerts for SC3 and the result estimates were computed 6 minutes and 11
minutes after the origin times. The numbers of false alerts for Mw(Mwp) are smaller than or equal tothose for Mw(mB) for all the cases, which indicates Mw(Mwp) is more accurate. The estimates within
11 minutes for Mw(Mwp) produced smaller numbers of false alerts than those for 6 minutes.
It takes more than 65 minutes for tsunamis from the Hellenic and Cyprian arcs earthquakes toreach the Egyptian coasts. In conclusion, tsunami messages based on the Mw(Mwp) estimates around
11 minutes after the origin time will effectively reduce tsunami damages for Egypt.
ACKNOWLEDGEMENTS
This research was conducted during the individual study period of the training course "Seismology,
Earthquake Engineering, and Tsunami Disaster Mitigation" by the Building Research Institute, JICA,
and GRIPS. I would like to express my sincere gratitude to my supervisor Dr. Tatsuhiko HARA for his
valuable support and experience, which helped me to complete my research successfully. I would liketo acknowledge Dr. Yushiro Fujii for his permanent support from the beginning to the end of the
program.
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