SnT2015 Conference
Comoros Islands/Regional seismic
sources and related effects
Ms.Mariama MADI
NDC Manager, Seismic Data Analyst
-Comoros-
Acknowledgement:
Volcano Observatory Comoros: Shafik Bafakih, Moussa Moegni Ali
PTS: Martin Kalinowski (Advice), Remmy PHIRI ( Data support),
Ranon Josef le Bras (KML hydro-Data provider),
Pierrick Mialle ( Infrasound details), Dale Robin (software)
This work is being performed based on the CTBTO Fellowship for Young Scien=sts and Engineers 2014, with objec=ve of raising awareness on natural Hazards inves=ga=on, However, how IDC Data contribute to Na=onal Issues for Civil and Scien=fic purposes and with interest of enhancing the scien=fic Documenta=on to the Na=onal Ins=tu=on CNDRS-­‐NDC-­‐Comoros SnT2015 Conference, Civil and Scientific Applications
Abstract n°: T1.5-01
SnT2015 Conference
Outline
•  Introduction
•  Statistical approach of Local Events and SEL3
Seismic Data evaluation
•  Events and Related Effects
•  Summary
SnT2015 Conference, Civil and Scientific Applications
Abstract n°: T1.5-01
SnT2015 Conference
I-Introduction
The Interest of evalua=ng the local seismic ac=vi=es in the region of Islands rely on understanding how the level of local acquisi=on behaves from volcanic ac=vi=es and seismic events in vicinity, with ≥ 1.5 Magnitude (Volcano-­‐OBS) and ≥3.7/4 IDC-­‐ SEL3s events. And, how IDC Data and Products contribute to answer some ques=ons in regard of small Islands geological Hazards (e.g: Comoro-­‐Islands), furthermore, reframe the Use of Data for Research purpose. The subject is focused on two main parts:
- Statistical approach of Local and SEL3s Seismic Data
- Events and Related Effects
SnT2015 Conference, Civil and Scientific Applications
Abstract n°: T1.5-01
SnT2015 Conference
Location
-­‐ Four principal islands, lying in a WNW–ESE
line at the northern end of the Mozambique
Channel
- Grand Comore (1148km2), hosting the active
“Karthala volcano” (rising up to
2361 m .al) (Lat: ~ 11°44’S/ Lon: ~43°20’E)
-  Moheli (211km2; 790m al.) , dated to 2,2Ma
(Lat: ~12°19’S/ Lon: ~ 43°44’E)
- Anjouan (424km2; 1595m al.) , dated to 1.5 Ma
(Lat: ~12°13’S/ Lon: ~44°26’E)
-  And Mayotte (374 km2; 660m al.),.dated to
~5.4 Ma, which is in an advanced stage of
erosion and subsidence, and is encircled by a
barrier reef…(Lat: ~12°48’S/ Lon: ~45°10’E)
SnT2015 Conference, Civil and Scientific Applications
Abstract n°: T1.5-01
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Region and Target Sources
Chronology of Karthala Volcano Seismic Events Region of Interest: Constained box Lat: -­‐15/-­‐9 Lon: 41/48 Years within the ‘2000-2014’ period of Interest
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IDC Data-­‐record Ressources IDC Products
SEL3s
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REBs-­‐IDC, 2000-­‐2014 Seismic Data Abstract n°: T1.5-01
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•  II-Statistical approach of Local Events and SEL3
Seismic Data evaluation
Mg
6 5 4 3 2 1 Magnitude events, Comoros OBS SEL3 0 7/24/1998 Magnitude threshold:SEL3s 4/19/2001 1/14/2004 10/10/2006 SnT2015 Conference, Civil and Scientific Applications
7/6/2009 4/1/2012 12/27/2014 9/22/2017 Abstract n°: T1.5-01
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AIssues raised from the evaluation process upon the
local acquisition (earthquakes, volcanic-seismic activities,...) are
likely to answer some of practical questions:
1-­‐ Gaps of Data generated from local seimic Network technical issues within
the period Interest would have been fulfilled taking in to account SEL3s Data period,
which is showing a continuity of recording, which could be interesting to understand the
aspect of events in vicinity during the period were the local recordings were missing.
SEL3s 6 4 2 0 7/24/1998 4/19/2001 1/14/2004 10/10/2006 7/6/2009 4/1/2012 12/27/2014 9/22/2017 Period 2-­‐ Absence of Appropriated So2ware for Local Data analyses and coherence would be fixed with some of the IDC purposes on NDC in-­‐a-­‐box so2ware (…): Local Data (volcanic activities) Conversion to CSS Format for
NDC analyses commitments.
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Process: (From Suds to GSE) 7 from the 39 dmx format converted: a-­‐ File: “Winsuds290” into “c: driver” or other drivers b-­‐ Files Structure: c:\winsuds290 -­‐ bin -­‐ data -­‐ doc -­‐ etc -­‐ keys -­‐ lib c-­‐ Place of Data -­‐data must be saved in \winsuds290\data\ Name file should be : YYYYMMDD*.dmx, YYYYMMDD and dmx are important, and (*) can be any combina=on of strings. Ex: 20130201_003643_KA_904.dmx d-­‐ Conversion Into “windows Dos prompt” : -­‐ Run the script for February 01, 2013: \winsuds290\bin\convert2css.bat 2013 02 01 e.g. of files: SnT2015 Conference, Civil and Scientific Applications
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Converted data into ‘Geotool’ and Waveform Results are: Unfiltered waveforms
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Filtered Waveforms
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B-­‐ Seismic activity region of Interest
1-­‐ West of Islands
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2- Regional Events and Facilities (IMS)
Assessing IDC Regional Arrivals (Pn) we notice the importance of 3
components Stations in narrow area as for Comoros Islands, then how evolving
the aspect of Data comparison, close events deduction and which of the IMS
facilities record the most of Seismic events. Further, they many contribute to
understand seismic records generate secondary effects, in the Region etc...
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Ex. 12 March 2014 Com.
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III- Events and Related Effects
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Effects in consideration
Analyses:
The area (Lat:-­‐15/-­‐9 and Lon:41/48), reveal significant path of Knowledge that can contribute to many aspects of risks management, combining the 3 Technologies (Seismic, Infrasound, Hydroacous=c). Some of Data showed strong usefulness to the Islands that contribute to disaster warning design for Small Islands; performance of the IDC Technology through IMS Network; but also contribute to enhance more the aspect of IDC products acquisi=on and other related issues. SnT2015 Conference, Civil and Scientific Applications
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1-­‐ Earthquake and hazard An earthquake was felt massively in Anjouan Island and made the popula=on of the Island in panic in the night of 12 March 2014. Few damages have been seen in the west of the Island (Mutsamudu region), as the popula=on has been witnessing at 20:43:32 night local =me. Tes$monies: Interviewed: -:« I was scared »
-: I though I would die, it was shaking roughly 8s
short moment
-: The last one accured in last February, with
moderated quakes, but the 12 March one,
definitely was 7 to 8s period but was enough to
make few and moderate landslides on small parts
of Mutsamudu mounts.
-: ….etc….
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Event Location
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2- Infrasound detections generated by the
2005 and 2006 volcanic eruptions in
Comoros (Gde-Comore Island)
Eruption period of consideration
From 2005 to 2006 the Volcano Observatory recorded sensitive seismic
activities accelerated from continuing magma activities, and generated
Explosive Eruptions.
Secondary
Crater
Principal
Crater
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Reported by IDC Infrasound Expert:
3 sequences of Karthala volcano have been observed and recorded in IRED (Infrasound Reference Event Database) in 16 and 17 April 2005, and 28 May 2006. These erup=ons have been reported in the Database of Smithsonian, at that =me, the Infrasound Technology hasn’t been yet considered among the Reviewed event Bulle=n REB records of the IDC. 17 April 2005
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28 May 2006
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3-­‐ Seismic hazard and tsunami effects in Comoro-Islands
3-­‐1-­‐ 2004 tsunami and Impacts in the Islands: A joined team (NDC included) has conducted surveys
on two of the areas of interest in Gde-Comore Island,
and part of the work was based on Villager Testimony
In 2006 and 2007 about 35 areas, were idenafied (South African Journal of Geology) during a survey. -­‐Record of Run up: 6-­‐7m -­‐High slope area (hilly) along coast line -­‐Sea wall height is about 3.0m above sea level -­‐Arriving of tsunami at 4:30-­‐5:00am local Time -­‐Inundaaon conanued unal 8:00 to 9:00am -­‐None of the wave overtopping across sea wall ader 2004 Tsunami -­‐First wave was the biggest and caused inundaaon SnT2015 Conference, Civil and Scientific Applications
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3-­‐2-­‐ Importance of KML Data on raising tsunami awareness These KML hydroacous=c Data provided by the IDC reinforce the regional sta=s=cal statement on the expecta=on of regional seismic sources likely to be genera=ng a small or big tsunami in the area SnT2015 Conference, Civil and Scientific Applications
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The Indian Ocean known as hosang major Sources of tsunami in the region, menaoning the exisang of subducaon zone along the Indonesian plate, remains a key area to scienafic invesagaaon. The 2004 Sumatra-­‐Andaman damaging Tsunami triggered the research path on the area of interest, and (unfortunately) contribute hypotheacally to assess future Sumatra Event sources in the Region. Representation of Data (Mg) through years
Data Location
Tphase detections
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Summary
-­‐ Almost 828 (from 1.5 Mg) Data from the Observatory were evaluated -­‐ Missing local system data loca=ons can be fulfilled through IDC Data and Products -­‐ Introducing exis=ng Data recorded by the local network into the NDC in a box sojware applica=ons to be analyzed and enhance the local bulle=n -­‐ With the existence resources we can make scien=fic local or regional commitments, Evalua=ng regional hazards, the reason why, further sophis=cate NDC sojware will be highly of Big interest -­‐ Meanwhile: -­‐ As it is missing IDC mb Threshold values between 2000 and 2003 records, it would be important to see how to generate these Data in the IDC Database, AND, -­‐ The historical archives of infrasound Data generated by volcanic erup=ons In order, both to support the Research aspect of the Ins=tu=ons showing interest to be provided this kind informa=on. SnT2015 Conference, Civil and Scientific Applications
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Thank you
Regional Course on NDC Capacity Building GHANA, Nov-­‐Dec 2011 Empower the young Generation
for a Future peaceful and
Innovative world
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SNT2013 Abstract n°: T1.5-01