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Recent earth tremors in Sri Lanka – Part II

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a critical review in relation with such activity in Tamil Nadu and the orogenesis of Himalayas based on a new theory of cratons and mobile belts in the Indian peninsular

By by DULIP JAYAWARDENA

Former Director Geological Survey Department and retired Economic Affairs Officer, United Nations ESCAP

MAGMATIC PULSES IN ASSEMBLY GONDWANA IN THE PERIPHRTAL OF VIJAYAN COMPLEX IN SRI LANKA

The lithology of Sri Lanka comprises mainly the Highland complex, the Wanni complex and the Vijayan complex. Co- related with other East Gondwana continental terrains, the Vanni and Vijayan complex is interpreted as volcanic arc terrains bought together by two-sided subduction. The Highland Complex is compressed between the Vanni Complex in the west and the Vijayan complex in the east.

Some Highland Complex rocks are in the Buttala, Kataragama and Kuda Oya within the Vijayan Complex and are interpreted as tectonic Klippe (geological feature of thrust fault terrain). — Samuel Wai-Pan Ng et al./Precambrian Research 294 (2017) pages 244-256.

EXPLANATION FOR RECENT TREMORS IN BUTTALA WALLAWAYA AREAS IN EASTERN SRI LANKA

Figure 1 shows the major geological divisions of Sri Lanka namely the Wanni Complex, Highland complex and the Vijayan Complex with a mixed rock group in the south east of Sri Lanka. It is of interest that the recent tremors recorded in the Buttala- Wellawaya areas comprises of High Nb granite, mafic rocks , granitoid gneisses and charnokites. This area is in the Highland – Vijayan tectonic zone (see Fig 2)

The age determinations carried out indicate the charnokitisation occurred at 562 + M during the Neoproterozoic regional metamorphism.

The research studies carried out show that eastern Vijayan Complex contains the Monaragala klippe, Buttala Klippe, Kataragama complex and the Kuda Oya rocks. The Okkampitiya klippe is a resent finding.

THE RELATIONSHIP OF PROTOZOIC CRATONS AND MOBILE BELTS IN INDIA EXTENDED TO SRI LANKA

It is noted that the theory of mobile belts and cratons of India has a direct relationship to Sri Lanka. The identification of klippe as indicated above are thrust faults and the cratons can be identified as charnokites of igneous origin shown in Fig 1 (after Kroner et.al. 2013) The map shows the Vanni Complex, Highland Complex, Vijayan Complex and an area showing a mixed zone between the Highland and Vijayan.

The recent earth tremors were in this mixed tectonic zone consisting of High -Nb granite mafic rocks, granitoid gneisses and charnokites.

Based on the Indian study of orogenic belts and cratons it is recommended this study should be extended to Sri Lanka.

MACROSEISMIC HAZARD ZONES IN SRI LANKA

A detailed study was carried out in 2020 on compilation of a seismic hazard map for Sri Lanka based on Peak Ground Acceleration (PGA- maximum ground acceleration that had occurred during earthquake shaking at a location). Deterministic Seismic Hazard Analyses (DHSA) predicts the seismic response by PGA. Probabilistic Seismic Hazard Analyses (PSHS A method used to estimate the level of ground motion with specified probability of exceedance.) was also applied.

Accordingly, PGA values selected cities in Sri Lanka ware determined at a magnitude of 6 and magnitude of 6.9 at 40 kms and 90 kms respectively. PGA values for different cities in Sri Lanka for 50, 475, and 2475 return periods respectively were determined.

Accordingly, a Seismic Hazard Map for Sri Lanka was compiled considering the average PGA value at each location two seismic zones were identified for various structures namely common buildings such as schools, hospitals etc., for important class of structures such as dams, power stations etc. and a third area for all types of structures

It has been recommended that there is urgent need to establish a network of seismic monitoring stations for actual seismic response for any part of the Island(Seneviratne at al http://doi.org/10.4038/engineer .v53i3.7418

The need to establish an effective network of seismic monitoring is again proved by two minor tremors of 2.6 and 3.0 recorded by GSMB at Kirinda in the south and Gomarankadawala near Trincomalee in the local media on 19 March 2023.

Both these locations are on the eastern boundary of the Highland and Vijayan Series rocks which has a continuous negative low and interpreted as a subducting plate boundary

HIMALAYAN EARTHQUAKES AND HISTORICAL SEISMICITY AND ITS FALLOUT IN SRI LANKA

It was reported by some Indian and local geoscientists that major earthquakes occurring along the Himalayan mountain range will be experienced in Sri Lanka which is at a distance of 2,363 km south.

In order to ascertain the validity of this statement reference is made to a detailed study done by Rodger Bilham of the CIRES and Geological Sciences, University of Colorado, Boulder 216 UCB Boulder co 80309 USA rodger.bilham@colorado.edu

The above study gives a summary of the recent knowledge of the past 1000 years of earthquakes of the Himalaya (Ref Table 1).

The Maximum recorded earthquake of 9 was in year 1100. The other earthquakes show a low of 6.5 to 8.5 Mw to and a high of 6 to 8.9 Mw (Mw Moment magnitude is on magnitude scale for ranking earthquakes by size). (See Table – Himalaya Earthquakes)

CONCLUSIONS

In this article I have very briefly attempted to analyze the earthquakes in the Indian sub-continent vis-a-vis its potential effecting Sri Lanka. I have also summarized the earthquakes and earth tremors that effected the Island since 1615.

Sri Lanka has the lowest gravity in the world and the south of the Island is conducive to launch space satellites with the least cost as there is no landmass south of the Island.

The importance of having a functioning seismic network covering the entire country with 65 000 square kilometers has been stressed.

A need to extend the application of cratons and mobile belts to Sri Lanka from South India especially Tamil Nadu is recommended.

It is also suggested to measure the altitudes of the three major mountains namely Pidurutalagala , kirigalpotha and Samanala Kanda (Adam’s Peak) to ascertain whether increase in height related to msl had taken place proving the these mountains could be plutons if the new theory of plutons and mobile belts extended to Sri Lanka .

Reference was made to the Himalayas and the earthquakes varying from 7 Mw to 9 Mw were analysed and these events were proved not to have any impact on Sri Lanka.

I also would like to refer to my article published in The Daily Mirror of 6 May 2015 titled “Nepal Earthquake and Possible Impact on Sri Lanka”. Accordingl, I would draw the reader’s attention to the issues covered in this article and also the recommendations .

Finally, I also would draw the attention to the geoscientists of Sri Lanka to carry out research studies in respect the earth tremors recently recorded and also try to work in close coordination with the Indian geoscientists on the new theory of plutons and mobile belts .I also recommend for the GSMB closely monitor the earth tremors in the Buttala , Wellawaya and Kuda Oya areas.

I would gladly make available all the research papers I have collected on this study so that the geoscientists can work further on the recent issued raised.

REFERENCES

WadBilham Roger – Himalayan earthquakes: a review of historical seismicity and early 21st. century slip potential-CIRES and Geological Sciences University of Colorado, Boulder216 UCB Boulder CO 80309, USA

Curry Joseph R. – Sri Lanka Is it a Mid -Plate Platelet? – Journal National Aquatic Research Agency (NARA) Sri Lanka vol.31 (1984)30 -50

Kroner et.al. Simplified Geological Map of Sri Lanka (2013)

Muhandiram P.M.S.S.B – Institution of Engineers – issue 42 (2018) <https:ioes18.wildapricot.org/article =earthquakes/#>

Ng Samuel Wasi_Pan et.al Ca. 820 -640 Ma SIMS U- Pb age signal in peripheral Vijayan Complex Sri Lanka: Identifying magmatic pulses in the asembly of Gondwanaland (2017) University of Hong Kong – Precambrian Research 294 (2017) 244-256

Ganapathy G.P. et al Seismic Hazard Analysis for Tamil Nadu State : A Deterministic Approach Indian Society of Engineering geology Jour of Engg Gol-Vol XXXVI Nos.1-4

Senaviratne H.N. et. al. – Seismicity around Sri Lanka from historical Records and its Engineering Implications ENGINEER- Vol. LIII No 02pp (47-52) http:doiorg10.4038engineer.53i2.7412 (2020)

Wadia D.N.1945 The Three Superposed peneplains of Ceylon ,Dept of Mineralogy Ceylon Professional Paper 1, 25-32



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Features

Political violence stalking Trump administration

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A scene that unfolded during the shooting incident at the recent White House Correspondents’ Dinner in Washington. (BBC)

It would not be particularly revelatory to say that the US is plagued by ‘gun violence’. It is a deeply entrenched and widespread malaise that has come in tandem with the relative ease with which firearms could be acquired and owned by sections of the US public, besides other causes.

However, a third apparent attempt on the life of US President Donald Trump in around two and a half years is both thought-provoking and unsettling for the defenders of democracy. After all, whatever its short comings the US remains the world’s most vibrant democracy and in fact the ‘mightiest’ one. And the US must remain a foremost democracy for the purpose of balancing and offsetting the growing power of authoritarian states in the global power system, who are no friends of genuine representational governance.

Therefore, the recent breaching of the security cordon surrounding the White House Correspondents’ Dinner in Washington at which President Trump and his inner Cabinet were present, by an apparently ‘Lone Wolf’ gunman, besides raising issues relating to the reliability of the security measures deployed for the President, indicates a notable spike in anti-VVIP political violence in particular in the US. It is a pointer to a strong and widespread emergence of anti-democratic forces which seem to be gaining in virulence and destructiveness.

The issues raised by the attack are in the main for the US’ political Right and its supporters. They have smugly and complacently stood by while the extremists in their midst have taken centre stage and begun to dictate the course of Right wing politics. It is the political culture bred by them that leads to ‘Lone Wolf’ gunmen, for instance, who see themselves as being repressed or victimized, taking the law into their own hands, so to speak, and perpetrating ‘revenge attacks’ on the state and society.

A disproportionate degree of attention has been paid particularly internationally to Donald Trump’s personality and his eccentricities but such political persons cannot be divorced from the political culture in which they originate and have their being. That is, “structural” questions matter. Put simply, Donald Trump is a ‘true son’ of the Far Right, his principal support base. The issues raised are therefore for the President as well as his supporters of the Right.

We are obliged to respect the choices of the voting public but in the case of Trump’s election to the highest public position in the US, this columnist is inclined to see in those sections that voted for Trump blind followers of the latter who cared not for their candidate’s suitability, in every relevant respect, and therefore acted irrationally. It would seem that the Right in the US wanted their candidate to win by ‘hook or by crook’ and exercise power on their behalf.

By making the above observations this columnist does not intend to imply that voting publics everywhere in the world of democracy cast their vote sensibly. In the case of Sri Lanka, for example, the question could be raised whether the voters of the country used their vote sensibly when voting into office the majority of Executive Presidents and other persons holding high public office. The obvious answer is ‘no’ and this should lead to a wider public discussion on the dire need for thoroughgoing voter education. The issue is a ‘huge’ one that needs to be addressed in the appropriate forums and is beyond the scope of this column.

Looking back it could be said that the actions of Trump and his die-hard support base led to the Rule of Law in the US being undermined as perhaps never before in modern times. A shaming moment in this connection was the protest march, virtually motivated by Trump, of his supporters to the US Capitol on January 6th, 2021, with the aim of scuttling the presidential poll result of that year. Much violence and unruly behaviour, as known, was let loose. This amounted to denigrating the democratic process and encouraging the violent take over of the state.

In a public address, prior to the unruly conduct of his supporters, Trump is on record as blaring forth the following: ‘We won this election and we won by a landslide’, ‘We will stop the steal’, ‘We will never give up. We will never concede. It doesn’t happen’, ‘If you don’t fight like hell, you’re not going to have a country anymore.’

It is plain to see that such inflammatory utterances could lead impressionable minds in particular to revolt violently. Besides, they should have led the more rationally inclined to wonder whether their candidate was the most suitable person to hold the office of President.

Unfortunately, the latter process was not to be and the question could be raised whether the US is in the ‘safest pair of hands’. Needless to say, as events have revealed, Donald Trump is proving to be one of the most erratic heads of state the US has ever had.

However, the latest attempt on the life of President Trump suggests that considerable damage has been done to the democratic integrity of the US and none other than the President himself has to take on himself a considerable proportion of the blame for such degeneration, besides the US’ Far Right. They could be said to be ‘reaping the whirlwind.’

It is a time for soul-searching by the US Right. The political Right has the right to exist, so the speak, in a functional democracy but it needs to take cognizance of how its political culture is affecting the democratic integrity or health of the US. Ironically, the repressive and chauvinistic politics advocated by it is having the effect of activating counter-violence of the most murderous kind, as was witnessed at the White House Correspondents’ Dinner. Continued repressive politics could only produce more such incidents that could be self-defeating for the US.

Some past US Presidents were assassinated but the present political violence in the country brings into focus as perhaps never before the role that an anti-democratic political culture could play in unraveling the gains that the US has made over the decades. A duty is cast on pro-democracy forces to work collectively towards protecting the democratic integrity and strength of the US.

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Features

22nd Anniversary Gala …action-packed event

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The Skyliners: Shanaka Viswakula (bass), Mario Ranasuriya (lead guitar), Daryl D'Souza (keyboards) and Kushmin Balasuriya (drums)

The Editor-in-Chief of The Sri Lankan Anchorman, a Toronto-based monthly, celebrating Sri Lankan community life in Canada, is none other than veteran Sri Lankan journalist Dirk Tissera, who moved to Canada in 1997. His wife, Michelle, whom he calls his “tower of strength”, is the Design Editor.

According to reports coming my way, the paper has turned out to be extremely popular in Toronto.

In fact, The Sri Lankan Anchorman won a press award in Toronto for excellence in editorial content and visual presentation.

However, the buzz in the air in Canada, right now, is The Sri Lankan Anchorman’s 22nd Anniversary Gala, to be held on Friday, 12 June, 2026, at the J&J Swagat Banquet Convention Centre, in Toronto.

An action-packed programme has been put together for the night, featuring some of the very best artistes in the Toronto scene.

The Skylines, who are classified as ‘the local musical band in Toronto’, will headline the event.

Dirk Tissera and wife Michelle: Supporting Sri Lanka-Canada community events, in Toronto, since launching The Anchorman
in 2002

They have performed and backed many legendary Sri Lanka singers.

According to Dirk, The Skylines can belt out a rhythm with gusto … be it Western, Sinhala or Tamil hits.

Also adding sparkle to the evening will be the legendary Fahmy Nazick, who, with his smooth and velvety vocals, will have the crowd on the floor.

Fahmy who was a household name, back in Sri Lanka, will be flying down from Virginia, USA.

He has captivated audiences in Sri Lanka, the Middle East and North America, and this will be his fourth visit to Toronto – back by popular demand,

Cherry DeLuna, who is described by Dirk as a powerhouse, also makes her appearance on stage and is all set to stir up the tempo with her cool and easy delivery.

“She’s got a great voice and vocal range that has captivated audiences out here”, says Dirk.

Chamil Welikala, said to be one of the hottest DJs in town, will be spinning his magic … in English, Sinhala, Tamil and Latin.


Both Jive and Baila competitions are on the cards among many other surprises on the night of 12 June.

This is The Anchorman’s fifth annual dance in a row – starting from 2022, 2023, 2024 and 2025 – and both Dirk and Michelle, and The Anchorman, have always produced elegant social events in Toronto.

“We intend to knock this one out of the park,” the duo says, adding that Western music and Sinhala and Tamil songs is something they’ve always delivered and the crowd loves it.

“We have always supported Sri Lanka-Canada community events, in Toronto, since launching The Anchorman, in 2002, and we intend to keep it that way.”

No doubt, there will be a large crowd of Sri Lankans, from all communities, turning up, on 12 June, to support Dirk, Michelle and The Anchorman.

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Features

Face Pack for Radiant Skin

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* Apple and Orange:

Blend a few apple and orange pieces together. Add to it a pinch of turmeric and one tablespoon of honey. Apply it to the face and neck and rinse off after 30 minutes. This face pack is suitable for all skin types.

According to experts, apple is one of the best fruits for your skin health with Vitamin A, B complex and Vitamin C and minerals, while, with the orange peel, excessive oil secretion can be easily balanced.

* Mango and Curd:

Ripe mango pulp, mixed with curd, can be rubbed directly onto the skin to remove dirt and cleanse clogged pores. Rinse off after a few minutes.

Yes, of course, mango is a tasty and delicious fruit and this is the mango season in our part of the world, and it has extra-ordinary benefits to skin health. Vitamins C and E in mangoes protect the skin from the UV rays of the sun and promotes cell regeneration. It also promotes skin elasticity and fights skin dullness and acne, while curd, in combination, further adds to it.

*  Grapes and Kiwi:

Take a handful of grapes and make a pulp of it. Simultaneously, take one kiwi fruit and mash it after peeling its skin. Now mix them and add some yoghurt to it. Apply it on your face for few minutes and wash it off.

Here again experts say that kiwi is the best nutrient-rich fruit with high vitamin C, minerals, Omega-3 fatty acids and vitamin E, while grapes contain flavonoids, which is an antioxidant that protects the skin from free radical damage. This homemade face pack acts as a natural cleanser and slows down the ageing process.

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