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Remembering the Tsunami of August 1868

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This week (August 13-15, 2018) marks the 150th anniversary of one of the largest tsunamis in history. The tsunami was devastating in the source area along the Peru/Chile border and was recorded throughout the Pacific with significant effects including one death in New Zealand.

Event Details
Magnitude: At least Mw 9.0
Origin Times:
(UTC): 2130 hrs, August 13, 1868
(Source): 1730 hrs, August 13, 1868
(NZST): 0930 hrs, August 14, 1868

The 14th of August 1868 was a typical mid winter’s day throughout New Zealand. Coastal residents and workers went about their day completely unaware that one of the most powerful earthquakes the earth has ever produced had occurred in South America and that a deadly tsunami was at that moment racing across the Pacific Ocean towards them.

Occurring at approximately 5:30 PM local time in Arica (which was then part of Peru, but is now the northernmost city of Chile), the earthquake completely devastated the port city.  The earthquake was followed by a series of tsunami waves producing runup heights of approximately 15-20 m. Three large naval vessels (two American ships, the Wateree and the Fredonia and one Peruvian ship, the America) were in port at the time. The tsunami completely destroyed Fredonia, killing all but two of its crewmen, and grounded the other two vessels hundreds of meters inland. To this day, the rusting steel boilers of the Wateree sit in the sand hundreds of meters from shore.

  
(above) The city of Arica, flattened and the Peruvian warship America beached after the waves (source: Wikipedia).

   
(above) The USS Wateree as it was after the tsunami and as it can be found today. (Source: Wikipedia and Jose Borrero personal collection)

It took more than 13 hours for the waves to reach New Zealand waters arriving in the early hours of August 15, 1868. The surges first affected  the Chatham Islands where a village was washed away and one man was killed as he tried to secure a boat. An hour later the surges began affecting the east coasts of the North and South Islands with the strongest and most disruptive effects occurring in the ports and harbours.


(above) Computer simulation of the 1868 tsunami showing the maximum tsunami amplitudes across the Pacific. The white lines are 1-hour travel time contours for the tsunami wave front. (Data used with permission from the National Center for Tsunami Research and plotted by Jose Borrero, eCoast)


(above) Snapshots of the tsunami crossing the Pacific at 6, 10 and 14 hours after the earthquake. To see it animated, click here.

The historical record is filled with descriptive accounts of the tsunami affecting New Zealand. GNS’ New Zealand Tsunami Database is an excellent resource for reading in detail exactly what happened around the country as a result of the tsunami.

As noted above, the tsunami was most evident in the ports and harbours. Among these, the Port of Lyttelton in Christchurch was hit particularly hard with tsunami heights (peak to trough) of over 7 m causing extensive damage and strong currents that ripped boats from their mooring and causing numerous collisions.


(above) Snapshot of simulated tsunami currents from the 1868 tsunami along Cashin Quay in Lyttelton Harbour. See it animated here and here. Tsunami modelling done with the MOST tsunami model by Jose Borrero of eCoast.


(above) Simulated tide gauge record of the 1868 tsunami in Lyttelton Harbour. The dashed black line is the predicted tide curve for that day. The red line is the simulated tsunami + tide. The simulation matches well with historical accounts describing the initial drawdown of the water level some time around 3:30 AM, as well as with observations of water level fluctuations of ~25 feet (7.6 m) as indicated by the vertical black line.

So why should we care? This happened 150 years ago, what’s the big deal?

Well, the point is, it is going to happen again and New Zealand needs to be prepared!

Not all tsunamis cause the devastating ‘walls of water’ that we saw on television after the March 11, 2011 Japan earthquake. Those types of effects occur in the immediate source regions of powerful earthquakes, as was the case in Japan.

While New Zealand is indeed susceptible to those types of tsunami, we are also vulnerable to large tsunami generated from around the Pacific Ocean. These types of tsunami, known as ‘distant source’ or ‘far-field’ tsunami are much more likely to occur and affect New Zealand.

Recent tsunami events, such as the 2004 Boxing Day tsunami in the Indian Ocean and the 2010 Chile and 2011 Japan events in the Pacific, have each caused damage and/or disruption to port and maritime facilities at locations hundreds or thousands of kilometres away from the tsunami source region.

In the case of the 1868 tsunami, if it were to happen today, New Zealand could expect disruption and damage in several east coast ports. Lyttelton would be the most vulnerable with others such as Marsden Point, Gisborne, Napier, and Timaru all experiencing significant effects including strong currents, damage and possible shutdown of operations.


(above) Eddies (or whirlpools) such as this are a common feature caused by tsunami currents in ports or harbours.

Presently eCoast is working with the Northland Regional Council and Northland Civil Defence Emergency Management (CDEM) Group on a project sponsored by the Ministry of Civil Defence & Emergency Management to better understand the tsunami hazards in maritime facilities. The project builds on/extends existing tsunami modelling for the Northland Region and involves extensive computer simulations of tsunami effects in the ports and harbours as well as a detailed assessment of the types and condition of the infrastructure that is present at each facility.

The project aims to produce products designed to be used for on-the-ground emergency managers during an actual tsunami event. This will be done by producing decision-making ‘playbooks’ and harbor-based hazard maps that clearly define areas susceptible strong currents with the overall objective of reducing the uncertainty during the next tsunami so that disaster managers know what to do under a particular set of circumstances. The project is slated to continue through the year with results and products coming online in late 2018 or early 2019.


(above) An example of a prototype current speed hazard map produced for Marsden Point at the entrance to Whangarei Harbour in Northland. Modelling by Jose Borrero, eCoast

  
(above) Boats struggle at their moorings as surges and currents generated by the 2011 Japan tsunami force their way intoTutukaka Harbour, Whangarei , New Zealand, Saturday, March 12, 2011. Credit:NZPA / Malcolm Pullman

For more information see:

Websites:
EARTHQUAKE AND TSUNAMI OF 13 AUGUST 1868 IN ARICA, PERU – Website of Dr. George Pararas – Carayannis

1868 Arica Earthquake – Wikipedia

Scientific Journal Articles
Borrero, J.C., Lynett, P.J. and Kalligeris, N. (2015) Tsunami Currents in Ports, Philosophical Transactions of the Royal Society A ,373: 20140372. http://dx.doi.org/10.1098/rsta.2014.0372.

Borrero, J.C., Goring, D.G. (2015) South American Tsunamis in Lyttelton Harbor, New Zealand, Pure and Applied Geophysics, 10.1007/s00024-014-1026-1.

Borrero, J.C., Goring, D.G., Greer, S.D. and Power, W.L. (2014) Tsunami Hazards in New Zealand Ports, Pure and Applied Geophysics, 10.1007/s00024-014-0987-4.

Lynett, P.J., Borrero, J.C., Son, S., Wilson, R.W. and Miller, K. (2014) Assessment of the tsunami-induced current hazard, Geophysical Research Letters, DOI: 10.1002/2013GL058680.

 

 

 

 

 

 

New Publication

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eCoast is pleased to announce the publication of a paper in the Journal of Biogeography. Co-authored by eCoast scientist Dougal Greer, in collaboration with the University of Western Australia, the publication focused on understanding the connectivity of seagrass (Posidonia australi) meadows around Victoria and southern New South Wales in Australia.

This is a significant study as it helps us to understand the propagation of seagrass which is in decline worldwide. Seagrasses is a highly important link in the food chain as they provide food, habitat, and nursery areas for numerous species which depend on the plant.

Dougal’s role in the study was to use state of the art hydrodynamic and particle modelling to determine the potential for seagrass seeds to travel between different meadows. The study involved simulating sea grass seed transport over 19 years to provide spatial probability maps of seed settlement and hence the potential for connectivity between separate sea grass meadows. Results were compared with connectivity patterns established by genetic analysis of sampled sea grass shoots from across the meadows and was found to be in good agreement.

Global Wave Conference Wrap-Up

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From October 11-14, 2015 eCoast’s Ed Atkin joined a force of like-minded groups and individuals at the 4th Global Wave Conference (GWC) held in Cornwall in the far south west of England. The aim of the conference was to meet, discuss and share information on worldwide efforts related to surfbreak conservation and coastal environmental protection. Among the topics discussed were the latest solutions to better protect surf habitats, innovations in sustainability in the surf industry and lowering the impact of surf tourism. The event was hosted by Surfers Against Sewage (SAS), a UK based non-profit dedicated to protectiing Britain’s waves oceans and beaches.

The conference delegates were joined by pro surfers Brad Gerlach, Greg Long, Ramón Navarro and Tom Curren, all of whom were happy to share stories and listen to others. The pros were all inspirational in their own right, however the conference presentations and the people who gave them were just as impressive.

Credit must go to Surfers Against Sewage who not only organised a stunning venue and a seamless conference, they managed for the speakers and delegates to meet with members of parliament in the Churchill Room of the House of Commons, Westminster Palace, London. It was a grand finale, with an address by Steve Double, the MP for the sub-region where the conference was held and awards presented to Tom Curren, for his efforts in setting up Surfrider Foundation Europe, and Chris Hines (MBE), the co-founder of Surfer Against Sewage.

Anticipation for the next conference is high with a real sense of momentum in bringing like-minded people together and learning from their skills and experiences. While the overriding common theme for this conference was one of collaboration, the unifying force, which probably spans each of the conferences to date, is clearly the passion to protect. Hopefully this passion will be strong enough to further long-standing alliances between diverse, yet undeniably enthusiastic contributors, in to creating a unified body, a Global Wave Alliance of surfers, scientists and activists dedicated to protecting and preserving the world’s surfing resources.

 

eCoast Representation at the 2015 Coasts and Ports Conference

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eCoast was well represented at this year’s Coasts and Ports Conference.  In total the group presented four papers during the technical sessions. The individual papers can be downloaded from the links below.

Jose Borrero: Observations and Modelling of Tsunami Currents at the Port of Tauranga, New Zealand

Tim Haggitt: Makara Estuary Monitoring: Effects-based monitoring within a degraded, yet dynamic, coastal environment

Shaw Mead: Application of Climate Change Adaptation, Resilience, and Beach Management Strategies on Coral Islands

Dougal Greer: Understanding water Quality in Raglan Harbour

The conference was well attended by over 300 delegates from New Zealand, Australia and around the world.

West Coast field work

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(Above) Surveying Awakino Estuary.

Field work is under way for the Waikato west coast estuary study!

eCoast researchers have been busy collecting data at Mokau, Awakino and Marokopa as part of the first phase of the Waikato west coast estuary project. Focus will soon be placed on Port Waikato, Raglan, Aotea and Kawhia Harbours for the next phase.

The work which is due to be completed in April 2016 aims to understand harbour circulation patterns, how water enters from rivers and gets exchanged with the open ocean and how this impacts water quality. This will help to identify areas of the harbours particularly vulnerable to pollution from rivers, sewage spills or other sources of contamination.

eCoast senior consultant Dougal Greer, who is leading the project, notes that this is the first time that research has been undertaken for many of the harbours on the west coast of the Waikato.

“Historically research has been focused more on east coast harbours, so it is great to see some attention focused on the west coast and it’s exciting to be a part of it. As part of this project we have been consulting with local communities based around the harbours and they have all been very supportive of us doing this work”.

The study involves mapping the sea floor in and around the harbours and measuring oceanographic data such as currents, sea level, water temperature and salinity. A second component of the study will involve creating computer models of each harbour to simulate tidal and wind driven circulation patterns. Ultimately this will be used to understand how different parts of each harbour are flushed by ocean water.

While it is well known that the water quality in harbours is strongly affected by river inflows which is in turn affected by land use activities upstream, the link between how the harbours are affected by land use is poorly understood and Mr Greer says this study is a big step towards changing that.

“Some of our preliminary results were quite surprising. We found that when it comes to faecal coliform contamination, the effect of recent sewage spills in Raglan Harbour was almost negligible when compared to what enters the harbour from rivers and storm drains after a heavy rain. This is not to downplay the effect of a sewage spill, but it is also important to understand what else flows into our harbours on a regular basis”.

Greer and colleagues from eCoast present results from this study at the bi-annual Coasts and Ports Conference being held from 16-18 September in Auckland.

eCoast Marine Consulting and Research is a small, independent marine and freshwater research consultancy based in Raglan on the west coast of New Zealand’s North Island. As well as being life-long and passionate surfers and ocean enthusiasts, the company’s directors and employees all hold Ph.D.’s or other postgraduate qualifications in coastal science, oceanography, engineering, marine biology and mathematics. The group strives to be a world leader in sustainable coastal development and science based decision making in the coastal zone.

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Ed gathering depth measurements upstream at Awakino.

 

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Left to right, Ed Atkin, Dr Shaw Mead and Dr Tim Haggitt preparing to retrieve an instrument and download the data at Awakino.

 

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Reggie the field dog assesses the incoming rain at Marokopa while Ed finds shelter for the laptop.

Internship Positions at eCoast

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We are looking for individuals to undertake internship positions at the eCoast office in Raglan, New Zealand. Applicants should have a background in either environmental science, computer science, physical science or engineering disciplines. Feel free to email us on info@ecoast.co.nz and attach a cover letter, CV, university transcripts of grades, and any other relevant information.

Northeast Fiji reef inspection

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Dr Tim Haggitt inspects a bleached coral reef in far northeast Fiji.

The island of Maqai was hit by tropical cyclone Tomas in 2010.  The result was widespread devastation both on land and below the waterline.  eCoast’s biologists frequently visit this remote location to monitor the increasing health of the reefs.