USA: Alaska Hit By Large Earthquake


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Sydney storms could be making the Queensland fires worse


Claire Yeo, Australian Bureau of Meteorology

A strong low-pressure system has meant severe thunderstorm and hail warnings are in effect for much of the New South Wales South Coast. At the same time, very dry conditions, strong winds and high temperatures are fuelling dozens of bushfires across Queensland.

The two events are actually influencing each other. As the low-pressure system moves over the Greater Sydney area, a connected wind change is pushing warm air (and stronger winds) to Queensland, worsening the fire conditions.




Read more:
Drought, wind and heat: when fire seasons start earlier and last longer


These lows over NSW are the kind we might see a couple of times a year – they’re not just regular weather systems, but neither are they massively out of the ordinary.

However, when combined with the current record-breaking heat in Queensland, the extra wind is creating exceptionally dangerous fire conditions. Queensland’s emergency services minister, Craig Crawford, has warned Queenslanders:

We are expecting a firestorm. We are expecting it to be so severe that it won’t even be safe on the beach […] The only thing to do is to go now.

Conditions in Queensland

At least 80 bushfires were burning in Queensland on Wednesday, with more than a dozen fire warnings issued to communities near the Deepwater blaze. Queensland Police Deputy Commissioner Bob Gee said that “people will burn to death” unless they evacuate the area.

These fires have come during a record-breaking heatwave. On Tuesday Cooktown recorded 43.9℃, beating the previous November high set 70 years ago by more than two degrees. Cairns has broken its November heatwave record by five whole degrees.

Grasslands and forests are very dry after very little rain over the past two years. Adding to these conditions are strong winds, which make the fires hotter, faster and harder to predict. This is where the storm conditions in NSW come in: they are affecting air movements across both states.

NSW low is driving winds over Queensland

A large low-pressure system, currently over the Hunter Valley area, is causing the NSW storms. As it moves, it’s pushing a mass of warm air ahead of it, bringing both higher temperatures and stronger winds across the Queensland border.

Once the low-pressure system moves across the Hunter area to the Tasman Sea east of Sydney, it will drag what we call a “wind change” across Queensland. This will increase wind speeds through Queensland and temperatures, making the fire situation even worse.

This is why emergency services are keeping watch for “fire tornado” conditions. When very hot air from large fires rises rapidly into a turbulent atmosphere, it can create fire storms – thunderstorms containing lightning or burning embers. Strong wind changes can also mean fire tornadoes form, sucking up burning material. Both of these events spread fires quickly and unpredictably.




Read more:
Turn and burn: the strange world of fire tornadoes


What does this mean for the drought

Unfortunately, it’s not likely the heavy rains over NSW will have a long-term effect on the drought gripping much of the state. While very heavy rains have fallen over 24 hours, the drought conditions have persisted for years.




Read more:
Trust Me, I’m An Expert: Australia’s extreme weather


The wet weather may bring some temporary relief, but NSW will need much more rain over a longer period to truly alleviate the drought.

In the meantime, the Bureau of Meteorology will be monitoring the Queensland situation closely. You can check weather warnings for your area on the bureau’s website.The Conversation

Claire Yeo, Supervising Meteorologist, Australian Bureau of Meteorology

This article is republished from The Conversation under a Creative Commons license. Read the original article.

The bitter lesson of the Californian fires



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A firefighter in California. Firefighting is getting more and more expensive as fires get more destructive.
PETER DASILVA

David Bowman, University of Tasmania

California is burning, again. Dozens of peoples have been killed and thousands of buildings destroyed in several fires, the most destructive in the state’s history.

The California fires are just the most recent in a series of major wildfires, including fires in Greece in July this year that killed 99 people, Portugal and Chile in 2017, and Australia.

Why do wildfires seem to be escalating? Despite president Donald Trump’s tweet that the California fires were caused by “gross mismanagement” of forests, the answer is more complex, nuanced, and alarming.

What caused the California fires?

The current California fires reflect a complex mix of climate, social, and ecological factors. Fuels across California are currently highly combustible due to a prolonged drought and associated low humidity and high air temperatures. Indeed, it is so dry fires burn freely through the night. Such extreme weather conditions have the fingerprints of climate change.




Read more:
Wildfires in Mediterranean Europe will increase by 40% at 1.5°C warming, say scientists


Compounding the desiccated fuels are the seasonally predictable strong desert winds (the Diablo and Santa Ana) that help fires spread rapidly towards the coast.

Low density housing embedded in flammable vegetation has created an ideal fuel mix for these destructive fires. Having people scattered across the landscape ensures a steady source of ignitions, ranging from powerline faults to carelessness and arson, making fires a near certainty when dangerous weather conditions arise.

One of the fires burning in California.
MIKE NELSON

Decades of wildfire suppression have created fuel loads that sustain intense fires. That these fuels are burning in late autumn is even more alarming. Under severe fire weather forest fires can engulf entire communities, with fires spreading from house to house, and human communities turning into a unique wildfire “fuel”. Suburbs can burn at the rate of one house per minute .

The standard response to wildfires is to fight them aggressively, using a military-style approach involving small armies of fire fighters combined with aircraft that spread fire retardant and saturate fire-fronts with water. Such approaches are extraordinarily costly. Annual spending on fire fighting has been steadily rising. In the US, annual fire-fighting costs now exceed several billion dollars, with individual fire campaigns costing ten to over a hundred million dollars.




Read more:
Spiraling wildfire fighting costs are largely beyond the Forest Service’s control


Although industrial fire-fighting approaches currently enjoy political and social support, the strategy is economically unsustainable. And they are impotent in the face of climate change driven fire disasters such as those currently occurring in California.

A human disaster

Across the fire science community there is growing recognition this “total war” on fire approach has failed. The key to sustainable co-existence with flammable landscapes is instead managing fuels around settlements, and stopping wildfires from starting in the first place.

Spain and Portugal are good examples of why this is so important. In these Mediterranean lands, humans have sustainably co-existed with flammable landscapes for thousands of year. However, the near ubiquitous depopulation of rural lands following the second world war has led to the proliferation of flammable vegetation that had previously been held in check by intensive small-scale subsistence agriculture.

The Village of Rojas in Catalonia, Spain in 1946.
Institut Cartogràfic i Geològic de Catalunya
The same Spanish village in 2017. Large-scale rural depopulation has led to widespread abandonment of formerly agricultural land, massive fuel accumulation and subsequent historically unprecedented fires.
Institut Cartogràfic i Geològic de Catalunya

With the loss of this traditional agriculture Mediterranean countries are now experiencing regular fire disasters (such as the 2018 Greek fires and the 2017 Portuguese and Spanish fires). These are equivalent to fires in more recently settled flammable landscapes in the Americas and Australia.

This seems to be the story in most flammable landscapes on earth: the removal of traditional landscape management by colonisation and globalisation has combined with climate change to turn these landscapes into tinderboxes.

But just as it is unrealistic for Australia to faithfully restore Indigenous fire management practices, expecting a return to historical practices in the Mediterranean is not realistic. There is little economic or social reason for people to return to traditional rural lifestyles, and the gravitational pull of the social and economic advantages in urban areas is too great to stem rural depopulation.

Living with fire

But we can adapt traditional practices to help us live with fire. In the Mediterranean, people are already experimenting with different ways to manage landscapes, such as managing forests for cork and bioenergy, combined with prescribed burning and grazing.

Cork harvesting, selective cutting of trees for bioenergy, understory clearing, and cattle grazing are used in Catalonia, Spain to manage fire hazard by creating a ‘green fire break’.
David Bowman

This can create picturesque landscapes that are fire-resistant and easy to defend. Similarly, in Australia, the Victorian government has created parkland-like green fire breaks that were used for back burning operations to protect communities during 2009 Black Saturday wildfires.

A green fire break in mountain ash forest near Kinglake, Victoria.
David Bowman

The Hobart City Council is planning to use similar fire breaks to protect its outer suburbs with dense bushland. Such management could be used on a larger scale to substantially reduce fire risk. The challenge for landscape fuel management is providing financial and regulatory incentives for citizens and local communities to reduce fuel.

Currently, no society is sustainably co-existing with wildfire. Globally, the situation will worsen under a rapidly-warming climate with ballooning firefighting costs, and huge loss of life and destruction of property. This is the bitter lesson of the Californian fires.The Conversation

David Bowman, Professor, Pyrogeography and Fire Science, University of Tasmania

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Yes, a tsunami could hit Sydney – causing flooding and dangerous currents



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Manly’s The Corso pedestrian area could be flooded if a large tsunami arrived at Sydney Harbour.
from www.shutterstock.com

Kaya Wilson, University of Newcastle and Hannah Power, University of Newcastle

Sulawesi’s recent tsunami is a striking reminder of the devastating, deadly effects that the sudden arrival of a large volume of water can have.

Published today, our new research shows what might happen if a tsunami hit Sydney Harbour. A large tsunami could cause significant flooding in Manly. Even very small waves might result in dangerous currents in the entrance of the Harbour and in narrow channels such as at the Spit Bridge.

Beyond Sydney, large areas of the east coast of Australia would also be affected.




Read more:
Making waves: the tsunami risk in Australia


Our study considered a range of tsunamis, with heights ranging from just 5cm to nearly 1.5m when measured outside the Heads of Sydney Harbour. These wave heights sound small, but because the wavelengths of tsunami are so long (tens to hundreds of kilometres), these waves contain a very large mass of water and can be incredibly powerful and destructive. Wave heights also increase as the tsunami encounters shallower water.

A tsunami generated by an earthquake off Chile in 1960 created waves that reached Australia..
NSW Office of Environment and Heritage holdings

How a tsunami might happen

Most tsunamis are caused by earthquakes at sea, where a shift in the sea floor creates the sudden movement of a large volume of water.

Our study approach involved modelling the likely effects of different-sized tsunamis generated by earthquakes on the New Hebrides trench to the northeast (in line with the Vanuatu islands) and the Puysegur trench (south of New Zealand).

For each event we assigned Average Recurrence Intervals (ARI), which provide an average indication of how often tsunamis of different sizes are likely to occur.

The tsunamis we studied range from an ARI of 25 years to 4,700 years. The tsunami with an ARI of 4,700 had a wave height of 1.4m outside the Heads and is the largest tsunami we could reasonably expect in Sydney Harbour. An event with an ARI of 4,700 can also be considered as an event with a 1.5% chance of occurring over a 70-year lifetime.

What would the tsunami look like?

The tsunamis we’d expect to see in Sydney Harbour would be a sequence of waves with about 15-40 minutes on average between each peak. Some waves might break, and others might appear as a rapid rising and falling of the water level.

The highest water levels would depend on the tide and the size of the event – the largest events could raise the water level up to several metres higher than the predicted tide levels.

The visualisation below represents a tsunami in a fictional location, and shows the rise and fall of water levels (with time sped up).

Tsunami visualisation in a fictitious location (created by the IT Innovation team at the University of Newcastle).

What area is at highest risk?

A tsunami is not just one single wave, but generally a sequence of waves, lasting hours to days. Within the Harbour, larger waves are most likely to breach land, and high tide increases the risk.

The narrow part of Manly – where The Corso part-pedestrian mall is located – is one of the most exposed locations. The largest tsunamis we could expect may flood the entire stretch of The Corso between the open ocean and the Harbour.

The low-lying bays on the southern side of the Harbour could also be affected. A tsunami large enough to flood right across Manly is estimated to have a minimum ARI of 550 years, or at most a 12% chance of occurring over an average lifetime.

Maximum inundation estimated to occur for a tsunami sourced from a 9.0Mw earthquake at the Puysegur trench.
Kaya Wilson, Author provided

Examining these worst-case scenarios over time shows how this flooding across Manly may occur from both the ocean side and the harbour side, isolating North Head.

Maximum inundation estimated to occur for a tsunami sourced from a 9.0Mw earthquake at the Puysegur trench and an animation showing the arrival of this tsunami at high tide. Each frame of the animation represents a two minute time interval.



Read more:
An Indonesian city’s destruction reverberates across Sulawesi


How fast would a tsunami move?

Even though the smaller tsunamis may not flood the land, they could be very destructive within the Harbour itself. Our modelling shows the current speeds caused by smaller tsunamis have the potential to be both damaging and dangerous.

The map below shows the maximum tsunami current speeds that could occur within the Harbour for the largest event we could reasonably expect.

Maximum current speeds estimated to occur for a tsunami sourced from a 9.0 magnitude earthquake at the Puysegur trench.
Kaya Wilson, Author provided

Areas exposed to the open ocean and locations with a narrow, shallow channel – such as those near the Spit Bridge or Anzac Bridge – would experience the fastest current speeds. A closer look at the area around the Spit Bridge, shows how even smaller tsunamis could cause high current speeds.

The animation below shows a comparison between the current speeds experienced during a regular spring high tide and those that may occur if a tsunami generated by a 8.5 magnitude earthquake on the New Hebrides trench coincided with a spring high tide. A tsunami of this size (0.5m when outside the Harbour) has been estimated to occur once, on average, every 110 years (a 47% chance of occurring over a lifetime).

Current Speed animation and maximum current speeds expected to occur at the Spit Bridge for a tsunami sourced from a 8.5MW earthquake at the New Hebrides trench. Each frame of the animation represents a 2 minute time interval.

This video below shows similar current speeds (7m/s based on video analysis) when the Japanese tsunami of 2011 arrived in the marina in Santa Cruz, California, and caused US$28 million of damage.

A small, fast-moving wave can have a huge impact.

Historical records show us what happened when a tsunami generated by an earthquake off Chile reached Sydney Harbour in 1960. We didn’t have any instruments measuring current speeds then, but we have witness accounts and we know that many ships were ripped from their moorings.

Fort Denison tide gauge records of the 1960 Chilean tsunami in Sydney Harbour.
NSW Office of Environment and Heritage holdings

A whirlpool and significant erosion was also reported in the Spit Bridge area. Photographs from the time show just how much sand was washed away at Clontarf Beach.

Clontarf beach erosion: (Left) 2014 in usual sediment conditions and (right) 1960 post tsunami.
Northern Beaches Council holdings

How to stay safe

A large tsunami affecting Australia is unlikely but possible. Remember that tsunamis are a sequence of waves that may occur over hours to days, and the biggest wave in the sequence could occur at any time.

The Joint Australian Tsunami Warning Centre (JATWC), jointly operated by Geoscience Australian and the Bureau of Meteorology, provides a tsunami warning system for all of Australia.

Warnings when issued are broadcast on radio and television, through the Bureau of Meteorology Tsunami warning centre and on twitter (@BOM_au).

State Emergency Services are trained to respond to a tsunami emergency and there are online resources that can help communities with awareness and preparation.


The bathymetry compilations used by this research are publicly available and can be viewed as a publication with links for free download.The Conversation

Kaya Wilson, PhD Candidate, University of Newcastle and Hannah Power, Senior Lecturer in Coastal Science, University of Newcastle

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Why Indonesia’s tsunamis are so deadly



File 20181002 98878 bkk90i.jpg?ixlib=rb 1.1

MAST IRHAM/EPA

Anja Scheffers, Southern Cross University

The magnitude 7.5 earthquake, and subsequent tsunami, that struck Indonesia days ago has resulted in at least 1,200 deaths.

Authorities are still gauging the extent of the damage, but it’s clear the earthquake and tsunami had a devastating effect on the Sulawesi region, particularly the city of Palu.

It’s not the first time earthquakes have caused mass destruction and death in Indonesia. The tsunamis that follow are particularly damaging. But why?

A combination of plate tectonic in the region, the shape of the coastline, vulnerable communities and a less-than-robust early warning system all combine to make Indonesian tsunamis especially dangerous.




Read more:
Would a better tsunami warning system have saved lives in Sulawesi?


Tectonic plates

Indonesia covers many complex tectonic environments. Many details of these are still poorly understood, which hampers our ability to predict earthquake and tsunami risks.

The biggest earthquakes on Earth are “subduction zone” earthquakes, which occur where two tectonic plates meet.

In December 2004 and March 2005, there were a pair of subduction zone earthquakes along the Sunda Trench offshore of the west coast of Sumatra. In particular, the magnitude-9.1 quake in December 2004 generated a devastating tsunami that killed almost a quarter of a million people in countries and islands surrounding the Indian Ocean.

But only looking out for these kinds of earthquakes can blind us to other dangers. Eastern Indonesia has many small microplates, which are jostled around by the motion of the large Australia, Sunda, Pacific and Philippine Sea plates.

The September quake was caused by what’s called a “strike-slip” fault in the interior of one of these small plates. It is rare – although not unknown – for these kinds of quakes to create tsunamis.

The fault systems are rather large, and through erosion processes have created broad river valleys and estuaries. The valley of the Palu river, and its estuary in which the regional capital Palu is located, have been formed by this complex fault system. Studies of prehistoric earthquakes along this fault system suggests this fault produces magnitude 7-8 earthquakes roughly every 700 years.

The sea floor shapes the wave

Another important factor for tsunamis is the depth and shape of the sea floor. This determines the speed of the initial waves. Strong subduction zone earthquakes on the ocean floor can cause the entire ocean water column to lift, then plunge back down. As the water has momentum, it may fall below sea level and create strong oscillations.

The bulge of water moving outward from the centre of a earthquake maybe of limited height (rarely much more than a metre), but the mass of water is extremely large (depending on the surface area moved by the earthquake).

Tsunami waves can travel very fast, reaching the speed of a jet. In water 2km deep they can travel at 700km per hour, and over very deep ocean can hit 1,000km per hour.

When the wave approaches the shallower coast, its speed decreases and the height increases. A tsunami may be 1m high in the open ocean, but rise to 5-10m at the coast. If the approach to the shoreline is steep, this effect is exaggerated and can create waves tens of metres high.

Despite the fact that the waves slow down near the coast, their immense starting speeds mean flat areas can be inundated for kilometres inland. The ocean floor topography affects the speed of tsunami waves, meaning they move faster over deep areas and slow down over submarine banks. Very steep land, above or below water, can even bend and reflect waves.

The coastlines of the Indonesian archipelago are accentuated, in particular in the eastern part and especially at Sulawesi. Palu has a narrow, deep and long bay: perfectly designed to make tsunamis more intense, and more deadly.

This complex configuration also makes it very difficult to model potential tsunamis, so it’s hard to issue timely and accurate warnings to people who may be affected.




Read more:
Explainer: after an earthquake, how does a tsunami happen?


Get to high ground

The safest and simplest advice for people in coastal areas that have been affected by an earthquake is to get to higher ground immediately, and stay there for a couple of hours. In reality, this is a rather complex problem.

Hawaii and Japan have sophisticated and efficient early warning systems. Replicating these in Indonesia is challenging, given the lack of communications infrastructure and the wide variety of languages spoken throughout the vast island archipelago.

After the 2004 Indian Ocean disaster, international efforts were made to improve tsunami warning networks in the region. Today, Indonesia’s tsunami warning system operates a network of 134 tidal gauge stations, 22 buoys connected to seafloor sensors to transmit advance warnings, land-based seismographs, sirens in about 55 locations, and a system to disseminate warnings by text message.

However, financing and supporting the early warning system in the long term is a considerable problem. The buoys alone cost around US$250,000 each to install and US$50,000 annually for maintenance.

The three major Indonesian agencies for responsible for earthquake and tsunami disaster mitigation have suffered from budget cuts and internal struggles to define roles and responsibilities.

Lastly, the Palu tsunami event has highlighted that our current tsunami models are insufficient. They do not properly consider multiple earthquake events, or the underwater landslides potentially caused by such quakes.

No early warning system can prevent strong earthquakes. Tsunamis, and the resulting infrastructure damage and fatalities, will most certainly occur in the future. But with a well-developed and reliable early warning system, and better communication and public awareness, we can minimise the tragic consequences.

With earthquakes that occur very close to the beach – often the case in Indonesia – even an ideal system could not disseminate the necessary information quickly enough. Indonesia’s geography and vulnerable coastal settlements makes tsunamis more dangerous, so we need more and concerted efforts to create earthquake and tsunami resilient communities.The Conversation

Anja Scheffers, Professor, Southern Cross University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Would a better tsunami warning system have saved lives in Sulawesi?


Jane Cunneen, Curtin University

The death toll from the magnitude 7.5 earthquake and resulting tsunami that struck near Palu, Indonesia, on Friday evening continues to rise, with several regions yet to be reached by rescue teams.

But the size and location of the earthquake should not have come as a surprise. Palu is situated at the end of a long, narrow bay which is the surface expression of a very active fault, the Palu-Koro fault.

The area is at high risk of tsunami, with several large earthquakes and tsunamis occurring along the fault within the past 100 years.




Read more:
Explainer: after an earthquake, how does a tsunami happen?


Details of Friday’s incident are limited, but already there are questions being asked about the effectiveness of Indonesia’s tsunami warning system.

It was developed after the devastating 2004 Boxing Day tsunami that occurred after an earthquake near Sumatra, but in this recent event the warning did not reach many of the people who were affected.

The tsunami occurred in an area where there are no tide gauges that could give information about the height of the wave. There are reports that a more high-tech system could have saved lives if it had been fully implemented.

Most of Indonesia’s deep ocean tsunameter buoys, specially designed to detect tsunamis in the open ocean, have not been working since 2012.

The Indonesian Tsunami Warning System issued a warning only minutes after the earthquake, but officials were unable to contact officers in the Palu area. The warning was cancelled 34 minutes later, just after the third tsunami wave hit Palu.

Tsunami history of Palu

Large earthquakes are not uncommon in Palu, with 15 events over magnitude 6.5 occurring in the past 100 years. The largest was a magnitude-7.9 event in January 1996, about 100km north of Friday’s earthquake.

Several these large earthquakes have also generated tsunamis. In 1927, an earthquake and tsunami caused about 50 deaths and damaged buildings in Palu. In 1968 an earthquake with magnitude 7.8 near Donggala generated a tsunami wave that killed more than 200 people.

Despite this history, many people in Palu were not aware of the risk of a tsunami following the earthquake. Ten years on from the 2004 Boxing Day tragedy that killed at least 226,000 people, there were concerns about tsunami warning systems across the region.

An advanced warning system currently only in the prototype stage may not have helped the people of Palu, as the tsunami struck the shore within 20 minutes of the earthquake.

Such early warning systems are most useful for areas several hundred kilometres from the tsunami source. In regions like Palu where the earthquake and tsunami source are very close, education is the most effective warning system.

It is not yet clear whether Friday’s tsunami was caused by movement on the fault rupture from the earthquake, or from submarine landslides within Palu bay caused by the shaking from the earthquake.

The sides of the bay are steep and unstable, and maps of the sea floor suggest that submarine landslides have occurred there in the past.

If the tsunami was generated by a submarine landslide within the bay, tsunami sensors or tide gauges at the mouth of the bay would not have sensed the tsunami wave before it struck the shore in Palu.

Communication networks

High tech tsunami warning systems are able to send out warnings through phone networks and other communications channels, and reach the community through text messages and tsunami sirens on the beaches.

But in areas where a devastating earthquake has occurred, this infrastructure is often too damaged to operate and the warning messages simply can’t get through. In Palu, the earthquake destroyed the local mobile phone network and no information was able to get in or out of the area.

Timing is also crucial. Official tsunami warnings require analysis of data and take time – even if it is only minutes – to prepare and disseminate.

This time is crucial for people near the earthquake epicentre, where the tsunami may strike within minutes of the earthquake. Those living in such areas need to be aware of the need to evacuate without waiting for official warnings, relying on the earthquake itself as a natural warning of a potential tsunami.




Read more:
Be prepared, always: the tsunami message from New Zealand’s latest earthquake


The need to raise awareness of the risk becomes even more challenging when large tsunamis occur infrequently, as in Palu. Many residents would not have been born when the last tsunami impacted the town in 1968.

So high tech warning systems may not be effective in areas close to the earthquake epicentre. Ongoing awareness and education programmes are the most important part of a tsunami warning system in coastal areas at risk of tsunami, no matter how infrequently they occur.The Conversation

Jane Cunneen, Research Fellow, Curtin University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Lombok earthquakes: different building designs could lessen future damage



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A 6.9 magnitude earthquake led to the collapse of thousands of houses in the northern parts of the Indonesian island of Lombok.
Adi Weda / AAP, CC BY-SA

Graeme MacRae, Massey University

The series of earthquakes in North Lombok and others further east goes on. But hopefully the worst is over and the intensity will recede from now.

Hundreds of people have been killed and a lot more injured, many of them seriously. Nearly all this human suffering was caused by collapsing buildings. The subsequent homelessness will go on for many months for hundreds of thousands of people.

But a lot of this suffering need not have happened.




Read more:
After devastating earthquakes, Indonesia must embrace radical change


Changing building standards

The strongest quake on August 5, 6.9 in magnitude and at a relatively shallow depth, is large by any standard. But, as photos and video footage show, not all buildings collapsed. Among the landscape of devastation are many buildings that appear to have suffered little if any damage.

According to one estimate, 70% of buildings suffered serious damage, which means 30% did not. In many parts of the world, such as Japan, New Zealand and Chile, buildings are designed to withstand earthquakes of this scale and many of them do, repeatedly.




Read more:
Two types of tectonic plate activity create earthquake and tsunami risk on Lombok


About 70% of buildings suffered serious damage in the Lombok earthquakes, but some stood up to the shaking.
AAP, CC BY

Traditional buildings in most of Indonesia, including northern Lombok, were built of timber framing with thatched roofs. In an earthquake they flex and sway but rarely collapse. If they do, it is likely to happen slowly and incompletely and any falling roofing is relatively light and soft.

But over recent decades, building materials and methods have changed. Timber and thatch have become scarce and expensive and popular tastes have shifted towards houses that look, at least superficially, like those of the global modern middle class – little villas with plastered walls, glass windows and tiled roofs.

But underneath the (often picturesque) facades, the construction is of brick or concrete blocks, held together only with weak mortar and supported by little or no framing. The better ones may have some concrete framing, but the quality of the concrete is usually poor and the steel reinforcing, especially at joints, is minimal. These facades do not reliably support infill materials and they are heavy when they fall.

Roof tiles are only loosely secured and ceilings below them are too light to catch them. If one had to design a system of construction for easy collapse and maximum injuries, this would be the perfect model.

Learning from past earthquakes

In Yogyakarta, in central Java, in May 2006, at least 150,000 houses of exactly this kind collapsed in less than a minute of shaking caused by a lesser earthquake than the largest in Lombok. Nearly 6,000 people were killed and thousands more injured. Farm animals housed in traditional buildings mostly survived.

A massive international humanitarian aid response and significant government programmes followed and within a year Yogyakarta was largely rebuilt – an astonishing result in the circumstances. Both government and international agencies went to considerable lengths to design safer methods, educate people about them and offer support, materials and incentives to “build back better”.

An expert report ten years later (unfortunately not yet published) concluded that:

The overall poor quality of construction however has almost certainly placed more people at increased risk of larger, heavier building elements collapsing upon them.

Northern Lombok has not had this kind of experience in recent decades and, because it is a relatively poor part of Indonesia, until 20 years ago, many people outside the urban areas lived in traditional houses. However, over recent years, partly as a result of tourism revenues, many houses have been built or extended in the new style and construction.

Here too, construction standards tend to be low, and even lower for poorer households. The video evidence shows exactly the kind of failures as in Yogyakarta 12 years ago, because of exactly the same basic weaknesses of design. The next earthquake, wherever it may be in Indonesia, will almost certainly have the same effects.

Houses in Lombok collapsed because of design failures similar to those in Yogyakarta 12 years ago.
AAP, CC BY

No easy solutions

A recent article makes similar points and blames inadequate enforcement of building codes and lack of government commitment. Unfortunately the reality is not so simple.

The Yogyakarta experience shows that even with a massive campaign by government and international agencies, and with the fear of earthquakes still fresh in people’s minds, the rebuilding was little better than what it replaced. Building codes do exist in Indonesia, but they are rarely followed, easily evaded, and rarely enforced, least of all at the level of owner-built local housing.

Even if there were a serious effort to implement codes, it would be undermined by well-known levels of bureaucratic inefficiency and corruption, as well as public resistance and evasion. It would also have unintended consequences, including making decent housing even less affordable, especially for poorer people.

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The Conversation

There will be no easy solutions, but national education in basic structural design principles, subsidised design, production and distribution of cheap and simple hardware for mitigating the most common failures of design and financial incentives for appropriate construction might be worthwhile places to start.

Graeme MacRae, Senior Lecturer in Social Anthropology, Massey University

This article was originally published on The Conversation. Read the original article.

The Laos disaster reminds us that local people are too often victims of dam development


Jason von Meding, University of Newcastle; Giuseppe Forino, University of Newcastle, and Tien Le Thuy Du, University of Houston

On July 22, the Xepian-Xe Nam Noy hydropower dam under construction in Laos’ Attapeu Province collapsed. Flash flooding inundated eight villages, killing at least 29 people and leaving 131 officially reported missing. The final number of casualties could be much higher.

Disaster response activities are ongoing. The deputy secretary of the province claimed that more than 1,100 people were still unaccounted for, as of July 27. Laotian authorities are investigating whether the collapse was caused by heavy rainfall, inadequate construction standards, or a combination of the two.

The dam is part of a larger joint venture between Laotian, Thai and South Korean companies, which are reportedly helping with the rescue and restoration effort. The companies are also sending experts to assess the damage and investigate the cause of the disaster.




Read more:
Chinese hydropower electrifies southeast Asia, but at a cost



This is not the first time that a hydropower project in Southeast Asia has been in the spotlight. It again raises questions about the benefits of such projects for local communities, considering the risks to which local people are exposed.

Not only do large developments interfere with ecosystems, but they often affect local communities even in the absence of catastrophe. This was indeed the case for the Xepian-Xe Nam Noy project, which had already cost many villagers their land and livelihoods before disaster struck.

As much as we tend to focus on the “natural” triggers for disaster – in this case heavy rain – the reality is more nuanced. These incidents are often also the result of flawed development, and as such they are social and political disasters too.

So, was this disaster just a terrible accident? Or is it emblematic of a development agenda that is out of sync with the needs of a healthy environment and local community?

The impacts of hydropower

Hydropower projects in Southeast Asia, and particularly in the Mekong catchment, have long exposed vulnerable communities to risk while developers reap the rewards. Millions of people depend on the Mekong river for water, fish, transport and irrigation.

Dam developers promise that their projects will deliver a wide array of benefits: renewable energy, bountiful reservoir fishing, profitable reforestation, harmonised water allocation, and better flood control. But these controversial projects often dramatically change local livelihoods for the worse.

A map of dams on the lower Mekong.
ICEM

We have seen this before, both in Laos and in its neighbouring countries. The Nam Song Diversion Dam, completed in 1996, affected more than 1,000 Laotian families – first by removing their access to productive agricultural land and causing a severe decline in fish stocks. Since then, deliberate water surges – for electricity generation – have been blamed for three deaths and widespread loss of boats and fishing equipment.

The Nam Theun 2 Hydropower Project boasted rigorous social and environmental safeguards – but these soon became broken promises. This project also followed a disturbing trend relating to hydropower development in Southeast Asia: the dispossession of already marginalised ethnic minorities.

In neighbouring Cambodia, the Kamchay Dam displaced thousands of people, jeopardised their livelihoods, and caused irreparable damage to the environment. The Pak Chom Dam in Thailand similarly put local livelihoods at risk.

So despite providing clean renewable energy, many hydropower projects in Southeast Asia have also deepened inequality and marginalisation.




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People vs profit

This latest disaster should therefore be seen in the context of broader criticism concerning damming the Mekong and its tributaries.

Some analysts have argued that local communities in the Mekong delta are being caught in the middle of a cross-border water grab. Private and state-backed actors from China, Thailand, and Laos profit handsomely from hydropower projects, but critics argue that all too often the negative impacts of dams are ignored.

Local protests against development projects are often suppressed, and governments regularly align with private interests to maximise profit and protect developers from any repercussions. In recent years, affected communities have made some gains, but displacement and disempowerment are still rife.

The exploitation of the Mekong river is only likely to increase. China has a clear energy agenda and Laos aspires to be the “battery of Southeast Asia”. But while exporting much of its hydroelectric power to Thailand, Vietnam and Cambodia, the Laotian government imports the same power back at increased cost from Thailand. Local people feel that something is amiss.

Communities from the Mekong villages of Mo Phu and Pak Paew villages have been told to prepare for resettlement due to the planned construction of the Phou Ngoy Dam. They face uncertainty as to the living conditions at their new location.

Development isn’t always positive

The World Bank ranked Laos as the 13th fastest growing economy of 2016, and the Asian Development Bank predicts that its economy will grow at 7% a year for the remainder of this decade.

Hydropower is a major contributor to this economic growth. But hydropower projects promote displacement, put livelihoods and food security at risk, and destroy biodiversity and ecosystems. Without considering both international and local social and environmental costs, hydropower development exacerbates everyday struggles for many people in Southeast Asia.

Many of the destructive projects on the Mekong are supported by the World Bank and the Asian Development Bank. These powerful international stakeholders should not be above criticism.




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The kind of development that is primarily concerned with profits for corporations always occurs at the expense of the most marginalised communities and individuals. All too often their voices are silenced and political accountability is absent.

The ConversationThe evidence indicates that it may not be so simple to decouple economic growth from environmental harm.

Jason von Meding, Senior Lecturer in Disaster Risk Reduction, University of Newcastle; Giuseppe Forino, PhD Candidate in Disaster Management, University of Newcastle, and Tien Le Thuy Du, PhD Candidate in Geosensing and water management, University of Houston

This article was originally published on The Conversation. Read the original article.

After devastating earthquakes, Indonesia must embrace radical change


Jonatan A Lassa, Charles Darwin University

An earthquake on Lombok island in Indonesia has left 98 people dead and 20,000 people homeless, according to the National Disaster Mitigation Agency.

Around 70% of North Lombok’s housing stock has either collapsed or been severely damaged. Just a week earlier, a 6.5-magnitude earthquake hit a nearby region, destroying tens of houses and claiming 10 lives, and injuring more than a dozen people.




Read more:
Two types of tectonic plate activity create earthquake and tsunami risk on Lombok


As the area recovers, we need to ask: how can Indonesia address its vulnerability to earthquakes?

We know that Indonesia can improve its response to natural disasters, which has happened with tsunami preparedness. The next challenge is to apply these lessons to seismic activity.

Prepare for tourists

Thousands of tourists were caught in panics after both earthquakes. It’s time for Indonesia’s emergency systems to address the vulnerability of foreign visitors as well as its own citizens.

With tourism on the rise in many earthquake-prone areas, solid preparation measures need to be put in place. Vulnerable hotels and fragile houses can jeopardise tourism’s future.

The past 30 years have been filled with wake-up calls. A 1992 earthquake that struck Flores island caused 15,000 houses to collapse in a single district alone. It took almost 20 years for tourism to recover.

More technology isn’t the answer

It’s often easier to attract international funding to sophisticated new technology for hazard prediction and monitoring – for example, the Australia-funded Inasafe, which has the potential to help government to develop scenarios for better planning, preparedness and response activities, and the US-funded Inaware which is a disaster management tool aimed at improving Indonesia’s risk assessment and early warning systems.

At the same time, it is not clear how these technological advancements will serve to help small hotels or households in earthquake-prone regions. What people really need is need help to build structures in accordance with proper construction codes, so that they don’t become death-traps during an earthquake.

This points to a deeper problem. Such building codes already exist, but local governments are currently showing little desire to comply with national building regulations.

For example, before 2011, less than 12% of local governments adopted and endorsed the Building Law 2002. By 2016 that figure had risen to 60% – an improvement, but still not enough.

In North Lombok, where most houses collapsed in the recent earthquakes, the local government only endorsed national building regulations in 2011. It will take years for the local administrators to actually implement them.

The no-regreat approach

To save lives, we need to move beyond the idea that perfect risk assessment exists.

Seismic mitigation measures need to start immediately, at the local level. Thousands building are built every day and right now, while many are rebuilding after disaster, is the time for local governments to put into practise the codes and standards that exist at a national level.

Local and central governments can embrace innovation. Central government and local governments in Indonesia must focus on transforming the way houses are built, including checking earthquake preparedness when issuing building permits.

Can local government radically audit all vulnerable houses? And can we create a machine of local bureaucrats who can deal with the risk assessment on every single house in earthquake prone regions?

It may seem hard, but good practices are already available. Apart from creating incentives for local engineers, contractors, and building consultants to be mindful of seismic measures, local governments can also gradually audit critical public buildings, which are particularly crucial to disaster to response (and may be especially dangerous if they collapse).

Indonesia could even follow California’s example and publicly shame the owners of buildings that the building code.

A sign from California alerting passers-by to a potentially dangerous building.

It will require radical reform in public administration, including construction at local level. Without this radical change, the status quo will remain and people will continued to be killed by their houses when moderate to big earthquakes hit their area.




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The ConversationThe present approach is failing. Stronger political and administrative commitments are needed at all levels.

Jonatan A Lassa, Senior Lecturer, Humanitarian Emergency and Disaster Management, Charles Darwin University

This article was originally published on The Conversation. Read the original article.

Two types of tectonic plate activity create earthquake and tsunami risk on Lombok


Jane Cunneen, Curtin University and Phil R. Cummins, Australian National University

Several large earthquakes have struck the Indonesian island of Lombok in the past week, with the largest quake killing at least 98 people and injuring hundreds more.

Thousands of buildings are damaged and rescue efforts are being hampered by power outages, a lack of phone reception in some areas and limited evacuation options.

The majority of large earthquakes occur on or near Earth’s tectonic plate boundaries – and these recent examples are no exception. However, there are some unique conditions around Lombok.

The recent earthquakes have occurred along a specific zone where the Australian tectonic plate is starting to move over the Indonesian island plate – and not slide underneath it, as occurs further to the south of Lombok.

This means there is earthquake and tsunami risk not only along the plate boundary south of Lombok and Bali, but also from this zone of thrusting to the north.




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Jammed subduction zone

Tectonic plates are slabs of the Earth’s crust that move very slowly over our planet’s surface. Indonesia sits along the “Pacific Ring of Fire” where several tectonic plates collide and many volcanic eruptions and earthquakes occur.

Some of these earthquakes are very large, such as the magnitude 9.1 quake off the west coast of Sumatra that generated the 2004 Indian Ocean tsunami. This earthquake occurred along the Java-Sumatra subduction zone, where the Australian tectonic plate moves underneath Indonesia’s Sunda plate.

But to the east of Java, the subduction zone has become “jammed” by the Australian continental crust, which is much thicker and more buoyant than the oceanic crust that moves beneath Java and Sumatra.

The Australian continental crust can’t be pushed under the Sunda plate, so instead it’s starting to ride over the top of it. This process is known as back-arc thrusting.

The data from the recent Lombok earthquakes suggest they are associated with this back-arc zone. The zone extends north of islands stretching from eastern Java to the island of Wetar, just north of Timor (as shown in map below).

Earthquake hazards along plate boundaries near Indonesia. The dates in the map show historical earthquakes, and Mw indicates earthquake magnitude.
Edited by P. Cummins from an original by Koulali and co-authors

Historically, large earthquakes have also occurred along this back-arc thrust near Lombok, particularly in the 19th century but also more recently. (Dates and sizes of past earthquakes are shown in the map above).

It is thought that this zone of back-arc thrusting will eventually form a new subduction zone to the north along from eastern Java to the island of Wetar just north of Timor.




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Tsunami risk

Lombok’s recent earthquakes – the August 5 6.9 magnitude quake plus a number of aftershocks, and the 6.4 magnitude earthquake just a week before it – occurred in northern Lombok under land, and were quite shallow.

Recent earthquakes on Lombok were also felt on the neighbouring island of Bali.
US Geological Survey

Earthquakes on land can sometimes cause undersea landslides and generate a tsunami wave. But when shallow earthquakes rupture the sea floor, much larger and more dangerous tsunamis can occur.

Due to the large number of shallow earthquakes along the plate boundaries, Indonesia is particularly vulnerable to tsunamis. The 2004 Indian Ocean tsunami killed more than 165,000 people along the coast of Sumatra, and in 2006 over 600 people were killed by a tsunami impacting the south coast of Java.




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The region around Lombok has a history of tsunamis. In 1992 a magnitude 7.9 earthquake occurred just north of the island of Flores and generated a tsunami that swept away coastal villages, killing more than 2,000.

Nineteenth century earthquakes in this region also caused large tsunamis that killed many people.

The areas around Lombok and the islands nearby, including Bali, are at high risk for earthquakes and tsunamis occurring both to the north and the south of the island.

The ConversationUnfortunately, large earthquakes like the ones this week cannot be predicted, so an understanding of the hazards is vital if we are to be prepared for future events.

Jane Cunneen, Research Fellow, Curtin University and Phil R. Cummins, Professor, Australian National University

This article was originally published on The Conversation. Read the original article.