Tsunami

Dramatic rescues as tsunami-like flood hits Japan city

September 10, 2015 by Nasheman

More than 100,000 flee homes after Kinugawa river breaks banks, leaving houses submerged and residents stranded.

The building of an open-air spa, right, that belongs to Kinugawa Plaza Hotel, falls into the rapid stream of the Kinugawa River swollen by heavy rainfall in Nikko, northeast of Tokyo [Kyodo News/AP]

by Al Jazeera

Military helicopters have plucked residents from the top floors of their homes after raging floodwaters poured in and inundated a wide swath of a city north of Tokyo.

As heavy rain pummelled Japan for a second straight day, the Kinugawa River broke through a flood berm on Thursday, sending a tsunami-like wall of water into Joso, about 50km northeast of Japan’s capital.

The flooding has forced more than 100,000 people from their homes, at least 17 people were injured. Two people were missing.

A 63-year-old woman was missing in a landslide that hit her home while a man in his 70s in Joso was feared trapped when water engulfed his home, NHK national television said.

Earlier, NHK showed aerial footage of rescuers lowered from helicopters and clambering onto second-floor balconies to reach stranded residents.

In one dramatic rescue by a military helicopter, the rescuer could be seen descending four times over about a 20-minute period to take four people up one-by-one, as a deluge of water swept around the home.

Yuko Yoshida from the Japanese Red Cross told Al Jazeera that the exact number of those in need of emergency rescue was not known because many people had evacuated before the rains came in.

“From our assumptions, the government has managed this situation well. Medical facilities are operating,” Yoshida said.

Woman missing

Elsewhere in the region, one woman was missing hours after a landslide hit houses at the foot of a steep, wooded incline. Bullet train services were partially suspended.

Others waved cloths from their veranda as torrents of water around them washed away cars and knocked buildings off their foundations.

Tokyo was also drenched with rain, but the hardest-hit area was to the north in Ibaraki and Tochigi prefectures.

The rain came on the heels of Tropical Storm Etau, which caused similar flooding and landslides Wednesday as it crossed central Japan.

The Fire and Disaster and Management Agency said 15 people were injured by Etau, two seriously. Both were elderly women knocked over by strong winds.

Al Jazeera’s weather forecaster, Everton Fox, said the worst of the rains would clear within the next 12 to 18 hours, adding that by Friday the downpour will have largely stopped.

“The floods are likely to peak for some time because the run off from the higher ground will seep through for a couple of days and then we can expect a gradual improvement in the situation,” Fox said.

A man carries belongings through a flooded street in Oyama, northeast of Tokyo on Thursday [Kyodo News/AP]

Ten years after the Boxing Day tsunami, are coasts any safer?

December 27, 2014 by Nasheman

The day after: a Sri Lankan man begins the slow process of rebuilding. EPA/Mike Nelson

by Emily Heath, The Conversation

Ten years ago we witnessed one of the worst natural disasters in history, when a huge earthquake off the coast of Sumatra triggered a devastating tsunami which swept across the Indian Ocean.

An estimated 230,000 people lost their lives, and 1.6 million people lost their homes or livelihoods.

The impact was greatest in northern Sumatra because of its proximity to the earthquake. Catastrophic shaking was followed within minutes by the full force of the tsunami.

Avoidable deaths

Thousands of people were also killed in distant countries, where the earthquake could not be felt. If they had received a warning of the approaching tsunami, they could have moved inland, uphill or out to sea, and survived. Tsunami take several hours to cross an ocean, becoming much larger and slower as they reach the coast.

Back in 2004 there were long-established tsunami warning systems in the Pacific Ocean, which has many subduction zones – places where two tectonic plates collide – capable of generating huge earthquakes or volcanic eruptions.

Other regions, including the Indian Ocean, did not have a warning system. The probability of a major tsunami was judged to be too low to justify the cost, especially for poorer countries.

The Boxing Day 2004 disaster changed all that.

Progress in the past decade

In early 2005, the UN agreed to develop an international warning system including regional systems in the Indian Ocean, North East Atlantic & Mediterranean, and Caribbean. The Indian Ocean tsunami warning system was developed between 2006 and 2013, at a total cost of at least $19 million.

Japan has installed more buoys in the wake of its own 2011 disaster. NOAA

In the three years prior to October 2014, bulletins were issued about 23 Indian Ocean earthquakes, resulting in a small number of potentially life-saving coastal evacuations. Most of these 23 earthquakes did not actually generate a threatening tsunami because they did not cause significant uplift or subsidence of the seafloor. But false alarms can provide reassurance that communications work well, or highlight weaknesses.

Communications and evacuation procedures are also regularly tested by international mock drills, often based on worst case scenarios.

How do tsunami warning systems work?

All warning systems work in the same general way. First, a network of broadband seismometers detects the seismic waves generated by an earthquake, which travel at speeds of several kilometres per second. When several seismometers have detected the seismic waves, the location and approximate magnitude of the earthquake can be computed. If the epicentre is under water and the magnitude large (greater than 6.5 on the Richter, or moment magnitude, scale) a tsunami bulletin, watch or warning is issued to local communication centres, ideally within three minutes of the earthquake. If the epicentre is nearby and the probability of a tsunami is high, evacuation procedures will be initiated immediately.

If all else fails, follow the signs. Kallerna, CC BY-SA

Otherwise, local centres will standby for confirmation of whether a tsunami has actually been generated. Confirmation comes within about 30-60 minutes, using a network of tsunami buoys and seafloor pressure recorders. These detect the series of waves (usually less than a couple of metres high and travelling at about 800 km/h) in the open ocean, and transmit the data by satellite to a regional control centre.

Tsunami warnings reach the public via TV, radio, email, text messages, sirens and loudspeakers. You can sign up to receive tsunami alerts anywhere in the world by SMS on your mobile phone, thanks to a not-for-profit humanitarian service called CWarn.org.

Many high-risk areas also have signage to alert people to “natural” warnings (such as strong shaking or a sudden withdrawal of the sea), and direct them to higher ground.

Limitations of warning systems

The Pacific and Japanese warning systems helped to ensure the major tsunami generated off the coast of Japan on 11 March 2011 caused far fewer deaths (15,000) than the 2004 disaster. However, it showed that even a wealthy and well-prepared nation such as Japan cannot fully protect people from extreme hazards, and that warning systems can sometimes lead to a false sense of security.

Japan, 2011: fewer lives were lost but the damage was immense Chief Hira, CC BY-SA

The slow rupture of the subduction zone near Japan meant the initial warnings underestimated the magnitude of the earthquake and resulting tsunami. Many people did not move to higher ground in the vital few minutes after receiving the warning, because they wrongly assumed the tsunami would be stopped by 5-10 m high sea walls.

Japan has learned from this tragedy and, among other things, made changes to tsunami warning messages, improved coastal defences, and installed more seismometers and tsunami buoys.

Will more tsunami disasters occur?

It is impossible to predict exactly when or where the next major tsunami will occur. They are very rare events in our limited historical record. But by dating prehistoric tsunami deposits, we can see that major tsunamis happen on average every few hundred years in many coastal regions.

Future tsunami disasters are inevitable, but with better technology, education and governance we can realistically hope that a loss of life on the scale of the 2004 tsunami disaster will not happen again.

Emily Heath is a Senior Teaching Associate, Lancaster Environment Centre at Lancaster University.

Tsunami alert sparks panic in Indonesia

November 15, 2014 by Nasheman

Kota Ternate, Indonesia/AFP: A powerful 7.1-magnitude earthquake rocked the Maluku Islands in eastern Indonesia Saturday, sparking a tsunami warning and causing panicked people to flee their homes.

Small waves generated by the undersea quake were detected in several parts of the sprawling archipelago, local authorities said, although there were no reports of casualties or major damage and the tsunami warning was lifted after a short while.

Nevertheless, the prospect of a major tsunami set nerves on edge in one of the most seismically active countries in the world, almost a decade after quake-triggered destructive waves devastated western Aceh province.

The tsunami of December 26, 2004, left more than 170,000 people dead in Aceh, on Sumatra island, and tens of thousands more in countries with coasts on the Indian Ocean.

Saturday’s tremor struck northwest of the town of Kota Ternate, at 0231 GMT, the US Geological Survey said. It was followed by a series of aftershocks that measured between magnitude 4.3 and 5.8, the USGS said.

“Tsunami waves are possible for coasts located within 300 kilometres,” said the Pacific Tsunami Warning Center.

The centre also warned of small tsunami waves in the Philippines, Japan, Taiwan and islands in the South Pacific.

On the tiny Sangihe Islands close to the epicentre in Indonesia, people ran out of their homes when the quake hit, Toni Supit, head of the islands’ Sitaro district, told AFP.

“People in coastal areas felt the strong quake, which lasted for quite some time, and they immediately went to the sea to see if the water was receding abnormally, which is a sign of an incoming tsunami,” he said.

Ring of fire –

Tsunami waves nine centimetres high were detected at Jailolo on Halmahera island, in the Maluku Islands, the meteorological agency said. Tiny waves were also detected in Tobelo on Halmahera, and in Manado, on nearby Sulawesi island.

An agency official on Sulawesi said early reports indicated that cracks had appeared in the walls of some houses after the quake, although full damage reports had yet to come in.

The Pacific Tsunami Warning Center said earlier that waves up to one metre high could hit parts of Indonesia, while waves below 30 centimetres were forecast for the coasts of the Philippines.

Indonesia’s meteorological agency warned people in the northern Maluku Islands and in the north of Sulawesi in particular to stay away from the coast.

Julius Galgiano, a Philippine government seismologist, said the Philippines had also issued a tsunami warning.

“We are telling (local communities) to have a tsunami watch in areas along the coast,” he said, but added that no evacuation orders had been issued and the tsunami waves were not expected to be high.

Around two hours after the quake, the warning centre said there was no longer a tsunami threat.

“The tsunami threat from this earthquake has now mostly passed. Any remaining threat should be evaluated by local authorities in impacted areas,” it said.

Indonesia sits on the Pacific “Ring of Fire” where continental plates collide, causing frequent seismic and volcanic activity, and has been hit by numerous deadly earthquakes over the years.

A 6.1-magnitude quake that hit inland in Aceh in July last year left at least 30 people dead and thousands homeless. It caused a mosque to collapse in one village, killing six children as they took part in a Koran reading session.

Dramatic rescues as tsunami-like flood hits Japan city

Ten years after the Boxing Day tsunami, are coasts any safer?

Tsunami alert sparks panic in Indonesia

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