London's a shallow Christian sea with islands of other faiths​

Although London is predominantly Christian, this map shows an archipelago of different faiths throughout the city.

Distribution of religions through London
London is dotted with areas where high concentrations of Sikhs, Jews, Muslims, Hindus, and Buddhists live (Ben Flanagan).

Religions are universal and transcendent, but they're also local and personal. This map shows where in London religious people live—quite often, very close to other people of the same faith.


Each dot on the map represents a single religious person. The different colors correspond to that person's faith. Blue is for Christian, turquoise for Muslim, and yellow for Jewish. A purple dot represents a Hindu, an orange one a Sikh, and a green one a Buddhist (red is for "other").

This map was created by cartographer Ben Flanagan, who chose the dot density method to illuminate the clustering of certain faiths in certain areas: "Dot density maps are really effective at normalising data by geographic area. This is because places with fewer people fade away, while densely populated areas become more prominent."

As the map suggests, Christianity is still the biggest faith in London. But Greater London is the least Christian region in the UK: less than half (48.71%) of all Londoners are Christian. London does have the country's highest percentage of Buddhists (1.01%), Hindus (5.05%), Jews (1.84%), and Muslims (12.56%). However, the Midlands has more Sikhs (2.39%) than any other region.

So, if London still looks like a Christian sea, it's a fairly shallow one—and dotted with large islands and archipelagos peopled by other faiths.

Map of London, color-coded by religion (Ben Flanagan).
  • Greenwich has the highest share of Buddhists (1.66%), while Havering has the lowest (0.32%). The most Buddhists live in Barnet (4,521)—a relatively small number, so it's pretty hard to observe those green spots.
  • London's most Jewish boroughs are Barnet (15.18%), Hackney (6.28%), and Camden (5.10%)—the three yellow centers in the north. The least Jewish borough is Bexley (0.10%). Barnet also has the highest number of Jews (54,084), and Bexley the lowest (234).
  • Hounslow is the Sikh capital of London in relative terms (8.96%), while neighboring Ealing has the most in absolute terms (26,778); both are clearly visible on the map.
  • In Harrow—the pink spot in the northwest—just over 1 in 4 is Hindu (25.27%). Harrow also has the highest number of Hindus in absolute terms (60,407, followed by neighboring Brent, with 55,449). Hackney is the least Hindu borough of London (0.64%).
  • Tower Hamlets is London's most Muslim borough (37.84%), followed by Newham (31.97%), Redbridge (23.30%), and Waltham Forest (21.89%)—together forming the turquoise area in the northeast. In absolute figures, Newham (98,456) is ahead of Tower Hamlets (96,157), Redbridge (64,999), and Brent (58,036). Islam is an inner-city faith in London. The least Muslim boroughs are all on the outskirts: Havering (2.04%), Bexley (2.43%), Bromley (2.53%), and Richmond (3.28%).
  • Blue may be everywhere, but it is deepest in Havering, the borough furthest east in London, and with the city's greatest concentration of Christians: 66%. Croydon, on the other hand, has the highest number of Christians (205,022). Tower Hamlets has London's lowest percentage of Christians (29.55%).
  • Not shown on this map are the third of Londoners who indicated in the 2011 Census that they had no religion. The tiny City of London, a.k.a. the Square Mile, is London's central business district. It is almost entirely dedicated to the business of making money, with no more than 7,375 permanent residents. Those also happen to be the most godless bunch of Londoners (34.20%)—although Islington (32.98%) and Camden (29.08%) come a close second and third. Overall, 12 of London's 32 boroughs have more than a quarter of irreligious inhabitants. Just two have unbelievers in the single digits, and then only just: Newham (9.54%) and Harrow (9.57%).

Mr. Flanagan repeated the method for other areas of the UK, including Manchester, Yorkshire, and Tyne and Wear. See more of his work here.

Strange Maps #938

Got a strange map? Let me know at strangemaps@gmail.com.

A landslide is imminent and so is its tsunami

An open letter predicts that a massive wall of rock is about to plunge into Barry Arm Fjord in Alaska.

Image source: Christian Zimmerman/USGS/Big Think
Surprising Science
  • A remote area visited by tourists and cruises, and home to fishing villages, is about to be visited by a devastating tsunami.
  • A wall of rock exposed by a receding glacier is about crash into the waters below.
  • Glaciers hold such areas together — and when they're gone, bad stuff can be left behind.

The Barry Glacier gives its name to Alaska's Barry Arm Fjord, and a new open letter forecasts trouble ahead.

Thanks to global warming, the glacier has been retreating, so far removing two-thirds of its support for a steep mile-long slope, or scarp, containing perhaps 500 million cubic meters of material. (Think the Hoover Dam times several hundred.) The slope has been moving slowly since 1957, but scientists say it's become an avalanche waiting to happen, maybe within the next year, and likely within 20. When it does come crashing down into the fjord, it could set in motion a frightening tsunami overwhelming the fjord's normally peaceful waters .

"It could happen anytime, but the risk just goes way up as this glacier recedes," says hydrologist Anna Liljedahl of Woods Hole, one of the signatories to the letter.

The Barry Arm Fjord

Camping on the fjord's Black Sand Beach

Image source: Matt Zimmerman

The Barry Arm Fjord is a stretch of water between the Harriman Fjord and the Port Wills Fjord, located at the northwest corner of the well-known Prince William Sound. It's a beautiful area, home to a few hundred people supporting the local fishing industry, and it's also a popular destination for tourists — its Black Sand Beach is one of Alaska's most scenic — and cruise ships.

Not Alaska’s first watery rodeo, but likely the biggest

Image source: whrc.org

There have been at least two similar events in the state's recent history, though not on such a massive scale. On July 9, 1958, an earthquake nearby caused 40 million cubic yards of rock to suddenly slide 2,000 feet down into Lituya Bay, producing a tsunami whose peak waves reportedly reached 1,720 feet in height. By the time the wall of water reached the mouth of the bay, it was still 75 feet high. At Taan Fjord in 2015, a landslide caused a tsunami that crested at 600 feet. Both of these events thankfully occurred in sparsely populated areas, so few fatalities occurred.

The Barry Arm event will be larger than either of these by far.

"This is an enormous slope — the mass that could fail weighs over a billion tonnes," said geologist Dave Petley, speaking to Earther. "The internal structure of that rock mass, which will determine whether it collapses, is very complex. At the moment we don't know enough about it to be able to forecast its future behavior."

Outside of Alaska, on the west coast of Greenland, a landslide-produced tsunami towered 300 feet high, obliterating a fishing village in its path.

What the letter predicts for Barry Arm Fjord

Moving slowly at first...

Image source: whrc.org

"The effects would be especially severe near where the landslide enters the water at the head of Barry Arm. Additionally, areas of shallow water, or low-lying land near the shore, would be in danger even further from the source. A minor failure may not produce significant impacts beyond the inner parts of the fiord, while a complete failure could be destructive throughout Barry Arm, Harriman Fiord, and parts of Port Wells. Our initial results show complex impacts further from the landslide than Barry Arm, with over 30 foot waves in some distant bays, including Whittier."

The discovery of the impeding landslide began with an observation by the sister of geologist Hig Higman of Ground Truth, an organization in Seldovia, Alaska. Artist Valisa Higman was vacationing in the area and sent her brother some photos of worrying fractures she noticed in the slope, taken while she was on a boat cruising the fjord.

Higman confirmed his sister's hunch via available satellite imagery and, digging deeper, found that between 2009 and 2015 the slope had moved 600 feet downhill, leaving a prominent scar.

Ohio State's Chunli Dai unearthed a connection between the movement and the receding of the Barry Glacier. Comparison of the Barry Arm slope with other similar areas, combined with computer modeling of the possible resulting tsunamis, led to the publication of the group's letter.

While the full group of signatories from 14 organizations and institutions has only been working on the situation for a month, the implications were immediately clear. The signers include experts from Ohio State University, the University of Southern California, and the Anchorage and Fairbanks campuses of the University of Alaska.

Once informed of the open letter's contents, the Alaska's Department of Natural Resources immediately released a warning that "an increasingly likely landslide could generate a wave with devastating effects on fishermen and recreationalists."

How do you prepare for something like this?

Image source: whrc.org

The obvious question is what can be done to prepare for the landslide and tsunami? For one thing, there's more to understand about the upcoming event, and the researchers lay out their plan in the letter:

"To inform and refine hazard mitigation efforts, we would like to pursue several lines of investigation: Detect changes in the slope that might forewarn of a landslide, better understand what could trigger a landslide, and refine tsunami model projections. By mapping the landslide and nearby terrain, both above and below sea level, we can more accurately determine the basic physical dimensions of the landslide. This can be paired with GPS and seismic measurements made over time to see how the slope responds to changes in the glacier and to events like rainstorms and earthquakes. Field and satellite data can support near-real time hazard monitoring, while computer models of landslide and tsunami scenarios can help identify specific places that are most at risk."

In the letter, the authors reached out to those living in and visiting the area, asking, "What specific questions are most important to you?" and "What could be done to reduce the danger to people who want to visit or work in Barry Arm?" They also invited locals to let them know about any changes, including even small rock-falls and landslides.

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