Self-organizing Criticality is much preferable to Evil Hive Mind

Zombie hording behavior is crucial to decision-making after the zombiepocalypse. Assuming that our rotting foes are dumb beasts with no mind at all may be our downfall, but all the classic texts seem to contain two fundamental assumptions:

  • Zombies have absolutely no sentience or intellect
  • Zombies gather together in hordes

Some texts also assume that zombies retain a very very rudimentary and instinctive memory of their activities as humans (crowding to shopping centres, walking along roads, etc.) but this could be a mistaken conclusion based on their hording behavior. How zombies form hordes is a key part of the zombiepocalypse puzzle: consider the ending of The Walking Dead[1] season 2, where zombies see a helicopter, follow it, and when they lose sight of it just keep walking in a straight line. This is very specific hording behavior, not necessarily matched to any existing understanding of self-organizing behavior. Understanding what happens in these kinds of situations is essential to planning anti-zombie defenses.

In most of my posts about zombie survival spots here I’ve worked on the assumption that zombies are mindless moving objects, kind of like the famous physicists’ perfect point particle. They move slowly away from their point of origin in a random direction, so if one moves away from a city one can imagine the wave of zombies emerging from the city just like a supernova, in a perfect sphere disrupted only by objects. I’ve also assumed that they follow the path of least resistance, so move along roads and open areas in preference to built up areas and forests. This means that a well-designed fence or hiding in a large complex of well-sealed buildings will tend to direct zombies away from a small group of survivors, and once the main wave of initial infecteds has spread outward, survival will become considerably easier.

However, this doesn’t seem to be how hordes function in the seminal texts. They seem to stay together and move purposively. This means, I think, that they have some kind of hording technique – some sort of self-organizing criticality, like insects. I think that their moans of bestial hunger serve the same purpose as an ant’s scent – when a zombie hears a moan, it moves towards the sound and itself moans, drawing other zombies. In The Walking Dead they also comprehend the difference between zombie and human scent, so maybe they remain close together due to some kind of scent marking process. The nature of this behavior is crucial, because if we assume that zombies horde together through a signaling mechanism and move along the path of least resistance, our tactics change:

  • Staying hidden is essential when even single zombies appear, since the sound of their bestial rage may bring others
  • Staying away from major roads is a good survival tactic
  • As roads spread out away from cities, remaining out of sight in an area far from major roads will enable survivors to escape the worst hording behavior
  • Major cities and megacities (like Tokyo, Chongqing) will have hordes of zombies potentially in the hundreds of thousands in size. If zombies have any kind of hording behavior, getting out of cities before the worst of the epidemic hits is essential. Once a significant number of zombies has been created, attempting to escape a city will be close to impossible, since being seen by even a single zombie will likely draw others very quickly
  • If zombies can horde, tactics need to be developed to enable escape from a situation where a zombie sees the group before the group sees it. This makes choice of bases and camps much harder, and makes subterfuge much more important than weapon use

I think it is reasonable to assume that zombies adopt insect-like scent-marking and hording patterns, and to find ways to fool or avoid them. The best use of this behavior is in setting up traps from which large numbers of zombies can be easily culled, or establishing distractions which enable survivor groups to flee. Understanding zombie hording behavior is essential to identifying good survival patterns. Is it an insect-like self-organizing system, some kind of voodoo, vestigial human behavior that is easily fooled, or simple particle mechanics?

fn1: which I consider to be the seminal text, much more knowledgeable than earlier efforts at Zombie science

picture taken without permission from Detrain C, Deneubourg J.Collective Decision-making and foraging patterns in ants and bees. Advances in Insect Physiology,35; 2008: 123-173.

A cold planet ... a Zombie planet!

Ikaho is a hot spring resort in the mountains Northwest of Tokyo, about an hour and a half from Tokyo by bullet train and local train and bus. It is famous for being the historical summer home of emperor’s, and also for having a huge flight of stone stairs that runs from the bottom of town to the top. This flight of stairs is lined with shops, and at the top is the source of the town’s hot spring water. I’ve been told that even today, hot spring water is allocated from this source in strict accordance with the degree of nobility of the recipient’s heritage, though I don’t know whether that’s true or not. The town is essentially a resort town, with no other business to be found except tourism. It’s also slowly crumbling, as are many rural towns in Japan, as the population ages and the young people leave for the cities. A good proportion of the buildings in this town, that used to hold thriving businesses, are now derelict. In fact, you can’t see it from the second rate photo I took from my second-rate hotel room, but in front of my ageing hotel there was a wide patch of scrub grass on a slope, essentially untended and growing very tall, in amongst which a few crumbling sheds were being slowly reclaimed by nature. A room with a view indeed … However, Ikaho’s fading charms aside, it does make quite an excellent mountain fastness from which to weather the zombiepocalypse.


Defensibility: Although Ikaho is accessible from several locations, much of the town consists of multi-storey buildings on slopes accessible only through a single road or steps. In some cases (such as my hotel) the area in front of the buildings is open space, and some of these buildings may have an exit to the hillside that is above the entrance (e.g., my hotel had an emergency exit on a higher level than the main entrance, and the exit emerged from the opposite side of the hotel). In other cases, buildings may be quite isolated from the rest of the town and surrounded by quite thick forest. This makes them potentially quite defensible (Japanese forest at its thickest is impenetrable for people). At the top of the town is a long flight of steps, perhaps 200 m long, lined with small souvenir shops and restaurants. These steps are joined at regular intervals by narrow side streets, but these side streets would be easy to block. At the top of the steps is a kind of hotel or administrative building, surrounded by walls and a gate, and near that is the source of the hot spring water. By blocking the streets and closing off the buildings one can establish a quite defensible redoubt – live at the base of the steps and, if a zombie horde encroaches, flee up the steps, drawing them into the natural death trap formed by the souvenir shops – then roll rocks down on them, or close off a single barrier and use stakes and spears to destroy them. In this sense the town is defensible in quite a low-tech way.

Escape routes: In addition to the obvious ways in and out of the town, at the very top of the steps after a short run one can reach a river in a kind of canyon, that is crossed by two small bridges. If one were to park a car on these bridges they would become essentially uncrossable, but there is a road on the far side that – I guess – leads out of town through a little-used route. This gives a good escape route from the town, assuming a zombie horde came from the lower reaches (i.e. closer to the nearest towns) and not from the mountains. By establishing a small car pool on the far side of this bridge and preparing mobile barriers for the bridge itself (or, better still, a means of knocking the bridges down) one would have a fairly reliable escape option. As far as I can tell the only other way across this canyon is through the riverbed, but like most rivers in Japan it is concrete-lined and hard to scale. Ikaho also features a rope way leading up to a mountain top, so another option could be to establish a flying fox mechanism from their back into town – then, lead the zombies up the mountainside, and when you get to the top use the flying fox to rapidly get back down the hillside, leaving them lost and confused on the mountainside.

Location: Ikaho is located far from Tokyo, but it is not in as secluded a location as Hakone. It is a short bus ride from the town of Shibukawa, a typical sprawling (by Japanese standards) rural supply town. The most likely approach will be through Shibukawa, with a stop to get urgent supplies; this would be dangerous. There are bypasses which take the intrepid survivor group through smaller country towns, and this is the best bet if one wants to guarantee rapid and safe access to Ikaho. Ikaho’s slight remove from Shibukawa is useful though, because it gives survivors the option of raiding Shibukawa’s shopping centres (“doing a run” as they say in The Walking Dead) for essentials. Looking at the map of the area, I notice that there are quite a few golf courses nearby, which at least provide a wide range of clubbing weapons and possibly a clubhouse to raid for supplies. However, the nearness to Shibukawa and the main roads running north from Tokyo means that Ikaho may be a target for random zombie encounters and/or hordes. Remoteness is a useful property in a survival location.

Concealment: Like Hakone, Ikaho is largely invisible from the larger towns, so zombies won’t congregate on its distant lights or the sounds of habitation here – it will only draw zombies who are already just wandering through the mountains aimlessly. Assuming zombies radiate outward from Shibukawa randomly once they’ve eaten all its residents, it is likely that they will mostly miss Ikaho and wander into the wilderness. Establishing a solid barrier at a suitable juncture – such as in front of the visitor’s centre at the edge of town – might cause them to turn down a different road leading away from the area long before they receive any indication that there are humans in the town. Thus even small hordes would be less likely to approach the town, and defending it would likely consist of keeping an eye out for occasional lone wandering zombies. Unfortunately, these zombies will still have many places to hide and cause trouble – the crumbling buildings and scrubland make it easy for a zombie to be missed even from the best vantage points in town, so patrols might be necessary in order to ensure the town’s safety.

Sustainability: As a remote tourist town, Ikaho boasts a lot of restaurants and a small resident population. It’s likely that in the short term there would be a large stock of fresh and preserved foods to consume while preparing defenses. It’s worth noting here that tourist towns in Japan contain a lot of souvenir shops selling food, and much of this food is preserved food – dried and pickled fish are very popular souvenirs, as are low-sugar sweets (dumplings and cakes) that are designed to last for up to a month after purchase. So upon arrival, the group could establish a simple consumption order: first the fresh food that can spoil, while the fridges are still running; then the frozen goods once the electricity dies; then move onto the preserved foods. Potentially in a place like Ikaho one would have as long as a month to establish a mechanism for sustainable food supplies, and maybe even longer. There would likely be huge stocks of rice on hand, and these would be easy to cook – one can establish a steaming mechanism using the onsen (hot spring) water from the top of the hill, and in fact there is a little restaurant at the top of the town which serves eggs boiled in onsen water, so the mechanism has already been established.

Most importantly though, Ikaho comes with a supply of fresh meat and a potential farming area pre-prepared. Near the bottom of the town is a tourist ranch, holding cows and sheep and goats, that will likely still be functioning if the survivors arrive fast enough. In addition to holding the animals, the ranch is intended as an educational enterprise so likely contains basic information on how to milk and herd them. If the ranch staff are still there they could even be convinced to participate in establishing the long-term survival of the community. The nearby golf-courses can be converted into rice paddies, as probably could the stepped slopes of the town itself, and there is ample scrubland for planting potatoes and vegetables. Just a short drive away from the town is Haruna lake, which in addition to a source of fresh water for the town (through the aforementioned stream) also probably contains fish. Haruna lake is unlikely to be thronged with zombies, being even more remote than Ikaho, so a pair of people visiting the lake could fish for the group with relative impunity.

Ikaho’s main sustainability problem is its lack of fuel and distance to the local town, but this could be easily solved by bringing a large number of bicycles, and using them to move to and from Haruna lake. Then fuel can be conserved for visits to the town of Shibukawa – and that fuel need only be used for the drive back, since cars could coast to the town. With such mechanisms in place it is likely that Ikaho could provide a good long-term survival spot from which to weather a few seasons of the zombiepocalypse.

Natural hazards: The main risks to life in Ikaho are the possibility of collapsing buildings, forest fires and of course the ever-present risk of rock falls and landslides. Ikaho is far removed from the centre of Japan’s typhoon zone and unlikely to flood, but one problem it does have is winter. Being north of Tokyo and in the mountains, it will have a long, harsh winter. Even in early April when I visited there was no sign of a single new leaf on even one tree – it was barren as far as the eye could see. With potentially 6 months where nothing grows, winters will be harsh if one does not arrive with a very large stock of rice and tinned goods. The local stocks of rice – particularly in the hotels – would likely last a whole season, but the work in the next summer to secure sufficient rice and potatoes for a second winter could be hard. Staying warm in winter would not necessarily be a challenge – in addition to the ample local wood supplies, the onsen water could be used to warm houses, or one could just sit out the winters in an onsen. Winters of this severity also offer the opportunity for a respite from zombie incursion, as zombies will likely freeze, and this gives the residents potentially a three month period in which to work freely on establishing defenses, preparing the ranch, and so on. Winters after the first could be lean times, but provided some farms could be established in the first year, they will be survivable.


In fleeing to the countryside one should remember that Japanese rural towns all have many automatic rice-dispensing facilities, which can carry hundreds of kgs of rice. Before the electricity runs out these will be easy to use – take a large supply of money and sacks, and just feed the money in! One great thing about vending machines is that they can’t profiteer, so while the rice sellers in town will soon be hiking up their prices, unless the companies are very organized and somehow immune to the general societal collapse, these rice hoppers will continue to sell rice at peacetime prices. Money isn’t going to be relevant, but a good supply of rice is going to be priceless. If one wants to survive long-term in Japan after the zombiepocalypse, the first thing one should grab is a very very large stash of sacks. Every hopper you come to, loot for everything its got. Then you have both a barter good for dealing with people you meet, and a source of long-term survival that, if treated carefully, may last more than a year.

Ikaho’s defenses are not so intuitive as in Takao, so to prepare a proper defense of the town – with its winding streets and multiple possibly inter-connected crumbling buildings – would require poring over a map, establishing choke points and defensive layers, and preparing fall back positions. It’s probably also not such a good place for a very small group of survivors – I would guess that with less than 20 people in your group you won’t be able to set up the required defensive positions quickly. Upon arrival the best idea is probably to establish a redoubt at the top of the stairs, and to fan out from there securing the rest of the town once the group has its first base intact. Because it’s a tourist town, it’s easy to pick up maps and guides when one arrives, and the town is self-contained and small enough for new arrivals to quickly get a sense of all its ways and byways. Starting from a small base, one could slowly secure the town and establish defensive rings and tactics.


Ikaho is not as defensible as Takao but offers better long-term sustainability options, and is further removed from the hordes of Tokyo. With its local ranch and nearby golf courses, as well as a nearby fishing lake, it offers both short term and long term food supplies, and the presence of a strong and reliable local onsen source reduces the need for electric power for cooking and heating. Provided that some degree of farming can be established within a year and mechanisms put in place for weathering the worst of winter, it may be an ideal spot to weather the initial storm of the zombiepocalypse, and a good base from which to reclaim at least a small part of the world for human habitation.

Praying While Tokyo Burns

Takao Mountain (高尾山), on the western edge of the Tokyo metropolis, is a low (approximately 500m high) peak on the edge of a small nature reserve, easily accessible on the Keio line or the Chuo line. The mountain top hosts a temple, Yakuoin (薬王院), and some hiking paths, and although it is a steep climb it is easily reached by foot in 40 minutes, on paths that zig-zag through light forest. It’s also accessible by a ropeway (essentially a ski-lift) or a cable car (that is really a type of train). At the base of the mountain is a small and cute village of tourist shops, noodle stores and another small temple. As such it is a popular tourist destination, and also popular as a place to do hatsumode (初詣), the traditional new year shrine visit. My friend went with a billion other people to see the first sunrise of the new year, and I went with some friends in the afternoon for the traditional shrine visit.

In addition to being an excellent tourist day trip, Takao Mountain is also a viable zombie survival spot, offering short term defensibility, an easy escape route, and some possibility of sustainability. It’s probably not entirely suitable to a solo survivor, but a good choice for a group.


Defensibility: The mountain itself is accessed by three pathways on the Tokyo side, at least one of which is wide enough to drive cars up. As far as I know there are no direct pathways on the Western side, which in any case faces onto low population density areas and a wide range of bushland. There is a single railway line leading up to the summit (for the “cable car”). All three pathways have a series of steep switchbacks interspersed with periods of long, straight, steep climbs, they are narrow, and there are regular viewing spots on the higher sections of these paths from which defenders can look down on the lower sections of the slopes. Other hillsides are steep, heavily forested and slippery, scattered with sheer climbs or scree slopes that make climbing extremely difficult for mindless undead. Any of these paths would be easy to block off at lower sections, and easy to defend with suitable firearms. From higher vantage points, with a large supply of ammunition, it would be easy to pick off approaching zombies in complete safety. The main difficulty with defensibility is in monitoring all these approaches: to properly defend the mountain would require maintaining constant vigilance over all the access paths and the forests of the western side, and opens the risk that occasional lone zombies would make it up to a higher location without being identified. This would necessitate continuous caution and the establishment of safe inner bastions. Fortunately the Yakuoin temple offers just such a bastion, as does the monkey park. Overall, the area is highly defensible, if your group contains more than 5 people.

Escape routes: Although not ideal, the forested slopes of the western face offer a last-ditch escape route in the event that the temple and the path to the higher slopes are cut off simultaneously. Furthermore, the ropeway offers an ideal rapid escape route. In the absence of electric power, one could use a simple flying-fox type arrangement to return to the base of the mountain in just a few (hair-raising) minutes, and it’s likely that zombies will lose track of you due to the speed of descent. Even if a zombie horde had come up from the base station, it’s likely given the defensibility of the setting that the zombies would have all left the base area by the time evacuation became necessary; thus, one would arrive at a relatively depopulated lower camp area, and be able to escape rapidly – possibly to a pre-established safe house in the lower town, there to wait until the mountain could be retaken after the horde dispersed or moved on.

Location: Far removed from central Tokyo, Takao Mountain is also slightly separate, being located on the far side of a small rural area. This means that its local zombie population is likely to be small and scattered, and it is less likely to have been raided extensively by non-local populations. Additionally, it contains significant supplies for the tourist industry, as well as a non-transient local community likely to have themselves stocked up on food, leaving more supplies for scavenging. The mountain is not on any major road transport routes, though it is near(ish) to an expressway. It’s also on the end of a train line, which is likely to be the only way to get to the location – roads in Tokyo will be blocked and car transport over long distances likely impossible. But a railway line is a relatively safe and easy way to move across Tokyo – it is elevated and likely clear of obstacles. The mainline to near Takao is the Central Line, which is about 8 tracks wide – it may be possible to drive small cars along this line, enabling transport of supplies and rapid escape from central Tokyo. The mountain also has a tourist centre and various restaurants at different elevations, so even if one arrives without supplies it may be possible to go straight to the top and subsist on scavenged foods for a few days while the world goes to hell.

Concealment: From the base of the mountain, almost nothing is visible of the human habitations higher up, and many of the main tourist attractions – especially the temple – are set back from the slopes of the hill. The sounds and sights of a functioning group of survivors would be virtually unidentifiable from the ground, especially in the temple, so it would be possible to have lights, cooking and reasonably normal human interaction without fear of alerting zombies or humans. This means the necessary preparations for survival over a Japanese winter could proceed fairly smoothly, and even an electricity generator could be used without alerting zombies. Movement between locations on the mountain would also be fairly unlikely to attract attention from zombies at the foot of the mountain, which would make defending the mountain very easy.

Sustainability: The mountain holds several tourist restaurants, a monkey park, visitor centre and temple. Even if a group arrived on foot carrying only the supplies in their backpacks, it would be fairly easy to subsist on the mountainside for a few days. The temple almost certainly contains a generator, and it’s likely (though I didn’t see any) that there is at least some solar power somewhere on the hill, so at least some lighting would be possible. There is a parking space containing some snow ploughs, which means that they also have batteries and fuel (and probably some spare fuel). The mountain is riddled with vending machines, but the restaurants sell dango and fresh soba, so likely hold stocks of buckwheat and barley flour, oil and – if they had been evacuated rapidly – eggs. For the first few days, supplies of water could be obtained from vending machines and kettles, until the first rain filled up some buckets. Of course, buckets and water storage mechanisms are commonplace in a temple, and easily converted to survival. There is enough flat space higher up the mountain to plant potatoes and possibly even a rice crop, and the monkey park comes readily supplied with cages for raising and protecting chickens and goats. In the longer term, the area is already supplied with buildings and a defensible temple, but there is one significant long term problem: water. Being on the top of a mountain, most water will be flowing down, and in dry periods there will be little freestanding or potable water. The best solution to this is to use the higher parts of the mountain to set up a water course for trapping and channeling water. Nonetheless, water storage – in a tank of some kind, and perhaps also in containers looted from the restaurants – would likely be a very wise plan. Otherwise, regular trips down the mountain to collect water would be required, and this would be both dangerous and exhausting.

Longer term, the mountain offers a lot of opportunities to establish a sustainable community. It is reasonably close to Tachikawa, a suburb with large stores, and houses in the nearby town could be looted for solar power supplies. With the elevation of the mountains, it could be possible to set up a solar storage system using pumped water. Plentiful wood means that even when fuel and electricity ran out it would be possible to stay warm for at least the first year, and to build fairly solid barriers against zombie and human infiltration – some forest clearing would even be necessary to establish kill zones. The higher viewing points hold a number of coin-operated binoculars that could be used to ensure that zombies can be spotted at very long distances and monitored, and gun nests with good viewing points could be built around these viewing machines. The mountain holds all the necessities of medium-term survival for a reasonably large group, provided that the water problem can be solved fairly rapidly.

Natural Hazards: Although it contains no sizable buildings capable of collapsing in an earthquake, Takao mountain is obviously vulnerable to landslides, which could be dangerous for those on the lower slopes. However, it’s most significant problem is the risk of forest fires, which could wipe out a community very rapidly. The rope way provides a method for rapidly escaping during a significant fire, but keeping it clear of trees would be essential in order to use it successfully. With roaming gangs of humans likely to spot them, back burning to reduce fire risk is not likely to be an option at first, and in any case water supplies may not be sufficient to do this safely. Constant caution and evacuation planning would be necessary to keep this risk under control. The best solution to this problem would be water and forestry management, and any group unable to do these two things would likely ultimately be driven off the mountain by the difficulties of supply and the risks of fire. But if this problem can be solved, the mountain would no doubt be safe for habitation by even up to 100 people.


Takao Mountain is highly defensible, and with suitable tactics potentially close to impregnable in a zombie holocaust. If defenders are armed with rifles, it would be easy to defend against a very large horde of slow-moving shambler zombies. Even if guns were not available, a suitable set of barriers could be established on steeper pathways to enable, for example, a single person armed with a pike to kill struggling zombies in relative safety. At the switchbacks, it would be possible to stand in the crook of the switchback and beat down zombies with a pole or pike. Alternatively, traps could easily be set for mindless undead: establish a barrier at a point on the path just past one of the steeper slopes, and present oneself on a high point of one of the slopes to the side of the path just before the barrier. Zombies then reach the barrier and, unable to pass it, attempt to climb the slope on the side of the path. While they slip and fall on the scree, the defender can easily kill them using a suitable pole weapon.

The railway line is even easier to defend, because the top- and bottom-most extents pass through a smooth tunnel. Using a human target, zombies could be funneled into this tunnel and then trapped against a barrier on the upper side; from there, fire could be used safely inside the tunnel to kill large numbers of them. Alternatively, if active defense is not desired, the lower tunnel could be filled with scree, logs and debris, and a series of large rocks – or even, possibly, the train car itself – used as weapons to clear the upper tunnel. The upper platform itself also has a series of fairly solid barriers for passenger control, and is on a steep slope, so it’s possible that even large numbers of zombies wouldn’t be able to get the momentum necessary to push through them. The station itself thus forms another strong defense point, and suitable use of human bait could enable zombie hordes to be funneled into this killing zone, then beaten, burnt and shot into oblivion.

As the linked map shows, there are multiple stages on the mountain; first the lower peak with the temple, then an upper peak with visitor information centre, and then several more, higher peaks, each accessible by a decreasing number of paths. If a zombie wave overwhelms the lower slopes, the higher sections are all highly defensible, enabling even the most exhausted defenders to repel a numerically superior zombie horde with relative ease. With proper preparation, barriers could be set here and used to slow zombie approach while fleeing. With the steep sides of the mountains a constant threat, it could also be possible to break up hordes by throwing members over the slopes, or using rope traps to drag large numbers off the trail. This wouldn’t stop them permanently, but would break apart the horde so that it would be easier to kill as its members attempted to stagger up the steep mountainsides.

Finally, if long-term defenses were needed it might be possible to use back-burning techniques to establish zones higher up the mountain that are safe from fire. In the worst case scenario, with a huge horde approaching, the lower slopes could be fired – possibly using projectiles lobbed beyond the zombies – and the defenders could then retreat into the back-burnt zones. The zombies, struggling up the steep slopes, would be overrun by the fires and potentially destroyed en masse. This is an extremely risky tactic and only useful in summer, and would obviously attract attention from nearby survivors.


A highly defensible, concealed community can be established on Takao Mountain, capable of defending itself capably from even very large zombie hordes, and able to escape rapidly if overwhelmed. The community could potentially be sustainable and even maintain some of the luxuries of modern society – especially, hot water and some lighting – and, although the early years would be hard work, could become a thriving base for recolonization of the world after a zombie apocalypse. If you’re living in Tokyo and worried about the zombie apocalpyse, you should visit Takao Mountain and familiarize yourself with an escape strategy to this excellent post-apocalyptic base.