When the ground moves, the first thing people usually reach for is a phone. It is almost a reflex now, learned through years of living inside a mesh of mobile towers, fiber links, cloud services, messaging apps, and location-sharing platforms. In ordinary life, that reflex works so well that the underlying infrastructure becomes invisible. A message crosses a city in milliseconds, a photo of damaged buildings travels through several data centers before a responder has finished speaking, and a family group chat can become an improvised emergency coordination room. But earthquakes have a way of making the invisible visible. They remind us that communication is not magic; it is steel, glass, silicon, antennas, power supplies, software, towers, routers, and cables. When those systems are overloaded, damaged, or simply deprived of power, the modern world can become suddenly quiet.
That is why the amateur radio response after the August 10, 2026 earthquake in Colombia is more than a hobbyist footnote. Colombian radio amateurs activated a national emergency network after the quake, and international amateur-radio organizations asked operators to avoid several high-frequency emergency communication channels, including the areas around 3985, 7060, 7240, 7275, 14300, 18160, and 21360 kHz. The ARRL reported that Colombian amateur operators were supporting communications after the earthquake and aftershocks, and that IARU Region 2 emergency coordination requested clear frequencies to reduce interference to relief traffic. For anyone outside the radio world, that list of frequencies may look like a technical detail. For emergency communicators, it is closer to a map of last-resort resilience: a set of paths through the ionosphere that can still connect people when terrestrial networks are fragile.
The practical lesson is stark. High-frequency radio, usually called HF, remains one of the few communication systems that can work independently of mobile-phone infrastructure, commercial internet access, local fiber backhaul, and intact power grids. It is not glamorous in the way satellite internet constellations are glamorous, and it does not carry the seductive smoothness of a smartphone interface. It is noisy, variable, sometimes slow, and deeply dependent on operator skill. Yet that is precisely why it continues to matter. HF emergency communication is not a competitor to modern networks in normal times; it is the older, stubborn layer underneath them, a technology that refuses to disappear because disaster physics keeps giving it a reason to exist.
A Disaster Reveals the Shape of a Network
The Colombian case followed a pattern that emergency radio operators know well. A sudden natural disaster creates an information vacuum. Local authorities need situational reports, shelters need coordination, families need reassurance, and relief organizations need channels that do not collapse under public demand. In the first hours after an earthquake, communication is not merely about sending dramatic updates to the outside world. It is about small, specific, high-value facts: which roads are blocked, where medical help is needed, which communities are cut off, whether repeaters are still powered, which hospitals can receive patients, and where volunteers should not go because the route is unsafe. These facts are often less photogenic than collapsed buildings, but they are the raw material of response.
In Colombia, reports from the amateur-radio community indicated that the Liga Colombiana de Radioaficionados, Colombia’s national amateur radio organization, used IARU Region 2 emergency frequencies as part of the response. The listed HF channels included 80 meters, 40 meters, 20 meters, 17 meters, and 15 meters, with 146.520 MHz also mentioned for operators within VHF range of Colombia. The ARRL later reported that after 124 hours of continuous operation by the Colombian Amateur Radio League’s national emergency network, the frequencies previously protected for emergency use were released for general amateur operation, while noting that the release did not necessarily mean all communications work had stopped. That distinction matters. Emergency radio activity often shifts from intense national coordination to lower-profile local support, welfare checks, logistics, and standby monitoring long after the first alert fades from international attention.
The frequencies themselves tell a story about scale. The lower HF bands, such as 80 meters around 3985 kHz and 40 meters around 7060, 7240, and 7275 kHz, are commonly useful for regional communication, especially when propagation conditions favor shorter or medium-distance paths. Higher HF bands such as 20 meters, 17 meters, and 15 meters can support longer-distance communication when the ionosphere cooperates. This is why emergency plans do not rely on a single frequency. They distribute risk across bands, modes, distances, day-night cycles, antenna types, and operator availability. A working emergency network is less like a single hotline than a living web of fallback options, each one imperfect but collectively powerful.
That structure is easy to underestimate in the era of always-on connectivity. Most users experience communication as an application layer: WhatsApp, Signal, iMessage, Telegram, email, social media, video calls. Beneath those applications, however, are layers of dependency. Mobile phones depend on cell sites, cell sites depend on backhaul, backhaul depends on fiber, microwave links, routing facilities, and power, and the cloud services behind many apps depend on distant data centers and network routes that may be unaffected by the disaster but unreachable from the disaster area. HF radio slices through that dependency stack. A transceiver, antenna, power source, trained operator, and favorable propagation can produce a direct or relay-assisted path without any local telecom company in the middle.
This does not make HF invincible. It is subject to interference, atmospheric noise, solar storms, poor antenna installations, inexperienced operators, language barriers, and congestion during crises. It is also narrowband by modern standards. Nobody should imagine an HF net as a substitute for a national cellular network or a fiber-fed emergency operations center. But that is the wrong comparison. HF emergency communication matters because it can carry essential information when richer systems are unavailable, unreliable, or overwhelmed. In disasters, the difference between no information and modest information is often the difference that matters.
The Old Technology That Refused to Become Obsolete
HF radio’s resilience comes from a feature that sounds almost antique: skywave propagation. Unlike VHF and UHF signals, which usually behave more like line-of-sight radio, many HF signals can refract through ionized regions of the upper atmosphere and return to Earth far beyond the horizon. The ionosphere is not a fixed mirror. It changes with solar radiation, time of day, season, latitude, geomagnetic activity, and frequency. This makes HF both fascinating and frustrating. A frequency that works beautifully in the afternoon may fade after sunset. A long-distance path that is open one day may vanish during a geomagnetic disturbance. Operators learn to treat the spectrum as weather, not plumbing.
This variability is exactly why experienced emergency communicators think in terms of bands rather than single channels. The Colombian frequency list illustrates that philosophy. Around 3985 kHz, operators are in the 80-meter band, where regional night-time coverage can be valuable but noise levels can be high. Around 7060 to 7275 kHz, the 40-meter band often offers a strong compromise between regional and longer-distance coverage, making it one of the classic workhorses of emergency and disaster communication. Around 14300 kHz, the 20-meter band can reach across countries and continents when conditions are favorable. The 18160 and 21360 kHz frequencies sit higher still, where propagation may support wider-area or international communication during suitable solar conditions. The IARU emergency telecommunications guidance notes that local and regional emergency communication often uses VHF/UHF FM and lower HF bands, while HF frequencies are selected for wider-area and international traffic handling.
HF radio survived the internet age because its value is not bandwidth but independence. A mobile network is a marvel of dense infrastructure. It is engineered for capacity, efficiency, mobility, authentication, billing, and seamless handover across cells. But its sophistication creates dependencies. HF radio is primitive by comparison, yet that primitiveness can be strategic. A portable station can be carried into a community, powered from a battery, a generator, or a solar panel, and connected to a wire antenna thrown into a tree. In skilled hands, that station can pass voice traffic, formal messages, email-like digital traffic through systems such as Winlink, or simple status reports to stations outside the affected area. The link may be scratchy and slow, but it exists.
The history of radio emergency communication is a history of these stubborn links. Amateur operators have assisted after hurricanes, earthquakes, floods, wildfires, and infrastructure failures around the world. Their role varies by country and by incident. Sometimes they supplement government systems. Sometimes they provide welfare traffic when families cannot reach one another. Sometimes they connect hospitals, shelters, logistics centers, or local authorities. Often their greatest contribution is not a dramatic rescue transmission but disciplined message handling over many hours, especially when official networks are saturated. Emergency communication is rarely cinematic. It is procedural, repetitive, patient, and valuable because it preserves order when information wants to fragment.
This is also why the culture around amateur emergency frequencies matters. A frequency is not protected by physics; it is protected by discipline. Amateur radio is a shared spectrum environment, and emergency traffic often depends on voluntary cooperation from operators who may be hundreds or thousands of kilometers away. A DX operator chasing a rare contact, a contest station calling rapidly for points, or a casual operator unaware of current emergency requests can unintentionally cause harmful interference. The Colombian request to keep frequencies clear was therefore not symbolic etiquette. It was an operational measure designed to reduce congestion around channels being monitored for disaster-related traffic.
Why “Keep the Frequency Clear” Is an Engineering Requirement
To non-radio users, the instruction to avoid certain frequencies can sound quaint, almost like asking people not to speak too loudly in a hallway. In radio engineering terms, however, interference is not a social inconvenience; it is a system failure mode. HF signals are often weak by the time they arrive. They may be distorted by fading, overlapped by atmospheric static, partially buried under other stations, or shifted by changing propagation paths. A strong station outside the disaster area can dominate a channel even if it has no intention of interfering with emergency traffic. Because HF propagation can reach across borders and oceans, the people capable of causing interference may be far from the affected country and may not hear the emergency station they are covering.
This asymmetry is one of HF’s strangest properties. You may interfere with a station you cannot hear. A contest operator in one region may call CQ on what appears to be an open frequency, while a weaker disaster net control station is being received clearly somewhere else. The operator’s receiver gives a local version of reality, not a universal one. During emergency activations, therefore, responsible operators check national society bulletins, IARU announcements, ARRL notices, cluster comments, and community alerts before operating near known emergency centers of activity. The ARRL’s report on Colombia specifically relayed the request from IARU Region 2 emergency coordination to avoid the listed HF frequencies in order to minimize interference to emergency communications.
The phrase “around the frequency” is also important. Emergency nets do not always occupy a mathematically exact point forever. Voice signals require bandwidth; single-sideband operation spreads energy across a few kilohertz. Operators may shift slightly to avoid interference, equipment differences, regional band plans, or propagation conditions. A station calling near 7060 kHz, for example, can still affect operations centered on that frequency. Good amateur practice during emergencies is not merely to avoid the exact number in a bulletin but to leave a respectful guard area, listen carefully, and move elsewhere if there is any doubt. In a crowded contest weekend, that discipline can feel costly. In a disaster, it is part of the social contract that makes shared spectrum possible.
This is where DX and contest culture intersects with emergency communication. DXing and contesting are often portrayed as recreational extremes of amateur radio: high antennas, powerful stations, fast exchanges, rare countries, multipliers, strategy, and competitive endurance. Yet the skills developed there are not unrelated to emergency work. Contest operators understand propagation, weak-signal reception, logging discipline, station reliability, and band awareness. DX operators understand patience, listening, split operation, and the global character of HF. The same skills that make someone effective in a pileup can make them responsible during an emergency activation—provided they remember that not every open-sounding frequency is truly open.
In fact, the Colombian earthquake is a useful reminder that emergency communication awareness should be part of advanced operating culture. A serious HF operator already checks solar conditions, band openings, DX spots, contest calendars, and equipment status. Adding emergency-frequency awareness is not a burden; it is a natural extension of situational awareness. Before a major contest or DX session, especially during a known disaster, operators should know which centers of activity are active, which regions are affected, and whether national societies have requested quiet channels. This is not just courtesy. It is the operational maturity expected of stations whose signals can travel far beyond their own horizon.
The Anatomy of a Resilient HF Emergency Network
An emergency HF network is not simply a group of people talking on radios. It is a coordination system with roles, procedures, priorities, and fallback logic. At the center is usually a net control station, or several rotating net controls, responsible for organizing traffic, identifying stations, setting priorities, and preventing chaos. Field stations may report from affected areas, shelters, hospitals, municipal offices, or mobile units. Relay stations may bridge weak paths or connect local VHF/UHF traffic into wider HF networks. Liaison stations may carry traffic between amateur networks and partner organizations. Behind the voices are logs, message forms, power plans, antennas, spare equipment, and people trained to remain calm when the channel is noisy and the news is bad.
The first engineering challenge is power. A radio without electricity is just a box. In disasters, emergency stations must assume that mains power may fail or become unreliable. Batteries, generators, solar panels, charge controllers, and low-power operating techniques become as important as the transceiver itself. HF stations can be surprisingly efficient when designed for emergency use. A modest 100-watt transceiver, or even a lower-power portable radio under favorable conditions, can sustain useful communication if paired with an effective antenna and disciplined operating. The power budget must include not only transmission but also receiving time, lighting, laptops or tablets for digital modes, battery charging, and sometimes environmental constraints such as rain, heat, or dust.
The second challenge is antennas. Modern communication infrastructure hides antennas in towers, rooftop panels, small cells, vehicles, and devices. HF makes antennas visible again. A field station may use a dipole, inverted-V, end-fed wire, vertical, loop, or portable mast, each with tradeoffs in radiation pattern, efficiency, required space, grounding, and setup time. In mountainous regions, dense urban areas, or damaged towns, ideal antenna geometry may be impossible. Operators improvise with trees, poles, buildings, vehicles, or temporary supports. A poorly placed antenna can turn a capable radio into a frustrating one; a simple but well-deployed wire can outperform expensive equipment. Emergency communication rewards fundamentals.
The third challenge is propagation planning. HF emergency nets must think about near vertical incidence skywave, or NVIS, for regional coverage, especially on lower frequencies. NVIS uses high-angle radiation to cover areas within a few hundred kilometers that may be too far for VHF line-of-sight and too close for conventional low-angle long-distance HF paths. In earthquake response, this can be especially useful when terrain, damaged roads, or failed repeaters isolate communities across a region. Higher-angle antennas on 40 or 80 meters may provide practical coverage where mobile networks are unreliable. But NVIS is not a magic setting. It depends on frequency relative to ionospheric conditions, time of day, antenna height, and noise. Operators have to adapt, sometimes hour by hour.
The fourth challenge is traffic discipline. A disaster net is not a talk show. The channel must remain available for priority messages, and operators must avoid speculation, emotional chatter, and duplicate reports. Formal message handling exists because memory is unreliable under stress. A good emergency message is concise, attributable, time-stamped, and actionable. It identifies who needs what, where, by when, and who originated the information. In the best networks, operators are trained not just to transmit but to filter: to distinguish urgent traffic from routine traffic, confirmed information from rumor, and operational communication from general conversation. The value of the network depends on trust, and trust depends on disciplined procedure.
Digital tools have added a modern layer to HF emergency communication without replacing voice nets. Systems such as Winlink can move structured messages and email-like traffic over radio links, including HF, allowing stations to send forms, situation reports, and welfare messages when internet access is unavailable locally. Other digital modes can provide robust low-bandwidth communication under weak-signal conditions. But digital communication introduces its own dependencies: computers, interfaces, software configuration, message gateways, operator familiarity, and sometimes regulatory constraints. Voice remains important because it is immediate, flexible, and human. The strongest emergency communication systems use both, matching the mode to the mission rather than treating any one technology as a universal answer.
Colombia, the Ionosphere, and the Geography of Dependence
Colombia’s geography makes the communication problem especially interesting. The country includes Andean mountain ranges, Pacific and Caribbean coastlines, dense cities, rural communities, forests, valleys, and regions where terrain can complicate terrestrial communication even in normal conditions.
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