What can and cannot a smartphone do during a major earthquake? Preparedness and initial response based on the 2026 Kumamoto Earthquake

Around 16:27 on July 28, 2026, an earthquake occurred with its epicenter in the Kumamoto region of Kumamoto Prefecture, registering a seismic intensity of 7 in Uki City and Hikawa Town.

The Japan Meteorological Agency has named this earthquake and the subsequent series of seismic activities the "2026 Kumamoto Earthquake", as it met the criteria of a magnitude of 7.0 or greater on land and a maximum seismic intensity of 5-upper or greater.

We extend our deepest sympathies to those affected and to those who have family or acquaintances in the disaster area.

To those currently in the disaster area: Only 3 high-priority items

Assuming you may not have the time to read a long article, I will list just three points first.

1. Prioritize your physical safety. Your smartphone comes later

This time, extreme heat and power outages are occurring simultaneously. Heatstroke in an environment where air conditioning cannot be used is life-threatening.

Small children, the elderly, and those with underlying health conditions, in particular, may not easily notice heat or thirst.

Before looking for a way to charge your smartphone, please secure a cool place, water, and salt immediately. Please also check on those around you.

Smartphones themselves will stop working if they get too hot. Do not leave them on a car dashboard or in direct sunlight.

2. Keep safety check messages "short and send only once"

The more people who are worried about you, the more your battery will drain from replying.

• Send only these three points: "I am safe," "Where I am now," and "My battery is low"

• Instead of individual replies, post once to a family group or your own social media and have them check that

• Text (SMS, messaging apps) is easier to connect and drains less battery than voice calls

Voice calls may be restricted during disasters due to high traffic.

3. Only look at official information

Currently, misinformation regarding evacuation centers and damage is circulating on social media.

Please check official local government websites, official social media accounts, and reports from sources like NHK. Please stop and think before spreading information that comes through social media.

In this instance, NHK has taken emergency measures to allow its online services to be viewed without a reception contract as well.

Key points of this article: What smartphones can and cannot do

In short, a smartphone is a powerful tool only when there is electricity, communication is active, and the information flowing in is accurate.

This time, a fourth condition, "extreme heat," has also been added.

Therefore, preparedness is not about buying a charger. It is about having things written on paper, a radio, and family agreements ready.

The details are organized below.

In writing this article

Articles about disasters tend to be written in a way that can easily be read as "it is the fault of those who were not prepared."

However, in a situation like this, where a magnitude 7 earthquake strikes without warning on a midsummer evening, almost no household is perfectly prepared. Not being prepared is no one's fault. It is not an issue to blame anyone for.

Here, I would like to organize only "what can be done now and what can be applied next time."

What happened in terms of communication and IT this time

Furthermore, mechanisms for disaster situations actually functioned.

• NTT East and West's Disaster Emergency Message Dial (171), mobile carriers' disaster message boards, and LINE's safety confirmation feature

• Free public wireless LAN for disasters "00000JAPAN" (also available to users of other carriers)

• Inter-carrier roaming (JAPAN Roaming) that allows communication across mobile carriers

• Opening of NHK's online services without a reception contract

On the other hand, a massive amount of misinformation spread on social media.

Fake damage videos created with generative AI, repurposing of footage from past disasters, fake rescue requests with non-existent addresses, and posts posing as disaster victims to solicit money transfers via QR codes or PayPay have been confirmed.

The Ministry of Internal Affairs and Communications requested action from five major platforms, and the National Consumer Affairs Center and the National Police Agency called for caution regarding donation fraud and home repair scams.

Part 1: Things to prepare in advance

Simply "buying a mobile battery" is not enough. IT-related preparedness can be broadly divided into five categories.

1. Decide on a "plan" for safety confirmation in advance

The biggest problem during a disaster is not the lack of tools, but the fact that the method has not been decided among family members.

No one is calm immediately after the shaking. It is impossible to think about "how to contact each other" at that moment.

There are four things you should decide during normal times:

• Where to post: A family group chat, a disaster message board, or 171

• What to write: Whether you are safe, your location, and whether you can move

• Do not wait for a reply: Even if there is no "read" receipt, it is highly likely that the battery is dead or there is no signal

• Meeting place: First and second choices if your home cannot be used

Especially important is sharing the rule in advance that "not receiving a reply does not mean the worst-case scenario".

If you do not decide this, family members who are away will call repeatedly out of anxiety, draining the battery of those in the disaster area.

The disaster message dial "171" can be used even without a smartphone

171 is a system that allows you to record and play back voice messages using a phone number as a key. It is opened during disasters and can be used from landlines, public phones, and mobile phones.

This is important for elderly family members. Even those who find it difficult to operate a smartphone can use it just by pushing the phone number.

However, if you have never used it, you will not be able to use it in a real emergency.

NTT East and West provide days for trial use. I strongly recommend that you try it out with your family once.

Disaster message boards of mobile carriers

Each mobile carrier will open a message board during a disaster. It is a system where you register your safety with your phone number, and family members can search and view it using that phone number.

Please check the URL and how to use it once during normal times as well.

2. Always keep at least one communication channel other than your smartphone

This time, situations were reported where emergency calls could not be made.

If your smartphone is your only means of communication, you will be completely isolated if it stops working.

• Battery-powered radio: This provides a way to get information even during a power outage. Battery-powered models are more reliable than hand-crank ones.

• Paper notes: I will explain this later.

• Landline phone: If you have a fiber-optic line, it will not work during a power outage, but traditional analog lines may still work. Please check which type you have at home.

"Writing things down on paper" is the most overlooked form of preparation.

If your smartphone battery dies, you won't be able to see your contacts, addresses, insurance policy numbers, or anything else.

Please write the following information on paper and keep it in your wallet or emergency evacuation bag.

• Names and mobile numbers of family members (in full; do not rely on smartphone speed dial)

• Contact information for distant relatives (phone lines within disaster areas will be congested)

• Contact information for your workplace or school

• Your primary care physician and the names of medications you are taking

• Your insurance company and policy number

• First and second choice meeting locations

This is especially effective for children and the elderly. Simply keeping this in a name tag or an amulet pouch makes it easier for adults around them to help.

3. Power supply preparation

Guidelines for mobile battery capacity

• Around 10,000mAh: Charges a smartphone about 2 times

• Around 20,000mAh: Charges a smartphone about 4 times

Considering the number of family members, it is realistic to have one 20,000mAh class unit or multiple 10,000mAh class units.

What is important is to recharge them once every six months. Mobile batteries left unattended will be empty when you need them most.

Keep "multiple types" of batteries

• Mobile batteries (for daily use + emergency stockpile)

• Battery-powered charger and spare batteries

• Car cigarette lighter charger (for those who have a car)

• Portable power station (if you can afford it; especially useful in summer as it can power a fan)

• Solar panels (they do not generate power as expected on cloudy days; consider them as a supplement)

In conditions like this, where power outages last for several days and it is extremely hot, whether you have a power source with enough capacity to run a fan will significantly change your quality of life.

Precautions for using a car

You can charge from your car, but spending a long time with the engine running is dangerous due to both carbon monoxide poisoning and gasoline consumption.

In particular, absolutely avoid doing this in places where there is rubble around or where the exhaust pipe could be blocked.

4. Data and account preparation

Photos you should take

Please take photos with your smartphone camera and save them. Paper documents can be lost due to water damage or misplacement.

• Driver's license/My Number card (front and back)

• Health insurance card

• Relevant pages of your medication notebook, prescriptions

• Insurance policy

• Cover of your bank passbook

• The exterior of the house and the state of each room (can be used as proof of damage for disaster certificates and insurance claims)

Photos of your home serve as documentation to show 'what it was like before' after a disaster. Taking new photos once a year is sufficient.

However, you must be careful about 'where you store' photos of your ID.

Images of your driver's license or My Number card are information that can be misused. If you just take them and leave them, your preparation turns into a new risk.

• Set a strong passcode and biometric authentication on your device (avoid 4-digit codes)

• Set up two-factor authentication for your cloud account

• Do not store them in shared albums, family shared folders, or social media drafts

• If you send them to a chat for communication, delete them once the purpose is served

• If possible, put them in a password-protected folder or use the attachment feature of a password manager

It is not just 'safe if you put it in the cloud,' but 'putting it in a protected cloud' that makes it a complete set.

Things to keep available offline

• Maps: Download offline maps for the areas around your home and workplace

• Evacuation shelter locations: Save screenshots of your local government's hazard map

• Emergency contacts: Use features like 'Emergency Contacts' or 'Medical ID' provided by your smartphone's OS

Using a mechanism that allows emergency contacts to be viewed from the lock screen enables people around you to contact someone if you collapse.

However, this means that anyone who picks up your phone can also see them. It is safer to register only the bare minimum and avoid writing down relationships like 'eldest son' or 'wife'. Also, keep medical information limited to what is necessary for rescue (allergies, medications, medical history).

The password problem

If your smartphone breaks and you lose the device containing your two-factor authentication app, you will be unable to access your accounts.

• Print out your recovery codes (backup codes) and store them in a location other than your home (or save them on a USB drive (encrypted) inside a personal safe, etc.)

• Use a password manager and leave instructions for emergency access for your family

• Save your important contacts on your family members' smartphones as well

5. Preparedness for elderly family members and small children

This is an area that people around them should set up on their behalf rather than the individuals themselves.

Things to do for elderly family members

• Register emergency contacts with names that appear at the top of the phonebook

• Set the text size to be larger

• Check if emergency alert emails are turned on

• Write down how to use 171 and stick it next to the phone

• For those who do not carry a smartphone, keep a paper contact card in their wallet

Rather than "installing apps," it is more reliable to keep things within the scope of operations they can already perform.

Regarding small children

• Have them memorize their guardian's mobile number or write it on something they wear

• Decide on a specific place to wait if you get separated

• Set up location sharing features on devices used by children

However, constant location sharing consumes battery. In a disaster, you will also need to decide to use it only when necessary.

Part 2: What to do when a disaster occurs

1. The first few tens of minutes: Safety confirmation and how to conserve battery

Specific operations to extend battery life

• Lower the screen brightness to near minimum (a significant portion of consumption is the screen)

• Turn on power saving mode / low power mode

• Switch to Airplane Mode if you have no signal: The process of constantly searching for a signal in areas with no reception consumes the most battery. Switch to a routine of periodically turning it off to check for a signal.

• Avoid videos and games: These also cause the device to heat up, which is doubly disadvantageous.

• Turn off unnecessary notifications

• Disable constant use of Bluetooth and location services

Use text instead of voice calls

Immediately after a disaster, voice calls tend to concentrate, which may lead to restrictions.

On the other hand, SMS and messaging apps tend to be easier to get through even on congested networks.

"Cannot connect by phone" does not mean "cannot communicate." Please try using text.

In extreme heat, the device itself will shut down

This is a particularly important point in the current situation.

When smartphones get too hot, they may reduce performance, stop charging, or power off.

• Do not expose to direct sunlight

• Do not leave it behind in a car

• Since charging generates heat, place it in a well-ventilated, hard location rather than on a futon or cushion

• If it gets hot, stop using it and let it cool down in the shade (avoid rapid cooling with a refrigerator or ice, as this causes condensation)

2. How to obtain information

Sources to check

Consider the reliability to be higher from the top down.

1. Japan Meteorological Agency: Primary information on earthquakes, tsunamis, and weather

2. Official municipal websites and social media: Living information such as evacuation centers, water supply, waste disposal, and disaster victim certificates

3. News organizations such as NHK

4. Official information from utility providers: Power outage information from electric power companies, water outage information from water bureaus, and service disruption information from mobile carriers

In reality, items 2 and 4 are the most directly relevant to daily life. Information on the opening of evacuation centers and the locations of water supply stations is faster and more accurate when provided by local governments than by news organizations.

Changing how you use social media

This time, many people voiced that the 'For You' tab on X is not useful for gathering information during a disaster. Ayumi Matsuyama, Representative Director of X's Japanese subsidiary, also encourages users to use the 'Following' timeline and change the display order to 'Latest'.

Posts selected by algorithms are 'posts that are viewed often,' not 'correct posts.' During a disaster, this difference can be fatal.

• Switch the timeline to 'Following' and 'Latest'

• Create a list of only official accounts for local governments and the Japan Meteorological Agency during normal times

3. How to identify misinformation

This time, the following things were actually confirmed.

5 points to check

• Date and time of the post: Is it a post from before the earthquake?

• Season and scenery: Do the clothing, weather, and plants match the current season?

• Are there multiple posts with the same text?: If it is a rescue request, check a map to see if the address actually exists.

• Sender: Is that account really a person in that area? Are there any unnatural points in their profile?

• Is it in primary information?: Be skeptical of any 'major facts' that have not been announced by the Japan Meteorological Agency or local governments.

And, most importantly.

If you are not sure, please do not spread it.

False rescue requests spread with good intentions bury real rescue requests. 'Sharing just in case' can be harmful during a disaster.

4. Fraud and malicious business practices that take advantage of the situation

The National Consumer Affairs Center of Japan and the National Police Agency are calling for caution regarding the following three main points.

• Fraud involving fake donations: Public institutions will never ask for money over the phone.

• Home repair scams: Tactics that incite anxiety by saying "it will leak if left as is" to demand high fees.

• Solicitations claiming to use insurance payouts

Principles for response

• If asked for money over the phone, hang up and consult with family or the police.

• Make donations through official accounts published by local governments or the Japanese Red Cross Society (Kumamoto Prefecture has also officially announced donation accounts).

• If you are rushed into a contract, do not make a decision on the spot. The cooling-off period system may be applicable.

• If you are unsure, call the Consumer Hotline 188 or the police consultation phone number #9110

Please do not use QR codes or money transfer links circulating on social media, regardless of the amount.

Additionally, while major platforms have begun accepting donations, if you use them, please make sure to verify that they are officially announced by the operator. Fake sites that look identical can be created.

5. IT at evacuation centers

When using "00000JAPAN"

This is a public wireless LAN made available for free during disasters. By selecting the SSID "00000JAPAN," even users of other carriers can use it without a password.

Because it is designed to prioritize connectivity, communications are not encrypted.

• Avoid online banking, entering credit card numbers, or entering important passwords.

• Limit usage to viewing information or communicating your safety.

• If absolutely necessary, wait until mobile network services are available.

Regarding charging

Power sources at evacuation centers are limited. This is not a technical issue, but a matter of consideration.

• Do not occupy the charger until fully charged; stop once you have enough.

• Prioritize the elderly, those with infants, and those using medical equipment.

• If you have your own mobile battery, charge that instead and vacate the seat.

Initiatives by companies and local governments to provide charging support are also beginning. Please check local information.

Photos and Privacy

Evacuation centers are living spaces.

• Do not post photos on social media that include other people.

• Do not publish photos, especially those of children, without the consent of the individuals or their guardians.

• Even if you want to convey the situation, do so in a way that does not identify individuals.

"Keeping a record" and "making it public" are different things.

Part 3: For those worried from afar

The actions of people outside the disaster area can sometimes increase the burden on those within it. Here are things you can do from an IT perspective.

1. Do not make too many phone calls

It is natural to be worried, but incoming calls consume battery power.

• Communicate via text, and send all information in one message.

• Write in a way that does not require a reply (e.g., "If you are safe, just reading this is enough").

• Designate one person in the family to be the "representative contact" and have that person inform other relatives.

You can also try using disaster message boards or the 171 service to confirm safety. This may allow you to check on them without placing a burden on the person.

2. Do research on their behalf

This is the most practical support that only someone in a remote location can provide.

In disaster-stricken areas, battery power and communication are precious, and there is no luxury to use them for research.

• Look up the location and hours of water supply stations and send only the essential points

• Compile information on open stores, gas stations, and bathing facilities

• Look up how to apply for a disaster victim certificate and the details of support programs

• Check information on passable roads

A short message saying, "I looked it up for you, here are the main points," is the most helpful.

3. Stop before you share

The fact that well-intentioned sharing contributes to the amplification of misinformation has been repeated in past disasters.

• If you see a request for rescue, first verify if the address actually exists

• For shocking videos, first suspect the possibility of AI generation or old footage

• Do not share with the excuse of "I haven't confirmed it, but just in case"

Stopping yourself from sharing may not be a visible contribution. Even so, it is definitely helping someone.

4. Make donations through official channels

Please do so through the official websites of local governments, the Japanese Red Cross Society, or trusted organizations.

Please do not use QR codes or personal bank accounts that appear on social media.

Things I want you to do just once when things have calmed down

I think this earthquake was an event that many people felt was "not someone else's problem."

While that feeling is still fresh, if you do just these three things, it will make a big difference next time.

1. Spend 5 minutes talking to your family about "communication rules"

Where to post, where to meet up, and not to panic even if there is no reply. These three things are enough.

2. Charge your mobile battery

If you already have one, just keeping it fully charged now is enough.

3. Take photos of your driver's license and health insurance card and save them to a protected cloud

Please do this after confirming your device passcode and the two-step verification for your cloud service.

If you aim for perfect preparation, you will end up doing nothing at all. You can do these three things today.

Summary

A smartphone is an extremely powerful tool during a disaster. You can find out about safety, the location of evacuation centers, and water supply information all in one place.

However, what became clear this time is that that strength is conditional.

• Having electricity

• Having active communication networks

• The information being shared is accurate

• And in this case, the device being within an operating temperature range

If even one of these is missing, your smartphone will suddenly become unreliable.

Therefore, IT preparedness is not about "installing convenient apps."

It is about preparing paper, a radio, and a plan on the assumption that your smartphone will not work, and ensuring you can reach reliable information sources while your smartphone is still working.

I hope that the recovery of the affected areas progresses as quickly as possible, and that as few people as possible suffer from health issues during this intense heat.

Related Articles

We have compiled official information on donations and relief funds for the 2026 Kumamoto Earthquake.

This article is for disaster preparedness. You never know when you might be affected by a disaster. This article is organized as a personal guide on "what to prepare" as part of that "preparedness."

Reference Information

Primary Information (Information sources to check first during a disaster)

• Japan Meteorological Agency

• Japan Meteorological Agency: "Regarding the earthquake in the Kumamoto region of Kumamoto Prefecture on July 28, 2026, at approximately 16:27 (2nd Report)" (Naming of the earthquake)

• Japan Meteorological Agency: Regarding the "2026 Kumamoto Earthquake" (3rd Report)

• Prime Minister's Office of Japan: "Regarding the 2026 Kumamoto Earthquake"

• Ministry of Internal Affairs and Communications: "Regarding damage status, etc., related to the 2026 Kumamoto Earthquake"

• Kumamoto Prefecture Official Website

Safety Confirmation and Communication

• NTT East: Disaster Emergency Message Dial (171)

• NTT West: Disaster Emergency Message Dial (171)

• NTT Docomo: Disaster Message Board

• NTT Docomo: "Status of mobile phone services due to the 2026 Kumamoto Earthquake"

• SoftBank: "Status of mobile phone services due to the 2026 Kumamoto Earthquake"

• Wireless LAN Business Promotion Liaison Council: "00000JAPAN"

Caution regarding misinformation and fraud

• Seismological Society of Japan FAQ: 'Is it possible to artificially cause a major earthquake and create damage?'

• Seismological Society of Japan FAQ: 'Earthquake Clouds'

• Japan Fact-check Center

• National Consumer Affairs Center of Japan

• National Police Agency Disaster Information

Commentary and Reporting

• piyolog: 'A summary of misinformation on social media taking advantage of the 2026 Kumamoto Earthquake'

• Keitai Watch: 'Maximum seismic intensity 7 earthquake in Kumamoto Prefecture, disaster message board activated'

• Keitai Watch: 'Docomo, KDDI, and Rakuten affected by Kumamoto intensity 7 earthquake, emergency calls also unavailable'

• ITmedia NEWS: 'Mobile carriers experience communication failures in parts of Kumamoto, "JAPAN Roaming" to other networks begins'

• ITmedia NEWS: 'Emergency Wi-Fi "00000JAPAN" activated in Kumamoto'

• ITmedia NEWS: 'NHK online services become accessible without a reception contract in emergency response to Kumamoto Earthquake'

• ITmedia NEWS: '"X is not useful for gathering information..." Complaints emerge following the Kumamoto Earthquake'

• NHK: "Kumamoto: False information and baseless rumors spreading on social media; please respond calmly"

• NHK: "Kumamoto Earthquake: Fake rescue requests on social media and fake videos created by generative AI; please be cautious"

• Risk Taisaku.com: "2026 Kumamoto Earthquake: Spreading rumors, how to distinguish them? How to engage with social media"

• TKU: "[Lifeline Information] 32,110 households in Kumamoto without power; water outages and murky water spreading"

• Nikkei: "Kumamoto Earthquake death toll reaches 18; life infrastructure damaged, extreme heat forecast for the 30th"

Heatstroke and heat countermeasures

• Ministry of the Environment: Heatstroke Prevention Information Site

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