Tsunami: the signs, the warnings and what to do
If you are near the coast and feel a strong earthquake, go to high ground now. Do not wait to be told: PHIVOLCS says a local tsunami can reach the shore in two to five minutes.
A tsunami usually starts as an earthquake under the sea, so this page sits beside the earthquake guide: what to do before, during and after. Everything below is PHIVOLCS's, and each section links the document it came from.
What a tsunami is
PHIVOLCS defines it as a series of sea waves, commonly generated by under-the-sea earthquakes, whose heights could be greater than five metres.
How long you have depends on where it starts. A local tsunami, from a nearby earthquake or landslide, can reach the shoreline within two to five minutes. A distant one, from elsewhere in the Pacific, can take one to twenty four hours to reach the coast.
It is a different thing from the sea rising in a typhoon, which PHIVOLCS says people mistake it for. How a storm surge differs from a tsunami has its own page.
Source: PHIVOLCS, Introduction to Tsunami. Read 1 October 2026.
The three natural signs
PHIVOLCS names three things that tell you a tsunami may be coming. Any one of them is enough to leave.
- Sign 1
A felt earthquake
Shaking you can feel while you are near the coast.
- Sign 2
An unusual change in sea level
For example the sea level dropping rapidly and pulling back from the shore.
- Sign 3
A rumbling sound from the sea
PHIVOLCS describes it as the rumbling sound of approaching waves.
Source: PHIVOLCS, Introduction to Tsunami. Read 1 October 2026.
What to do
PHIVOLCS gives four instructions, and all four are about distance and height.
- Do not stay in low-lying coastal areas after a felt earthquake. Move to higher ground immediately.
- If you see unusual sea conditions, like the sea level dropping fast, move towards high ground immediately.
- Never go down to the beach to watch for a tsunami. When you can see the wave, you are too close to escape it.
- Stay off the shoreline when the sea retreats. The exposed seabed draws people out, and that is where the danger is.
Where the high ground is, and how you get there from home, school or work, is worth settling before you need it. The evacuation plan template has a space for exactly that, and the go bag checklist is what you carry when you go.
Source: PHIVOLCS, Introduction to Tsunami. Read 1 October 2026.
What the PHIVOLCS bulletins ask
After a large earthquake PHIVOLCS issues numbered tsunami information bulletins, posted on its tsunami information page. Two levels ask something of people on the coast. The wording below is from two real bulletins, quoted to show what each level says. They are past events, not current warnings.
Tsunami Warning
- Expected wave height
- More than one metre above the normal tides, and possibly higher in enclosed bays and straits
- What it asks
- People in the coastal areas named are strongly advised to evacuate immediately to higher ground or move farther inland.
Source: PHIVOLCS, Tsunami Information No. 3, Tsunami Warning, issued 10 October 2025, 09:53 AM. Read 1 October 2026.
Tsunami Advisory: minor sea-level disturbance
- Expected wave height
- Less than one metre
- What it asks
- Stay away from the beach and do not go to the coast. People in homes on the shoreline move farther inland. Boat owners secure their boats and move away from the waterfront.
Source: PHIVOLCS, Tsunami Information No. 2, Advisory: Minor Sea-Level Disturbance, issued 30 July 2025, 09:22 AM. Read 1 October 2026.
For a local tsunami, do not wait for a bulletin. The shaking is the warning, and PHIVOLCS says the wave can reach the shore within two to five minutes.
Tsunamis that have hit the Philippines
PHIVOLCS names two to make the point that it happens here. On 17 August 1976 a magnitude 8.1 earthquake in the Moro Gulf sent waves as high as nine metres onto the coast, and about 8,000 people were killed or went missing. PHIVOLCS calls it the most disastrous tsunami to hit the country in the last four decades. On 15 November 1994 a magnitude 7.1 earthquake off Mindoro caused a tsunami in which 38 people drowned.
The faults offshore that PHIVOLCS names as the reason the country stays exposed are the Manila Trench, the Cotabato Trench and the Philippine Trench.
Source: PHIVOLCS, "Prepare for tsunami," urges Usec. Solidum. Read 1 October 2026.
The rest of the earthquake guidance
The tsunami is one of the hazards that follow the shaking. The earthquake guide covers the rest: the house, the shaking itself and the hours after.
Read the earthquake guide Duck, cover and hold The West Valley Fault