Hellmuth Sievers: a life dedicated to understanding the ocean and tsunamis

When Hellmuth A. Sievers began working in oceanography in the late 1950s, the discipline was still in its early stages in Chile. There was little equipment, few specialists and much still to be learned about the ocean.

After subsequently training in Physical Oceanography at the Scripps Institution of Oceanography, University of California, San Diego, Sievers developed a long career spanning scientific research, teaching and institutional management. His work ranged from the Humboldt Current System to the southern channels and fjords and the Southern Ocean, while he also contributed to building capacities and institutions that supported the development of marine sciences in Chile.

His story is also closely linked to the development of Chile’s tsunami preparedness capacities. In 1958, he participated in Chile’s incorporation, as the first foreign country, into the warning system established in Hawaii. Years later, in response to the 1960 Valdivia earthquake and tsunami, the Member States of UNESCO’s Intergovernmental Oceanographic Commission (IOC-UNESCO) established the international Pacific tsunami warning system in 1965, which today brings together 46 Member States.

That international cooperation continues to this day. In August 2026, Chile once again hosted the ITP-TEWS, jointly promoted by the International Tsunami Information Center (ITIC), of the United States National Oceanic and Atmospheric Administration (NOAA), and IOC-UNESCO, and co-organized by SHOA. The initiative brought together specialists from the Pacific and the Caribbean to share experiences and strengthen capacities in tsunami monitoring, warning and preparedness.

That same year, on the occasion of the 60th anniversary of the National Tsunami Warning System (SNAM), SHOA recognized Sievers for his scientific contribution, pioneering vision and commitment to the country’s oceanographic development. At 94 years of age, he continues to observe the ocean with a conviction that has accompanied him throughout his career: the more we investigate, the more new questions arise.

How did your interest in the ocean and oceanography begin?

My first real contact with the sea took place during my time at the Naval Academy, on short cruises and later on the Midshipmen training cruise across the Pacific Ocean, which took us to different ports along the west coast of the Americas as far as Canada, as well as Easter Island and the Galápagos Islands.

My interest in a scientific career, specifically in Physical Oceanography, arose rather by chance. It was related to the organization and implementation of scientific research for the International Geophysical Year of 1957–1958.

At what is now the Hydrographic and Oceanographic Service of the Chilean Navy, someone was needed to take responsibility for oceanographic activities and lead the planned work. I was offered the position and accepted it, even though at the time I had no specialized studies beyond what I had learned at the Naval Academy.

How do you remember those early years of oceanography in Chile?

At that time, very little was known about oceanography, particularly its physical aspects. This lack of knowledge created some initial difficulties, both at institutional and university level and among the general public.

To carry out the first studies, we had to improvise, bringing together the limited equipment available in the country and training, as we went along, the personnel who had to take measurements and collect samples.

The first research expeditions were the AGRIMAR cruises in 1959 and MARCHILE I in 1960. The work carried out between Coquimbo and Chiloé produced the first descriptions of the physical, chemical and biological oceanography of that region and also helped train researchers and technical staff for subsequent studies.

After so many years studying the ocean, has your way of understanding it changed?

Our understanding of the ocean develops step by step through research. New phenomena and processes are constantly being discovered, many of them thanks to satellite observations and the development of new measuring and recording instruments.

A good example is the Humboldt Current System. Based on measurements taken from ships, we understood it as a general south-to-north circulation running parallel to the coast. Satellites, however, allow us to observe large areas almost instantaneously and have shown that the current is much more dynamic, made up of small and large eddies and meanders, even though its overall direction remains northward.

After so many years studying tsunamis, what is something the public often does not know about them?

There is widespread confusion about the difference between storm surges, tsunamis and tides, both among the public and, unfortunately, in some media outlets as well.

A storm surge is caused by the action of the wind. Tides are produced by the gravitational pull of the Moon and the Sun. Tsunamis, by contrast, are waves with periods measured in minutes and wavelengths measured in kilometres.

In addition, when people hear the word tsunami or seaquake, they often immediately imagine large waves similar to breakers crashing onto the shore. These can occur and can be extremely destructive, but tsunamis often take the form of rapidly advancing floods involving enormous volumes of water that sweep away everything in their path.

What has changed in Chile between the 1960 tsunami and today?

Although the 1960 tsunami was a terrible experience, the passage of time and a long period of calm gradually eroded its memory among the population, even in coastal areas. There was no real “tsunami culture” in Chile.

The major change at national level came after the earthquake and tsunami of February 2010. The extensive coverage of what happened generated a much greater understanding of these phenomena and their consequences.

Since then, important changes have taken place. SHOA has produced inundation maps for numerous coastal cities; evacuation routes have been signposted; drills are held; sirens have been installed; and new ways of transmitting warnings through communication networks are available. Today, knowledge is much more widespread and the population remains more alert, at least in coastal areas.

What is the difference between receiving a tsunami warning and actually being prepared to respond?

Science is still unable to predict earthquakes or determine their intensity in advance. Where it can make a contribution is in studying the geographical and geomorphological conditions of the seabed and coastal areas, and in developing models that take different scenarios into account: the origin and intensity of the event, wave propagation, speed, tide height and weather conditions, among other factors.

But being prepared also requires that this knowledge reach the population. Perhaps one of the most important measures is to carry out evacuation drills periodically, with broad public information and careful planning. Clear signage for evacuation routes and safe areas is also needed.

When an earthquake occurs, whether local or distant, the population must receive information about the possible risk of a tsunami. If this is confirmed, the warning must be disseminated through all available channels: sirens, social media, radio, television, police and fire services.

This vision is aligned with the early warning systems approach promoted by IOC-UNESCO, which integrates monitoring and warning with public information, community preparedness and response capacity.

After a lifetime studying the ocean, what question would you still like to be able to answer?

There are many questions. But one that particularly interests me concerns El Niño and La Niña.

The causes that trigger these ocean warming and cooling processes, particularly in the central and eastern Pacific, are still not fully understood. Several factors are likely involved, beginning with ocean-atmosphere interaction, both governed by a complex circulation pattern.

Thanks to the many instruments that constantly record temperatures in the upper layer of the ocean, we can forecast their occurrence. However, we still need to understand what causes them.

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