To intervene on the Hazard means to intervene on the ground motion. Consequently, consolidation techniques that improve soil mechanical properties can help in terms of site effect mitigation, such as slope slides, liquefaction and ground motion amplification phenomena.

On the other hand, earthquakes themselves still cannot be avoided or mitigated, even if some human activities are well known to be able to alter the stresses and strains on the Earth's crust so that a certain seismicity can be induced, and maybe potentially also reduced.

Without decreasing vulnerability, as far as I know, the only way to mitigate the risk is to control the transmission of hazard to the entire structure.

There are tons of techniques to do that. As suggested by Ivan dealing with soil layers is among alternatives. Going up we reach to Arman's comment which,as far as I understood, indirectly referred to base isolation. Go upper through the stories you can use different kinds of dampers and when you reach to the roof, you would find it a good place for putting some vibration absorbers such as TLCD, or TMD.

Many experts consider base isolation and dissipative devices (dampers, absorbers, etc.) as techniques of vulnerability reduction, just like strengthening techniques.

Risk is not only a function of vulnerability. Apart from hazard and vulnerability, risk is also a function of exposure. Thus, reducing exposure also reduces the risk by keeping Hazard and Vulnerabilty the same. Ex: Consider some urban zone where there is already some level of risk. An Urban Plan is considering replacing some old buildings with new ones. Even if the new buildings are less vulnerable, doubling the number of people in that area, the risk may be increasing. Naturally, with fewer people even keeping the vulnerability of the building stock, the risk becomes lower.

Thanks, Francisco. Good point. An effective evacuation plan must be considered an option in many cases.

In the area around the Vesuvio volcano, near Naples, people are encouraged to move away and abandon the most risky zones.

Early warning systems developments will permit mitigate risk without reduce vulnerability, under very restricted conditions: operative efficient system; magnitud and hypocentral distances enough greater to have useful lead times. There are regional and on-site promising methods to mitigate risk in some way reducing exposure. At present ,EWS have been developed and instaled in Japan, Mexico, California, Istanbul, Switzerland (other countries?). They are under development in SW Spain (Alert_Es project). Are all they operative in a practical way?

I think the question is not clearly understand.

reducing hazard can be possible for few hazards like landslides .fires. aaltering or stabilising the slopes. Its big tough task in earthquakes.

However landuse urban plan is the best solution. Pl you can read unfriendly manual for disaster prevention for further reference

User freiendly

UNDRO manual 1978 disaster prevention compendium of current. Knowledge

thank you X. Goula for contributing to the debate introducing EWS techniques. I agree it is an interesting aspect of helping reducing vulnerability and improve seismic protection. I think EWS still have margins to be improved and it is a good research theme.