Whenever a violation of § 150.60 is discovered upon reinspection and the violation presents an immediate danger of injury to the occupants of the premises or to an adjoining property or persons or to the public and the cost of alleviating the violation is not reasonably related to the value of the building, a notice of intent to order the demolition of the building shall be served on the owner by the building inspector, by certified mail, to the post office address of the owner as the same is shown on the city tax rolls; or, if his address is unknown and cannot by the exercise of reasonable diligence be ascertained, then notice shall be by publication for not less than two (2) times within ten (10) consecutive days in the official newspaper of the city. Such notice shall state a time for the public hearing to be had before the City Council for a determination of whether or not violation exists. If such a violation is found to exist and if the violation is not eliminated within thirty (30) days from the date of said hearing, the city may demolish and remove said building or cause the same to be done and charge the expenses incurred in doing such work or having the same done to the owner of said land. If such work is done at the expense of the city, then the said expense shall be assessed against any salvage resulting from the demolition of the building and against the lot, tract, or parcel of land, or the premises upon which such expense was incurred. For the purposes of this section, any repair, alteration, or improvement which is determined by the building inspector to cost more than fifty percent (50%) of the gross assessed valuation of the building, exclusive of land value, shall be deemed not to be reasonably related to the value of the building. The city may elect to obtain a judicial determination by a decree of a court of competent jurisdiction of the existence, in fact, of a public nuisance. Such judicial determination may include any available remedy for the abatement of such a nuisance. In the event the municipality elects to obtain abatement of the nuisance through judicial decree, it shall be unnecessary to serve the owner with a notice to demolish.