Please contact the PWD Bureau of Engineering and Construction, Right of Way Maintenance 238-3651. If this damage was done by official city street tree its up to PWD to repair the sidewalk. The repair must be done in concrete not asphalt per PWD own rules. If this is not a city tree it is up to the fronting property owner to maintain and repair the sidewalk. (Section 5610 of the Calif State Streets and Highway Code and Section 1204 of the Oakland Municipal Code).