The maximum S-amplitude, given in mm scale of a recorded earthquake by a standard seismometer at 100 km away from the epicenter, is converted to magnitude (M) by the following relation. About 900-1,000 times more energy.
MG is a British automotive marque registered by the now defunct MG Car Company Limited, a British sports car manufacturer begun in the 1920s as a sales promotion sideline within W R Morris's Oxford city retail sales and service business by the business's manager, Cecil Kimber.
Note:MGB roadsters between 1971 and 1980 have the same top frameand can take the same top !In 1977 MG introduced the zip down center rear windowto improve air flow when the top is up.So an original 77-80 top with a zippered rear windowwill fit fine on a 71 to 76.