If an Earthquake registered high on the Richter scale and low on the Mercalli scale, then it occurred most likely in which type of location?

The Earthquake most likely occurred in a location where the seismic wave or the energy released causing the earthquake to happen and the magnitude of the earthquake is high but the observed effects of the earthquake and its intensity is low.

Explanation:

In order to get a good understanding of the answer above we have to get familiar with some terms and concepts. The first term we would consider is the magnitude of an Earthquake, according to Earthquake Glossary,

The magnitude of an earthquake is a number that characterizes the relative size of an earthquake. Magnitude is based on measurement of the maximum motion of an earthquake seismic waves (waves produced by an earthquake that travels through the Earth's layers) recorded by a seismograph.

We also need to understand the term Intensity of an Earthquake which is the number (written as a Roman numeral) describing the severity of an earthquake in terms of its effects on the earth's surface and on humans and their structures.

Finally we have to understand that, the Mercalli scale bases its measurement on the observed effects of the earthquake and describes its intensity. It is a linear measurement. On the other hand, the Richter scale measures the seismic waves, or the energy released, causing the earthquake and describes the quake's magnitude. It is a logarithmic. For example, a magnitude 4 earthquake is 10 times as tense as a magnitude 3 earthquake. The calculation for the Mercalli scale is quantified from the observation of the earthquake's effect on the earth's surface. It is also based on the effect on humans, objects, and man-made structures.