Final answer:
The earthquake activity on the east coast of North America is relatively low due to it being a passive margin. To assess whether regions like Australia are tectonically active, one would examine topography, volcanic activity, and earthquake data. Subsurface areas can result from processes like subsidence or past tectonic activity.
Step-by-step explanation:
Understanding Earthquake Activity along Passive Margins and Geologic Activity Evidence
When examining the earthquake activity along the east coast of North America, it can be characterized as relatively low, especially compared to active plate boundaries like the Pacific Ring of Fire or subduction zones such as the Nazca Plate beneath the South American Plate. As a passive margin, the east coast of North America does not experience the intense tectonic forces that create frequent and large-magnitude earthquake events typical of active plate boundaries.
To determine if a region like Australia is tectonically active today, one would look at the topography for signs of recent uplift, volcanic activity, or the presence of earthquake data indicating ongoing movement. The Australian topography, coupled with geologic history and present-day seismic data, would provide clues as to whether it is currently tectonically active.
Areas that are below sea level on continents can occur due to various processes, including subsidence, the presence of ancient tectonic activity that has since ceased, or due to the prolonged action of erosion and sediment deposition. A hypothesis to explain these areas could involve any of these processes or a combination thereof.
Finally, to identify whether an area like Morocco was tectonically active in the past, a geologist would look for signs like folded or faulted strata, the presence of ancient volcanic rocks, and orogenic formations indicating past collisional events.