Panagea theme shows full size image for posts.
If you want to crop it, please do following.
Please find following code in /functions.php file.
add_image_size( 'panagea-slider-thumb', 280, 140, true );
And add following code under it.
add_image_size( 'panagea-post-thumb', 280, 140, true );
btw, 280 and 140 are image size, so you should change them.
for example add_image_size( 'panagea-post-thumb', 500, 400, true );
And edit /templates/loop-blog.php file.
You can find following code.
<?php the_post_thumbnail( 'full' ); ?>
replace it to following
<?php the_post_thumbnail( 'panagea-post-thumb' ); ?>
After that, please install Regenerate Thumbnails plugin and regenerate all the image thumbnails.